TRACE ELEMENT HYDROGEOCHEMISTRY OF SADO AREA, NORTHWESTERN NIGERIA.
Daspan, R.I, Dibal, H.U., Yakubu,J.A and Lar, U.A Department of Geology and Mining, University of Jos,
ABSTRACT A trace element study of the surface and groundwaters of Sado area in Northwestern Nigeria has been carried out. Values obtained from the determination of heavy metals in the different water sources have been interpreted with a view to identifying the factors controlling partitioning of metal contaminants as well as the possible health effects of high concentrations of some of these elements on the inhabitants. Different sample media such as well-water, stream-water, and borehole - water and dam - water were analyzed. Results show that both surface and groundwater in the study area have V, Cr, Ni, Pb and Fe concentrations above the WHO admissible levels, while the concentration of Mo in all waters is below the WHO admissible level. The mean concentration of V, Cr, As and Zn is more in the borehole water as compared to well and stream waters. This could be because of the deeper level of penetration of the borehole hence intercepting the bedrock. The concentrations of Fe, Co, Ni and Cu are higher in stream water as compared to the wells and borehole waters. The high concentrations of V, Cr, Ni, Fe and Pb in the waters could be as a result of the already high concentrations of these elements in the underlying mafic/ultramafic rocks in the area. The abnormal concentration of Cr, Ni, and Pb in the waters may introduce toxicity in humans and animals and could result in their accumulation in vital organs such as kidney, lungs, heart, gonads and skin, thereby, causing their malfunction. KEYWORDS: Trace elements, hydrogeochemistry, WHO admissible, limit,mafic,ultramafic toxic.
INTRODUCTION The study area, Sado, forms part of the Anka Schist belt in the basement complex of Northwestern Nigeria. The area is located between latitude 60 9’ 25” E and 60 13’ 30”E and longitude 120 24’38”N and 12028’5”N. (Figure 1). The study area is notable for its mineral endowment especially gold and chromite amongst others. As a result of the association of the area with gold mineralization, the geology of the area is relatively well understood. However, the trace element hydrogeochemistry of the area is only now receiving attention with this paper presenting a pioneer result of the trace element concentration of the water sources. GEOLOGY AND HYDROGEOLOGY Sado area falls within the Anka Schist belt of the basement complex of Northwestern Nigeria (Figure 1). The area has been of interest primarily because of the discovery of gold mineralisation and also because of its relatively good rock exposures and its importance in the geological evolution of the Precambrian Basement Complex of Nigeria. Pioneer workers on the geology of the Northwestern Nigeria basement complex include Falconer, 1911; Russ, 1934 and 1975; Farghar,1961;Truswell, 1962;Turner,1964; McCurry, 1976,1978; McCurry and Wright,1977; Ajibade, 1976; Ogezi, 1977; Holt, 1982 and Turner, 1983;Bungwon,1983;Shibayan,1985; Woakes et al,1976. The area (Sado) is underlain by metasedimentary rocks which comprise of phyllites, schist, quartzite, amphibolites and gneiss of Paleoproterozoic age. Intrusive into these rocks are mafic/ultramafic rocks mainly gabbros and serpentinites that host chromium and gold mineralization. The groundwater situation is typical of the Nigerian Basement Complex (Offodile, 1976). Of hydrogeological interest is the metasediments which traverses the Basement. The formation is fractured in
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Daspan, R.I et al:Continental J. Applied Sciences 4: 1 - 7, 2009 most places and sometimes deeply weathered below the ground. Boreholes and hand dug wells drilled in the area, confirm that the most favourable groundwater is the fractured and weathered areas. Thickness of
weathered basement is in the range of 20 – 35 m and the fractured area is between 35 – 45 m (Offodile, 1976). Yeild of boreholes drilled in the area is about 0.8 l/s MATERIALS AND METHODS Sample collection Fifteen (15) water samples were collected from the study area as shown in Table 1,Figure 1. The water samples include nine (9) well water, three (3) streams, one (1) dam and one (1) borehole (Figure 1). The water samples were collected in a one litre capacity plastic bottle. Before sampling, the sample bottles were soaked overnight in de-ionised water. In the field, each bottle was rinsed with the water to be sampled three times before it was collected. Clean plastic containers were used to sample water from the wells. Samples collected were labelled according to location, nature of sample and date of collection. Sample Preparation and Analysis A 0.4µm Millipore filter paper was used to filter all water samples so as to free them of suspended particles. Bottles containing the samples were sealed and kept in a refrigerator at a temperature of 40C for two weeks before analysis. The pH of all the water samples was measured in the field with an Oakton conductivity/pH/ temperature probe. The water samples collected (well, stream, borehole and dam water) were acidified with HNO3 so as to prevent absorption and precipitation of the trace components in solution. . Analytical Technique The major and trace elements were analyzed using Energy Dispersive X-Ray Fluorescence Spectrometer (EDXRF) at the Center for Energy Research and Training (CERT), Ahmadu Bello University, Zaria. This technique has numerous advantages amongst which are its multi - element detection capacity both in water and rocks, very low detection limit (ppb) and its rapidity. Trace elements analyzed are (Ti,Fe,Mn,V,Cr,Co,Ni,Cu,Zn,As,Pb,Br,Sr,Sn, Vb, Y, Nb, Mo, Zr, S and Se). The instrument has a detection limit as low as parts per billion (ppb) with precision and an accuracy in the order of 2%. RESULTS The results of the trace element concentrations of the water samples analyzed are presented in Table 1.The average for the different sample media were compared with the World Health Organization (WHO) admissible values (Table 2) to ascertain the their
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Daspan, R.I et al:Continental J. Applied Sciences 4: 1 - 7, 2009 Table 1: TRACE ELEMENT (PPM) CONCENTRATIONS OF SURFACE AND GROUNDWATERS.
Daspan, R.I et al:Continental J. Applied Sciences 4: 1 - 7, 2009 Table 2.Comparism of mean concentration (in ppm) of trace elements of stream,well,borehole waters with admissible values (2000).
Samples V Cr Mn Fe Co Ni Cu Zn As Se Pb Br Rb Sr Zr Mo
Daspan, R.I et al:Continental J. Applied Sciences 4: 1 - 7, 2009 quality. The results are also discussed with respect to the solubility of the elements based on their ionization potentials are discussed below.
1. Soluble cations (IP <3) Rb, Sr, Fe, Mn). Rb and Sr are much more enhanced in the dam water (0.04 and 0.04 ppm). Sr is more enhanced in the surface water. The concentration of Rb in the well and borehole water (0.038 and 0.035 are relatively more than that of the stream water (0.031ppm). Though the high concentration could be attributed to interaction in the surficial environment, part of it comes presumably from underground. Fe and Mn are enhanced in the surface water bodies (0.33 and 0.28ppm respectively, in the stream water). The concentration of Mn in the dam follows next with 0.27. Both Fe and Mn, give concentrations that are above WHO admissible limits of 0.05ppm for Mn and 0.3ppm for Fe. 2. Moderately soluble cations (IP= 3 to 10) (V, Cr, Co, Ni, Cu, Zn, Rb, As, Se, Mo, Zr).Co and Ni are enhanced in the stream water (0.25 and 0.16mm) closely followed by the concentration in the borehole water (Co= 0.158ppm). V on the other hand is enhanced in the dam water (0.56ppm) and closely followed by borehole water (0.51ppm). Like these other elements mentioned above Cu, As and Se are relatively enhanced in the surface water (stream water/dam (0.128, 0.11 and 0.06 ppm respectively). Zn on the other hand presents relatively higher content in the borehole water (0.92ppm). But like Cu, their concentration is below WHO admissible limits of 2ppm for Cu and 3ppm for Zn. The concentration of As in all the water media exceeds the WHO admissible limit of 0.01ppm. Likewise the Se content in all the water bodies exceeds WHO values (0.05ppm). A similar scenario is obtained for Pb where its concentration is enhanced in the dam water (0.15ppm) closely followed by that in the well water (0.13ppm).These values are slightly above WHO limits. Br is enhanced in the borehole water (0.42) and much less in surface waters (0.04ppm). Both Zr and Mo are enhanced in the stream water (0.3 and 0.03ppm respectively). However, the concentrations of these elements in the borehole follow closely. DISCUSSION The geology of sado area is characterized by two main rock types namely the metasedimentary rocks, which are basically crustal rocks and form the basement into which mafic/ultramafic rocks (serpentinite and gabbros) intruded. These serpentinites are sources of important Cr and Au mineralisation in the area, thus the level of the concentration of these elements analysed in all the water bodies in the area would depend on the geochemical compositions of these ultramafic/mafic rocks and the host metasedimentary rocks in the area. The geochemistry of the serpentinites supposedly derived from the mantle is distinct from that of host crustal rocks. The serpentinites are composed essentially of ferromagnesian minerals and are
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Daspan, R.I et al: Continental J. Applied Sciences 4: 1 - 7, 2009 therefore enriched in V, Cr, Fe, Mn, Ni, Co, Mg whereas the crustal rocks ordinarily are expected to be enriched in incompatible elements such as Ti, Nb, Zr, Rb, ,Pb, the REE and the alkaline elements. The soluble cations are those elements with large ionic potential (IP) < 3. It is expected therefore that those elements will be carried away in solution. Our results show that except for Rb, all these elements are enhanced in the surface water bodies especially the stream water indicating that elements must have been leached from the surrounding crustal rocks. A contribution from the underground cannot be ruled out since the concentration of these elements in the underground water bodies (borehole) follow closely. All waters in the study area display a very similar distribution pattern of transition elements (Table 1, Figures 2). Similarly the concentration of moderately soluble cations with IP= 3 to 10 follow the same pattern as the soluble cations above. Except for Zn and Br which are relatively enhanced in borehole water, all other elements are relatively enhanced in the surface water (stream water and/or dam). These observations underline the fact that the main sources from which all the elements are released are mainly surficial rock bodies, as opposed to underground rock bodies. The concentration of Rb, Sr, Zr, Pb, As, Se must have been influenced by the composition of crustal rocks since they are abundant in these rocks. Fe, Mn, V, Cr, Co, Ni, Cu, Zn were leached away from serpentinite bodies mainly by the action of torrential flows. Little contribution of these elements came from the non-exposed basement rocks as indicated by values from boreholes and well waters. Of all the elements analysed, Fe, Mn, Ni, Cr, As, Se and Pb are very toxic (WHO, 2002) and all present concentrations in all water bodies (Table 2) above WHO admissible limits. This implies that whatever is the source of water in Sado area, such water is unsafe for drinking purposes. Their cumulative ingestion over time by humans could lead to serious health hazards such as long ingestion of Pb in waters can lead to Pb accumulation in tissues and other vital organs of human. It can also affect the nervous system, causing peripheral neuropathy (WHO 2002). Excess Pb concentration has also been known to cause encephalopathy in humans and also retards learning ability of children (WHO 2002). Although the concentration of Pb is high, studies have not been carried out in the study area to establish these negative effects on the inhabitants. The high concentration of Ni above the W.H.O standard poses a potential threat to human health. It is known to cause disease that affects nasal cavities, lungs and skin (WHO 2002). CONCLUSIONS From the results of this study, the following conclusions can be drawn: i. In all the water samples analyzed, Cr, Ni, Pb, As, Se show high concentrations above the WHO admissible
limit. The high concentration of these elements in the analyzed water samples could have been as a result of the already high concentration of these elements in the underlying rocks as the area studied is underlain to a great extent by mafic-ultramafic rocks.
ii. The abnormal concentration of Cr, Ni, and Pb in the waters introduce toxicity in humans and animals. Though this was not investigated, the ingestion of these trace elements could result in their accumulation in vital organs such as kidney, lungs, heart, gonads and skin causing their malfunction in humans. For example, Cr could have negative health effect on humans e.g. gastrointestinal disorder and
convulsion. Other negative health effects of Cr include cardiovascular shock (WHO, 1996).
ACKNOWLEDGEMENT We hereby wish to acknowledge the assistance of Fatoye Badejoko for sample collection, Centre for Energy Research and Training, Zaria for sample analysis and Mr. Anthony Kahuwai for the drawings. The reviewers are acknowledged for improving the quality of the original paper
REFERENCES Bungwon, A. D. (1983): The geology and preliminary soil geochemical investigation of possible gold Bearing features in the Tserita-Tungan Kudaku area near Anka, Sokoto State unpublished M.Sc Thesis, Ahmadu Bello University, Zaria, Nigeria. Falconer, J. D. (1911). The Geology and geography of Northern Nigeria. MacMillan, London. Farghar, M. N. (1961). The Precambrain geology of the 1:100,000 sheet no. 52 (Anka), Sokoto province Geol. Surv. Nigeria, Rept. No. 1324.
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Daspan, R.I et al:Continental J. Applied Sciences 4: 1 - 7, 2009 Holt, R. W. (1982). The Geotectonic evolution of the Anka Belt in the Precambrain basement complex of N. W. Nigeria. Unpublished Ph.D Thesis; The open University. McCurry P. and Wright, J.B. (1977). Geochemistry of calc- alkaline volcanics in northwestern Nigeria, and a possible Pan-African suture zone. Earth Planetary Science Letter 37, 90-96. McCurry, P. (1976). The geology of the Precambrian to Lower Palaeozoic rocks of northern Nigeria- a review, in: Kogbe, C.A(ED), Geology of Nigeria. Elizabethan Publication Company Lagos. McCurry, P. (1978). Geology of degree sheets 10(Zuru), 20(Chafe) and part of a (Katsina) Nigeria,overseas Geol. Min. REs, 53, London 53, 9pp. Ogezi, A. E.(1977). Geochemistry and geochronology of basement rocks from northwestern Nigeria. Ph.D dissertation, University of Leeds. Russ, W. (1934). Review of the Nigeria gold field Geol. Surv. Nigeria, Ann. Rept. Russ, W. (1957). The geology of parts of Niger, Zaria and Sokoto province with special reference to the occurrence of gold. Shibayan, Y (1985). Investigation of possible chromite bearing serpentinite and associated rocks of NW Nigeria. Unpublished M.Sc Thesis, Ahmadu Bello University, Zaria, Nigeria.
Truswell, J.F(1962). Report on the geology of the crystalline basement of 1:100,000 sheet 53(Maru) and
part of 1:100,000 sheet 31(Talata Mafara). Geol. Surv. Nigeria, Rept. No. 1319. Turner, D.C. (1964). Notes on field work on the basement rock of sheets 7 and 8. Geol. Surv. Nigeria. Report No: 5503. Turner, D.C; (1983). Upper Proterozoic schist belts in the Nigerian sector of the Pan-African province of West Africa. Precambrian Research 21, 55-59. W.H.O (2002) Guidelines for drinking water Quality, 2nd edition volume 2, Health criteria and other Supporting information modified 22nd may by W.H.O regional office for South Asia. 2nd edition Geneva Woakes, M., Rahaman, M. A. and Ajibade, A. C. (1976). Some metallogenic features of the Nigerian Basement. In: Geology of Nigeria (Edited by Kogbe, C. A). pp 111-121. Elizabethan, Lagos Received for Publication: 23/09/08 Accepted for Publication: 10/04/09 Corresponding Author R.I. Daspan. Department of Geology and Mining, University of Jos.
MONITORING OF SEWAGE QUALITY FOR SMALL – SCALE IRRIGATION: CASE STUDIES IN
SOME FADAMA LANDS IN ZARIA CITY, NIGERIA
A. Haruna, A.Uzairu, G.F.S Harrison Department of Chemistry, Ahmadu Bello University, Zaria, Nigeria
Abstract: The gradual decline in availability of fresh water to be used for irrigation in northern Nigeria has led to the need of wastewater reuse. As a consequence, the use of sewage and other industrial effluents for irrigating agricultural lands is on the rise particularly during dry seasons. Besides, reuse of sewage as irrigation water has for long been identified by dry season farmers as one of the best options to reduce the stress on limited fresh water available today and to meet the nutrient requirement of crops. However, the use of sewage could change the physicochemical status of soil and hence may cause phyto-toxicity. For this reason, sewage quality should be identified. Hence, case studies were undertaken to assess the quality of sewage used for irrigation in the flood plains (Fadama lands) along Kubanni River basin in Zaria City, Nigeria. The sewage physicochemical characteristics were investigated in a 3-month monitoring programme (i.e. February to April, 08, which was the topical period of dry season and time of intensive usage of sewage for irrigation). The assessment of sewage quality was performed on the basis of pH, temperature, conductivity, alkalinity, total hardness, total suspended solids, total dissolve solids, chloride, sulphate, phosphate, nitrate and ammonia. The quantitative determination of trace metals i.e. Pb, Cd, Cu, Ni and Zn was also carried out. Levels of chloride, nitrate and sulphate were higher than the maximum permissible limits for irrigation water set by Food and Agriculture Organisation (FAO). Similarly, the levels of Cd, Cu, Pb and Ni (in some few cases) were also beyond the recommended maximum permissible limits set by FAO. Therefore, this suggested that the sewage samples can be classified as polluted and thus unsuitable for irrigation of vegetable crops. Thus, the sewage around the Kubanni River basin was highly polluted.
Keywords: Sewage water quality, suitability for irrigation, trace metals.
INTRODUCTION Agricultural irrigation has contributed tremendously to rapid economic growth in northern igeria, and demand for its product has continued to increase with in creasing population growth. This has resulted in more irrigation enterprises, one of which is vegetable production at fadama lands along river banks or/and other water ways in northern states of Nigeria using wastewater for irrigation during dry seasons. Although irrigation is useful for sustaining/increasing agricultural production it is imperative that good quality water be used (Singh, 2000). Regardless of its sources, soluble salts are always dissolved in irrigation water which could affect the physical and chemical properties of soils (London, 1991). In addition, since the sewage water is heavily polluted with faecal matter and trace metals there are some risks attributed to its use. The application of sewage water for irrigation can contaminate agricultural products externally or internally with coli form bacteria and other pollutants, putting not only the farmers but also the consumers at risk when the produce is externally or in tern ally with coli form bacteria and other pollutants putting not only the4 formers but also the consumers at risk when the produce is eaten raw (Furedy and Chowdhury, 1996). By now, there is lot of literature outlining benefits and risks of using sewage. Sewage can be advantageous due its combined function of irrigation and fertilizing farms at the same time, it can cause soil sickness such
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Haruna A et al: Continental J. Applied Sciences 4: 8 - 17, 2009 as salinity and sodicity hazards (Furedy and Chowdhaury, 1996). Therefore, in order to highlight the deficiencies and implication of usage of sewage water from Kubanni River basin (which is mainly sewage-bearing River during dry seasons), well designed detail data are required on water quality; so that policy makers and farmers would know what quality water they can use. As the wastewater available for irrigation, often does not meet national standard or international guidelines for wastewater reuse, this pose a challenge to the safe development of agricultural irrigation (Blumenthal at al., 2004). As a result, this study was initiated to assess the quality and suitability of sewage as irrigation water, as suitability of sewage for reuse as irrigation water is influenced by the chemical composition and mineral pickup of sewage (Lewcock, 1995). Fig. 1: Study area along Kubanni River Basin. MATERIALS AND METHODS Description of Study Area Zaria, Nigeria is situated on a plateau at a height of about 570.56m above the sea level in the center of northern Nigeria, and more than 644km away from the sea. Zaria is located within latitudes 11031N and longitudes 70401E. The study area is the Kubanni River basin which is located within this region forms part of the River Galma (Fig. 1). Kubanni drainage basin is one of the drainage basins that drain southern Zaria. The Ahmadu Bello University, Zaria, the Institute for Agricultural Research and the Nigerian College of Aviation Technology, Zaria, are located on the northern side of the Kubanni River basin which flows to form a natural frontier between Tudun-wada on one hand and Sabon-Gari on the other. It also flows through the back of the Nigeria Military School, the Nigeria Army Depot and the Advanced Teachers’ College, before emptying into the River Galma. Kubanni is relatively a seasonal river with intermittent flows occurring in flashes mainly during rainy seasons (Eigbefo, 1978). Thus, Kubanni is a sewage-bearing river during dry seasons.
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Haruna A et al: Continental J. Applied Sciences 4: 8 - 17, 2009 Samplings Sites and Sample Collection Ten points were demarcated in Kubanni River and the localization of the points is shown in Fig. 1. The sewage water samples were collected based on their proximity to where sewage waters are being pumped onto the farm lands. Therefore, a total of ten sewage water samples were collected (SW1,SW2,SW3,SW4,SW5,SW6,SW7,SW8,SW9,SW10).
TABLE 1: The physicochemical characteristics of sewage (sw) for the month of Feb, 08
Sampling was according to the procedure recommended by America Public Health Association (APHA, 1992). Sample containers were thoroughly washed with detergent, rinsed with water and then with distilled water before soaking in 10% HNO3 for 24h. Containers were finally rinsed with distilled water before being used for sampling. About 2.5 litres of sewage water sample from each point was collected in a plastic can and were kept cooled en route to the laboratory and kept refrigerated at 4oC until chemical analysis was carried out.
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Haruna A et al: Continental J. Applied Sciences 4: 8 - 17, 2009 Physicochemical Analysis The pH, temperature and electrical conductivity of sewage water samples were determined directly on site with pH/temperature/conductivity meter (Hanna brand). Total dissolve solids and total suspended solids were determined by the evaporation-drying method. The chemical analyses performed include total hardness, alkalinity and chlorides using titration method, phosphate, nitrate and ammonia contents using colorimetric method and sulphate by photometric method (APHA, 1992). TABLE 3: The physicochemical characteristics of sewage (sw) for the month of April, 08
TABLE 4: *Mean % recoveries (+SD) of trace metal standard added to sewage water sample
Metals Spiked Concentration (mg/l) Recoveries (%)
Zn 0.5 91.7 + 0.4
Ni 0.5 93.2 + 03
Cu 0.5 87.1 + 02
Pb 0.5 95.7 + 0.5
Cd 0.5 88.6 + 0.4
*Values are mean of triplicate analyses, SD = standard deviation.
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Haruna A et al: Continental J. Applied Sciences 4: 8 - 17, 2009
Trace Metal Analysis. Open beaker digestion protocols were employed for the trace metal analysis of sewage water samples. The trace metal concentrations were determined by digesting the sewage water samples with concentrated HNO3 as described by APHA (1992) and then analysed by atomic absorption spectroscopy (AAS). Triplicate digestion and analyses of the samples together with blank were carried out.
Quality Assurance The quality assurance for sewage water samples was also conducted through spiking method, evaluating a sample digestion process and the effectiveness of AAS machine. A chemical analysis protocol through Multi-element standard (MESS) was applied as follows: 100ml of pre – digested sewage water sample was measured into a 250ml beaker and spiked with 10ml of multi-element standard solution at level of 0.5mg/l Cd, Pb, Cu, Ni and Zn. 5ml of concentrated HNO3 was added and the solution was boiled slowly and evaporated on a hot plate to about 20ml (digested completed). The beaker wall was washed with distilled water and the solution was then transferred into a 50ml standard flask and made up to volume with distilled water, which was then analysed using atomic absorption spectroscopy (AAS). Triplicate digestion and analyses of the samples together with blank were carried out. The concentrations of metals in spiked and unspiked samples were used to calculate the percentage recovery in order to validate the method as follows:
% recovery of metal = concentration of metal in spiked sample (determined)/ concentration of metal in spiked sample (calculated)
RESULTS AND DISCUSSION. Table 1, 2, 3 report the temperature, pH, electrical conductivity, alkalinity, total hardness, total suspended solids, total dissolved solids, chloride, sulphate, phosphate, nitrate and ammonia results obtained in the analysis of the sewage water samples for the month of February, March and April, 2008, respectively. The temperature during the sampling was found to vary from 18.40C to 31.80C. It was observed that the temperature of the water samples had the highest value of 31.80C and lowest value of 18.40C in the month of April and February, 2008, respectively. This was as a result of seasonal variation from cool/ harmattan to extremely hot season. Temperature is basically important for its influence on other properties of sewage, for instance, is known to influence the pH of water. The pH of the water sample varied sharply in the months of study. The pH ranged from 7.39-7.93, 8.02-8.38, and 8.14-8.49 for the month of February, March and April, respectively. Thus, the pH of the water samples tended to be higher in April. A similar result of 8.92-10.34 was also reported by Akan et al. (2008) in similar work. In general, the water samples tended to be alkaline with pH value fell within the range of 7.39-8.49, which were within the normal range with the exception of 8.49 in sampling point SW9 (Table 3) in irrigation water (Ayers and Westcot, 1985; London, 1991) as 6.5-8.4. Therefore, the pH values of the water samples were normal and thus the water could not cause nutrients imbalance, as it was reported that abnormal pH in irrigation water may cause nutrient imbalance and such waters may contain a toxic ion (Ayers and Westcot, 1985). The alkaline nature of the water samples might be due to ammonia intrusion, as it was established that domestic sewages are usually alkaline in nature due to the of presence of ammoniacal compounds (Khaiwal et al., 2000). As shown in Table 1, 2, and 3, electrical conductivity (EC) and total dissolved solids (TDS) values varied widely. However, the salinity levels were generally high (EC 1090-1483, 1357-1924, 1675-2030 µS/cm and TDS 533-752, 648-986, 849- 1031 mg/l) for the months of February, March and April, respectively. The values of EC and TDS were again found to be more in the month of April, which might be attributed to greater solubility of ions at higher temperature. The values of EC and TDS indicated that the sewage waters were fit in their use for irrigation which might not affect the soil infiltration rate. This is owing to the fact that very low salinity water (<200 µS/cm) almost invariably results in water infiltration problems (Ayers and Westcot, 1985). However, higher values of EC and TDS of range between 1021-1534µS/cm and 2210-2655 mg/l were also reported (Akan et al., 2008). Regarding the values of total suspended solids (TSS), the water samples showed much presence of contaminants, as the values ranged from 124-167mg/l throughout the months of study. Conversely, TSS value is usually taken as an index of contamination potential of water (Ahmed, 2005). The TSS values (1131-2673 mg/l) reported by Akan et al. (2008) were much higher than the values obtained in this work. Literature classified wastewater TSS as follows: TSS less than 100 mg/l as
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Haruna A et al: Continental J. Applied Sciences 4: 8 - 17, 2009 weak, TSS greater than 100 mg/l but less than 220 mg/l as medium and TSS greater than 220 mg/l as strong wastewater. Results of the study area indicated that sewage water from the Kubanni River basin could be classified as medium wastewater.
The total hardness of the water ranged from 285.12 - 320.03, 318.73 -358.03 and 335.18 - 382.15mg/l for the month of February, March and April, respectively. The result indicated that the water samples of the area of study could be classified as very hard since water with hardness of 201-500 is very hard water (Sawyer and MacCarty, 1967). Hardness of 300 mg/ l is however, permissible for domestic use, but for irrigation, an upper limit of 150mg/l is usually recommended (Khaiwal et al., 2000). Thus, the hardness of water samples was relatively high showing their unsuitability for irrigation. Alkalinity values of the waters were more in April (122-168 mg/l), followed by the values in March (112-162 mg/l) and less in February (94-158 mg/l). Alkalinity serves as pH reservoir for inorganic carbon. It is usually taken as an index productive potential of water (Manahan, 1994). The high values of alkalinity during the months of studies revealed that the waters had ability to support alga growth and thus, the sewage was not suitable for irrigation. The anionic concentration of water samples are still presented in Table 1, 2 and 3 for months of February, March and April, respectively. Excess of Cl- in water is usually taken as index of pollution (Khaiwal et al., 2000). During the period of investigation, the Cl- content of the water samples was quite high (31.79-49.10 mg/l for February, 32.43-58.02 mg/l for March and 39.19-72.17mg/l for April) indicating not clearer waters. Besides, irrigation water with 4mg/l is considered safe for irrigation (Ayers and Westcot, 1985). Therefore, the sewage was unsuitable for irrigation since the values for all the samples fell not within the safe limits. Available literature suggest that irrigation waters with (mg/l) 5(NO3
-), 300, 960 (SO42-) and 0-2
(PO43-) are considered safe for irrigation (Ayers and Westcot, 1985; London, 1991). The SO4
2- and PO43-
values for all the samples fell within the safe limits respectively ranged from (mg/l) 220-350, 0.02-0.09 for the month of February, 255 – 344, 0.07 – 0.21 for the month of March and 290 – 375, 0.07 – 0.26 for April. But in contrast, the nitrate content in all the samples was above the safe limits for irrigation with the exception of 4.4mg/l in sampling point SW8 (Table 1). The nitrate content in water promotes primary productivity and excess of it in surface water is taken as a warning for algal blooms. Thus, the sewage was quite polluted. In a similar work, very high concentration of nitrate and phosphate (211.43-284.35 and 103.23-164.22 mg/l) were reported (Akan et al., 2008), but the sulphate values obtained in this work was higher than the values reported by them. Similarly, another indicator of pollution in water is the content of ammonia. The values of ammonia in all the waters indicated that the water samples were quite sewage. The percentage recovery of spiked water sample with metal standard solution using open beaker digestion method is presented in Table 4. The percentage recoveries from spiked water sample for metals ranged from 87.1+0.2 to 95.7+0.5. Therefore, the digestion method and the AAS machine gave a good consistent recovery, hence was applied to metal determination. Results of analysis of trace metals (i.e. Zn, Cu, Ni, Pb and Cd) in the water samples are presented in Table 5, 6 and 7 for the months of February, March and April, respectively. The composition of metals in the water samples ranged from 0.445+0.008-1.323+0.030, 0.624+0.007-1.813+0.010, 0.139+0.008-0.438+0.009, 0.056+0.004-0.193+0.040 and 0.053+0.001-0.124+0.008 mg/l for Zn, Ni, Cu, Pb and Cd, respectively, for the whole period of investigation. The concentrations of trace metals in the Kubanni drainage basin were in the following order Ni>Zn>Cu>Pb>Cd. The high concentration of Ni found in the water samples might be attributed to old battery wastes, components of automobiles, old coins, and many other items containing stainless steel and other Ni alloys that were much present in the drainage basin. The total metal concentrations found in this study were lower than the levels (11.65-18.45 mg/l for Ni; 2.32-3.78 mg/l Cu; 1.23-2.87 mg/l Pb and 1.00-3.58 mg/l Cd) reported for Jakara wastewater channel (Akan et al., 2008). Available literature suggests that irrigation water with (mg/l) 0.01 (Cd), 0.065 (Pb), 0.017(Cu), 1.4 (Ni) and 2.0 (Zn) is considered safe for irrigation (Ayers and Westcot, 1985; USEPA, 2001). Cadmium, Pb, Cu and Ni (in some few cases) contents in all the water samples were not within the reference permissible limits, however, total amount of Cd, Pb and Cu permitted in the irrigation waters i.e. 0.01 mg/l,
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Haruna A et al: Continental J. Applied Sciences 4: 8 - 17, 2009 0.065 mg/l and 0.017 mg/l, respectively, were violated by all the water samples during the months of investigation. Therefore, the high concentrations of Cd, Pb, Cu and Ni (in some few cases) found in this study had rendered the sewage from the drainage basin unsuitable for irrigation.
In plant, trace metals like Cd, Pb and Ni are highly toxic at relatively low concentrations. Trace metal toxicity is as a result of complex interactions of major toxic ions with other essential or non essential ions. The metal can cause a reduction in the hydrolysis product viz., α-amylase, phosphate and proteins. They interfere in the enzymes action by replacing metal ions the metalo-enzymes and inhibit different physiological process of plants (Agarwal, 1999). In human beings and animals, heavy metals are highly toxic at relatively low concentrations. Eating vegetables contaminated with trace metals can cause irritation of stomach leading vomiting and diarrhea. Similarly, high levels of lead may decrease reaction time, and cause anemia a blood disorder in human being (Agency for toxic substances and disease registry, 1993). Therefore, it is our responsibility to advocate the proper reuse of different wastewaters in order to avoid soils, plants (vegetables) and man from metal contamination, for the sake of their health status. CONCLUSION Generally, analysis of sewage water samples showed that they were alkaline (pH 7.39-8.49) and appeared not to have infiltration problems (EC 1090-2030 µS/cm and TDS 533-1031 mg/l). Accordingly, sewage water from all the sampling points was polluted as its physicochemical parameters were not within the desirable level with the exception of sulphate and phosphate and thus rendered the sewage unsuitable for irrigation. Regarding the trace metals, this study revealed that the levels of Cd, Pb, Cu and Ni (in some few cases) were not within the permissible limits. Therefore, the elevated levels of Cd Pb and Cu that were detected in the water samples could be directly detrimental to the vegetables and indirectly to man since the sewage is used to irrigate vegetables, hence continual monitoring and assessment are highly essential. REFERENCES Agarwal, S. K. (1999) Studies on the Effect of Autoexhaut Emission on the Mitragyna Patrillora. M.Sc Thesis. MDS University, Ajmeer, India. Agency for Toxic Substances and Disease Registry (ATSDR, 1993) Toxicology Profile of Cadmium. Department of Health and Human Service, Public Health Service, Atlanta, U.S.A. Ahmed, M.I. (2005), Surface Water Resource Management Strategies in the metropolitan Kano, Nigeria. Wa’adalla Environmental able Consult (WADEC), Kano, Nigeria. Akan, J.C., Abdulrahamn F.I, Dimari, G.A and Ogugbuaja, V.O (2008). Physicochemical determination of pollutants in wastewater and vegetable samples along Jakara Wastewater Channel in Kano Metropolis, Kano State, Nigeria.European Journal of Scientific Research, 23(1): 122-133. APHA, AWWA, WCF. (1992). Standard Method for Examination of Water and Waste Water 18th edn., American Public Health Association, Washington, DC, U.S.A. Ayers, R. S and Westcot, D W. (1985) Water Quality for Agriculture-FAO. Irrigation and Drainage Paper No.29, Rev.1. Blumenthal, U. J., Mowa, D., Peasey, A., Ruiz, G. and Stott, R. (2004). Reducing the Health Risks of using Waste Water in Agriculture: Recommended Changes to WHO Guidelines. In: Word Health Organization (WHO), WHO Handbook, Geneva, 2005.
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Haruna A et al: Continental J. Applied Sciences 4: 8 - 17, 2009
TABLE 5: *Mean + SD of the metal concentration (mg/l) in sewage (sw) for Feb, 08 Element SW1 SW2 SW3 SW4 SW5 SW6 SW7 SW8 SW9 SW10 Recommended
Source: USEPA, 2001; bsource; Ayers and Westcot, FAO, 1985, * Values are mean of triplicate analyses, standard deviation
TABLE 6: *Mean + SD of the metal concentration (mg/l) in sewage (sw) for March, 08
* Values are mean of triplicate analyses, SD=Standard deviation.
Element
SW1 SW2 SW3 SW4 SW5 SW6 SW7 SW8 SW9 SW10
Zn 0.823 +0.020
0.941 +0.009
0.902 +0.010
0.647 +0.030
0.832 +0.007
0.784 +0.010
0.832 +0.010
1.204 +0.008
1.081 +0.050
1.142+0.006
Ni 1.284 +0.040
1.561+0.030
0.784 +0.010
1.311 +0.005
1.328 +0.009
0.963 +0.020
1.086 +0.008
1.058 +0.010
0.941 +0.007
0.635+0.004
Cu 0.218+ 0.008
0.291+0.020
0.287+0.002
0.253+0.010
0.214+0.006
0.326+0.007
0.378+0.030
0.438+0.009
0.153+0.004
0.194+0.020
Pb 0.061+ 0.005
0.093+0.007
0.098+0.010
0.065+0.002
0.084+0.002
0.136+0.007
0.148+0.010
0.103+0.005
0.129+0.008
0.114+0.005
Cd 0.057+ 0.001
0.076+0.007
0.085+0.004
0.072+0.003
0.104+0.003
0.114+0.007
0.083+0.010
0.124+0.008
0.086+0.009
0.059+0.005
16
Haruna A et al: Continental J. Applied Sciences 4: 8 - 17, 2009 TABLE 7: *Mean +SD of the metal concentration (mg/l) in sewage (sw) for April, 08
Element
SW1 SW2 SW3 SW4 SW5 SW6 SW7 SW8 SW9 SW10
Zn 1.103 +0.020
0.875 + 0.040
0.943 + 0.009
0.528 + 0.010
1.094 + 0.008 0.861 + 0.050
0.856 + 0.007
1.012 + 0.008
1.303 + 0.010
1.224 + 0.008
Ni 1.327 + 0.008
1.813 + 0.010
0.752 + 0.009
1.433 + 0.020
0.859 + 0.007 1.025 + 0.008
0.976 + 0.040
1.316 + 0.005
1.014 + 0.009
0.771 + 0.030
Cu 0.183 + 0.010
0.301 + 0.005
0.249 + 0.020
0.316 + 0.007
0.143 + 0.009 0.259 + 0.030
0.318 + 0.009
0.391 + 0.004
0.184 + 0.006
0.166 + 0.040
Pb 0.173 + 0.007
0.188 + 0.030
0.106 + 0.009
0.193 + 0.040
0.159 + 0.008 0121 + 0.006 0.110 + 0.009
0.189 + 0.004
0.095 + 0.005
0.098 + 0.009
Cd 0.062 + 0.008
0.088 + 0.010
0.074 +0.005
0.081 + 0.007
0.095 + 0.006 0.073 + 0.004
0.097 + 0.020
0.102 + 0.004
0.068 + 0.010
0.071 + 0.009
* Values are mean of triplicate analyses, SD = standard deviation
17
Haruna A et al: Continental J. Applied Sciences 4: 8 - 17, 2009 Eigbefo, C. (1978). Hydrology of Kubani Drainage Basin. MSc Thesis, Geology Department, Ahmadu Bello University, Zaria, Nigeria. Furedy, C. and Chowdhury, T. (1996) Liquid Waste Reuse and Urban Agriculture Delemmas in Developing Counties: The Bad News and Good News. A Paper Presented at Joint International Congress, Ryerson Polytechnic University Toronto, U.S.A. Khaiwal, R., Ameana, Meenakshi, Monica, Rani and Kanshik, A. (2000). Seasonal Variation in Physicochemical Characteristics of River Yamuna in Haryana and its Ecological Best Designed use. A Research Paper Published by Micro and Trace Analysis Centre, Department of Chemistry, University of Antwerp, Belgium. London, J. R. (1991). Booker Tropical Soil Manual. Longman Scientific and Technical, Booker Tate, New York, U S A. Lewcock, C. P. (1995). Case Study of the Use of Urban Waste Water by Urban Farmers in Kano, Nigeria. A Visual Report of National Resources System Programes. In: Use of Reclaimed Water and Sludge in Food Crop Production, 1996. Retrieved from http:// www.nap.edu/openbook/0309054796/html. Manahan, S. E. (1994). Environmental Chemistry. Lewis Public.CRC Press, U.S.A. Sawyer, C. N. and MacCarty, P. L. (1967). Chemistry of Sanitary engineers, 2nd edn. – McGraw – Hill Publishing Co. Ltd. Singh. B. R. (2000). Quality of Irrigation in Famada Lands of Northwestern Nigeria. Ground and Surface Waters in Kebbi State, Nigeria. J. Basic Appli. Sci. 9(2): 133 – 148. USEPA (2001). Water Quality Criteria. Retrieved from http // www.epa. gov/waterscience/criteria /wqcriteria.
Received for Publication: 23/02/09 Accepted for Publication: 10/04/09 Corresponding Author A. Haruna, Department of Chemistry, Ahmadu Bello University, Zaria, Nigeria Email: [email protected]
FOOD AND FEEDING HABITS OF Synodontis resupinatus (BOULENGER, 1904) IN GBEDIKERE LAKE, BASSA, KOGI STATE, NIGERIA.
Adeyemi, S.O1, Bankole, N.O2, and Adikwu I.A.1
1Department of Biological Sciences, Benue State University, Makurdi. 2National Institute for Freshwater Fisheries and Research, New Bussa, Niger State.
ABSTRACT The food and feeding adaptations of Synodontis resupinatus (Boulenger, 1904) in Gbedikere Lake, Bassa Local Government Area of Kogi State Nigeria were studied. Fish samples were collected from July to December 2007; the stomach contents were analyzed using frequency of occurrence method. The fish is an omnivore, feeding mainly on phytoplankton, diatoms, plant leaves and seed, fish scales, crustacean, insect larvae, pupae, worms, fish parts and detritus. The juveniles showed more indignation towards phytoplankton, diatoms and plant parts while the adults exhibited more diverse and complex feeding habits.
Gbedikere Lake. INTRODUCTION The fish family Mochokidae is presented mainly by genus Synodontis commonly known as catfish. Reed et al, (1967) described twenty Synodontis species found in Northern Nigeria, while Holden and Reed (1972) indicated that at least twenty one species have been identified in River Niger. The different Synodontis species vary in commercial status in different locations, many are important food fishes and some have attractive hues and exhibit behavioral characteristics that make them potential ornamental candidates. Synodontis accounts for important parts of the commercial catches in Northern Nigeria and, according to Reed et al (1967), they are available throughout the year. In the River Niger, Synodontis accounted for 18.00% by number and 18.68% by weight of the total fish caught (Mortwani and Kanwai 1970). Reed et al, (1967) reported some natural food substance of some common Synodontis species. The food and feeding habits of ten species captured in River Niger have been investigated (Imevbore and Bakare, 1970). Olatunde (1989) conducted similar studies on Synodontis schall in Zaria, Nigeria. Synodontis resupinatus are found through out Africa, except in the Southernmost parts of Magreb, although most species occur in Central and West Africa, the species occur throughout most of the freshwaters of the Sub-Saharan Africa and the Nile River (Friel and Vigliotta, 2006). The state of knowledge on the various Synodontis species in Nigeria is largely on their gross anatomy and some behavioral characteristics. The available scientific investigations on their biology are still inadequate for their propagation and management. This study examines the food and feeding habits of S. resupinatus in Gbedikere Lake, Bassa Local Government Area of Kogi State. MATERIALS AND METHODS STUDY AREA Lake Gbedikere is a natural lake located between Latitudes 30240 and Longitudes 5014E and is about 10km to the East of Oguma the Head quarter of Bassa Local Government Area of Kogi State. Water enters the Lake from tributaries that run from River Benue during rainy or flood season. When the season is over, the Lake separates out. The Lake is about 450m north of Gbedikere village. The water body covers about 400 – 450m and a depth of 10 – 14m deep, depending on the season. The Lake is used for fishing and other domestic activities; consequently most of the settlers around the Lake are fishermen (Upper Benue River Basin Development Authority, 1985). The lake experience two
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Adeyemi, S.O et al: Continental J. Applied Sciences 4: 18 - 25, 2009 seasonal periods; the rainy season starts in the month of May and last till October and is characterized by heavy down pour which sometimes have an extensive flood action. The dry season is from late October to April and is characterized by cold, dusty -dry wind followed by intense heat. The lake contains fish, other aquatic animals and some macrophytes such as wire grass (Cyperus articulatus) which are used for waving mats. COLLECTION OF SAMPLES Samples of S. resupinatus were obtained from Oguma market, Bassa Local Government Area in Kogi State. The samples were purchased weekly from the fishermen form July to December 2007, and examined fresh, and transported into the Biological Sciences Laboratory of Kogi State University, Anyigba while those that could not be treated were preserved in a freezer until the next day. A total of sixty specimens (60) were examined. The total length (TL, cm) of each sample was measured. The gut of the fish was removed by making a longitudinal incision along the mid ventral line form the mouth to the anus to expose the visceral organs. The gut was removed carefully by detaching it from other internal organs and fatty tissues. The gut length (GL) was then measured to the nearest cm on a graduated measuring board. The stomach was cut off from the gut and weighed on an electric top-loading balance (Sartorius) to obtain the stomach weight (SW). The stomachs were scored 0, 25, 50, 75 and 100% according to its fullness as described by Olatunde (1979). IDENTIFICATION OF STOMACH CONTENTS Each stomach was split open and the contents emptied into a Petri-dish. The contents were then observed under a monocular microscope. The food materials were identified with the aid of keys provided by Needham and Needham (1962) and Mellanby (1975). ANALYSIS OF STOMACH CONTENTS The stomach contents were analyzed by frequency of occurrence method as described by Hynes, (1950). Each food item was identified and number of stomachs in which each food occurred was counted and expressed as a percentage of stomach containing food. The method showed the proportion of individuals eating a particular food item in a species. The occurrence of each food item was expressed as a percentage of all stomach with food.
That is, P = (b/a) x 100
Where, a = Total number of fish examined with food in the stomach; b = Number of fish containing a particular food item; P = Percentage of occurrence of each food item. STATISTICAL ANALYSIS The relationship between the fish TL and GL was computed using a linear regression model GL = a + b TL Where GL is Gut length (cm); TL is Fish total length (cm); a is Constant; b is Exponent. RESULTS FOOD CONTENTS Analysis of the fullness of the stomach shows that 89.6% (juvenile 50.2%, adult male and female 49.8%) had food content while 10.3% had empty stomach (Table 1). The percentage of the stomach with food items was highest in August and September and lowest in November and December. These period falls within the rainy and dry season in the study area respectively.
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Adeyemi, S.O et al: Continental J. Applied Sciences 4: 18 - 25, 2009 Table 1: The mean of the stomach fullness condition of Synodontis resupinatus in Gbedikere Lake, Bassa
Local Government Area, Kogi State. Sex 0/4
(n=14) 4/4
(n=9) ¾
(n=16) ½
(n=14) ¼
(n=7) Subtotal Percentage (%)
total AF 0.36 0.22 0.19 0.14 0.43 1.34 26.91 AM 0.21 0.33 0.25 0.21 0.14 1.14 22.89 Grand total
0.99
0.99
1.00
1.00
1.00
4.98
100%
AF = Adult female, AM = Adult male, JV = Juveniles, 0/4 = Empty stomach, ½ = Full stomach, ¾ = Three quarter full stomach, ½ = Half full stomach, ¼ = One-quarter full stomach.
Table 2 contains the frequency of occurrence of the food items with respect to size and whole sample. The percentage total from the result shows that plants part accounted for 41.7%, algae 18.2%, insect 0.32%, insect appendages 1.63%, insect larvae 0.16%, crustacean parts 0.16%, fish scales 0.16%, sand grains 29.16%, mud 1.63%, unidentified items 6.84%. In all plants component was the highest food item followed by sand grains, insect larvae, crustacean parts and fish scales. Table 2: The mean of the food items of Synodontis resupinatus Gbedikere Lake, Bassa Local Government
Grand total 0.3061 0.2084 0.4853 0.9998 100% The percentage of occurrence of food substances varied with month, season and size class. The result of this study shows occurrence of plant materials were more in the stomach of juvenile than adults in the month of September and October. This indicate more intense feeding at one group than the other and it could be as a result of partitioning of food resources in a bid to avoid intra-specific competition and may be attributed to the fact that this period fall within the rainy season characterized by abundance of plant materials. This result supports the findings of Low-McConnell (1975) who reported availability of plant, invertebrates and fish in tropical waters during the rainy season. Plant had the highest frequency in juvenile similar to the result obtained by Owolabi (2005) in Jebba Lake, Nigeria. It also agrees with Laleye (2006) in Queme River, Benin, this indicate that Synodontis is a omnivorous fish during rainy season even at its offset, followed by sand grain and this aid them in digestion of hard food like plants. This also shows the species under study is a benthic fish.
21
Adeyemi, S.O et al: Continental J. Applied Sciences 4: 18 - 25, 2009 Length and weight frequency distribution of Synodontis resupinatus is shown in Table 3. The standard length (cm) and the weight (cm) for adult male, adult female, combined sex and juveniles is 10.2 to 10.3cm/25 - 75g, 12.0 - 14.3cm/50 – 80g, 20.2 – 14.3cm/25 – 80g and 6.7 – 13.1cm/14.5 – 11.5g respectively. Table 3: Length and weight frequency distribution in Synodontis resupinatus in Gbedikere Lake, Bassa Local
Government Area, Kogi State. Sex Standard length (cm) Total weight (g)
n = Number, Min = Minimum, Max = Maximum, S.D = Standard deviation. The males length-weight relationship is express by the regression equation Log TW = -2.3486 + 0.1607 Log TL (r = 0.7558) as shown in figure 1. The females’ length-weight relationship is expressed by the regression equation Log TW = -1.9353 + 0.4865 Log TL (r = 0.5276) as shown in figure 2. The combined sexes’ length-weight relationship is expressed by the regression equation Log TW = -2.3906 + 0.1489 Log TL (r = 0.7361) as shown in figure 3. The juveniles’ length Lot TW = -2.2261 + 0.0651 Log TL (r = 0.8310) as shown in figure 4. The relative condition factor ( K) of Synodontis resupinatus is shown in Table 4. The minimum condition factor (K) is 0.78 while maximum is 1.99. Table 4: The mean relative condition factor (K) of Synodontis resupinatus in Gbedikere Lake, Bassa Local
Government Area, Kogi State. Sex Relative condition
Juveniles 1.35 + 0.26 26 0.78 1.99 2.2261 0.0651 0.8310 K = Condition factor, a = intercept of the regression, b = Slope of the regression, r = correlation coefficient, S.D. = Standard Deviation, Min =Minimum, Max = Maximum.
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Adeyemi, S.O et al: Continental J. Applied Sciences 4: 18 - 25, 2009 DISCUSSION The proportion (10.3%) of S. resupinatus found with empty stomach may not be unexpected, and it is attributable mainly to post harvest digestion. Large percentages of empty stomach have been found in similar studies with some carnivorous fish such as Pellornula afzeliusi and Lates niloticus (Balogun, 1985), but lower proportions were obtained in Tilapia guineensis and Hyperopisus bebe occidentalis which are omnivores (Fagade, 1978; Ipinjolu et al, 1996) and in a carnivore (Ipinjolu et al, 1988). The variety of food substances found in the stomachs shows that S. resupinatus is an omnivore, feeding on plant food substance such as phytoplankton, diatoms, desmids, plant parts (leaves and seeds), and animal food sources comprising of insects larvae, pupae and adults, crustacean, annelid worms, fish remains, nematodes; and detritus. Imevbore and Bakare (1970) reported that two individuals of S. resupinatus captured in River Niger were found feeding mainly on insect larvae and bivalve molluscs, but variety of plant and animal food materials were found in some other Synodontis species. The results of the present study indicate that S. resupinatus exhibit more versatile and complex omnivorous feeding habit in Gbedikere Lake which is similar to the finding on the food and feeding habits of S. schall Zaria area (Olatunde, 1989). However, S. schall fed more on animal materials than plants. The juveniles showed more indignation towards soft plant materials particularly phytoplankton, diatoms, leaves and insect larvae while the adults exhibited more versatile feeding nature. These indicate that the food preference of S. resupinatus change with age as found with Clarias gariepinus (Ayinla and Faturoti, 1990) and Brienomyrus longianalis (Ikomi, 1996). The distribution of food taxa indicates that S. resupinatus could explore wide range of food substances which are influenced by season and water hydrology. The length-weight frequency distribution shows that adult female had the highest standard length 14.3cm than the adult male 13.3cm and juvenile 13.1cm, so also was the total weight in adult female 80g and 4.5g for the juveniles. This shows that the rate of increase in body length is not proportional to the increase in body weight. The values of relative condition factor (2.3 – 4.90) were obtained from this study were slightly higher than the range mean values of the condition factor (2.65 – 3.32) indicated by Baijot and Bouda (1997) especially for some slow-growing important fishes in Africa, the adult (male and female) S. resupinatus has the tendency to increase in size and mass (Laleye, 2006). CONCLUSION S. resupinatus is an omnivore, feeding on diverse on plant and animal food substances. However, the juveniles show more indignation towards phytoplankton, diatoms, leaves and insect larvae, while the adults exhibit more versatile and complex feeding habit. This fish explore food items of aquatic and terrestrial origin depending on availability as influenced by season and water hydrology.
REFERENCES Ayinla, O.A. and E.O. Faturoti (1990). The food and feeding habits of African Mud catfish, Clarias gariepinus (Burchell 1822) caught from the wild. J. West African Fisheries 5: 249 – 255. Balogun, J.K. (1985). Fish Distribution in Kainji Lake Nigerian Journal of Biology. 29:289 – 498. Baijot, E., J. Moreau and S. Bouda (eds) (1997). Hydrobiologica aspects of Fisheries in small reservoirs in the Sahel region. C.T.A. Publication. 252p.
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Adeyemi, S.O et al: Continental J. Applied Sciences 4: 18 - 25, 2009 Fagade, S.O (1978). The food and feeding habits of Tilapia species from the Lagos lagoon. Journal of fish Biology. 3:151 - 156 Friel, J.P. and T.R. Vigliotta (2006). Synodontis acanthoperca, a new species from Ogooue River System, Gabon with comments on spiny ornamental and sexual dimorphism in mochokid catfishes (Siluriformes:Mochokidae). Zootaxa. 1125:45-56. Holden, M. and W. Reed (1972). West African Fresh Water Fishes West African Nature Book Longman Publications, London. 68p. Hynes, H.B.N. (1950). The food of freshwater Stickle backs (Gasterosteus acculeatus and Pygoteus pungistis) with review of methods used in studies of the food of fishes. J. Animal Eco.19:36-58. Ikomi, R.B. (1996). Studies on the growth pattern, feeding habits and reproductive characteristics of Mormyrid, Brienomyrus longianalis (Boulenger) in the Upper Warri River, Nigeria. J. Fisheries Research. 26: 187-198. Imevbore, A.M.A. and O. Bakare (1970). The food and feeding habits of non-cihlid fishes of the River Niger in the Kainji Reservoir area. In: S.A (Ed). Kainji-a Nigerian Man-made. Lake Kainji Lake Studies, Vol. 1-Ecology. Nigerian Institute of Social and Economic Research, Ibadan, Nigeria. pp 49-64. Ipinjolu, J.K; S.A Garba and G.G. Bako (1988). Length-weight relationships, condition factor and stomach contents of Bagrus macropeterus (Daget) in River Rima, Sokoto State, Nigeria. J. Basic and Applied Sciences 2(2): 25-29. Ipinjolu, J.K., B.C. Nwosu and S.T. Osanaye (1996). Some aspects of the biology of Hyperopisus bebe occidentalis (Gunther) in Goronyo Dam, Sokoto State, Nigeria. J. Basic and Applied Sciences 5(1 and 2): 25-30. Laleye P.A. (2006). Length – Weight and length – length relationship of fishes from the Queme River in Benin (West Africa). Journal of Applied Ichthyology 22:330 – 333. Lowe – McConnell, R.H (1975). The ecology of the fishes in the tropical waters. The institute of biological studies, biology series 76 Edward Arnold Ltd. Pp59. Mellanby, H. (1975). Animal Life in Freshwater 6th ed. A guide to Freshwater Invertebrates. Chapman and Hall, London. 323p. Mortwani, M.P. and Y. Kanwai (1970). Fish and Fisheries of coffer-damned right channel of the River Niger at Kainja. In: V.A. Visser (Ed) Kainji- a Nigerian man-made Lake. Kainji Lake Studies Vol. 1 Ecology. Nigerian Institute of Social and Economic Research, Ibadan, Nigeria. pp 27-48. Needham, P.R. and J.G. Needham (1962). A guide to the study of freshwater biology. 5th Ed. Holden Day Inc. 108p. Reed, W., J. Burchard, A.J. Hopson, J. Jennes, I. Yaro (1967). Fish and Fisheries of Northern Nigeria. 1st Ed. Ministry of Agriculture, Northern Nigeria. 226p. Olatunde, A.A. (1979). The food and feeding habits of Eutropics niloticus (Ruppel), Family Schilbeidae (Osteichthys:Siluriforms) in Lake Kainji. Hydrobiologia 57: 197-203. Olatunde, A.A. (1989). Some Aspects of Biology of Synodontis schall (Bloch and Schneider, 1801) in Zaria, Nigeria. Journal of Aquatic Sciences. 4: 49-54.
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Adeyemi, S.O et al: Continental J. Applied Sciences 4: 18 - 25, 2009 Owalabi, O.D. (2005). Some aspects of the biology of Synodontis membranaceous. (Geoffory Saint Hilarie) in Jebba Lake, Nigeria. Ph.D. Thesis, University of Ilorin, Nigeria. 258P. Upper Benue River Basin Development Authority, (1985): Feasibility study of Lake Geriyo by Upper Benue River Basin Development Authority. Authority Information Manual.
Fig 1 Length-weight relationship of adult male Synodontis resupinatus in Gbedikere Lake, Bassa,
Kogi State
Fig 2: Length-weight relationship of female Synodontis resupinatus in Gbedikere Lake, Bassa, Kogi State.
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Adeyemi, S.O et al: Continental J. Applied Sciences 4: 18 - 25, 2009
Received for Publication: 23/02/09 Accepted for Publication: 10/04/09 Corresponding Author (Present Address) Adeyemi, S.O Department of Biological Sciences, Kogi State University, Anyigba. Email: [email protected]
Length (cm) Fig 4: Length-weight relationship of juvenile Synodontis
resupinatus in Gbedikere Lake, Bassa, Kogi State.
Standard length (cm) Fig 3: Length-weight relationship of combined sexes of Synodontis resupinatus in Gbedikere Lake, Bassa, Kogi
LENGTH – WEIGHT RELATIONSHIP AND CONDITION FACTOR OF Heterobranchus bidorsalis IN GBEDIKERE LAKE, BASSA, KOGI STATE, NIGERIA.
Adeyemi, S.O1, Bankole, N.O2, and Adikwu I.A.1
1Department of Biological Sciences, Benue State University, Makurdi. 2National Institute for Freshwater Fisheries and Research, New Bussa, Niger State.
ABSTRACT Length-weight relationships and condition factor of males, females, combined sex and juveniles of Heterobranchus bidorsalis in Gbedikere Lake Bassa, Kogi State was studied. One hundred and fourteen fish samples of total length ranging from 15.0cm to 44.0cm and weight between 36.2g and 580.0g collected between June and December 2007 were analyzed. Results showed that the males, females, combined sex and juveniles have b-values of 2.74, 2.79, 2.78 and 3.62 respectively. The males and females exhibited negative allometric growth, while juveniles exhibited positive allometric growth. Juveniles were in a better condition than male and females. The condition factor of the population varies from 0.65 to 1.79; females were in better condition than males. Condition factor between males and females was not significantly different (P>0.05). Gbedikere Lake is a good environment for growth, reproduction and survival of Heterobranchus bidosarlis.
Gbedikere Lake, Kogi State. INTRODUCTION Fish found in tropical and sub-tropical water system experience frequency growth fluctuations due to factors such as food composition changes, environment changes, rate of spawning to mention but a few, length weight relationship can be used to assess the influence of these factors in fish. Kulbicki et al, (1993) and King (1966) reported that fish growth, mean weight of a given body length of fish estimation and the relative well being in fish can be known through this relationships length-weight relationships studies have been done in different water bodies and on different fishes. Notably among these are the report of King (1996) on some Nigerian fresh water fishes, Taiwo and Aransiola (2001) on Chrysichthys species in Asejire Lake, Fafioye and Oluajo (2005) on five fish species in Epe Lagoon, Nigeria and Laleye (2006) on Oreochromis niloticus in Oeume River in Benin. Heterobranchus bidorsalis belong to the family Clariidae is a common and important fish in Africa and Asia. It can attain a maximums size of 800mm and has no serrations on the anterior part of the pectoral spine and could be found in upper and lower Niger, Benue and Chad. It is a valuable food fish that is very important in aquaculture (Olasebikan and Raji, 2004). The study present information on the length-weight relationships and the condition factor of this valuable fish species is in order to aid its management. MATERIALS AND METHODS STUDY AREA Lake Gbedikere is a natural lake located between Latitudes 30240 and Longitudes 5014E and is about 10km to the East of Oguma the Headquarter of Bassa Local Government Area of Kogi State. Water enters the Lake from tributaries that run from River Benue during rainy or flood season. When the season is over, the Lake separates out. The Lake is about 450m north of Gbedikere village. The water body covers about 400 – 450m and a depth of 10 – 14m deep, depending on the season. Continental J. Applied Sciences 4: 26 - 31, 2009
27
Adeyemi, S.O et al: Continental J. Applied Sciences 4: 26 - 31, 2009 The pond water is only used for fishing; consequently most of the settlers around the Lake are fishermen (Upper Benue River Basin Development Authority, 1985). The lake experience two seasonal periods; the rainy season starts in the month of May and last till October and is characterized by heavy down pour which sometimes have an extensive flood action. The dry season is from late October to April and is characterized by cold, dusty -dry wind followed by intense heat. The Lake contains fish, other aquatic animals and some macrophytes such as wire grass (Cyperus articulatus) which are used for weaving mats. SAMPLES COLLECTION Fish samples were identified and collected from the fishermen catches using gill nets and Malian traps between June and December 2007. Total length (cm) and weight (g) were taken using measuring board and top loading balance. Length-weight relationship was calculated using the formula: W=aLb which was transformed to logarithm of the form
Log W=Log a + b log L
Using instat statistics package Where W= body weight of the fish (g),
L=total body length of fish (cm) a and b=values estimated by regression formula.
The condition factor (K) was calculated using the K=100w (Pauly, 1984) L3
Where K= condition factor, L=Total body length of fish (cm)
W=body weight of fish (g). RESULTS AND DISCUSSION A total of one hundred and fourteen species of Heterobranchus bidorsalis were collected for the study. The length-weight frequency distribution of the fish species in Gbedikere Lake is shown in Table 1.The standard length (cm) and weight (g) for the species are, Males 22.2cm – 44.0cm/115.2 – 580g, Females 22.8cm - 39.2cm/105.7g – 492.9g as the corresponding weight, Combined sex 22.2cm – 44.0cm/105.7g – 580g and the juveniles 15.0 – 23.2cm/36.2g – 117.9g respectively. Table 1: Length and weight frequency distribution of Heterobranchus bidorsalis in Gbedikere Lake, Bassa
Kogi State. Sex
Standard Length (cm) Body Weight (g)
n Min Max Mean + S.D Min Max Mean + S.D
Male 42 22.20 44.0 30.1+4.8 115.2 580.0 267.3+121.9
Combined sex 84 22.2 44.0 30.7+4.5 105.7 580.0 268.2+116.5 Juveniles 30 15.0 23.2 19.1+2.1 36.2 117.9 80.0+38.3 n=Number, Min=Minimum, Max=Maximum, SD = Standard Deviation. The male length-weight relationship is expressed by the regression equation: Log W=-0.0224 + 2.7398 Log L (r = 0.9630) Fig 1.
28
Adeyemi, S.O et al: Continental J. Applied Sciences 4: 26 - 31, 2009 The female length-weight relationship is expressed by the regression equation: Log W=-0.02 + 2.7859 Log L (r = 0.9637) Fig 2. The combined sex’s length-weight relationship is expressed by the regression equation: Log W=-0.0199 + 2.7814 Log L (r = 0.9631) Fig 3. The juveniles’ length-weight relationship is expressed by the regression equation: Log W = -0.0017 + 3.6153 Log L (r = 0.9016) Fig 4. The total length (cm), for males, females, combined sex and juveniles ranged between 25.5 to 88.4, 27.0 to 43.4, 25.5 to 88.4 and 17.5 to 26.9 respectively (Table 2). The slope with b-value 19.609, -1.007, 16.241 and 0.5033 for males, females, combined sex and juveniles respectively. The coefficient of determination (r) was 0.6088, 0.9946, 0.6889 and 0.9897 males, females, combined sex and juveniles respectively. Table 2: Length-weight relationship of Heterobranchus bidorsalis River Niger. Sex Total length (cm)
Min Max Mean +S.D n a b r Males 25.5 48.4 35.38+9.96 42 0.2958 19.609 0.6088 Females 27.0 43.4 35.71+4.64 42 0.9028 -1.007 0.9946 Combined sex 25.5 48.4 35.54+7.73 84 0.4050 16.241 0.6889 Juveniles 17.5 26.9 21.99+2.47 30 0.8452 0.503 0.9897
SD = Standard deviation, n=Number, a=Intercept, b=Slope, r=Coefficient of determination.
The condition factor (CF) ranged between 0.65 to 1.16, 0.80 to 131, 0.65 to 131 and 0.86 to 197 for all the sex’s (Table 3).
Table 3: Condition factor of Heterobranchus bidorsalis in Gbedikere Lake, Bassa Kogi State.
Sex Minimum Maximum Condition factor (k) (Mean + SD) Males 0.65 1.16 0.93+0.11 Females 0.80 1.31 0.96+0.11 Combined sex 0.65 1.31 0.95+0.11 Juveniles 0.86 1.79 1.08+0.26
The b-values recorded for Heterobranchus bidorsalis males, females, combined sex and juveniles respectively recorded during the study was 2.74, 2.79, 2.78 and 3.62. This indicates that while males and females showed negative allometric growth, juveniles exhibited positive allometric growth base on Begenal and Tesch (1978) criteria of 3. Similarly Pauly (1984) did not report that a slope value greater than 3 denotes allometric growth; this is not familiar to the findings of Anibeze (1995) that recorded b-values of 2.025 for males and 2.353 for females of Heterobranchus longifilis which is similar to the finding of this study. This shows that species did not obey the cube law of growth (Le Cren, 1951) which is not commonly obeyed by most fishes. The b-values of 2.951 and 3.042 reported by Etim (2000) and Fafioye and Oluajo (2005) respectively for Chrysicthys nigradigitatus combined sex agree with the findings of this study. The condition factors obtained for males, females, combined sex and juveniles of Heterobranchus bidorsalis is within the range of 0.65 to 1.16 with the mean of 0.93, 0.80 to 1.31 with the mean of 0.96, 0.65 to 1.31 with the mean of 0.95 and 0.86 to 1.79 with the corresponding mean of 1.08 for each group respectively. The condition factor for males and females were not significantly different (P>0.05). CONCLUSION AND RECOMMENDATIONS The composition of both sexes gave a better overview of length-weight relationship and condition factor of Heterobranchus bidorsarlis. The result of this study show negative and positive allometric growth pattern
29
Adeyemi, S.O et al: Continental J. Applied Sciences 4: 26 - 31, 2009 and all the result presented in this study, the b-values were generally in agreement with results for fishes of the same genus obtained from other geographical areas. Confirming Gbedikere Lake Bassa, Kogi State is a good environment for the growth, reproduction and survival of the species. The study provides basic information on the length-weight and condition factor of the species that will be useful for fishery biologist and managers in Nigeria. The in-depth studies on the length-weight relationship and condition factors; and other aspect of biology and biodiversity of Heterbranchus bidorsalis towards sustainable management in Gbedikere Lake Bassa in Kogi State should be further elucidated. REFERENCES Anibeze, C.I.P. (1995). Aspect of ecobiology of Heterobranchus longifilis (Valenciennces, 1840) in Idodo River Basin (Nigeria) and their application of aquaculture. University of Nigeria, Nsukka. 153p Ph.D. Thesis. Bagenal, T.B. and F.W. Tesch (1978). Age Growth in Method of Assessment of Fish Production in Fresh Waters, (ed. T. Bagenal). Oxford Blackwell Scientific Publication. pp 101-136. Etim, L. (2000). Length-Weight Relationship of Eight Fish species from the Cross River, Nigeria. Global Journal of Pure and Applied Sciences. 6 (4): 571-575. Fafioye, O.O and O.A. Oluajo (2005). Length-Weight Relationship of five Fish Species in Epe Lagoon, Nigeria. African Journal of Biotechnology. 4(7): 749-751. King, R.P. (). Length-weight relationship of Nigerian freshwater fishes. NAGA: The ICLARM Quarterly 19(3): 49 – 52. Kulbicki, M., Moutham, G., Thollot, P. and Wanteiz, L; (1993). Length-weight relationship of fish from the lagoon of Mew Caledonia. NAGA ICLARM Quarterly 16 (2-3):26 -30. Laleye, P.A. (2006). Length-Weight and Length-Length relationship of fishes from the Oueme River in Benin (West Africa). Journal of Applied Ichthyology 22:330-333. Le Cren, E.D. (1951). The Length-Weight Relationship and Seasonal Cycle In: Gonad Weight and Condition in the Perch, Perca fluviatillis. Journal of Animal Ecology. 20:201-219. Olaosebikan, B.D. and Raji, A. (2004). Field Guide to Nigerian Fresh water fishes. 2nd Edition. Published by Federal College of Freshwater Fisheries Technology, New Bussa. Printed by UniIlorin Press, University of Ilorin, Nigeria. 111pp. ISBN 978 – 34760 – 0 – 9. Pauly, D. (1984). Fish Population Dynamics in Tropical Waters: a manual for use with Programmable calculators. ICLARM Studies and Revision. 8: 325pp. Taiwo, I.O., and Aransiola, M.O. (2001). Length-weight relationship, condition factors and fecundity of Chrysichthys nigrodigitatus and Chrysichthys walkeri in Asejire Lake. Proceeding of the 16th Annual Conference of the Fisheries Society of Nigeria (Maiduguri, 2001), pp.277-281. Upper Benue River Basin Development Authority, (1985): Feasibility study of Lake Geriyo by Upper Benue River Basin Development Authority. Authority Information Manual.
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Adeyemi, S.O et al: Continental J. Applied Sciences 4: 26 - 31, 2009
Figure 1: Length-weight relationship of males Heterobranchus bidorsalis in Gbedikere Lake, Bassa,
Kogi State.
Standard length (cm) Fig 2: Length-weight relationship of female Heterobranchus
bidorsalis in Gbedikere Lake, Bassa, Kogi State
31
Adeyemi, S.O et al: Continental J. Applied Sciences 4: 26 - 31, 2009
Received for Publication: 17/03/2009 Accepted for Publication: 13/05/2009 Corresponding Author (Present Address) Adeyemi, S.O Department of Biological Sciences, Kogi State University, Anyigba. Email: [email protected]
Standard length (cm) Fig 3: Length-weight relationship of combined sex Heterobranchus
bidorsalis in Gbedikere Lake, Bassa, Kogi State.
Standard length (cm) Fig 4: Length-weight relationship of juveniles Heterobranchus
A MATHEMATICAL MODEL FOR THE DYNAMICS OF PREDATOR-PREY INTERACTIONS
IN A THREE-TROPHIC LEVEL FOOD WEB
J. N. Ndam and T. G. Kassem Department of Mathematics, University of Jos, P.M.B 2084, Jos, Nigeria
ABSTRACT It has been shown that the predator-dependent functional responses have better stability properties than the Holling’s type functional responses. The Holling’s type III functional response on the other hand has an inherent protection for the prey populations at low densities. We have exploited these properties to construct a model for predator-prey interactions in a food web. A combination of Holling’s type III and the BD-functional responses were used in the model. The result indicates a stable coexistence of the three species, without any resource enrichment. The result also shows that omnivory does not destabilise the food web, contrary to some conclusions of previous studies. This may depend on the functional response(s) used. However, chaos is induced by over harvesting of the top-predator. KEYWORDS: Trophic level; food web; Holling’s functional response; DB-functional response; Limit cycles.
INTRODUCTION Mathematical modelling of the interactions between preys and predators in an ecosystem is a very popular subject of mathematical ecology. Enormous research articles have been published on various aspects of these interactions, especially in two and three-trophic level simple food chains. Three or more trophic level interactions are considered more appropriate for describing predator-prey inter- actions in a natural ecosystem such as aquatic species (Lee et al, 2004), than two trophic levels. One of the central issues in the formulation of a realistic mathematical model for predator-prey interactions is the rate at which a given predator feeds on the prey, commonly referred to as the predators’ functional response. This is the predator’s instantaneous per capita feeding rate as a function of prey abundance. Skalski and Gilliam (2001) described it as the transfer of biomass between trophic levels. Different forms of functional responses have been used predator-prey interactions models in food webs and food chains (Dubey et al, 2004). The two major categories of functional responses commonly used in biological models are the prey-dependent and predator-dependent functional responses. The first category consists of the popular Holling’s types (I-IV) functional responses and the Michaelis-Menten functional response which is a special case of Holling’s functional response (Hsu et al, 2003; Edelstein-Keshet, 2005). The predator-dependent functional response comprises the Beddington-DeAngelis functional response (usually called the BD-functional response), the Michaelis-Menten ratio-dependent functional response, and the Hassell-Varley type which take into consideration the effect of mutual interference among predators as they compete for resources (Basset et al, 1997; Cantrell et al, 2001; Hwang, 2003; Kot, 2001). The ratio-dependent functional response is a special form of the predator-dependent functional response when the response function f (x,y) = f (x / y) ,
with x and y as the densities of the prey and the predator respectively. The Holling’s type functional
response, especially the type II is the most commonly used functional response by researchers (Skalski and Gilliam, 2001). However, there have been arguments (Hsu et al, 2001; Liu and Beretta, 2006; Skalski and Gilliam, 2001) that the predator-dependent type functional responses are physically more realistic than the Holling’s type. This is due to the fact that the predator-dependent type functional responses take into account predator interference which naturally occurs in most predator-prey systems. Another reason advanced for this class of functional responses is that they generally have stabilising effects on population dynamics (Arditi et al, 2004), subject to a certain threshold of the interference constant. Holling’s type II functional response tends to be unstable for a wide range of parameters (Basset et al, 1997; Hsu and Waltman, 2004), as a result of what is commonly referred to as the ‘paradox of enrichment’ which states that increasing the carrying capacity
33
J. N. Ndam and T. G. Kassem: Continental J. Applied Sciences 4: 32 - 43, 2009 of the prey (enriching the predator-prey system) leads to an increase in the equilibrium density of the predator but not in that of the prey, and thus destabilises the positive equilibrium with the likelihood of the predator going into extinction. The Holling’s type III, which has been shown to be more stable (Basset et al, 1997) is preferred, and tends to eliminate the ‘paradox of enrichment’ scenario due to its inherent resource refuge effect, i.e scarce resources become better protected. Some of the properties of theses functional responses have recently been exploited by Kassem and Ndam (2009) to constructa food chain model. The Holling’s type III functional response is given by
f (x) =mx2
a2 + x2 (1)
where x is the prey density, m is the maximum consumption rate of the predator and a is the half saturation constant. For more details, the interested reader can consult (Basset et al, 1997) and (Hsu et al, 2003). A typical ratio-dependent functional response is the BD-functional response given by
f (x,y) =αx
λ + x + γ y (2)
where x is as defined above and y is the density of the intermediate predator, while α, λ and γ are positive constants, representing the maximum consumption rate, the saturation constant and the predator interference parameter, respectively.
In this paper, we construct a mathematical model for the interactions between predators and preys in a three-trophic level food web, where the primary producer x , is a prey to an intermediate predator y , and y is a prey
to another predator called the super-predator (Lee et al, 2004) or the top-predator (Chiu and Hsu, 1998), z . We shall adopt the term ‘top- predator’ in this paper. The top predator also feeds on the primary producer x, thus making the system a simple food web. From some of the references we have consulted, especially those related to species interactions in food chains and food webs (Cushing, 1984; Dubey and Upadhyay, 2004; Chiu and Hsu, 1998; Hsu et al, 2000; Hsu et al, 2001; Hsu et al, 2003 and Loladze et al, 2004), very few are related to a food web. Most of the publications are based on either simple three-trophic level food chains, or two predators competing for a single prey. The works of Basset et al (1997), Diehl and Feibel (2000), Tanabe and Namba (2005) and Mccann and Hastings (1997) are some of the few that considered a three-trophic level predator-prey interactions, with omnivory. Omnivory here refers to the feeding on nonadjacent trophic levels, either simultaneously or at different times in the life-history of the predator. However, while Basset et al examined the effect of enrichment on the stability of a general system, Tanabe and Namba, and Mccann and Hastings considered the effects of omnivory on the stability of a food web. There seems to be no agreement yet on whether or not omnivory destabilises a food web. Tanabe and Namba (2005) in their work concluded that the addition of omnivory to a food chain completely destabilises it. On the contrary, Maccann and Hastings (1997) submitted that omnivory rather stabilises a food web. In the current work, we want to argue that omnivory, in general, does not destabilise a food web. The stability or otherwise of a food web may depend on the functional response(s) used. This is rather intuitive, and is therefore subject to more rigorous analysis. We are interested in determining conditions for coexistence of the three interacting species, using specific and realistic functional responses. The remaining parts of the paper are organised as follows: section 2 is dedicated to the formulation of the model, analysis of the model will be the subject of section 3. Numerical simulation will be done in section 4. We conclude by giving the summary of main results.
Mathematical formulation We construct a model for predator-prey interactions in a three-trophic level food web. This model consists of a primary producer x, called the prey, an intermediate predator y, and a top-predator, z. The simple food web under consideration is typical of a pond food web with the Benthos as the prey, crayfish as the intermediate predator and fish as the top-predator. The interactions of these three species are represented in Fig 1.
34
J. N. Ndam and T. G. Kassem: Continental J. Applied Sciences 4: 32 - 43, 2009
x y z
Figure 1: A diagrammatic representation of a three-trophic level food web The model is based on the following basic assumptions: (i) the prey x has a logistic growth in the absence of predators. (ii) the intermediate predator y has a BD-functional response, while the top- predator z, has a Holling’s type III functional response. (iii) intraspecies competition is more intense among the intermediate predators than among the top-predators for obvious reasons, hence the use of the BD-functional response which captures such interference. (iv) the intermediate predator has no economic value in the sense that the farmer is only interested in the fish, thus only the top-predator is being harvested at a rate proportional to its density. (v) the intermediate predator and the top-predator have the same natural mortality rate, µ.
We then have the system
dx
dt= rx 1−
x
K
−a1xy
λ + x + γ y−
a2x2z
α 2 + x2 (3)
dy
dt=
b1xy
λ + x + γ y−
a3y2z
β 2 + y2− µy (4)
dz
dt=
b2x2z
α 2 + x2+
b3y2z
β 2 + y2− µz− qz (5)
x(0) > 0, y(0) > 0, z(0) > 0 (6)
where r > 0 is the intrinsic growth rate of the prey and K > 0 is its carrying capacity, µ > 0 and q > 0 are the mortality rate of the predators and the combined harvesting effort of the top-predator respectively. The other positive constants ai , bj , α, β, λ and γ, with i, j = 1, 2, 3 have the same meanings as defined in
(1) and (2) above. We normalise equations (3)-(5) using the following scaling variables:
t =t *
r, x = Kx* , y = Ky* , z = Kz* , a1 = ra1
* , a2 = ra2* , a3 = ra3
* , b1 = rb1* ,
b2 = rb2* , b3 = rb3
* , µ = rµ* , q = rq* .
35
J. N. Ndam and T. G. Kassem: Continental J. Applied Sciences 4: 32 - 43, 2009 We then obtain the following system after dropping asterisks:
dx
dt= x 1− x( )−
a1xy
m1 + x + γ y−
a2x2z
m22 + x2 (7)
dy
dt=
b1xy
m1 + x + γ y−
a3y2z
m32 + y2 − µy (8)
dz
dt=
b2x2z
m22 + x2 +
b3y2z
m32 + y2 − µz− qz (9)
where m1 =λK
, m2 =αK
, m3 =βK
.
Analysis of the Model We are particularly interested in the existence and stability of the interior equilibrium point (xc , yc, zc ).
However, for the coexistence of the three species x, y and z , it is sufficient that the system admits the
coexistence of x and y in the absence of z , and the coexistence of x and z in the absence of y (Brauer et
al, 2001). One then obtains the systems
dx
dt= x(1− x) −
a1xy
m1 + x + γ y
dy
dt=
b1xy
m1 + x + γ y− µy (10)
and
dx
dt= x(1− x) −
a1x2z
m22 + x2
dy
dt=
b2x2z
m22 + x2
− µz− qz (11)
For system (10), we obtain the interior equilibrium points (xc1, yc1
) and (xc2, yc2) ,
Where
xc1 =1
2b1γA + A2 + 4a1b1m1γµ
, yc1 =
1
µγ[(b1 − µ)xc1 − µm1],
xc2 =1
2b1γA − A2 + 4a1b1m1γµ
, yc2 =
1
µγ[(b1 − µ)xc2 − µm1]
and A = γ b1 + a1µ − a1b1. We note that the first interior equilibrium point (xc1, yc1
) exists if and only if
b1xc1 ≥ µ(xc1 + m1) and γ b1 + a1µ ≥ a1b1,
36
J. N. Ndam and T. G. Kassem: Continental J. Applied Sciences 4: 32 - 43, 2009 while the second point (xc2, yc2) exists if and only if
γ b1 + a1µ ≥ a1b1 + A2 + 4a1b1m1γµ
and b1xc2 ≥ µ(xc2 + m1). The Jacobian matrix J1, for this system becomes
J1 =1− α11 −α12
α21
b1
a1
α12 − µ
where α11 = 2xci + a1yci
(m1 + γ yci )
(m1 + xci + γ yci )2, α12 =
a1xci(m1 + γ xci )
(m1 + xci + γ yci )2
and
α21 =b1yci(m1 + γ yci )
(m1 + xci + γ yci )2,
and i = 1,2. Thus the interior equilibrium (xci,yci ) is locally stable if and only if
1+b1
a1
α12 < µ + α11 and µα11 + α12α21 +b1
a1
α12 > µ +b1
a1
α11α12 .
System (11) has the interior equilibrium point (xc, zc) , where
xc = m2
µ + q
b22 − (µ + q)
, zc =(1− xc)(xc + m2
2)
a2xc
and this exists for b22 > µ + q and of course, xc ≤ 1 .
To determine the local stability of this equilibrium point, we obtain the Jacobian matrix,
J2 =1− β11 −β12
β21
b2
a2
β12 − (µ + q)
where
β11 = 2xc +a2m2
2zc
(mc2 + xc
2)2, β12 =
a2xc2
mc2 + xc
2, and β21 =
b2m22zc
(mc2 + xc
2)2.
37
J. N. Ndam and T. G. Kassem: Continental J. Applied Sciences 4: 32 - 43, 2009 The equilibrium point is therefore locally stable if and only if
β11 + µ + q > 1+b2
a2
β12
and
β12 β12 +b2
a2
+ β11(µ + q) > µ + q +
b2
a2
β11β12.
It is also worth noting that the origins for the systems (10) and (11) are both unstable, which further supports the possibility of a stable coexistence of the three species x, y and z. It is worth noting here that the stability of the interior equilibria of the systems (10) and (11) implies the stability of the interior equilibrium points of the three-dimensional system (7) − (9) (Brauer et al, 2001). The stability of the intermediate and top-predator washout equilibrium point
(1, 0, 0) is also examined. The Jacobian matrix at this point is given by
J =
−1 −a1
m1 + 1−
a2
m22 + 1
0b1
m1 + 1− µ 0
0 0b2
m22 + 1
− µ − q
The characteristic polynomial is given by
λ 3 + α1λ2 + α2λ + α3 = 0, (12)
where
α1 = 1+ 2µ + q −b1
m1 + 1−
b2
m22 + 1
,
α2 =b1b2
(m1 +1)(m22 + 1)
+ µ + (1+ µ)(µ + q) −b1(1+ µ + q)
m1 + 1−
b2(1+ µ)
m22 + 1
and
α3 =b1b2
(m1 + 1)(m22 + 1)
+ µ(µ + q) −b1(µ + q)
m1 + 1−
b2µm2
2 + 1.
Thus, the (1, 0, 0) is locally asymptotically stable if and only if
α1 > 0, α3 > 0, α1α2 > α3.
38
J. N. Ndam and T. G. Kassem: Continental J. Applied Sciences 4: 32 - 43, 2009 That is
1+ 2µ + q >b1
m1 + 1+
b2
m22 +1
,
b1b2
(m1 + 1)(m22 + 1)
+ µ + (1+ µ)(µ + q) >b1(1+ µ + q)
m1 + 1+
b2(1+ µ)
m22 + 1
,
b1b2
(m1 + 1)(m22 + 1)
+ µ(µ + q) >b1(µ + q)
m1 + 1+
b2µm2
2+1
and A1B1 + A2B2 + C2 > A1B2 + A2B1 + C1,
where
A1 = 1+ 2µ + q, A2 =b1
m1 +1+
b2
m22 , B1 =
b1b2
(m1 + 1)(m22 + 1)
+ µ + (1+ µ)(µ + q),
B2 =b1(1+ µ + q)
m1 + 1+
b2(1+ µ)
m22 + 1
, C1 =b1b2
(m1 + 1)(m22 + 1)
+ µ(µ + q)
and
C2 =b1(µ + q)
(m1 + 1)+
b2µm2
2 + 1.
Numerical Simulation The solution of the system is obtained numerically using Matlab ODEs solvers. The parameter values used in the simulation are a1 = 0.8, a2 = 0.6, a3 = 0.25, b1 = 0.9, b2 = 0.5, b3 = 1.9, m1 = 0.4, m2 = 0.2, m3 = 0.2, µ = 0.1, γ = 0.9 and q = 0.5. These are rather arbitrary, though similar to those used by Steffen et al (1997). The results show a wide variation in the dynamics of the model. The figures shown in this work are only meant to highlight some special aspects of the model.
39
J. N. Ndam and T. G. Kassem: Continental J. Applied Sciences 4: 32 - 43, 2009
Figure 2: Stable oscillations of the interacting species with time. The parameter values used in this figure are a1 = 0.8, a2 = 0.6, a3 = 0.25, b1 = 0.9, b2 =0.5, b3 = 1.9, m1 = 0.4, m2 = 0.2, m3 = 0.2, µ
= 0.1, γ = 0.9, q =0.5.
Figure 3: (a) Steady state coexistence of the species with initial values (0.3, 0.2, 0.1) and parameter values m1 = 0.8, m2 = 0.25, m3 = 0.16, and the rest are as in figure 2. (b) Coexistence of three species in form of limit cycle. Parameter values used are the same as in figure 2.
For instance, figure 2 shows stable oscillations of the three species for certain parameter values, while figures 3(a) and 3(b) show steady state coexistence of the three species and coexistence in form of a limit cycle respectively. In this figure, the limit cycle may surround an unstable equilibrium, but does not lead to extinction of the species since it is far away form the origin, as argued by Arditi et al (2004). The results shown on the figures have been plotted for 0 ≤ t ≤ 200, where t is the time course of the solution.
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J. N. Ndam and T. G. Kassem: Continental J. Applied Sciences 4: 32 - 43, 2009
Figure 4: Stable interior equilibrium (xc , yc, zc ) = (0.44968, 0.19882, 0.73576) . Parameter values used are the same as in figure (3a).
The stability analysis of the equilibrium points indicates the existence of stable equilibria under certain conditions. In fact, with the parameter values used in figure 4, one obtains one interior equilibrium (0.44968, 0.19882, 0.73576). Figure 4 clearly depicts the stable interior equilibrium as predicted by the analysis carried out earlier.
Figure 5: Mean population density and amplitude oscillations against the top- predator’s maximum consumption rate. The parameter values used in this figure are the same as in figure 2
CONCLUSIONS/SUMMARY OF MAIN RESULTS A model for the interactions of three species in a food web has been constructed. A combination of the Holling’s type III and the BD-functional responses which are known to be most appropriate for capturing the interactions among species, especially vertebrates, in an ecosystem (Arditi et al, 2004; Hsu et al, 2003) have been used. The result shows the existence of a stable interior equilibrium. The results also indicates the coexistence of the three species in form of stable limit cycles as can be seen from figures (2) and (3b). There is steady state coexistence of the species as depicted in figures (3a) and (4). Omnivory does not destablise the food web in this model.
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J. N. Ndam and T. G. Kassem: Continental J. Applied Sciences 4: 32 - 43, 2009
Figure 6: Mean population density and amplitude oscillations against the com- bined harvesting efforts for the top-predator. The parameter values used in this figure are the same as in figure 2 An indication of that could be seen from figure (5). However, we note that over harvesting, that is, harvesting beyond a given value of the combined harvesting efforts q, induces chaos. This can be seen from figure (6). Instability sets in from q ≥ 0.8. This result could be useful in the management of fisheries and other species that interact in a similar manner. The implication of this is that it is possible to maintain for example, a fishery without the need for any resource enrichment, apart from the initial input, as the species will grow and stabilise, with a density-dependent harvesting of the economically more viable species, which in this case is the top-predator, provided stability conditions for coexistence of the species are observed. This may not be easy to manage, unless there is a way to determine the number of the viable species at any moment in time. Moreover, this model does not take into account the mobility of one or more of the species involved in the food web. However, the use of the Holling’s type III and the BD-functional responses still provide protection to the prey at low densities and also take into account the interference among predators, thus making the model physically realistic. Also, there is need for an experiment to verify the result. These are subjects for future consideration. ACKNOWLEDGEMENT This work is supported by the University of Jos, Faculty of Natural Sciences Research grant (FNS/RG/2006/2007/002). REFERENCES Arditi R., J.-M. Callois, Y. Tyutyunov and C. Jost (2004): Does mutual interference always stabilise predator-prey dynamics? A comparison of models. C. R. Biologies. 327: 1037-1057. Basset, A. D. L. DeAngelis and J .E. Defendorfer (1997): The effect of functional response on the stability of a grazer population on a landscape. Ecological Modelling. 101:153-162 Brauer F and C. Castillo-Chavez (2001): Mathematical Models in PopulationBiology and Epidemiology Springer, New York. Cantrell R. B and C. Cosner (2001): On the Dynamics of Predator-Prey Models with the Beddington-DeAngelis Functional Response. J. Math. Anal. Appl. 257:206-222. Cushing J. M. (1984): Periodic Two-Predators, One-Prey Interactions and the Time Sharing of a Resource Niche. SIAM Journal on Applied Mathematics. 44:392-410 . Diehl S. and M. Feibel (2000): Effects of Enrichment on Three-Level Food Chains with Omnivory. The American Naturalist. 155: 200-218.
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J. N. Ndam and T. G. Kassem: Continental J. Applied Sciences 4: 32 - 43, 2009 Dubey B and R. K. Upadhyay (2004): Persistence and Extinction of One- prey and Two-predators Systems. Nonlinear Analysis: Modelling and Control. 9: 307-329. Edelstein-Keshet L. (2005): Mathematical Models in Biology, Society for Industrial and Applied Mathematics, USA. Chiu C.-H. and S.-B. Hsu (1998): Extinction of top-predator in a three-level food- chain model. J. Math. Biol. 37: 372-380. Hsu S.-B, Y.-S. Li and P. Waltman (2000): Competition in the presence of a lethal external inhibitor. Mathematical Biosciences. 167: 177-199. Hsu S.-B,T.-W. Hwang and Y. Kuang (2001): Rich dynamics of a ratio-dependent one-prey two-predators model. J. Math. Biol. 43: 377-396. Hsu S.-B, T.-W. Hwang and Y. Kuang (2003): A ratio-dependent food-chain model and its applications to biological control. Mathematical Biosciences. 181: 55-83. Hsu S.-B and P. Waltman (2004): A survey of mathematical models of competition with an inhibitor. Mathematical Biosciences. 187: 53-91. Hwang T.-W (2003): Global analysis of the predator-prey system with Beddington- DeAngelis functional response. J. Math. Anal. Appl. 281: 395-401. Kassem T. G and J. N. Ndam (2009): On the dynamics of predator-prey interactions in a three-trophic level food chain. Far East Journal of Applied Mathematics.34: 95 - 110. Kot M (2001): Elements of Mathematical Ecology, Cambridge University Press, United Kingdom . Lee S.-H, H. K. Pak, H. S. Wi, T.-S Chon and T. Matsumoto (2004): Growth dynamics of domain pattern in a three-trophic population model. Physica A. 334: 233-242.
Liu S and E. Beretta (2006): A stage-structured predator-prey model of Beddington-DeAngelis type. SIAM J. Appl. Math. 66: 1101-1129. Loladze I, Y. Kuang, J. J. Elser and W. F. Fagan (2004): Competition and stoichiometry: coexistence of two predators on one prey. Theoretical Population Biology. 65: 1-15. Mccann K and A. Hastings (1997): Re-evaluating the omnivory-stability relationship in food webs. Proc. R. Soc. Lond. B. 264: 1249-1254. Skalski G. T and J. F. Gilliam (2001): Functional responses with predator interference: viable alternatives to the Holling’s type II model. Ecology. 82: 3083-3092. Steffen E, H. Malchov and A. B. Medvinsky (1997): Effects of seasonal perturbations on a model Plankton community. Environmental modelling and Assessment. 2: 43-48. Tanabe K and T. Namba (2005): Omnivory creates chaos in simple food web models. Ecology. 86: 3411-3414.
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J. N. Ndam and T. G. Kassem: Continental J. Applied Sciences 4: 32 - 43, 2009 Received for Publication: 17/03/2009 Accepted for Publication: 13/05/2009 Corresponding Author J. N. Ndam Department of Mathematics, University of Jos, P.M.B 2084, Jos, Nigeria Email address: [email protected]
AN INVESTIGATION INTO THE QUALITY OF COARSE AGGREGATE UTILIZED ON
CONSTRUCTION WORKS IN NIGERIA
Ayodele, Elijah Olusegun Department of Quantity Surveying, Rufus Giwa Polytechnic, Owo, Nigeria.
ABSTRACT This paper investigates into the quality of coarse aggregate utilized in the Construction Works in Nigeria. This was carried out by means of sieves and cubic measuring container to sieve and measure respectively, the quantity of gravels whose size of stones were between 5mm-40mm for foundation mass concrete, and between 5mm-20mm for reinforced concrete on both private developer and government client sites. Due to the constraints of fund and time, the investigation was limited to Ondo State of Nigeria, where 25 sites of private developers and 25 sites of government client were visited. Data obtained formed the basis of this study. The study showed that: local gravels were used on private developers’ sites, while granite were used on most government sites. For reinforced concrete work 24% of the private developers sites studied utilized gravel that is of good quality (containing above 70% of 5mm – 20mm stones in the load), while the rest 76% of sites visited utilized loads of gravel that are of a poor quality (containing less than 70% of 5mm – 20mm stones in the load. For mass concrete 20% of the private developers sites utilized gravel that are of a good quality (containing above 70% of 5mm – 40mm stones in the load), while 80% of the sites utilized a poor quality gravel (containing less than 70% of 5mm – 40mm stones in the load). It is therefore recommended that the use of local gravel be discouraged and the use of granite be encouraged. To encourage the use of granite; Nigerian government and private companies should establish quarries in places where there’s abundance of rock in Nigeria. When granite is produced in large quantity, price of it will fall within the available financial reach of private developers. KEYWORDS: Coarse Aggregate, Granite, Local Gravel, Construction Work, Ondo State, Nigeria.
INTRODUCTION According to Chudley and Greeno (2001) Concrete is a mixture of cement, fine aggregate, coarse aggregate and water in controlled proportions and a suitable quality. Seeley (1995) and, Chudley and Greeno (2001) describe Coarse aggregate as those materials which are retained on a 5mm sieve. Barry (1999) also describes coarse aggregate as gravel that has been crushed, washed and sieved so that the particles vary from 5mm to 50mm in size. Seeley (1995) asserts that the maximum size of coarse aggregate is determined by the class of work i.e. – with reinforced concrete the gravel must be able to pass readily between the reinforcement and it rarely exceeds 20mm, whereas for foundations and mass concrete work, the size can be increased to possibly up to 40mm. The type of aggregate used directly influences the fire protection and thermal insulation qualities of Concrete. Coarse aggregate commonly used in Nigeria are:
- Locally crushed/broken stones i.e. local gravel - Machine crushed/broken rock i.e. granite
In a building project, concrete is used as mass concrete in foundation trench, as mass concrete in floor slab, as reinforced concrete in upper floor slab, as reinforced concrete in lintels. The function of Concrete in any construction is to carry load and transfer same to a very hard stratum beneath, so as to make the structure stable. Bolaji (2002) asserts that in providing support for a building,
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Ayodele, Elijah Olusegun: Continental J. Applied Sciences 4: 44 - 49, 2009 concrete is the common material used in Nigeria (Steel is rarely used especially among private Clients). If this assertion is true, then the majority of building collapse in Nigeria must have been caused by problems associated with concrete. The choice of either mass concrete or reinforced concrete for use in foundation depends on the type of soil. Weak soil requires reinforced concrete. Background to the Problem It was reported that a four – storey shopping complex collapsed in Abuja – Nigeria on Tuesday 29th July 2008, where about 100 people were trapped. (Nigerian Tribune 30-07-2008). Table 1: Private Developers Construction Sites (20mm Coarse Aggregate
Note: 1-25 are local gravel loads According to Fadamiro (2002) the following building collapsed as a result of poor quality materials: Multi storey building at Ojuelegba, Lagos Nigeria on 28th April 1999 where three people died; Two – Storey residential building at Road 3 Plot 10 Funbi Fagun Street Abeokuta, Ogun State of Nigeria in November 1998 although no life was lost; Ogunsemi (2002) also reported the following building collapse in Nigeria due to the use of poor quality materials: Building on a Plot at junction of Ayilara Street Ojuelegba road Surulere Lagos; building at 5, Idunsagbe lane off Obun, Eko-Street Lagos; building at 44 Bamigbose Street Lagos; building 134 Tokunbo Street, Central Lagos; building at Oke Aliji Compound off John Street Lagos; Four storey building at Ajao estate, Lagos.
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Ayodele, Elijah Olusegun: Continental J. Applied Sciences 4: 44 - 49, 2009 Bamidele (2000) in a survey carried out in Lagos State discovered that 45% of building collapses were caused by poor materials and workmanship. Coarse aggregate is a major ingredient in concrete work, in construction of projects all over the world, since concrete work includes appropriate mixture of cement, sand and coarse aggregate, and reinforced concrete work includes the appropriate mixture of cement, sand, coarse aggregate and reinforcement; this study is put in place to determine the quality of coarse aggregate utilized in building projects in Ondo State of Nigeria. The objectives of this investigation are to:
1. Determine the percentage of 5mm – 40mm stones in 3.81m3 in 3 load of coarse aggregate (used in foundation)
2. Determine the percentage of 5mm – 20mm stones in 3.81m3 3 load coarse aggregate (used in reinforced concrete).
METHODOLOGY The instruments for the study include cubic measuring container, sieve etc. Populations are the 3.81m3 loads of coarse aggregate deposited on construction sites in Ondo State. Because of the constraints of finance and time, construction sites are limited to ones available in Ikare, Owo, Akure, Ondo, Okitipupa and their immediate environments. With the aid of measuring container, the volume of actual stones and other roughages in each of the 3.81m3 loads are determined on each of those sites. The information from the twenty five sites of private developers and twenty five sites on government Clients form the data, the basis of this study, the data were analyzed by percentages. RESULTS Results of the study are depicted in Tables 1 – 5. Table 2: Private Developers Construction Sites (40mm Coarse Aggregate)
Note: 1-21 are granite loads, 22-25 are local gravel loads FINDINGS Private Developers Sites: (20mm Coarse aggregates)
- Local gravel is used as coarse aggregates. - None of the local gravel has 100% stones of sizes 5mm – 20mm - Only 6 out of 25 sites (24% have above 70% of stones in the gravel load (good quality), the
rest 19 out of 25 sites (76%) has less than 70% of stones in the gravel load (poor quality). This translates to the fact that on most sites the combination of stones (5mm – 20mm) and roughages (sand, dust, dirt) add up to became local gravel. These roughages make the quality of the local gravel very poor on the private developer’s sites. Private developer sites: (40mm coarse aggregates)
- Local gravel is utilized as coarse aggregate - None of the load of gravel has 100% stones of sizes 5mm – 40mm - Only 5 out of the 25 sites (20%) have above 70% of stones in the gravel load (good quality);
the rest 20 out of 25 sites (80%) have less than 70% of stones in the gravel load (poor quality). It therefore translates to the fact that poor quality coarse aggregates have been used in construction works on private developer’s sites.
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Ayodele, Elijah Olusegun: Continental J. Applied Sciences 4: 44 - 49, 2009 Table 4: Government Client’s Construction Sites (40mm Coarse Aggregate)
Note: 1-19 are granite loads, 20-25 are local gravel loads Government Client Sites: (20mm Coarse aggregate)
- Granite and local gravel were used as coarse aggregate. - 21 out of 25 sites (84%) studied utilized granite, containing 100% stones (5mm – 20mm),
(good quality). - 4 out of 25 sites (16%) studied utilized local gravel: 2 of the 4 sites (50%) has less than 70%
of stones in the gravel load (poor quality), the rest 2 out of 4 sites (50%) have above 70% of stones in the gravel load (good quality). All these boil down to the fact that 2 out of 25 sites (8%) utilized poor quality coarse aggregate on Government client sites.
- Government Client Sites: (20mm Coarse aggregate) - Local gravel and granite were used as coarse aggregate. - 19 out of 25 sites (76%) studied utilized granite containing 100% stones (good quality). - 6 of the 25 sites (24%) studied utilized local gravel: out of the 6 only 2 sites (34%) made use
of local gravel that have above 70% stones (good quality) while the other 4 sites (66%) made use local gravel whose gravel loads have less than 70% of stones (poor quality). This translates to the fact that of the 25 sites, only 4 (16%) made use of poor quality coarse aggregate on Government client sites.
DISCUSSION The finding that none of the local gravel utilized in the works has 100% broken stones, explained further Odunlami (2002) who discovered that aggregates brought to sites come with certain percentages of impurities which may be injurious to cement and reinforcement rods.
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Ayodele, Elijah Olusegun: Continental J. Applied Sciences 4: 44 - 49, 2009 It further explains the findings of Ogunseni (2002) who surveyed the causes of collapse for selected buildings in Lagos State and one of the reasons was the use of poor quality material. Table 5: Summary of Findings
Coarse Aggregate Private Developers Sites Government Clients Sites Local
Gravel
20mm: 24% Good 76% Poor
40mm: 20% Good 80% Poor
20mm: 50% Good 50% Poor
40mm: 34% Good 66% Poor
Granite 20mm: NIL 40mm: NIL
20mm: 100% Good 40mm: 100% Good
Another finding is that all the granite utilized on sites studied has 100% broken stones/rocks and is used by government Client sites. The price of granite currently is about three times the cost of local gravel. The government can afford this, may be because it’s richer and may be because the professionals handled the jobs. The private developers made not be able to afford granite because of the poverty situation. This is in agreement with Bolaji (2002) who asserted that high cost of building materials cause Contractor/Client to resort to the use of poor quality materials. RECOMMENDATIONS Since 100% of stones may be very difficult to get in local gravel, Nigerian government and private companies should endeavour to establish quarries in places where there is large quantity of rock in Nigeria. When such rocks are broken, large quantity of granite result. The cost of granite will drop and can be purchased and used in constructions works by private developers also. REFERENCES Bamidele E.O (2000) An assessment of collapse of building structures in Nigeria (A case Study of Lagos State). Unpublished PGD Thesis, Federal University of Technology Akure Barry R. (1999) The Construction of Buildings, Vol. 1, Sixth edition. New-Delhi: Affiliated East-West Press Pvt Ltd. Bolaji E.O. (2002) Building materials specifications and enforcement on sites. In Ogunsemi D.R. edited: Building collapse: causes, prevention and remedies. Nigeria Institute of Building Workshop, Akure Chudley R. and Greeno (2001) Building Construction Handbook; 4th edition. Oxford: Butterworth-Heinman. Fadamiro J.A. (2002) An assessment of building regulations and standards and the Implication for building collapse in Nigeria: In Ogunsemi D.R. edited Building collapse: Causes, prevention and remedies Nigeria Institute of Building Workshop Akure. Nigerian Tribune (30th July 2008) Abuja Tragedy: 100 trapped in collapsed shopping plaza. Odunlami A.A. (2002) Building materials specification and enforcement on site. In Ogunsemi D.R. edited: Building collapses: causes, prevention and remedies Nigerian Institute of Building Workshop, Akure. Ogunsemi (2002) Cost Control and quality standards of building projects. In Ogunsemi D.R.edited: Building collapses: causes, prevention and remedies Nigerian Institute of Building Workshop, Akure. Seeley I.H. (1995) Building Technology, 5th edition. New York. Palgrave Received for Publication: 17/05/2009, Accepted for Publication: 13/06/2009
Idowu, I.A, Abdurasid, A.A and Adeniyi, M. O Department of Mathematics, Lagos State Polytechnic Ikorodu.
ABSTRACT In this paper a quality discussion was carried out on arresting the constantly recurring of performance in mathematics in our various higher institutions. To arrest this situation is to evaluate the extent of the students who have been inspired to think and create ideas. Therefore effective teaching involves all activities which would help inspire the students to learn and create ideas, so we look into some strategies. KEYWORDS: Arresting, poor performance, higher institutions, inspired, strategies.
INTRODUCTION Mathematics is among the most fascinating of all intellectual disciplines, the purest of all forms, and the most challenging of games. The study of Mathematics have an opportunity to makes a lasting contribution to society by helping to solve problems in such diverse field as medicines, management, economics, government, computer science, physics, psychology, engineering and social science. A bachelor’s degree in mathematics will prepare you for fascinating jobs in statistics, actual science, Mathematical modeling and cry photography; for teaching; as well as for graduate school leading to a research career in mathematics or statistic. A string background in mathematics is also necessary for research in many areas of computer science, social science and engineering. Ale (1980) consider in his study of the difficulties confronting teachers of Mathematics in West Africa, identified through the use of questionnaires. And part of the objective of his study was to determine the major difficulties confronting Mathematics teachers and also to quantify the gravity of these difficulties. OBJECTIVES OF THE STUDY (a) To develop a technique for obtaining solutions to the problem of constantly recurring of poor
performance in Mathematics. (b) To analyzes the arresting of constantly recurring of poor performance in Mathematics. (c) To carry out some possible solutions that can help the situation.
APPLICATION The result can be used by both teachers in primary and secondary school, also the lecturers in our various higher institutions.
PROBLEM
(A) Students:- The main problems of student in this regard is : Poor attitude to work:- students of nowadays find it difficult to devote time to study generally because they are lazy and want to enjoy life without putting anything into it. To do assignments, projects and even to listen in class become a big problem.
(B) Lecturer:- Lecturer is the main determinants of quality/quantity of any educational system. Teaching is far more than transmitting facts and information. Hence, it is a saying that ‘a poor teacher tells’ ‘an average teacher informs a good teachers and an excellent teachers inspires”
(C) Government: - Not just anybody should be employed to teach Mathematics, hence, unqualified Mathematics teachers should not be employed and large classes should be addressed.
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Idowu, I.A et al.,: Continental J. Applied Sciences 4: 50 - 53, 2009 METHOD OF SOLUTIONS. To arrest the situation, is to evaluate the extent the students have been inspired to think and create ideas. Therefore effective teaching involves all activities which would help to inspire the students to learn and create ideas, so, we look into strategies: Strategies For Effective Teaching For effective teaching, lecturer must know the stuff, the pupils whom they are stuffing and how to stuff them artistically. This artistry of teaching involves motivating and sustaining the interest of students in mathematics and challenge many reluctant learners who comes our oath daily. The strategies are: Developing The Interest Of Students:- Student can learn and will learn when appropriate program are provided to generate their interest in mathematics. Interest leads to positive which leads to better performance of students.
We can develop interest of student through (i) enrichment of content such as Mathematics games. History of Mathematics and application of Mathematics (ii) Good lesson plan: (iii) good presentation of lessons and goals of instruction that rise curiosity, (iv) Punctuality to class, use of instructional materials, use of relevant teaching methods and popularization of Mathematics in the school. Adoption Of Discovery Method Of Teaching:- The use of “ the telling method” should be out of place. This involves preparing lessons notes and just passing the knowledge to the students by telling them. It is not effectives. Teachers are therefore encouraged to use discovery methods of teaching in the classroom. This is supported by the popular Chinese proverb: “What I hear I forget, what I see I remember, what I do I understand” Think of how to teach the following topics using the discovery approach
i. Sum of angle of the triangle ii. Circle theorem iii. Area of rectangles iv. Logics v. Binary system vi. Set theory vii. Indices & logarithms viii. Bearings e.t.c.
Awards To Good Students:- Awards for some levels of achievement in Mathematics is a source of extrinsic motivation of interest. We could organize competitions and reward the good students. This could be informed of assignments, Mathematics of the week e.t.c.
Popularization
Better performance Interest
Positive Attitude
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Idowu, I.A et al.,: Continental J. Applied Sciences 4: 50 - 53, 2009
Formation of Mathematics Club:- This helps to popularize Mathematics in the school and leads to generation of interest in the studying of the Mathematics among students. Part of the clubs activities include counseling, remedial lessons, excursions, organizing Mathematics days, drama, making of models and charts of Mathematics concept and general exchange of ideas in Mathematics.
Keeping students abreast with topics covered in secondary schools:- one major problems affecting student of Mathematics is that many of them may understand Mathematics topics during lesson but they soon either forget, or find it difficult to revise the topics after some times. Hence they soon forget the topics already thought. For instance 100 levels student hardly remember Senior Secondary School topics. This is one of the reasons why some Students perform poorly in higher institution. The teachers therefore should introduce some strategies to enables student revise topics in Senior Secondary School classes. Some strategies are: assignment on past topics, revision and project work. Adoption of Reader Friendly Textbooks:- many Mathematics textbooks are not reader friendly. Hence many students find it difficult to read them. This also affects student performance. A reader friendly Mathematics textbook should have the following qualities:
(i) High level of simplistic approach to Mathematics concepts (ii) Attractive and enjoyable to the pupils reading the book. (iii) Arouses and sustain the interest of students while reading the book (iv) Simple style of language for explaining Mathematics concepts (v) Logical arrangement of topics to enhance understanding by students. (vi) Gives various examples on a concept (topics) showing different way by which questions
could be asked on the topics
Establishment of Mathematics Corners: - Mathematics corner could be informed of notice boards where Mathematics facts, formulae and information could be displayed for the students on weekly basic. This helps the student to revise the Mathematics topics and also popularize Mathematics in the school. Classroom organization: - A number of factors complicate the problem of classroom organization such as the number of students, the size of the room, the furniture, the availability of space and facilities. In many schools no class is fewer than fifty students, one wonders how a single teacher could take care of fifty students (or more) at a time. In most cases the rooms are too small and poor ventilated. It becomes very difficult for any teacher to establish any chose individually contacts with the students. Two major problems emanate form of the above: to arrange Children into suitable learning groups and how to provide them with the materials with which to explore. Recruitment of Qualified Mathematics Lecturer: - Mathematics lecturer employed is few and most of them are not adequately qualified. Without proper qualifications and proper training they fail to do justice to the subject. An adequate high qualification develops self confidence in the teacher and serves as a source of inspiration to his students. When a teacher has too much teaching loads, he cannot adopt and prepared for effective methods as he very little time available forth-hearted worker shim. His teaching load should be lightened to enable him show his originality and initiative. Also training and re-training of Mathematics teachers will go a long way in the improvement of the undergraduate results. Lecturer incentive and promotion: - The economic position of lecturer not good enough. He is always worried about his financial position and, a worried lecturer cannot give off his to the learners. He is tempted to engage in part- time activities to supplement his income. Consequently teaching suffers, he is frustrated, discontented and half- hearted worker. So, there is need for
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Idowu, I.A et al.,: Continental J. Applied Sciences 4: 50 - 53, 2009
lecturer special salary and also promotion as at when due. CONCLUSION In conclusion, the new instructional style requires lecturer to move away from ‘telling’ or ‘lecturing method’ and move towards involving the student, Monitoring the students’ readiness and checking for understanding. Lecturer should not stay gloved to the chalkboard as this promotes students passivity and management problems in the classrooms. This also limits the ability of lecturer to effectively diagnose the students’ readiness and understanding. Our government should on the hand find every way of making teaching and learning conducive for lecturers and students respectively. REFERENCE Bills, C. (2003): What can teachers learn from the language that children use? Education 3-13, 31(1): 66 71. http:11 www. Leeds. ac.uk/ educol /document/ 00003267. htm Misherry, K and Ollerton, M (2002): Grouping patterns in primary schools. Mathematics in school, 31(1): 2-7 Myhill, D. (2002): Bad boys and good girls? Patterns of interaction and responses in whole class teaching, British Educational Research journal, 28(3): 339-352. Raiker, A. (2002): Spoken language and mathematics, Cambridge Journal of Education 32 (1): 45-60 Sam O. Ale (1980): Difficulties facing mathematics teachers in developing countries – A case study of Nigeria Educational studies in mathematics 12: 499- 489. Received for Publication: 17/12/2008 Accepted for Publication: 13/05/2009 Corresponding Author Idowu, I.A, Department of Mathematics, Lagos State Polytechnic Ikorodu. E-Mail: ejabola@yahoo. Com.
Ihom,A.P1, Ogbodo Joy2, Agunsoye Johnson3 and Bam, S.A4 1National Metallurgical Development Centre, Jos, PMB 2116 Jos- Plateau State, 2Scientific Equipment
Development Institute, Enugu, 3University of Lagos Akoka, Dept. of Materials and Metallurgical Engineering, 4University of Agriculture, Makurdi, Dept. of Mechanical Engineering, PMB 2373 Makurdi.
ABSTRACT A simplified chucking-indexing fixture has been designed, to be used on the lathe machine. It is a modification of the one used on the milling machine. The design have specified the dimensions, and materials to be used for the production of the individual components of the simplified chucking – indexing fixture. A complete drawing of the fixture has also been done. Stress and load analysis of the critical parts of the simplified chucking-indexing fixture has been carried out. The specified compression spring has a spring constant of 3.75KN/m. The loading on the spring due to a deflection of 30mm is 112.5N. The shear stress on the coils of the spring was 350.3MPa at the same loading of 112.5N. The shear stress was far less than the ultimate shear stress of the compression spring, which was equal to 833MPa. Therefore, the spring can be taken to be safe. The design of the collet extension shaft showed that the least diameter for the collet extension shaft given the design loading of 112.5N was 0.98mm. The design however, specified 20mm, since this diameter meets both the functional and strength requirement of the design. KEYWORDS: Design, Simplified, Chucking-indexing, Fixture, Lathe machine.
INTRODUCTION In an era where there is competition among producing outfits. Creativity and ingenuity is needed for survival of businesses. Tooling is often more of an art than a science. In the past, the secret techniques of the tooling ‘’artist’’ gave a trade advantage to many a successful businesses. Even the man in the shop jealously guarded his little secrets of the trade from fellow mechanics in the hope of economic gain. In this unfortunate atmosphere, the art often died with the artist (Harold, 1967). Today, the climate is changing. Technical books, trade journals, and professional and trade associations have done much to promote an interchange of information. Still, there remains a notable sluggishness in the spread of tooling ideas. Techniques that make an operation simple in one shop are too often unknown in another. There are few fields where a cross fertilization of ideas is more sorely needed and ironically, more potentially profitable. The simplified chucking – indexing fixture was first used on the milling machine, where it was applied for milling eight radial slots (Harold, 1967). This design is intended to modify the simplified chucking – indexing fixture, for use on the lathe machine. The fixture to be produced has to be cheap, quick, easy to operate, and that makes the tooling device interesting. Lathe Machine The lathe is one of the oldest machine tools (Edgar, 1965). There are several other machine tools such as the shaper, grinder, milling machine, and drilling machine. These machines are used in the factory as production equipment. A diagram, showing the principal parts of the lathe machine is shown in figure 1. The characteristic features of the lathe such as: through-going hollow spindle, cross and longitudinal motion of its slides can be applied to develop and produce a simplified chucking – indexing fixture for the lathe machine, which holds a work piece on the inside diameter, while locating on the outside.
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Ihom,A.P et al: Continental J. Applied Sciences 4: 54 - 64, 2009 Design Process Ruiz (1964) defines design as the transformation of parameters influencing a physical process into concrete machine components, and the designer’s work as the realization of a required physical process by means of a practical solution, a task as complex as that of a researcher who has to deduce physical laws from observed natural phenomena. The objective of this study is to design a simplified chucking-indexing fixture for the lathe machine, clearly showing the design calculations and the necessary sketches of the fixture detail parts and the assembly drawing. MATERIALS AND METHODS Materials and Equipment The simplified chucking – indexing fixture which has its origin from the milling machine, has been redesigned for use on the lathe machine. For design purpose the materials and equipment which served as a guide were:
(i) a lathe machine with the following specifications: • lathe size according to British specification: 153mm x 775mm • power rating of driving motor: 2.2Kw • spindle diameter: outside diameter: 42.2mm, inside diameter: 32.4mm
(ii) a diagram of the simplified chucking – indexing fixture as was first used on the milling machine.
(iii) preliminary sketches of the simplified chucking – indexing fixture for the lathe machine, and
(iv) Design manuals, pencils and drawing instruments. Methods and Techniques The first step in the development of an idea is to prepare the preliminary sketches of the design (NYSVP, 1968). From the sketches produced of the new fixture, the important dimensions needed for the design of the simplified chucking –indexing fixture was: (i) the swing or the height of the lathe from the bed to the spindle center; (ii) the length from the headstock spindle center to the tailstock spindle center; and (iii) the dimensions of the headstock spindle. After the procurement of these dimensions, the dimensions of the fixture were then obtained. Figure 2, showed the simplified chucking- indexing fixture, as redesigned for the lathe machine. The simplified chucking- indexing fixture is designed in such a way that the blank is held using special collet B. The work- rest A eliminates the need for gauging depth dimensions of the parts to be machined. It also houses the compression spring; the collet extension shaft and the collet expander. The collet expander C is connected to the collet extension shaft F by screwing the extension shaft into the collet expander, which has a threaded hole. The collet extension shaft is attached to the operating lever G by riveting a pin that passes through them. The loading and unloading of the fixture is enhanced by the compression spring E. The lever is pressed to unload the work piece and released to load the work piece. The washer I lie between the collet expander and the compression spring, it enhances the compression of the spring because of increased contact. The holding pins H are used for fixing the fixture to the lathe machine. The housing D is made of standard steel tube of 120mm in diameter.
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Ihom,A.P et al: Continental J. Applied Sciences 4: 54 - 64, 2009 Techniques The fixture is going to be subjected to a turning moment or torque from the lathe machine. The cutting forces acting on the work piece are also transmitted into the fixt ure. This calls for a strong and solid design that can withstand these forces. According to Bolton (1991) materials selection for a product is based upon a consideration of the properties required. The design of structural systems is based on many considerations. Functional requirements certainly play the key role in the selection and arrangement of structural members and machine parts (Egor, 1968). The design, however will specifically look at ‘’ the design meeting strength requirements’’. The stress analysis and loading of the various parts will now be considered. Compression Spring Selection The design specifies the square and ground ends type spring to be used for the simplified chucking –indexing fixture. The functional requirements of this fixture depends on the compression spring, and therefore a detail analysis of the stresses and forces acting on the compression spring is preferred to just stating the compression spring specifications. The spring is made of carbon steel. The deflection of the spring gives rise to potential energy in the compression spring, which is used in gripping the work piece and unloading the fixture. The total number of coils is given by n + 2. The spring constant (Handa, 1987) is given by:
Ks = F/٨ = Gdw4/ 8D3n …. (1)
Where, D = Spring mean diameter (m); F/ ٨ = Load per deflection (N/m); G = Shear modulus of elasticity (N/m2) dw = Coil diameter of the spring (m) n = number of active coil. The selection of the compression spring is also based on the collet extension shaft diameter and the inside diameter of the work rest as well as its length and strength. The spring used has the following specifications: n = 8, dw = 3mm = 0.003m, D = 30mm= 0.03m, G = 80GPa. From equation (1)
Ks = 80 x 109 x (0.003)4/ 8 x (0.03)3 x 8 = 6.48/ 1.73 x 10-3 = 3.75 KN/ m The transverse load acting on the compression spring when it is loaded is given by
F = ٨ SK ….. (2) A deflection of 30mm is to be utilized for the gripping of the work piece. From equation 2 the loading on the spring is
F = Ks٨ = 3750 x 0.03 = 112.5N Higher spring compression can be obtained for unloading or removing the work piece from the fixture. The torsional moment on the spring coils is given by
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Ihom,A.P et al: Continental J. Applied Sciences 4: 54 - 64, 2009 Mt = FD/2… (3)
For a load of F = 112.5N M t = 112.5 x 0.03/ 2 = 1.69Nm The shear stress on the coils of the spring is given by
τ = Mtωt … (4) where, ωt = πd3/ 16 = 0.1964d3
ωt is the polar section modulus of the spring wire C is the spring index and is given by C = D/ d = 30/ 3 = 10 K is the spring factor and it is related to C as below
K = 4C + 2/ 4C – 3…. (5) By substituting Mt and ωt, equation 4 becomes,
= KMt/ ωt = K8FD/ πd3…. (6) C varies between 8 and 12 and K varies between 1.1- 1.2 (Orlov, 1980). For K = 1.1, D = 0.03m, F = 112.5N, π = 3.14, d = 0.003m, the shear stress on the coils of the spring is τ = 1.1 x 8 x 112.5 x 0.03 / 3.14 x 0.0033 = 350.3 MPa The shear stress of the compression spring, is equal to 833MPa. Therefore, the spring is safe (Baumeister, 1967 and Orlov, 1980). Potential energy due to compression or deflection is given by
U = F٨/ 2… (7) The potential energy of the spring for a deflection of 30mm (0.03m) is
U = 112.5 x 0.03/ 2 = 1.69 joules Collet Extension Shaft The collet extension shaft is attached to the collet expander by screwing it onto the collet expander. The collet extension shaft is designed of steel. The shaft is loaded in tension by the compression spring. The tension on the shaft is higher during unloading of the fixture. The stress generated in the shaft is axial. The shaft is loaded in tension. The stress (Champion, 1968) in the shaft is given by
σ = F/ A … (8) Where, σ Is the tensile stress F is the load acting on the shaft A is the cross- sectional area of the shaft The design of members for axial forces is rather simple (Egor, 1968). From equation 8 the required area for the shaft is
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A = F / σal … (9) For a circular cross-section
A = πd2 / 4…. (10)
d = √ 4A / π… (11) TABLE 1 : DESIGN CALCULATIONS AND SKETCHES
Initial Data Calculations and Sketches Results Select a structural steel rod with specification: E=207MPa σult = 414MPa σy = 25MPa σal = 150kPa F = 112.5N(calculated) Π = 3.14 The structural steel used for the shaft has an ample factor of safety against failure by plastic overload (Ashby and Jones 1994).
x F F σ x Fig.3. the Collet Extension Shaft under Tension. From equation 9 cross-sectional area of the shaft at section xx is A= 112.5/ 15X 104 = 0.75 X 10-6 m2 From equation 11 the diameter of the shaft, ds = √ 4 x 7.5 x 10-7/ 3.14 = 9.8 x 10-4m
The steel was bought in the market. The area of the cross-section at xx, A= 0.75 X10-6m2 ds = 9.8 x 10-4m = 0.98 mm
The Collet expander The collet expander holds the collet jaws. It moves and expands the collet jaws into the work piece, holding it tightly for machining. The collet expander is shown in figure 4. it has been designed to meet the functional requirement with the following specifications:
Length : 40mm Tapered end : 22mm Lower end : 30mm A threaded hole of 20mm diameter, for the extension shaft.
Collet Jaw The collet jaw is shown in figure 5. The collet jaws are three in number and they have been designed with the following specification:
Length : 40mm Width : 4mm Breadth : top : 8mm, end : 10mm.
Work- rest The work rest is a very important part in the fixture. It has been solidly designed. The work rest is shown in figure 6. It houses the assembly of the collet expander and the collet extension shaft. As the name implies, ‘’the work rest’’ provides a rest for the work piece. It is welded to the base plate, which is then screwed to the housing of the fixture. The work rest has the following specifications:
Ihom,A.P et al: Continental J. Applied Sciences 4: 54 - 64, 2009
Clamping Pins The pins are three in number. They are screwed into the base disc of the fixture housing. Clamping pin is shown in figure 7. These pins are used in clamping the fixture unto the lathe machine. The pins are standard with the following specifications
The best materials obtainable and consistent with cost have been indicated by the design so that the final product will be strong to withstand any load acting on it. Most of the materials to use will be subjected to quality control and materials testing. According to Azodo and Ihezie (2005), quality control and material testing reveals equipment capability to perform satisfactorily in service.
RESULTS AND DISCUSSION A careful selection of materials has been done in order to fulfill both the functional and strength requirements of the design. The selected compression spring is of the ground – ends type made of alloy carbon steel to make it tough. The result of the spring constant or deflection constant Ks of the spring is 3.75KN/m, this is a reasonable deflection and enough to grip and unload the work piece. The result of the design calculation showed that 112.5N is needed for a deflection of 30mm from the spring. According to Kinasoshvili (1978) these forces and dimensions of structural members are determined by calculation. The torque or torsional moment on the spring at a deflection of 30mm is 1.69Nm. This is quite small, but has to be so because of the loading force, which is small too. The potential energy stored at a deflection of 30mm is just 1.69Joules. Higher deflections will give higher potential energy level (Ihom, et al, 2006). The shear stress on the coils of the spring has been calculated. It showed that at a loading of 112.5N, the shear stress on the coils will be 350.3MPa. The shear stress was far less than the ultimate shear stress of the compression spring, which was equal to 833MPa. Therefore, the spring can be taken to be safe (Baumeister,1967, and Orlov, 1980). The design of the collet extension shaft, showed that the specified material was steel. The collet extension is under axial loading. It therefore experiences simple tension or tensile stress. The calculated required diameter of the collet extension shaft was 0.98mm.The minimium required diameter of 0.98mm is small, but it can be noticed that the operational loading force acting on the shaft is small too. Any diameter from 0.98mm and above can withstand the load acting on the shaft. However, for the purpose of this design we choose the diameter of the collet extension shaft to be 20mm. This diameter meets the functional requirements of the design by agreeing with other dimensions. This makes the collet extension shaft strong enough to withstand shock and other unforeseen forces acting on it . The result showed that the individual parts of the fixture have been designed to meet the functional requirement as well as the strength requirements.
CONCLUSION The design of the simplified chucking indexing fixture has been carried out and the following conclusions have been drawn:
1. The fixture which was first used on the milling machine has now been modified to be used on the lathe machine.
2. The design has analyzed the forces acting on the critical areas of the simplified chucking indexing fixture.
3. The design analysis and materials selection has shown that the design is capable of meeting both the functional and strength requirement of the fixture.
4. The materials selection of the key components of the fixture has been carried out and specifications clearly stated.
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ACKNOWLEDGEMENT The authors want to acknowledge the contributions of Engr. Dr. Tuleun, L.T. to the successful completion of this design work. We greatly appreciate his scholarly guide through out the course of this work.
REFERENCES Ashby, M.F and Jones, D.R.H(1994): Engineering Materials2, Fourth Edition, printed and bounded inGreat Britain, by BPC Wheatons Ltd, Exeter, P267- 276.
Azodo, U.C. and Ihezie, G.O.C (2005): Engineering Materials in the Manufacture of Foods and Drugs Equipment in Nigeria: the case of PRODA made integrated industrial confectionery oven, proceeding of the NMS, P51- 55.
Baumeister, T. (1967): Standard Handbook for Mechanical Engineers, 1st Edition McGraw-Hill Company, London.
Bolton, W. (1999): Materials for Engineering, Fourth Edition Butterworth- Heinemann Great Britain, P1-10.
Champion, R.C.(1968): Motor Vehicle Calculations and Science, Part2, Edward Arnold (publishers) Ltd. London, P282, 290.
Edgar, C.(1965): Fundamentals of Manufacturing Processes and Materials, Addison-Wesley Publishing Company, P42.
Egor, P.P. (1968): Introduction to Mechanics of Solids Prentice Hall, Inc. Eaglewood Cliffs, New Jersey, 5P.
Harold, W.B. (1967): Tooling Methods and Ideas Industrial Press Inc. New York, 336P.
Ihom, A.P. , Tuleun, L.T. ,and Anbua, E.E.(2006): The Effect of Cutting Tool Vibrations on the Surface Finishing of Work-pieces produced using a Simplified Chucking Indexing Fixture for the Lathe Machine, J. of Research in Engineering Vol. 3 No.2 P48-49.
Kinasoshvili, R. (1978): Strength of Materials, 2nd Edition Mir Publishers, 2 Pervy Rizhsky Pereulok, Moscow USSR, P1-2.
NYSVP,AA, (1968): Jigs and Fixture Design, Vol.1, NYSVP AA Publication
Orlov, P. (1980): Fundamentals of Machine Design, Mir Publishers, Moscow, P98.
Ruiz, K. (1964): Design for Strength and Production, 3rd Edition, Mir Publishers, P1-10.
Received for Publication: 17/12/2008 Accepted for Publication: 13/05/2009 Corresponding Author Ihom,A.P, National Metallurgical Development Centre, Jos, PMB 2116 Jos- Plateau State E-Mail:[email protected]
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Headstock (ii) Spindle Tool post (viii)
Tail stock (iii) Apron (on carriage) (vi) Tailstock spindle (i) (does not revolve) Compound rest and slide (swivels) cross slide Feed change gear box (v) carriage (saddle) Fig. 1: A Lathe Machine (sketch) Showing the Principal Parts.
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A B D G
C I E F H
Fig. 2: Simplified Chucking- indexing Fixture (Sectional view) KEY A is the work rest B is special collet C is collet expander D is fixture housing E is compression spring F is collet extension shaft G is the loading and unloading lever H is the holding pin I is a washer
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Ihom,A.P et al: Continental J. Applied Sciences 4: 54 - 64 , 2009
PROXIMATE COMPOSITION AND SENSORY ACCEPTANCE OF CAKES SUPPLEMENTED WITH BAMBARA GROUNDNUT FLOUR
Okoye, J. I. and Okpalanma, F.E
Department of Food Science and Technology, Madonna University, Elele Campus, P.M.B. 48, Elele, Rivers State, Nigeria.
ABSTRACT The proximate composition and sensory properties of cakes supplemented with bambara groundnut flour were studied. The wheat flour (WF) was composite with bambara groundnut flour (BGF) at the levels of 10%, 20%, 30%, 40% and 50%. The cakes produced from the flour blends were evaluated for their chemical and sensory qualities. From the results, the protein content of the cakes increased with increasing supplementation with bambara groundnut flour from 13.18% in 90:10 (WF: BGF) to 15.86% in 50:50 (WF: BGF) samples, while carbohydrate decreased. In the same vein, the energy content of the cakes increased as the level of fortification with bambara groundnut flour increased from 362.02KJ in 90:10 (WF:BGF) to 376.86KJ in 50:50 (WF:BGF). The results of the sensory evaluation also showed that the cake supplemented with 10% bambara groundnut flour was the most acceptable because there was no significant difference (p>0.05) between this sample and the control (Cakes prepared from 100% wheat flour). However, the other samples of cake were significantly different (p<0.05) from the control in colour, flavour, taste and texture. KEY WORDS: Cakes, proximate composition, sensory acceptance, supplementation, bambara groundnut flour.
INTRODUCTION Cakes are flour confections that are usually prepared from wheat flour and other essential ingredients. The consumption of cakes and other flour confectionery such as biscuits and bread prepared from wheat flour has become very popular in most developing nations of the tropics especially among children and adolescents (Idowu et al; 1996). The low protein content of the wheat flour, which is the most important ingredient used for the preparation of conventional snacks or bakery products has been of great concern to food scientists and nutritionists in its utilization. The supplementation or fortification of cakes and other baked goods with nutritious and inexpensive dietary staples derived from grain legumes has gained momentum particularly in regions where protein utilization is inadequate. This is because the nutritional value of grain legumes is related to their high protein content and their high lysine content which makes them good complements to cereal proteins which are low in lysine but high in the sulphur containing amino acids that are deficient in legume proteins (Ihekoronye and Ngoddy, 1985; Akapo et al; 1995; Nkama et al; 2001). Ideally, the ingredients for the production of low cost complementary baked goods must be derived from dietary staples available and affordable in the region of interest. The bambara groundnut (Vigna subterranea (L)verde) an indigenous African grain legume, is one of the lesser known and utilized legumes that can be used in various food formulations such as in bakery products and other flour confectionery because of its high protein content (Obizoba, 1983; Otunola et al; 2004). Like other legumes, it is a rich source of energy, carbohydrate and is relatively low in fat (Brough and Azim-Ali, 1992). The fortification of cereal -based baked goods such as cakes, biscuits and bread with adequately processed bambara groundnut flour will apart from reducing the cost of these products will also improve their nutritional value and protein content. The objective of this study was to examine the chemical and sensory properties of cakes supplemented with bambara groundnut flour at different levels of substitution. MATERIALS AND METHODS Mature brown variety of bambara groundnut seeds (Vigna subterranea(L) verde) and the wheat flour used for this study were procured from local markets in Owerri and Umuahia, respectively. This research work was carried out in National Root Crops Research Institute Laboratory, Umudike, Nigeria in May,2008, Preparation of Bambara groundnut Flour. The bambara groundnut flour was prepared according to the method described by Enwere (1998) as shown in Figure 1. During preparation, two kilogeams of bambara groundnut seeds which were free from dirts and other
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foreign materials such as sticks, stones and leaves were weighed, cleaned and soaked in deionized water for 4h. Therefore, the seeds were drained and dried in the tray dryer (60°C, 12h). The dried seeds were dehulled manually, boiled (100°C,30min) and dried further in the tray dryer(65°C,6h). During drying, the dehulled seeds were stirred at intervals of 20 minutes to ensure uniform drying. After that, the seeds were immediately milled (attrition mill) and sieved to pass through a 500µm mesh sieve. The cooked bambara groundnut flour produced was finally packaged in sealed polyethylene bags for blending and cake production. Table 1: Samples of Cake
Samples WF (%) BGF (%) A 100 0 B 90 10 C 80 20 D 70 30 E 60 40 F 50 50
Key: A – Cake made with 100% wheat flour , B – Cake made with 90% wheat flour and 10% bambara groundnut flour , C – Cake made with 80% wheat flour and 20% bambara groundnut flour, D – Cake made with 70% wheat flour and 30% bambara groundnut flour, E – Cake made with 60% wheat flour and 40% bambara groundnut flour, F – Cake made with 50% wheat flour and 50% bambara groundnut flour
Table 2: Means 1,2 of Proximate composition of cakes produced from WF and WF: BGF Blends on dry weight basis.
Samples Moisture (%)
Nx6.25 Protein (%)
Fat (%) Ash (%) Crude fibre (%)
Carbohydrate (%)
Energy KJ/100g
A 11.42a 11.68a 1.90a 1.90a 2.40a 74.28a 360.32a B 10.60b 13.18b 2.10a 2.44b 3.20b 72.70b 362.02b C 9.94c 14.04c 2.20a 2.64b 3.30b 70.32c 367.64c D 9.46d 15.44d 2.52b 2.80c 4.02c 68.68d 368.36d E 9.06d 15.62d 2.80c 2.88c 4.18c 66.96e 372.24e F 8.46e 15.86e 2.84c 3.02d 4.68d 64.84f 376.86f
1. Data are means of triplicate determinations, 2. Means with different superscripts within the same column are significantly different from each other (p<0.05). Table 3: Means 1,2 of Sensory evaluation of Cakes Produced from WF and WF: BGF Blends.
A 6.0a 8.2a 7.4a 7.6a 8.4a B 6.6b 6.8b 6.8b 7.0b 8.2a C 7.2c 6.4b 6.2c 6.6b 7.6b D 7.8d 6.2c 6.2c 6.2c 7.0c E 8.0d 5.6d 6.0c 5.6d 6.4d F 8.8e 5.2d 5.4d 5.2d 6.2d
1. Data are means of 20 untrained judges 2. Means with different superscripts within the same column are significantly different from each other (p<0.05).
Flour Blending. The wheat flour (WF) was composite with bambara groundnut flour (BGF) at the levels of 10, 20, 30, 40, and 50% in a Kenwood mixer (Model NX 908 G). Therefore, the flour blends obtained were packaged individually in sealed polyethylene bags and kept at ambient temperature conditions until used for the preparation of cakes.
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Okoye, J. I. and Okpalanma, F.E: Continental J. Applied Sciences 4: 65 - 70, 2009 Preparation of Cakes. The cakes were prepared according to the creaming method described by Eneche (2005) as shown in Figure 2. The basic formulation was 100% flour, 60% fat, 20% beaten egg, 40% sucrose, 2% baking powder, 20% milk and 2% vanilla essence. The 100% flour was systematically replaced for the wheat flour (WF) with 10,20,30,40, and 50% bambara groundnut flour (BGF). During the cake making, the sucrose (sugar) and fat were initially creamed in a mixer (Model NX 903 G) to produce fluffy mixture. After creaming, the already beaten egg was added immediately and the mixture was mixed continuously in a mixer until light and foamy mixture was obtained. Thereafter, the flour, milk, baking powder and vanilla essence were finally added and the mixture was further mixed thoroughly to form soft
Bambara groundnut seeds Ingredient
Washing Creaming
Soaking in water (for 4h) Mixing and aeration Drying (in the tray dryer at 60°C for 12h) Dividing Dehulling Moulding (shape) Boiling (100°C for 30min) Panning Drying( 65°C for 6h) Baking (180O for 40min) Milling (Attrition mill). Cooling
Sieving (Fine sieve, 500µm) Depanning
Cooked bambara groundnut flour Packaging
Packaging Fig 1: Flow chart for the production of cooked Fig 2: Flow chart for cake production bambara groundnut flour. consistent batter. The batter produced was manually divided and moulded to desired shapes of similar sizes. The moulded pieces of cake batter were placed into individual clean greased cake pans and baked in a hot air oven (180°C, 40min). The cakes produced were immediately cooled, depanned and packaged individually in air tight containers for
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Okoye, J. I. and Okpalanma, F.E: Continental J. Applied Sciences 4: 65 - 70, 2009 analysis. Wheat cakes were similarly prepared as reference. The various samples of cakes produced from wheat/ bambara groundnut flour blends are shown in Table 1. Chemical Analysis. The moisture, protein, fat, ash and crude fibre contents of each of the cakes were determined in triplicates according to the methods of AOAC (1995). The carbohydrate was determined by difference (Onuh et al; 2004). The food energy was calculated using the Atwater factor 4 x protein, 4 x carbohydrate, 9 x fat (Onwuka, 2005). Sensory Evaluation The cakes were evaluated by a 20-member panel of untrained judges drawn from the University Community for attributes of colour, flavour, taste, texture and overall acceptability on a hedonic scale of 1- 9 where 1 = dislike extremely and 9 = like extremely (Iwe, 2002). Statistical Analysis The means and standard deviations of all the analyses were calculated. The results were subjected to analysis of variance to detect significant differences (p< 0.05) among the sample values. The turkey test was used in separating significant means. RESULTS AND DISCUSSION The proximate composition of cakes made from wheat/bambara groundnut flour blends are shown in Table 2. The moisture content of the cake samples was significantly different from each other (p<0.05). They were also similar with those reported by Echendu et al; (2004). The protein content of the cakes differed significantly (p<0.05) from each other. The differences were observed because the protein content of the cakes increased steadily with increasing supplementation with bambara groundnut flour. In effect, bambara groundnuts have been reported to be good sources of protein (Linnemann, 1987). This addition effect was also observed for fat, ash and fibre. In other words, the fat, ash and fibre contents of the cakes increased as the level of fortification with bambara groundnut flour increased. The results generally are in agreement with those reported by Henshaw and Agunbiade (2004). However, the opposite effect (substruction effect) was observed for carbohydrate. The carbohydrate content of the cake samples decreased gradually with increasing level of substitution with bambara groundnut flour. The result of the carbohydrate content of the cakes is higher than those reported by Brough (1991). The energy content of the cakes ranged from 360.32 KJ/l00g to 376. 86KJ/100g. The increase in the energy content of the cakes could be due to their high protein and carbohydrate contents. They were also similar with those reported by Hoseney (1994). The supplementation of cakes with bambara groundnut flour at a level up to 50% produced the desired effect of increasing their protein, ash and energy contents. The results of the sensory evaluation of cakes produced from wheat/bambara groundnut flour blends are shown in Table 3. The scores of the various sensory attributes were high in all the samples of cake made from different flour blends. Generally, the cake fortified with 10% bambara groundnut flour (sample B) was most acceptable by the judges because there was no significant difference (p>0.05) between this sample and the control (sample A). In addition, there was significant difference (p<0.05) in colour, flavour, taste and texture between the control and the other samples of cake produced from the flour blends. The differences could be attributed to the unique baking quality of wheat flour (Okoye et a!; 2008). Further more, the result also indicated that the cakes produced from the blends containing different proportions of bambara groundnut flour generally had better colour and were also significantly different from the control (p<0.05). The improvement in colour of these samples could be due to the bleaching action of the colour pigments found naturally in bambara groundnut seeds during processing as a result of the scorching effect of heat (Enwere and Hung, 1996). The fortification of cakes with bambaara groundnut flour generally produced good results.
CONCLUSION Cakes of acceptable quality relative to those made from wheat flour were prepared from wheat/bambara groundnut flour blends. The fortification of cakes with bambara groundnut flour beyond 40% produced acceptable results. From the study, it was observed that the cakes produced from the flour blends had better nutrient density than those made from 100% wheat flour because of their high protein, ash, fibre and energy contents. The supplementation of cakes with bambara groundnut flour would help to alleviate the problem of protein-energy malnutrition prevalent among children and adolescents in Nigeria and other sub-Saharan African
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Okoye, J. I. and Okpalanma, F.E: Continental J. Applied Sciences 4: 65 - 70, 2009 countries. Further studies should be performed on wheat/bambara groundnut flour blended cakes to evaluate their respective protein quality and amino acid profile. ACKNOWLEDGEMENT The provision of research facilities by the National Root Crops Research Institute, Umudike is highly appreciated. Moral support received from Engr. E.N. Otaka is also acknowledged. REFERENCES Akapo, S.O., Oguntunde, A.T. and Ogundare, O.F. (1995). Nutritional evaluation of weaning food formulations prepared from soybean, sorghum and crayfish. Food and Nutrition Bulletin; 13:1-11. AOAC (1995). Official Methods of Analysis. Association of Official Analytical Chemists. 16th edn. Washington, DC. Pp. 226 -234. Brough, S.H. (1991). Biochemical composition of bambara groundnut (Vigna subterranean (L) verde) seeds in relation to soil moisture. Journal of Science of Food and Agriculture; 14: 64-67. Brough, S.H. and Azim - Ali, S.N. (1992). The effect of soil moisture on the proximate composition of bambara groundnut (Vigna sublerranea (L) verde) seeds. Journal of Science of Food and Agriculture; 15:18-20 Echendu, C.A, Onimawo, LA. and Adieze, S. (2004). Production and evaluation of doughnuts and biscuits from maize-pigeon pea flour blends. Nigeria Journal of Food Science and Technology; 22: 147-153. Eneche, H.E. (2005). Chemical composition and sensory properties of cakes produced from African yam bean and wheat flour blends. Nigeria Journal of Nutritional Sciences; 26:30-37. Enwere, N.J. and Hung, Y.C. (1996). Some chemical and physical properties of bambara groundnut (Vonadeia subterranean Thouars .L.) flour. International Journal of Food Science and Nutrition; 47:469 - 475. Enwere, N.J. (1998), Foods of Plant Origin. Afro-Obis Publications, Ltd, Nsukka. Pp. 59-61. Henshaw, F.O. and Agunbiade, A.E (2004). Chemical composition of snack foods produced by roasting cowpea (Vigna unguiculata) and bambara beans (Vigna subterranean (L) verde). Proceedings of the Nigerian Institute of Food Science and Technology; Pp 194— 195. Hoseney, R.C (1994). Cake Manufacture. In: Principles of Cereal Science and Technology. 2nd edn. Avi Publishing Company Inc, Westport, Connecticut. Pp. 214-218. Idowu, M.A; Oni, A. and Amusa, B.M (1996). Bread and biscuit making potentials of some Nigeria cocoyam cultivars. Nigerian Journal of Food Science and Technology; 14: 1-12. Ihekoronye, A.I. and Ngoddy, P.O. (1985). Integrated Food Science and Technology for the Tropics. Macmillan Publishers Ltd, London and Oxford. Pp. 160-172. Iwe, M.O. (2002). Handbook of Sensory Methods and Analysis. Rojoint Communication Services Ltd, Enugu. Pp. 76 - 82. Linnemann, A.R. (1987). Composition of some grain legumes in West Africa. Journal of Science of Food and Agriculture; 2:12-15.
Nkama, I., Dagwanna, F.N. and Ndahi, W.B. (2001). Production, proximate composition and consumer acceptability of weaning foods from mixtures of pearl millet, cowpea and food nutrient. Journal of Arid Agriculture; 11:165-169.
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Okoye, J. I. and Okpalanma, F.E: Continental J. Applied Sciences 4: 65 - 70, 2009 Obizoba, I. C. (1983). Nutritive value of cowpea, bambara groundnut and rice mixtures in adult rats. Nutrition Reports International; 27: 709 - 712. Okoye, J.I, Nkwocha, A.C. and Ogbonnaya, A.E. (2008). Production, proximate composition and consumer acceptability of biscuits from wheat/soybean flour blends. Continental Journal of Food Science and Technology; 2:6 — 13. Onuh, J.O., Akpapunam, M.A and Iwe, M.O. (2004) Comparative studies of the physico-chemical properties of two local varieties of sweet potato flours. Nigerian Journal of Food Science and Technology; 22:141-146. Onwuka, G.I (2005). Food Analysis and Instrumentation: Theory and Practice. Naphthali Publishers Ltd, Lagos. Pp. 89 - 90. Otunola, E.T., Ade-Omowaye, B.I.O and Akanji, A.S. (2004). Evaluation of some quality characteristics of hard dough biscuits produced from bambara groundnut and wheat flour mixes. Proceedings of the Nigerian Institute of Food Science and Technology; Pp. 39-40. Received for Publication: 17/05/2009 Accepted for Publication: 10/07/2009 Corresponding Author Okoye, J. I. 19 Uke Street Phase 1 Omagba Layout, P.O Box 273 Onitsha, Anambra State, Nigeria.
DISTRIBUTION OF SELECTED METALS IN THE BODY ORGANS AND TISSUES OF COMMERCIAL
FISH SPECIES IN ADO-EKITI, NIGERIA.
K. Adesina and D.O. Orimaiye Department of Food Technology, The Federal Polytechnic, Ado-Ekiti, Nigeria.
ABSTRACT A study into the concentrations and distributions of some metals in the organs and tissues of some commercial fish species in Ado–Ekiti was undertaken with a view to evaluating the interplay of the inorganic minerals in the various parts. The fish species have variable sizes. The fish organs analyzed were gills, liver, intestine, scales, eyes, head and body tissue appropriately. The metals were analysed using Atomic Absorption and Emission spectrophotometers using appropriate instrumental condition for each element. The levels of Zn, Fe, Na, K, Mn. and Cu were found to be highly concentrated in the intestine compared to other fish organs. Pb, Cr, Co and Hg were not detected in any of the samples. The concentration of the metals analysed were below the deleterious level of metal concentration in fishes. KEYWORDS: Metals; organs; tissues; commercial fish; Ado-Ekiti.
INTRODUCTION Animal protein intake by Nigerians has been very low in recent times due primarily to a decrease in per capital animal production (Olajide et al., 1972) and the rising growth in the human population (Oyenuga, 1986). The price of fish has stabilized, thus fish has become the major source of animal protein to the average citizenry. The importance of fish in the nutrition has contributed a lot to the research on its qualities. The time has come now when producers would not be paid on the quantity but quality of fish. With these views, the system of fish inspection and quality control come to light. Water is the medium in which fish grows or the habitat for fish. The presence of metal pollutants in such waters is known to disturb the delicate balance of aquatic ecosystems (Bender, 1982). Metals are introduced into aquatic systems as a result of the weathering of rocks and soils from volcanic eruption and from several human activities like mining, processing and uses of metals and industrial materials that contain metal contaminants (Marr and Creaser, 1983; Gutenmann et al., 1988). The increased use of metal-containing fertilizers due to agricultural revolution could lead to a continued rise in the concentration of metal pollutants in fresh water reservoir due to water run-off. Fishes are notorious for their ability to concentrate metals in their muscles. Some of these metals might be involved in haetropoiesis while others might be involved in regulation of metabolic processes, thus they need to be carefully screened to ensure that unnecessary high levels of some toxic trace metals are not transferred to man through fishes (Varshney, 1991). Therefore, this study is aimed at evaluating the concentrations and distribution of some metals in the various parts of commercial fishes in Ado- Ekiti, Nigeria. MATERIALS AND METHODS The common fishes of Scomber japanicus; Sarotherodom SP; Clarias garriepinus; Chipea pallastis and Ethmalosa fimbriata were purchased (still frozen) from five different markets, all within Ado-Ekiti township. The average length of the fish samples ranged from 25cm to 30cm while the weight range was from 330g to 390g. The fish samples were given about 2 h of defrosting before processing for analysis. After defrosting, the fish samples were washed with deionized water and each fish separated into head, gills, body tissue, eye, liver and scales using plastic knife. The samples were analysed as consumed (wet weight). About 0.5g of the different body organs of fish samples was digested by adding 2.0cm3 of concentrated nitric acid to each sample in a beaker, covered with a wash glass and allowed to stand over-night in a fume cupboard. The digestion was completed within 12 hours during which there was gentle heating on a hot plate until no visible solid materials was observed. Heating continued at a temperature between 750C -800C to near dryness.
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K. Adesina and D.O. Orimaiye: Continental J. Applied Sciences 4: 71 - 75, 2009 Table 1: Level of metals in Clarias gariepinus (Catfish) mg/kg
The digested samples were removed, covered with glasses and 2.0cm3 of 5% Lanthanum chloride solution was added. Heating continued the second time until near dryness. Each of the final solution was washed into a 25cm3
standard flask with 0.1MHNO3 and made up to the mark with distilled de-ionized water (Harper et al, 1989 and Varian, 1975). Zinc, lead, iron, copper, manganese, chromium, cobalt and mercury were analysed using a Perkin Elmer Model 200 Atomic Absorption while sodium and potassium were determined by Emission Spectrophotometer using appropriate instrumental conditions for each element (Harper et al, 1989 and Varian, 1975).
RESULTS AND DISCUSSION Levels of the metals in the fish parts are as shown in Tables I, II, III, IV and V. Lead, chromium, cobalt, and mercury were not detected in any of the fish parts analysed. The level of metals in fishes is an indication of the level of heavy metal pollution of the water from which they are caught (Waldron and Stofen, 1974). The non-detection of the heavy metals in any of the fish parts reported in this work is an indication that the waters in which the fishes were caught were not polluted. Thus the toxic metals will not get to man through fish consumption. The best sources for zinc and manganese in decreasing order from the fish samples analysed are Sarotherodon SP. > C. gariepinus > S. Japanicus > E. Fimbriata > C. pallasti (Tables I-V). This indicates that the contractions of these two metals may be a function of the species rather than a function of fish sizes. Value of zinc and manganese in the head, eyes and body muscles are useful to man since these are the areas of fish mostly consumed. Zinc is present in all the tissues of the body of man and is a component of more than 50 enzymes (Bender, 1992). Zinc of animal sources of protein is readily available and will be able to meet zinc allowances
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K. Adesina and D.O. Orimaiye: Continental J. Applied Sciences 4: 71 - 75, 2009 per day than those of vegetable and cereal sources of protein (National Academy of Science, 1971). Manganese functions as an essential constituent for bone structure, reproduction and normal functioning of the nervous system. It is part of the enzyme system (Fleck, 1976). All the fish samples analysed will complement the supply of zinc and manganese in food, which agrees with the findings of Adeyeye et al., (1996). The concentration of iron is high in the intestine of the fish samples mostly in sarotherodon sp. and C.gariepinus with a reducing level in S.japanicus and E. fimbriata with the least value in C. pallasti (Tables I-V). Next area of concentration is in the gills of E.fimbriata, C.gariepinus, Sarotherodon sp. and C. pallasti. The high level of iron in the intestine could be based on the fact that the intestine serves as the ultimate depository of all things coming into the fish alimentary system. This observation is in agreement with the report of Adeyeye, (1994). Copper is the least in the levels of metals concentration in the fish parts; however, it is mostly concentrated in the intestine, then in the gills. The likely sources of copper in the fish will likely be the source of the fingerlings particularly where copper is not present in the sediment or the water and the fishes may be feeding very near or from the sediment where copper is present in the water sediment (Adeyeye, 1994). The levels of potassium were consistently higher than sodium in the samples (Tables I-V). Animal tissues, in general, are much less rich in potassium, but, on the other hand, they usually contain more sodium (Suteliffe and Baker, 1974). This observation is not consistent with the report in this work. Potassium forms loose associations with protein and is an activator of pyruvate kinase and numerous enzymes. Over 40 enzymes are known to require a univalent cation for maximum activity in which potassium is usually the most effective. Transport ATP – ases from animal sources require sodium as well as potassium ions for maximum activity; sodium influences osmotic pressure and contributes to normal pH equilibrium (Suteliffe and Baker, 1974; Santead, 1967). All the fish species under studies are good sources of potassium and sodium. The metals analysed in the fish samples were more concentrated in the intestine and the gills compared to the other parts. Most consumers remove and discard of the intestines, the gills and in few cases, the head when processing fish for consumption, thus reducing the consumption and ingestion of metals from fish source. It was reported that fish and meat from wild animals are the chief sources of animal protein in the diet of the rural communities especially in the southern part of Nigeria (Petrides, 1962). Also, a projection that fish consumption in Nigeria by the year 2000 will be over 2 million tonnes with a per caput consumption of 14.49kg and above was also reported (Okpanefe, 1982). CONCLUSION The metals are distributed unevenly in the body organs and tissues of the fish species with the metals more concentrated in the intestine and the gills. Since the fish samples were determined as consumed (wet weight), it may still be concluded that the levels of the metals in the commercial fish samples analysed do not pose any health hazard to the consumers; however, there is need for a continuous monitoring to avoid the consumption of contaminated fishes. It is worthy of note that the fishes studies in this report contained reasonable concentrations of beneficial metals (zinc, iron, copper, manganese, sodium and potassium) and the levels are present within the safety limits of the FAO/WHO, 1991.
REFERENCES Adeyeye, E.I; Akinyugha, N.J; Fesobi, M.E and Tenabe, V.O., 1996: Determination of some metals in Clarias gariepinus (Cuvier and Vallenciennes), Cyprinus carpio (L.) and Oreochromis niloticus (L.) fishes in a polyculture fresh water pond and their environments. Aquaculture, 147:205-214. Adeyeye, E.I., 1994: Determination of trace metals in Illisha Africana fish and in associated water and soil sediments from some fish ponds. Int. J. Environs. Stud. 45:231-238. Bender, A., 1992: Meat and meat products in human nutrition in developing Countries. FAO Nutrition Paper 53, FAO, Rome, p. 91. Bender, A.E., 1982: Dictionary of Nutrition and Food Technology. London Butterworths Publ., pp. 61-70.
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K. Adesina and D.O. Orimaiye: Continental J. Applied Sciences 4: 71 - 75, 2009 FAO/WHO, 1991: Essential Amino acids and Minerals In: Report of a joint FAO/WHO Expert consultations. Food and Agricultural Organization of the United Nations, Rome, p. 280. Fleck, H., 1976: Introduction to Nutrition. 3rd edn., Macmillan Publ. Co. Inc. N.Y. 552pp. Gutenmann, W.H., Bache, C.A; McCahan, J.B and List, D.J., 1988: Heavy metals and chlorinated hydrocarbons in marine fish products. Nutr. Rep. Int., 38:1157-1161. Harper, B.J Fileman, C.F; May, P.V. and Potmann, J.E., 1989: Methods of Analysis for trace metals in Marine and other samples (Lowestoft Aquatic Environment Protection Analytical Methods, No 3). Marr. I.L and Creaser, M.S., 1983: Environmental Chemical Analysis. Pub. Blackie and Sons Ltd., London, p.104. National Academy of Science, 1971: Food Nutrition board: Zinc in human Nutrition. In: H. Fleck (Editor). Introduction to Nutrition, 3rd edn. Macmillan Publ. Co., Inc. N.Y., p. 235. Okpanefe, M.O., 1982: Demand Analysis for fisheries. In: E.O. Ita (Editor) Proceedings of the second Annual Conference of the Fisheries Society of Nigeria (FISON). Kanji Research Institute, New Bussa, pp. 193-200. Olajide, S.O; Olatubosun, D; Idusogie, E.O; and Abiagom, J.D., 1972: A Quantitative Analysis of Food Requirements, supplies and Demands in Nigeria 1968-1985. The Federal Department of Agriculture, Lagos, p. 113. Oyenuga, V.A; 1986: Nigeria’s Food and Feeding Stuffs. Ibadan University Press, Ibadan, pp 1-3. Petrides G.A. 1962: Advisory report on wildlife and national Parks in Nigeria. In: S.O. Olayide, D. Olatunbosun, E.O. Idusogie and J.D. Abiagom (Editors). A Quantitative Analysis of Food Requirements, Supplies and Demand in Nigeria 1968-1985. The Federal Departments of Agriculture, Lagos, p. 23. Santead, H.H., 1967: Present knowledge of minerals: In: H. Fleck (Editor), Introduction to Nutrition. 3rd edn. Macmillan Publ. Co. Inc. N.Y., p.204. Suteliffe, J.F and Baker, D.A., 1974: Plants and mineral Salts. Studies in Biology Number 48, Edward Arnold Pub. Ltd. London, p. 61. Varian Techtron, 1975: Basic Atomic Absorption Spectroscopy: A modern Introduction, Victoria, Australia. Varshney, C.K. (Editor), 1991: Water Pollution and Managements. Wiley Eastern Ltd. New Delhi, pp 88-89. Waldron; H.A and Stofen, 1974: Sub-clinical Lead Poisoning, Academic Press, New York., p. 1-224. Received for Publication: 17/05/2009 Accepted for Publication: 10/07/2009 Corresponding Author K. Adesina, Department of Food Technology, The Federal Polytechnic, Ado-Ekiti, Nigeria. E-Mail: [email protected]
CONCENTRATION LEVELS OF SOME HEAVY METAL POLLUTANTS IN SOILS, AND CARROT (DAUCUS CAROTA) OBTAINED IN MAIDUGURI, NIGERIA
E. I. Uwah
Department of Chemistry, Faculty of Science, University of Maiduguri, P. M. B. 1069, Maiduguri, Nigeria
ABSTRACT Levels of some heavy metal pollutants (As, Cd, Cr, Cu, Fe, Mn, Pb, Zn, Co) were investigated in the soils, and the edible portions of carrot (Daucus carota) vegetable obtained in Maiduguri. Concentration levels of the metals were determined using atomic absorption spectrophotometer (AAS). The levels of the metals in the carrot and soils were in the order: Cr > Fe > Mn > Co > Zn > Pb > Cu > As > Cd. There were significant differences (p < 0.05) in the metals’ levels in Daucus carota and soils between the two sample areas. The results also recorded higher levels of the metals in soil and vegetable samples obtained in the sample areas than their corresponding levels in samples from the control sites which may be due to possible pollution of the sample areas as a result of excessive usage of fertilizers, manures, agro-chemicals, irrigation with wastewater and of course from various industrial activities. Transfer ratio between the soil and Daucus carota samples indicated the following trend Pb > Cd > Cr > Co > Mn > Zn > Fe > Cu > As. The results were below the published threshold values considered excessive or toxic for mature plant tissue. Therefore consumption of carrot as food may not constitute possible health hazards to humans and animals at the time of the study.
KEY WORDS: Heavy metals, Daucus carota, soil.
INTRODUCTION Carrot (Daucus carota), a valuable source of vitamin A due to the presence of carotene, an orange pigment and a precursor of vitamin A, is among the various classes of vegetables that are grown in many parts of Nigeria. In Borno State, Northeast Region of Nigeria, carrot and other vegetables are heavily cultivated and consumed as food (Bokhari and Ahmed, 1985). It has been established that, Heavy metals and other pollutants in soils and vegetables are developed with the intensification of agriculture and large – scale use of fertilizers, pesticides and herbicides. Similarly, it could be said that human activities aimed at improving the productivity of low nutrient soils and enhancing food productions in tropical Africa, may facilitate accumulation of undesirable substances in plants and affect the quality of soils adversely (Anjana and Iqbal, 2006). Heavy metals concentrations in soil are associated with biological and geochemical cycles and are influenced by anthropogenic activities such as agricultural practices, industrial activities and waste disposal methods (Eja et al., 2003; Zauyah et al., 2004). Contamination and subsequent pollution of the environment by toxic heavy metals have become an issue of global concern due to their sources, widespread distribution and multiple effects on the ecosystem (Nriagu, 1990). Heavy metals are generally present in agricultural soils at low levels. Due to their cumulative behaviour and toxicity, however, they have a potential hazardous effect not only on crop plants but also on human health (Das et al., 1997). The use of polluted water in the immediate surroundings of big cities in a country like Nigeria for growing of vegetables is a common practice. Although this water is considered to be a rich source of organic matter and plant nutrients, it also contains sufficient amounts of soluble salts and heavy metals like Fe, Mn, Cu, Zn, Pb, Ni, Sn, Hg, Cr, As, Al. When such water is used for cultivation of crops for a long period, these heavy metals may accumulate in soil and may be toxic to the plants and also cause deterioration of soil (Kirkhan, 1983). Heavy metals like Fe, Cu, Zn, and Ni are important for proper functioning of biological systems and their deficiency or excess could lead to a number of disorders (Ward, 1995). Food chain contamination by heavy metals has become a burning issue in recent years because of their potential accumulation in biosystems through contaminated water, soil and air. The main sources of heavy metals to vegetable crops are their growth media (soil, air, nutrient solutions) from which these heavy metals are taken up by the roots or foliage (Lokeshwari and Chandrappa, 2006). Studies reveal that the presence of toxic heavy metals like Fe, Pb and Hg reduce soil
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fertility and agricultural output (Lokhande and Kelkar, 1999); and that treated sewage water also contains variable amounts of heavy metals such as Pb, Ni, Cd, Cu, Hg, Zn and Cr (Sharma et al., 2004), which have the potential to contaminate crops growing under such irrigation. Fertilizers which are considered as reasonable insurances against yield losses, contain not only major elements necessary for plant nutrient and growth, but also trace metal impurities such as Cd, Pb, Hg, As or Ni (Williams and David,1973; Singh, 1994; Nicholson and Jones, 1994; Zhang and Shan, 2001). They are therefore important anthropogenic sources of soil contamination with heavy metals (Mortvedt et al., 1981; Nriagu, 1990). The soil is an important sink for Cd, Pb, Hg, Cr, and other heavy metals (Alloway, 1990) and the uptake of these heavy metals by plants is an avenue of their entry into the human food chain with harmful effects on health. Obviously, pollution of plants is of concern for two major reasons: Firstly, pollutants may have direct or indirect phytotoxic impacts on the plants themselves, leading to a decline in crop yields and threatening our food supplies; secondly, the plants may act as a vehicle for transferring pollutants into the food chain. For example, Cd is readily accumulated by plants and may get to levels which are adverse to the plants themselves, consequently posing a significant threat to animals and humans that consume plants. Heavy metals and pesticides are major pollutants in this respect (Radojevic and Bashkin, 1999). Chiroma et al., (2003) studied heavy metal contamination of vegetables and soils irrigated with sewage water in Yola, Nigeria and reported high concentration of the metals (Fe, Zn, Cu, Mg, Mn and Pb) suggesting heavy metal contaminations of the soils irrigated with sewage water and their accumulations in different parts of plants cultivated in the soils. They also showed that the metal concentrations vary in the different parts of the plants; and said that the results indicated that Fe tends to accumulate in roots and leaves but Zn accumulates in roots and translocates gradually to the leaves while Mn and Mg show greater accumulations in unwashed leaves. The researchers noted that there was a tendency of high metal concentrations on the unwashed plants compared to the washed plants. Bunzl et al., (2000) in their study; Availability of Arsenic, Copper, Lead, Thallium, and Zinc to Various Vegetables Grown in Slag-Contaminated Soils, studied the soil to plant transfer of arsenic, copper, lead, thallium, and zinc by the vegetables bean (Phaseolus vulgaris L. ‘dwarf bean Modus’), kohlrabi (Brassica oleracea var. gongylodes L.), mangold (Beta vulgaris var. macrorhiza), lettuce (Lactuca sativa L. ‘American gathering brown’), carrot (Daucus carota L. ‘Rotin’, ‘Sperlings’s'), and celery [Apium graveiolus var. dulce (Mill.) Pers.], from a control soil (Ap horizon of a Entisol) and a contaminated soil (1:1 soil–slag mixtures). They reported that the addition of slags to the soil increased the metal content of all vegetables considerably and that similar or greater concentrations for several vegetables were observed when compared with published threshold values considered excessive or toxic for mature leaf tissue. www.actahort.org/members/showpdf?booknrarnr in their study; Genetic differences in heavy metal content of carrot roots, analyzed the levels of some heavy metals in a mixed sample of root tissue of four carrot hybrids ( Kama, Karo, Kalina and Karola) grown at three localities (Krzeszowice, Prusy and Wieliczka) situated near Krakow, Poland, with different level of soil pollution. They observed that the heavy metal content in carrot roots depended on the locality. The highest levels, except for cadmium the researchers noted, were found in carrots grown in Krzeszowice, and the lowest in Prusy. They stated that the high content of lead and copper observed in the plants grown in Krzeszowice was as the result of very high soil contamination and that at this locality, the concentration of lead in soil was 10 times higher than in Prusy and Wieliczka, and that of copper was 5 times higher. Pointing out that only the high level of zinc in Krzeszowice was not reflected in the root content. They also observed that the cultivars differed as to the heavy metal content of their roots. Adding that Kama F1 hybrid proved to be the best. Noting that it had the lowest concentration of lead, nickel, chromium, copper, manganese and iron, as well as an intermediate level of zinc. They pointed out that the highest content of toxic lead, zinc and manganese was found in the roots of Karo F1 cultivar. The only element that was found in similar amounts among all the cultivars they noted was cadmium and that cultivar differences in lead content amounted to 2.64 ppm in Kama and 4.31 ppm in Karo. They similarly pointed out that about twice much chromium was found in Karo and Karola cultivars as in Kalina. Calculating the content in dry weight, the researchers noted that all these differences were markedly larger if the concentration was expressed in the dry weight, not the fresh weight, of samples. Awode et al., (2008) investigated the levels and distribution of Pb, Cr and Cu in the soil and pepper (Capsicum annuum) on the bank of River Challawa, Nigeria. The study revealed high metal levels expressed in mg/kg dry
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E. I. Uwah: Continental J. Applied Sciences 4: 76 - 88, 2009 weights in the ranges: 60.00 – 143.30 for Pb (mean 114.79), 104.20 – 230.00 for Cr (maen181.66) and 58.30 – 207.50 for Cu (mean 248.59) in soil samples; while 11.33 – 27.00 for Pb (mean 18.90), 10.40 – 35.10 for Cr (mean 20.04) and 7.56 – 21.07 for Cu (mean 14.52) in pepper samples. The study also revealed the presence of correlation between metals in soil and pepper samples which indicate possible transfer of these metals into the food chain. Ebong et al., (2007) investigated the accumulation of some heavy metals by Talinum triangulare (water leaf) grown on waste dumpsites in Uyo Metropolis, Akwa Ibom state, Nigeria. Results obtained indicated the following ranges (expressed in mg/kg) for the metals in dumpsite soil: Cd: 1.85 – 8.65; Ni: 11.05 – 20.55; Fe: 183.00 – 237.20; Pb: 42.05 – 60.85 and Zn: 11.35 – 119.30. While the ranges in Talinum triangulare were Cd: 0.10 – 0.30, Pb: 0.33 – 1.55; Ni: 0.05 – 0.45; Fe: 223.43 – 260.00 and Zn: 2.20 – 29.95. These results indicated higher levels of the metals in soils and plants from the dumpsites than the values recorded from the control samples. The aim of this study is determination of heavy metals in soil, and carrot. This was carried out by analyzing spectrophotometrically the levels of As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn and Co in samples of carrot and soil collected from vegetable farms of Alau dam and Gongulon which supply most of the vegetables consumed in Maiduguri. MATERIALS AND METHODS Study area: Maiduguri, capital of Borno State and a commercial nerve center in the Northeastern Region of Northern Nigeria, lies between latitude 11o 51’N and longitude 30o 05’E at an altitude of 345 meters above sea level (Alaku and Moruppa, 1988). This area is known for its dryness, with Sudan type of Climate, Savanna or Tropical grasslands Vegetation, light annual rainfall of about 864mm (34 inches) and the temperature ranging from 22 – 31oC, with mean of the daily maximum exceeding 40oC between March and May before the onset of the rains in June (Adeleke and Leong, 1978). In this area, vegetables are irrigated with dam water and all kinds of available wastewater. Similarly, to enhance the yield of these vegetables, fertilizers and manures are occasionally added to the soil. There are therefore, the possibilities of over applications of these fertilizers and manures. Hence, the uptake and storage of some heavy metal pollutants from these wastewater, fertilizers and manures by the vegetables are very likely since these heavy metals are soluble and mobile in ground water. The map of the study area is shown in Figure 1. Sample and sampling: Edible portions of carrot (Daucus carota) vegetable and top or surface soil (0 – 20 cm) samples were collected from the vegetable farms of Alau dam and Gongulon, irrigated with the Alau dam water, sewage and all kinds of available wastewater, and cultivated with the applications of fertilizers, manures, herbicides and pesticides. Samples were also collected from experimental gardens cultivated on a piece of virgin land (left uncultivated for about 5 years), irrigated with unpolluted water and without the applications of fertilizers, manures, herbicides and pesticides, to serve as the controls. Collections were made from December, 2007 to May, 2008. Samples collections were made six (6) times during the period. During each collection, samples were randomly collected from different plots and homogenized into two composite samples in the two sample areas. Sample collections were carried out according to the methods described by Radojevic and Bashkin (1999) into pre-cleaned polyethylene bags and transported to the laboratory. Digestion of samples: Soil and sliced carrot samples were then dried in an oven at 105oC for 24 hours until they were brittle and crisp (APHA, 1992). A portion (1g) of dried, disaggregated and sieved plant and soil samples were placed separately in 50 mL, Teflon beakers and then digested with 10 mL of HNO3-HCLO4-HF to near dryness at 80 – 90oC on a hot plate. The digests were filtered into a 50 mL volumetric flask using Whatman No. 42 filter paper (USEPA, 1996; Radojevic and Bashkin, 1999; Umoren and Onianwa, 2005). Digestion of samples: Soil and sliced carrot samples were then dried in an oven at 105oC for 24 hours until they were brittle and crisp (APHA, 1992). A portion (1g) of dried, disaggregated and sieved plant and soil samples were placed separately in 50 mL, Teflon beakers and then digested with 10 mL of HNO3-HCLO4-HF to near dryness at 80 – 90oC on a hot plate. The digests were filtered into a 50 mL volumetric flask using Whatman No. 42 filter paper (USEPA, 1996; Radojevic and Bashkin, 1999; Umoren and Onianwa, 2005). Determination of heavy metals: Concentration levels of As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn and Co in the carrot (Daucus carota), soil and control samples were determined using an SP 1900 Pye Unicam Atomic Absorption
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E. I. Uwah: Continental J. Applied Sciences 4: 76 - 88, 2009 Spectrophotometer (AAS) equipped with an air – acetylene burner. The mean values of six determinations per sample were recorded. Determination of some physicochemical parameters and particle fractions of the soils: Organic carbon was determined by means of a potassium dichromate back titration method as described by McCleod, 1973. Cation exchange capacity (CEC) was determined by the silver thiourea method as described by Rayment and Higginson (1992). The soil pH (1:5 soil water extract), Electrical conductivity (EC) (1:5 soil water extract) and the soil particle size fractions were equally determined using standard laboratory methods as described by Rayment and Higginson, 1992. Transfer factors (TF) for heavy metals from soils to vegetables: Transfer factor (TF) is the ratio of the concentration of heavy metal in a plant to the concentration of heavy metal in soil. The transfer factors for each heavy metal were computed based on the method described by Harrison and Chirgawi, 1989, according to the following formula: TF = Ps (µg/g dry wt)/St (µg/g dry wt) Where Ps is the plant anion or metal content originating from the soil and St is the total anion or metal contents in the soil. Data analyses: Data collected were subjected to statistical tests of significance using the Student t-test and Analysis of Variance (ANOVA) at p<0.05 to assess pairs results in the carrot (Daucus carota) and soil samples. That is, to assess significant variation in the concentration levels of the heavy metals in the vegetable as well as in soils. Probabilities less than 0.05 (p < 0.05) were considered statistically significant. Correlation coefficient was used to determine the association between the heavy metals in carrot (Daucus carota) at p = 0.05. All statistical analyses were done by SPSS software for windows. RESULTS AND DISCUSSION Heavy metals in carrot and soil samples: The concentration levels of the heavy metals in the carrot vegetable samples ranged from low to high depending on the metals. The values ranged from 0.48 ± 0.02 and 0.87 ± 0.04 µgg-1 for Cd, to 46.20 ± 0.25 and 52.00 ± 2.58 µgg-1 for Cr, in Alau dam and Gongulon respectively (Table1). Concentration levels of the heavy metals in the soil samples obtained in the two areas also ranged from low to high. The values ranged from 0.56 ± 0.05 and 0.81 ± 0.06 µgg-1 for Cd, to 65.50 ± 0.68 and 76.18 ± 5.49 µgg-1 for Cr, in Alau dam and Gongulon respectively (Table 2). From Tables 1 and 2, statistical test of significance using the Student t-test and Analysis of Variance (ANOVA) showed significant differences (p < 0.05) among most of the metals concentration levels in the carrot and soil samples obtained in the two sample areas of Alau dam and Gongulon. These could be attributed to environmental factors and differences in farming activities going on in the sample areas. Similarly, the concentration levels of the metals in the carrot and soil samples obtained in the two sample areas were significantly higher (p < 0.05) than their corresponding concentration levels in the control samples. These could be attributed to possible pollution of the sample areas due to excessive usage of fertilizers, herbicides and other agro-chemicals as well as the use of waste water in irrigating the soils and the environmental factors pertinent in the study area (Kirkhan, 1983; Lokeshwari and Chandrappa, 2006). Aerial deposition of these metals could be another source (Onianwa, 2001; Yusuf et al, 2003). The higher concentration levels of the heavy metals in the vegetable and soil samples obtained in the Gongulon area could be attributed to possible pollution of the area due to excessive usage of fertilizers and other chemicals in the area. This is in addition to the downstream deposition of these chemicals in the area as the Alau dam waters flow through the River Nggada into the Gongulon area. Interestingly, the concentration levels of these metals in the carrot and soil samples considered were within the recommended ranges in plants and soils. Fe, Cu, Mn and Zn concentration levels were in appreciable amount in the vegetable. These could be attributed to the importance of these metals in proper functioning of the biological systems (Ward, 1995) and the importance of Fe in plant growth and abundance of the metal in the earth crust (Harrison and Chirgawi, 1989). The trend in the variations of the heavy metals in carrot and soil samples obtained in this study was: Cr > Fe > Mn > Co > Zn > Pb > Cu > As > Cd. The high Fe content followed by other micronutrients in the soil and carrot samples obtained in this study might be due to high content of micronutrients in the waste water used in irrigating the soils. The low concentration levels for Cadmium (Cd) recorded in this study could be attributed to the metal being non essential for plant
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E. I. Uwah: Continental J. Applied Sciences 4: 76 - 88, 2009 growth and metabolism (Shauibu and Ayodele, 2002). Importantly, the data may be compared with the published threshold values considered excessive or toxic for mature plant tissue (Kabata-Pendias and Pendias, 1984). Compared with the limiting values lower concentrations were observed. For As, the values considered as toxic are listed as 5 to 10 mg kg-1 dry weight. For Cu, the listed limiting values are listed as 20 to 100 mg kg-1. For Cu, the limiting values are 20 to 100 mg kg-1, for Pb 30 to 300 mg kg-1 and for Zn 100 to 400 mg kg-1.
Some physicochemical parameters and particle fractions of the soils: The results for the determination of some physicochemical parameters in soil samples are shown in Table 3. The results showed low organic carbon (OC) and organic matter (OM) in the study area. The values of OC (%) were 0.40 and 0.74 in Alau dam and Gongulon, respectively. Those of OM (%) were 0.69 and 1.28 in the two areas. Similarly, cation exchange capacity (CEC) in meq100-1g and the electrical conductivity (EC) in (µmhocm-1) values were generally low. The CEC (meq100-1g) values for the two areas were 5.33 ± 0.01 and 5.43 ± 0.10 and those of EC (µmhocm-1) were 0.22 ± 0.03 and 0.24 ± 0.05. The soil pH values in the two areas were as high as 6.23 ± 0.20 and 6.69 ± 0.04 respectively. As observed in Table 3, the high pH values of 6.23 ± 0.20 and 6.69 ± 0.04 in the two respective sample areas of Alau dam and Gongulon are indicative of slightly acidic environment. The high pH values in the study area may be attributed mainly to the buffering effect of carbonate containing materials such as cement or bricks (Abulude, 2005). Statistical test of significance using the ANOVA, revealed significant differences (p < 0.05) between the values of organic carbon (OC), and organic matter (OM) in the soil samples obtained in the two areas with their corresponding values in the control samples. However, cation exchange capacity (CEC), electrical conductivity (EC) and pH values in samples obtained in the two areas did not show statistical differences (p > 0.05) with their corresponding values in the control samples. Table 4 presents the levels of some particle fractions of the soils. Particle size analyses of the soils revealed the levels of clay (%) in the two respective areas to be: 9.00 and 11.50; sand (%) as 86.00 and 87.00 and silt (%) as 5.00 and 7.50. In Table 4, there were significant differences (p > 0.05) between the concentration levels of clay, silt in soil samples obtained in the two sample areas of Alau dam and Gongulon with their corresponding concentration levels in the control samples.
In general, the results revealed the soils in the sample areas to be loamy sand in texture and slightly acidic with low organic matter contents. The dominance of sand in the soils, along with the low activity and small amount of clay present, does not only contribute to their extremely low heavy metals concentration levels, but also lead to low retention of anthropogenically introduced metals (Abulude, 2005). Similarly, organic matter plays an important role in soil structure, aggregation, infiltration and retention of water, and other physical characteristics. Furthermore, the adsorption complex (clay and humus) serves the soil as a store of nutrients and is a significant contributor to the buffering capacity of soils even as cation exchange capacity can be used to determine the amount of lime that needs to be applied to reduce acidification. The electrical conductivity of soil can be used to assess the viability of saltwater flooded soils, in monitoring surveys and in assessing irrigation and drainage needs. It is also useful in determination of heavily fertilized soils such as soils in green houses and vegetable gardens. Conductivity of soil has also been related to plant growth (Radojevic and Bashkin, 1999).Obviously, their significant as measured in the study can not be overemphasized. Transfer factors (TF) for Heavy Metals from soils to carrot: Table 5 presents the transfer factors of heavy metals from soils to carrot. Transfer factor is one of the key components of human exposure to metals through the food chain. Transfer factors were computed for the heavy metals to quantify the relative differences in bioavailability of metals to plants or to identify the efficiency of a plant species to accumulate a given heavy metal. These factors were based on the root uptake of the metals and discount the foliar absorption of atmospheric metal deposits (Lokeshwari and Chandrappa, 2006; Awode et al., 2008). Highest TF values were obtained for Pb, Cd, Co, Cr and Mn. The TF values are below 1, except for Pb. The overall TF values of Zn, Cu, Pb and Cd are found to be significant and it supports the findings that accumulation of As and Ni is comparatively less while that of Cd, Cu and Zn is more in plants (Olaniya et al., 1998). The rate of metal uptake by the plant could have been affected by other factors such as plant age, plant species, soil pH, nature of soil and climate (Alloway and Ayres, 1997). CONCLUSIONS This study has been able to determine the concentration levels of some heavy metal pollutants (As, Cd, Cr, Cu, Fe, Mn, Pb, Zn and Co) in the soils, and carrot obtained in Maiduguri, Nigeria and also suggested possible pollution of the study area due to excessive usage of fertilizers, manures, pesticides, herbicides and other agro-chemicals as well as the use of wastewater in irrigating the soils and the environmental factors pertinent in the
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E. I. Uwah: Continental J. Applied Sciences 4: 76 - 88, 2009 study area. The concentration levels of some physicochemical parameters and particle fractions of the soils were also determined in the study. The results generally revealed that the levels of the metals in the vegetable were within the recommended ranges in plants, and were below the published threshold values considered excessive or toxic for mature plant tissue. Therefore, consumption of these vegetables as food may not pose or constitute possible health hazards to humans and animals at the time of the study. The concentration levels of the heavy metals in the carrot and soil samples would go a long way in providing a baseline data for the assessment of the concentration levels of some heavy metal pollutants in soils, and carrot (Daucus carota) obtained in Maiduguri, Nigeria. REFERENCES Abulude, O. F. (2005): Trace heavy metals contamination of Soils and Vegetation in the vicinity of livestock in Nigeria. EJEAFChe., 4 (2), 863 – 870. Adeleke,B. O. and Leong, G. C.(1978): Certificate Physical and Human Geography. West African Ed; Oxford University Press Nigeria, pp.171 – 173. Alaku, S. O. and Moruppa, S. M. (1988): Organ weight loss in Goats during long Dry Season in the Sahel Region of West Africa. J. Arid Zone Agric., 1, 23 – 24. Alloway, B. J. (1990): Heavy metals in soils. John Wiley and Sons, Glasgow, pp.122 – 151. Alloway, B.J. and Ayres, D.C (1997): Chemical principals for Environmental pollution. Blackie Academic Professional, pp.190 – 220. Anjana, U. S.and Iqbal, M.(2006): Nitrate accumulation in Plants, factors affecting the Process, and Human Health implications. A Review. INRA. EDP Sci., pp.1- 13. APHA (American Public Health Association) (1992): Standard methods for the examination of water and wastewater. 16th Ed. APHA. New York, pp.75 – 86. Awode, U.A; Uzairu, A; Balarabe, M.L; Okunola, O.J and Adewusi, S.G. (2008): Levels of some trace metals in the Fadama Soils and Pepper (Capsicum annuum) along the bank of River Challawa, Nigeria. Asian J. Sci. Res. ISSN 1992 – 1454, pp.1 – 6. Bokhari, M. H. and Ahmed, CH.M.S. (1985): Food Plants in Borno State Nigeria. Ghulamdi Publishers, Lahore, pp.1 – 46. Bunzl, K. Trautmannsheimer, M. Schramel, P. and Reifenhäuser, W. (2000): Availability of Arsenic, Copper, Lead, Thallium, and Zinc to various vegetables grown in Slag- contaminated Soils. Technical report on heavy metals in the Environment Chiroma, T.M; Hymore, F.K and Ebawele, R.O (2003): Heavy metal contamination of vegetables and soils irrigated with sewage water in Yola. NJERD. Vol.2, No.3, pp. 25 – 31. Das, P; Samantarary, S. and Rout, G.R. (1997): Studies on Cadmium toxicity in Plant. A Review. Environ. Pollut., 98, 29 – 36. Ebong, G.A., Etuk, H. S. and Johnson, A. S. (2007): Heavy metals accumulation by Talinum triangulare grown on waste dumpsites in Uyo Metropolis, Akwa Ibom State, Nigeria. J. Applied Sci., ISSN 1812 – 5654. Eja, M. E., Ogri, O. R. and Arikpo, O. E. (2003): Bioconcentration of heavy metals in surface sediments from the Great Kwa River Estuary, Calabar, Southeastern Nigeria. J. Nig. Environ. Soc., 1, 247 – 256. Harrison, R. M. and Chirgawi, M. B. (1989): The assessment of air and soil as contributors of some trace metals to vegetable plants I. Use of a filtered air growth cabinet. Sci. Total Environ., 83, 13–34. Kabata-Pendias, A. and H. Pendias. (1984): Trace elements in soils and plants. CRC Press, Boca Raton, FL.
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E. I. Uwah: Continental J. Applied Sciences 4: 76 - 88, 2009 Kirkhan, M. B. (1983): Study on accumulation of heavy metals in Soil receiving sewage and effluent water. Agric. Ecosystem. Environ., 9, 251. Lokeshwari, H. and Chandrappa, G. T.(2006): Impact of heavy metal contamination of Bellandur Lake on soil and cultivated vegetation. Curr. Sci., Vol. 91. (5), 622 – 627. Lokhande, R. S. and Kelkar, N. (1999): Studies on heavy metals in water of Vasai Creek, Maharashtra. Indian J. Environ. Protect., 19, 664–668. McLeod, S. (1973): Studies on wet oxidation procedures for the determination of organic carbon in soil. In ‘Notes on Soil Techniques’. (CSIRO Division of Soils: Melbourne), pp. 73 – 79. (www.actahort.org/members/showpdf?booknrarnr=379_26) Mortvedt, J. Mays D.A. and Osborn, G. (1981): Uptake by wheat of cadmium and other heavy metal contaminants in phosphate fertilizers. J Environ. Quality, 10,193 – 197. Nicholson, F.A. and Jones, K.C. (1994): Effect of Phosphate fertilizers and Atmospheric deposition on long-term changes in cadmium content of soils and crops, Environ. Sci. Technol. 28, 2170 – 2175. Nriagu, J.O. (1990): Global metal pollution poisoning the atmosphere. Environ., 7, 87 - 93. Olaniya, M. S., Sur, M. S., Bhide, A. D. and Swarnakar, S. N. (1998): Heavy metal pollution of agricultural soil and vegetation due to application of municipal solid waste – A case study. Indian J. Environ. Health, 40, 160 –168. Onianwa, P.C. (2001): Roadside topsoil concentrations of lead and other heavy metals in Ibadan, Nigeria. Soil sediment Contam., 10,577 – 591. Radojevic, M. and Bashkin, N. V. (1999): Practical Environmental Analysis. Royal Society of Chemistry and Thoma Graham House, Cambridge, pp. 180 – 430. Rayment, G.E. and Higginson, F. R. (1992): Australian laboratory handbook of soil and water chemical methods. Inkarta Press: Melbourne, pp.25 – 30. Shauibu, U. O. and Ayodele, J. T. (2002): Bioaccumulation of four heavy metals in leaves of Calostropis procera. J. Chem. Soc. Nig., 27, 26 – 27. Singh, B. R. (1994): Trace element availability to plants in agricultural soils with special emphasis on fertilizer inputs, Environ Rev., 2,133 – 146. Umoren, I. U. and Onianwa, P. C. (2005): Concentration and Distribution of some Heavy Metals in Urban Soils of Ibadan, Nigeria. Pak. J. Ind.Res., 48, 397 – 401. USEPA (United States Environmental Protection Agency) (1996): Acid digestion of Sediment, Sludge and Soils: Method 305B (USEPA: Washington), pp.5 – 15. Ward, N. I. (1995): Environmental Analytical Chemistry. In Trace Elements (Eds Fifield, F. W.and Haines, P. J.), Blackie Academic and Professional, UK, pp. 320 – 328. Williams, C. H., and David, D.J. (1973): The Effect of Super Phosphate on the Cadmium content of Soils and Plants, Aust. J. Res., 11, 43 – 56. www.actahort.org/members/showpdf?booknrarnr=379_26 Yusuf, A. A., Arowolo, T.A. and Bamgbose, O.( 2003): Cadmium, Copper and Nickel Levels in Vegetables from Industrial and Residential Areas of Lagos City,Nigeria. Food Chem. Toxicol., 41, 285 – 291.
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E. I. Uwah: Continental J. Applied Sciences 4: 76 - 88, 2009 Zauyah, S., Juliana, B., Noorhafizah, R., Fauzah, C. I. and Rosenami, A. B. (2004): Concentration and Speciation of Heavy Metals in some Cultivated and Uncultivated Ultisols and Inceptisols in Peninsular Malaysia, Super-Soil 3rd Austrlian New Zealand Soils Conference, University of Syndney Austrlia. Zhang, S. and Shan, X. (2001): Speciation of Rare Earth Elements in Soil and Accumulation by Wheat with Rare Earth Fertilizer application, Environ. Pollut., 112, 395 – 405. ACKNOWLEDGEMENT I sincerely acknowledged the contributions of Prof. V. O. Ogugbuaja and Dr. (Mrs.) N. P. Ndahi, both of the Department of Chemistry, University of Maiduguri, in proof reading the manuscript. Received for Publication: 17/05/2009 Accepted for Publication: 10/07/2009 Corresponding Author Email: [email protected]
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E. I. Uwah: Continental J. Applied Sciences 4: 76 - 88, 2009 Table 1: Concentrations in µgg-1 of some heavy metal pollutants in carrot vegetable samples obtained from Alau dam and Gongulon, from
The above values are means of replicate values (n = 6). Within column, means with different alphabets are statistically different (p<0.05). OC = Organic carbon, OM = Organic matter, CEC = Cation exchange capacity, EC = Electrical conductivity Table 4: Some particle size fractions of the soils
