Research ArticleAssessment of Trace Metals Concentration inTree Barks as Indicator of Atmospheric Pollution withinIbadan City South-West Nigeria
Ikechukwu P Ejidike1 and Percy C Onianwa2
1Department of Chemistry Faculty of Science and Agriculture University of Fort Hare PB X1314 Alice 5700 South Africa2Department of Chemistry Faculty of Science University of Ibadan Ibadan Nigeria
Correspondence should be addressed to Ikechukwu P Ejidike pejidikeufhacza
Received 23 July 2015 Revised 11 September 2015 Accepted 13 September 2015
Academic Editor Miguel de la Guardia
Copyright copy 2015 I P Ejidike and P C Onianwa This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited
Tree bark species were randomly collected from 65 sites having different anthropogenic activities such as industrial high trafficcommercial residential high and residential low traffic volume areas of Ibadan City Nigeria Levels of Cd Cu Pb Zn Co and Crof the dry-ashed bark samples were determined by AASThemeanmetal concentrations (mg kgminus1) in samples from industrial zonewere found as Pb 367 plusmn 197 Cd 010 plusmn 007 Zn 3096 plusmn 3205 Cu 729 plusmn 517 Co 091 plusmn 058 and Cr 261 plusmn 184 The trend ofmean trace metal concentrations at high traffic commercial zone follows the order Zn gt Pb gt Cu gt Cr gt Co gt Cd Residential hightraffic and low traffic zones revealed the same trend as Cd ltCo ltCr lt Pb ltCu lt Zn Relatively strong positive correlation betweenthe heavy metals at 120588 lt 005 such as Zn versus Cu (119903 = 079) and Co versus Cu (119903 = 077) was observed The results of the studysuggest that tree bark samples could potentially serve as bioindicators for Cu Pb Zn Cr and possibly Co and Cd Furthermoreinterspecies variation of heavy metal concentrations in plants barks is recommended
1 Introduction
Air pollution was not perceived as a major problem in mostcountries until late 1960s and early 1970s it was the globalcooling forecast that captured public imagination in urbanand industrialized areas [1] In 2014 WHO released a reporton air pollution as the instigator of about 7 million peoplersquosdeath in 2012 These air contaminants are released into theecosystem from immobile sources such as power stationsand other industries and itinerant sources such as motor-powered vehicles airplanes and ships [2 3] The release ofthese gaseous volatile organic and inorganic pollutants in theform of particulate matters with sizes lt10 times 10minus6m [4] bringsabout steady deterioration of the air quality giving rise tonumerous cases of illness and even death depletion of ozonelayer sulfurous and photochemical smog acid rains globalwarming greenhouse effect and physiological problem [3 5]One of the natural components (inorganic pollutants) of
the environment is heavy metals due to the proliferation ofindustries high immigrant rate and increased urbanization[6 7] Hence they have been added to the ecosystem in largequantity causing earthrsquos atmosphere deterioration as it formsthe life support of the planet [8 9] According toHashmi et al[10] heavy metals have been found to play an imperative rolein the biochemical biological chemical catabolic metabolicand enzymatic reactions in living cells [11] but when presentin excess amount they affect plants and animals leadingto various kinds of diseases due to their stumpy levels involuminous environmental and biological samples [12 13]
Biological materials are used to ascertain atmospherictrace metal concentrations [14ndash16] The use of biomonitoras it is easy to collect and cheap has higher concentra-tions than air and rainwater for measuring the trace metalconcentrations in the atmosphere [17 18] Bioindicators ofdifferent entities are being used including vascular plantsmosses woody plants and lichens [19 20] The use of vegetal
Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2015 Article ID 243601 8 pageshttpdxdoiorg1011552015243601
2 Journal of Analytical Methods in Chemistry
biomonitoring to evaluate air quality has been investigatedone alternative is to characterize gradients of air pollutionon a small scale by the use of biological monitors [21 22]In San Luis Potosi one of the most industrially developedcities in Mexico Beramendi-Orosco et al [23] studied thecorrelations between Zn Pb and Cu in tree-ring sequencesof Prosopis juliflora a tree species native to arid environ-ments The results suggested that the smelterrsquos emissionsare dispersed to longer distances through the tall chimneysthereby confirming Prosopis juliflora as a good bioindicatorthus providing information on the chronology and sources ofheavy metal pollution in urban and industrial areas Turkishred pine (Pinus brutia) a widespread evergreen tree hasbeen investigated by Baslar et al [14] in Mediterraneanand Aegean regions of Turkey The barks were examinedas biomonitor of Zn and Mn accumulation in the studiedarea Many studies have focused on the use of different treebark species as biomonitor However in some studies onlypine species were investigated to decide whether pine speciescan be used as a biomonitor for the determination of heavymetals Results of such studies showed that the barks ofthe pine trees are good adsorbents of airborne pollutantsincluding anthropogenic heavy metals Different authorshave reported the atmospheric pollutants bioaccumulationof pine tree species due to their widespread with evergreenneedle normally 3ndash5 inches haphazardly warped [19 22]including Turkish red pine (Pinus brutiaTen) [14]This studyrelates to a seasonal study in the city of Ibadan with the aimto determine the levels of heavy metals using tree barks asindicators of atmospheric trace metal pollution The metalsinvestigated are Pb Zn Cd Cu Co and Cr based on theirenvironmental concerns
2 Materials and Methods
21 Study Area Ibadan located in southwestern Nigeria isan ancient city categorized by urban sprawl and moderniza-tion [24] it falls within the basement complex of the geolog-ical setting of southern Nigeria which lies between latitude7∘151015840Nndash7∘301015840 and longitude 3∘451015840ndash4∘601015840E which possessestwo seasonal climates (wet and dry) andmoderately the sametemperatures in a given season of the year There has beenincreased industrialization and urbanization in Ibadan lead-ing to progressively increased discharges of heavymetals intothe atmosphere [24] The samples of tree backs with differentbark morphology were collected from 65 locations withinIbadan city (Figure 1) involving seven different speciesnamely Terminalia catappa Azadirachta indica Gmelinaarborea Mangifera indica Gliricidia sepium Prosopisjuliflora and Murraya species Decision on sampling zoneswas made after a careful survey of the traffic densities indus-trial distribution pattern covering the whole city of IbadanThe sampling points designated and number of samples col-lected include industrial zone (INZ
1ndash20) high traffic commer-cial zone (HTZ
1ndash14) residential high traffic zone (RHZ1ndash16)
and residential low traffic zone (RLZ1ndash11) The university
botanical garden (CTZ1ndash5) aided in the uncontaminated
reference point (control) being far-flung from traffic flowThetrees that were closer to the highways (about 5m) about same
age were chosen and the barks were cautiously detachedwith a clean stainless knife at a height of about 18ndash20mabove the ground level [25 26] The samples were collectedin duplicates and thereafter mixed to obtain whole sample
22 Experiment The samples were dried in the oven at atemperature of 60∘C for 3-4 hours to a constant weight Thedried samples were pulverized to uniform size with a labora-tory mill thoroughly cleaned and dried after each grindingto circumvent cross contamination Samples were kept inclean plastic bags until the time analysis About 2 g of thepowdered sample was weighed accurately into a precleanednumbered Vitreosil crucible They were then transportedinto the muffle furnace and were preashed in the furnacefor about 15 minutes at 150∘C until the fumes vanishedand ashed at the temperature of about 450ndash500∘C [27] Thecooled ashed samples were then liquefied with 10mL of 10HNO
3
solution and transfer to precleaned labelled centrifugetube The crucible was again rinsed with portions of acidsolution to make a total volume of 20mL and vortexed forproper mixing The samples were centrifuged for 30 minutesat 3000 rpm using HERMLE-Z323 Model The supernatantswere decanted into 100mL calibrated volumetric flasks madeup to the mark with the acid solution and evaluated formetal concentrations with the Buck Scientific Model 210VGP Atomic Absorption Spectrophotometer possessing air-acetylene flame (functioned in line with the instrumentrsquosguidebook) and calibrated using mixed calibration standardsolutions prepared asmandated [14 28] Blank solutions wereprepared without the samples using the same procedure
A spike recovery was used to verify the acid digestionprocedure used in this study by spiking portions of previouslyanalyzed samples six samples including onewith a high back-ground or low background These samples were oven-driedat 105∘C homogenized and passed through the extractionand analytical steps [29] The accuracy and validation ofmethod were determined by analyzing spiked samples usingthe same reagents apparatus and method as those used forthe samples Percentage recovery of Cr 9420 plusmn 840 Zinc9710 plusmn 891 Pb 9358 plusmn 1587 Cu 9493 plusmn 1150 Co8840 plusmn 467 and Cd 9732 plusmn 1029 was obtained Thefinal concentrations of the metals measured in the tree barksamples byAAS technique are likely to be the correspondingpercentages as the true values since 100 plusmn 20 recoveryis acceptable and all the metal concentrations were withinthe recovery range value [29ndash31] The format used for thecalculation of recovery is as follows Percent recovery (Recovery) = (119860 minus 119861)119862 times 100119860 is concentration of the spiked sample 119861 is concentra-
tion of the unspiked sample and 119862 is spike added
3 Result and Discussion
The extractable heavy metal concentrations in the sevenspecies of tree barks sampled from four zones (industrialhigh traffic commercial and residential high and low trafficzones) in addition to the control samples (botanical gardenUniversity of Ibadan) in Ibadan are presented in Table 1
Journal of Analytical Methods in Chemistry 3
Table 1 Summary of results for tree bark metal concentration (mean plusmn SD mg kgminus1 dry weight) in all zones
Metal Parameter Industrial zoneHigh trafficcommercial
Figure 1 Ibadan City map showing the various sampling points
Various heavy metals accumulation in different plant parts isdependent on the amount of metals present in the ecosystemand the metal accumulation levels differ within and betweenspecies of plants [9 32] Generally the same trend for metalconcentration as found in the control zone was also observed
in the industrial zone residential high traffic zone andresidential low traffic zone that is Zn gt Pb gt Cu gt Cr gt Co gtCd However Zn showed the highest metal concentrationwith mean magnitude of 4597 plusmn 4388mgkgminus1 amongall zones (Figures 2(a)ndash2(f)) Overall mean concentrations
4 Journal of Analytical Methods in Chemistry
Pb
0
2
4
6
8
10
INZ
HTZ
CTZ
RHZRLZ
Locations
INZHTZRHZ
RLZCTZ
Con
cent
ratio
ns (m
g kgminus
1 )
(a)
Cd
Con
cent
ratio
ns (m
g kgminus
1 )
INZ
HTZ
CTZ
RHZRLZ
Locations
INZHTZRHZ
RLZCTZ
0
002
004
006
008
01
012
014
(b)
Zn
Con
cent
ratio
ns (m
g kgminus
1 )
INZ
HTZ
CTZ
RHZRLZ
Locations
INZHTZRHZ
RLZCTZ
0
10
20
30
40
50
(c)
Cu
Con
cent
ratio
ns (m
g kgminus
1 )
INZ
HTZ
CTZ
RHZRLZ
Locations
INZHTZRHZ
RLZCTZ
55
6
65
7
75
(d)
Co
Con
cent
ratio
ns (m
g kgminus
1 )
INZ
HTZ
CTZ
RHZRLZ
Locations
INZHTZRHZ
RLZCTZ
0
02
04
06
08
1
(e)
Cr
Con
cent
ratio
ns (m
g kgminus
1 )
INZ
HTZ
CTZ
RHZRLZ
Locations
INZHTZRHZ
RLZCTZ
0
05
1
15
2
25
3
35
(f)
Figure 2 Metal concentrations in tree backs collected from all sampling zones INZ industrial zone HTZ high traffic commercial zoneRHZ residential high traffic zone RLZ residential low traffic zone CTZ control zone
(mg kgminus1 dry weight) of metals in tree bark samples obtainedfrom this study were found to be Pb 599 plusmn 525 Cd 009 plusmn007 Zn 2764 plusmn 2966 Cu 690 plusmn 554 Co 087 plusmn 045and Cr 284 plusmn 158 which varied from 075 to 2974 lt001to 026 370 to 16613 181 to 3912 023 to 235 and lt001
to 834mg kgminus1 respectively (Table 2) Abundance of metalconcentrations follows the order Zn gt Cu gt Pb gt Cr gt Co gtCdThe results indicate the presence of zinc copper and leadin high concentrations in samples taken from industrial hightraffic commercial and residential high traffic areas relative to
Journal of Analytical Methods in Chemistry 5
Table 2 Overall mean metal concentrations (mg kgminus1 dry weight) in tree bark samples
Range 75ndash2974 lt001ndash026 370ndash16613 181ndash3912 023ndash235 lt001ndash834
residential low traffic and control areas The concentrationsof the heavy metal investigated in this study when comparedwith metal levels reported by Mleczek et al [33] revealedthat the concentrations obtained in this study were higher formetals like Pb Zn Cu and Cr while the concentrations of Coand Cd were lower than those reported in another study thiscould be due to the addition of these metals in trace amountin Nigeria petrol as a means of enhancing the octane numberof gasoline [34 35]
The results for themetal concentrations showed amarkedvariation for samples obtained from the industrial zoneOpposite Procter amp Gamble Limited (INZ
5
) high trafficcommercial zone Iwo Roundabout (HTZ
13
) residential hightraffic zone Opposite Coca-Cola Mini Depot (RHZ
1
) andresidential low traffic zone Adeyi AvenueOld Bodija (RLZ
3
)this generally has the highest value of metal levels Zincconcentration varied widely in all zones with the residen-tial low traffic zone having the lowest level 1641mg kgminus1and the highly trafficked commercial zone possessing thehighest level with mean value of 4597mg kgminus1 The highestconcentration of Zn (16616mg kgminus1) was observed in thesample collected at Iwo Road Roundabout (Alakia axis)(HTZ
14
) within high traffic commercial zone The resultsshowed that there is a significant difference in the zincconcentration at 120588 lt 005 among the zones However nosignificant difference was observed in the zinc concentrationof high traffic commercial zone as compared to industrialzone This indication connotes emission and tyre wear frommotor vehicle pointers as a source of the environmentalzinc contamination Also zinc could be added to the envi-ronment during industrial activities like engine wear wastecombustion exhaust emission and the use of sewage sludgefrom industrial areas as fertilizer Zn promotes growth anddevelopment in the human body but its excessiveness maybe an indication of metal poisoning and growth impedance[36]
The concentration of lead in samples obtained from hightraffic commercial residential high traffic and residential lowtraffic zones varied slightly with average concentrations of962 670 and 596mg kgminus1 respectively However possiblecradles of metal contaminants in the environment are acrucial part of environmental pollution studies The chiefsource of lead (Pb) is the use of leaded gasoline in the20th century [37ndash40] which inevitably brings about leadpollutant in the ecosystem Lead content of Nigeria petrol[06ndash08 g Lminus1] ranks among the world highest content [41]Concentrations of lead reported in other studies showedhigher values than that obtained in this study except forlead concentration reported by [29 33 42 43] Humanexposure to lead brings about reproductive dysfunction
that exhibits biochemical-morphological features includingdecreased sperm quality disorganized epithelia and alteredsperm morphology [44] The analysis of variance showedno significant difference between the levels of copper in allzones at 120588 gt 005 Copper as a crucial micronutrient isessential for bone growth and formation neurologic systemsand nervous systems myelin sheaths [45] The high level(3912mg kgminus1) of copper concentration in samples sampledfrom Aworawo along Ojoo road (HTZ
9
) high traffic com-mercial zones could result from various human activitiesClose look at the results of copper level in residential highand low traffic zones suggests common source Increasedlevels could lead to cirrhosis rheumatoid arthritis mal-nutrition irregular hair growth and depigmentation furgrowth impairment and reproductive performance failureof the heart and disturbances in gastrointestinal systems[44]
Mean concentration of cobalt in the zones was found tofollow the trend high traffic commercial gt residential hightraffic gt industrial gt control gt residential low traffic (Figures2(a)ndash2(f)) with ranges There is no significant differenceobserved for the level of cobalt in all investigated zones at120588 gt 005 The highest cobalt concentration was found in theMangifera indica sample from behind Sumal Foods (chewinggum) (INZ
3
) industrial zone Chromium levels were largelylow in the study (Figures 2(a)ndash2(f)) and the residentiallow traffic zone posed the lowest level of chromium whichcould be attributed to natural sources In various zoneschromium pollution could be due to automobile engineand body erosion yellow lead chromate paint for roadpattern and few steel and glass industry activities [46ndash48] Chromium is known as a ubiquitous pollutant fromthe industrial and environmental activities also a knownhuman carcinogen with specificity in cancer of the lungs[49 50] There is no definite gradient in the concentration ofcadmium present in the investigated zones The residentiallow traffic zone gave 010mg kgminus1 and the lowest meanlevel of cadmium (Cd) was found in residential high trafficzone (006mg kgminus1) ranging from 001 to 015mg kgminus1 Theslight increase in the mean level of cadmium in the controlzone (014mg kgminus1) with the highest concentration foundin the Gmelina arborea species (025mg kgminus1) could belinked to the use of phosphate fertilizer which has cadmiumas a trace element for growing crops When cadmium isaccumulated above the recommended threshold limit itbrings about liver acute and chronic poisoning and also thereplacement of calciumwithin bonematrix of young children[44] it inhibits increased oxidative stress resulting in thedamage of membrane and membrane-enzymes bound losses[51]
6 Journal of Analytical Methods in Chemistry
Table 3 Correlation coefficient among metals in tree bark samplesfrom all zones (bold correlations are significant at 120588 lt 005)
Pb Cd Zn Cu Co CrPb 1Cd 040 1Zn 070 031 1Cu 027 050 079 1Co 024 020 054 077 1Cr 067 024 055 063 069 1
31 Correlation Matrix A coefficient matrix among PbCd Zn Cu Co and Cr concentrations in samples fromthe studied locations are presented in Table 3 The resultsshowed that the elements investigated in this study are highlycorrelated with one another suggesting common source andother possible uncommon sources of metal fallout There isrelatively high correlations amongst metals such as Zn andCu and Co and Cu Positive moderate correlation coefficientwas observed between Pb and Zn and Zn and Co The highcorrelation found between Pb andZn andZn andCu suggestsa common source and other possible well-mixed constituentsinitiating from different sources Positive moderate correla-tion coefficient was also observed between Cr versus Pb andZn and Cr versus Cu and Co Zn level in all the zones wasseen to be in high concentration followed by Cu and Pb Highvalues of Cu and Zn obtained indicate that emission and tyrewear from motor vehicle as a source of the environmentalzinc contamination high level of copper could come fromthe fabrication of brass alloy brake linings and electrical andmechanical working while lead could be the use of leadedgasoline in the Nigeria petrol This is because lead additivesin the form of tetraethyl lead (TEL[Pb(C
2
H5
)4
]) are added togasoline as the cheapestmeans of boasting the octane numberof Nigeria petrol and zinc in the form of organometalliccompounds such as zinc dialkyl dithiophosphate (ZDDP)lubricating oils and tyres [46 52 53]
4 Conclusion
The results of this survey demonstrate the suitability ofTerminalia catappa Azadirachta indica Gmelina arboreaMangifera indica Prosopis juliflora andMurraya species andGliricidia sepium bark species as potential bioindicators forCu Pb Zn Cr and possibly Co and Cd as well as the pointersof some degree of temporal heavy metals contaminationThe levels of the metals were higher in bark samples fromhighly trafficked commercial zone than in other zones Thedeviation in metal concentrations amongst the studied sitescould be due to various anthropogenic activitiesWith respectto the high contribution factors of Zn Cu and Pb to thepotential ecological risk of the area thorough study shouldbe piloted to determine the actual route of the metals entry tothe environment It is imperative that the environmental tracemetal levels be constantly examined to diagnose the stateand trend of environmental atmospheric pollution Furthermonitoring of plant barks species as well as the surrounding
lower epiphytes higher epiphytes and vascular plants isneeded in order to determine whether any temporal trendsexist in metal concentration among biological indicatorsPotential risk assessment of these heavy metals to cropsanimals and humans in the area is recommended Furtherfarming activities within the diameter of 15ndash10Km of thevicinity of the industries and high human activities should bediscouraged as there will be every possibility of heavy metalsuptake by planted crops which will in turn reach up thefood chain and finally to humans Furthermore interspeciesvariation of heavymetal concentrations in plants barks is alsorecommended
Conflict of Interests
Regarding the publication of this paper the authors declareno conflict of interests
Authorsrsquo Contribution
The authors contributed equally to the achievement of theresearch
Acknowledgments
Theauthors wish to acknowledge GovanMbeki Research andDevelopmentCentre (GMRDC)University of FortHare andNRF-Sasol Inzalo Fundation for financial support receivedThe authors acknowledge Eyitayo Fadipe and Ayoade Folukewho assisted in the sample collection
References
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[2] K Ravindra R Sokhi and R Van Grieken ldquoAtmosphericpolycyclic aromatic hydrocarbons source attribution emissionfactors and regulationrdquo Atmospheric Environment vol 42 no13 pp 2895ndash2921 2008
[3] C Woodford Air Pollution 2010 httpwwwexplainthatstuffcomair-pollution-introductionhtml
[4] U Makkonen H Hellen P Anttila and M Ferm ldquoSizedistribution and chemical composition of airborne particlesin south-eastern Finland during different seasons and wildfireepisodes in 2006rdquo Science of the Total Environment vol 408 no3 pp 644ndash651 2010
[5] J Wang Z Hu Y Chen Z Chen and S Xu ldquoContaminationcharacteristics and possible sources of PM10 and PM25 indifferent functional areas of Shanghai Chinardquo AtmosphericEnvironment vol 68 pp 221ndash229 2013
[6] G Qingjie D Jun X Yunchuan W Qingfei and Y LiqiangldquoCalculating pollution indices by heavy metals in ecologicalgeochemistry assessment and a case study in parks of BeijinrdquoJournal of ChinaUniversity of Geosciences vol 19 no 3 pp 230ndash241 2008
[7] C O Ogunkunle and P O Fatoba ldquoPollution loads andthe ecological risk assessment of soil heavy metals around
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[8] H A Sani A I Tsafe B U Bagudo and A U ItodoldquoToxic metals uptake by spinach (Spinacea oleracea) and lettuce(Lactuca sativa) cultivated in sokoto a comparative studyrdquoPakistan Journal of Nutrition vol 10 no 6 pp 572ndash576 2011
[9] D Satpathy andMVReddy ldquoPhytoextraction ofCd Pb ZnCuandmn by Indian mustard (Brassica juncea L) grown on loamysoil amended with heavy metal contaminated municipal solidwaste compostrdquo Applied Ecology and Environmental Researchvol 11 no 4 pp 661ndash679 2013
[10] D R Hashmi S Ismail and G H Shaikh ldquoAssessment ofthe level of trace metals in commonly edible vegetables locallyavailable in the markets of Karachi cityrdquo Pakistan Journal ofBotany vol 39 no 3 pp 747ndash751 2007
[11] G N Lion and J O Olowoyo ldquoPopulation health risk dueto dietary intake of toxic heavy metals from Spinacia oleraceaharvested from soils collected in and around Tshwane SouthAfricardquo South African Journal of Botany vol 88 pp 178ndash1822013
[12] B A Anhwange J A Kagbu E B Agbaji and C E GimbaldquoTrace metal contents of some common vegetables grown onirrigated farms along the banks of river Benue within MakurdiMetropolisrdquo Electronic Journal of Environmental Agriculturaland Food Chemistry vol 8 no 11 pp 1150ndash1155 2009
[13] S Baytak R Mert and A R Turker ldquoDetermination ofCu(II) Fe(III) Mn(II) and Zn(II) in various samples afterpreconcentrationwithRhizopus oryzae loaded natural cellulose(almond bark)rdquo International Journal of Environmental Analyt-ical Chemistry vol 94 no 10 pp 975ndash987 2014
[14] S Baslar Y Dogan N Durkan and H Bag ldquoBiomonitoringof zinc and manganese in bark of Turkish red pine of westernAnatoliardquo Journal of Environmental Biology vol 30 no 5 pp831ndash834 2009
[15] A Celik A A Kartal A Akdogan and Y Kaska ldquoDeterminingthe heavy metal pollution in Denizli (Turkey) by using Robiniopseudo-acacia Lrdquo Environment International vol 31 no 1 pp105ndash112 2005
[16] G Nabulo H Oryem Origa G W Nasinyama and D ColeldquoAssessment of Zn Cu Pb and Ni contamination in wetlandsoils and plants in the LakeVictoria basinrdquo International Journalof Environmental Science and Technology vol 5 no 1 pp 65ndash742008
[17] BWolterbeek S Sarmento andTVerburg ldquoIs there a future forbiomonitoring of elemental air pollutionA review focused on alarger-scaled health-related (epidemiological) contextrdquo Journalof Radioanalytical and Nuclear Chemistry vol 286 no 1 pp195ndash210 2010
[18] P K Rai ldquoEnvironmental magnetic studies of particulates withspecial reference to biomagnetic monitoring using roadsideplant leavesrdquo Atmospheric Environment vol 72 pp 113ndash1292013
[19] B Kord A Mataji and S Babaie ldquoPine (Pinus Eldarica Medw)needles as indicator for heavy metals pollutionrdquo InternationalJournal of Environmental Science and Technology vol 7 no 1pp 79ndash84 2010
[20] I Rodrıguez-Germade K J Mohamed D Rey B Rubio and AGarcıa ldquoThe influence of weather and climate on the reliabilityof magnetic properties of tree leaves as proxies for air pollutionmonitoringrdquo Science of the Total Environment vol 468-469 pp892ndash902 2014
[21] L Mulligan An assessment of epiphytic lichens lichen diversityand environmental quality in the semi-natural woodlands ofKnocksink Wood Nature Reserve Enniskerry County Wicklow[PhD thesis] Dublin Institute of Technology 2009
[22] B Kord and B Kord ldquoHeavymetal levels in pine (Pinus eldaricaMedw) tree barks as indicators of atmospheric pollutionrdquoBioResources vol 6 no 2 pp 927ndash935 2011
[23] L E Beramendi-Orosco M L Rodriguez-Estrada O Morton-Bermea F M Romero G Gonzalez-Hernandez and EHernandez-Alvarez ldquoCorrelations between metals in tree-ringsof Prosopis julifora as indicators of sources of heavy metalcontaminationrdquo Applied Geochemistry vol 39 pp 78ndash84 2013
[24] D G Shendell and G R E E Ana ldquoPromoting environmentalpublic health in rapidly urbanizing areas of less-developedcountries in Africa a collaborative interdisciplinary training inIbadan Nigeriardquo Journal of Environmental Health vol 74 no 1pp 26ndash35 2011
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[26] I Suchara P Rulık J Hulka and H Pilatova ldquoRetrospectivedetermination of 137Cs specific activity distribution in sprucebark and bark aggregated transfer factor in forests on the scaleof the Czech Republic ten years after the Chernobyl accidentrdquoScience of the Total Environment vol 409 no 10 pp 1927ndash19342011
[27] T Sawidis J BreusteMMitrovic P Pavlovic andK TsigaridasldquoTrees as bioindicator of heavy metal pollution in three Euro-pean citiesrdquo Environmental Pollution vol 159 no 12 pp 3560ndash3570 2011
[28] S Leshe and M Tessema ldquoDetermination of levels of essentialand toxic heavy metals in lentil (lens culinaris medik) by flameatomic absorption spectroscopyrdquo African Journal of ChemicalEducation vol 4 no 4 pp 16ndash34 2014
[29] F G Fujiwara D R Gomez L Dawidowski P Perelman andA Faggi ldquoMetals associated with airborne particulate matter inroad dust and tree bark collected in a megacity (Buenos AiresArgentina)rdquo Ecological Indicators vol 11 no 2 pp 240ndash2472011
[30] P C Ogbonna C Odukaesieme and J A Teixeira da SilvaldquoDistribution of heavymetals in soil and accumulation in plantsat an agricultural area of Umudike Nigeriardquo Chemistry andEcology vol 29 no 7 pp 595ndash603 2013
[31] A I Ajai S SOchigbo ZAbdullahi andP I Anigboro ldquoDeter-mination of trace metals and essential minerals in selected fruitjuices in Minna Nigeriardquo International Journal of Food Sciencevol 2014 Article ID 462931 5 pages 2014
[32] A R Ipeaiyeda and M Dawodu ldquoAssessment of toxic metalpollution in soil leaves and tree barks bio-indicators of atmo-spheric particulate deposition within a University communityin Nigeriardquo AES Bioflux vol 6 no 2 pp 101ndash110 2014
[33] M Mleczek I Rissmann P Rutkowski Z Kaczmarek and PGolinski ldquoAccumulation of selected heavy metals by differentgenotypes of Salixrdquo Environmental and Experimental Botanyvol 66 no 2 pp 289ndash296 2009
[34] S E Kakulu ldquoTracemetal concentration in roadside surface soiland tree back a measurement of local atmospheric pollution inAbuja Nigeriardquo Environmental Monitoring and Assessment vol89 no 3 pp 233ndash242 2003
8 Journal of Analytical Methods in Chemistry
[35] J G SpeightThe Chemistry and Technology of Petroleum CRCPress Taylor amp Francis Boca Raton Fla USA 5th edition 2010
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[37] A E Kelly M K Reuer N F Goodkin and E A Boyle ldquoLeadconcentrations and isotopes in corals and water near Bermuda1780ndash2000rdquo Earth and Planetary Science Letters vol 283 no 1ndash4 pp 93ndash100 2009
[38] N Robbins Z-F Zhang J Sun M E Ketterer J ALalumandier and R A Shulze ldquoChildhood lead exposure anduptake in teeth in the Cleveland area during the era of leadedgasolinerdquo Science of the Total Environment vol 408 no 19 pp4118ndash4127 2010
[39] A Roberts ldquoChronology of leaded gasolineleaded petrol his-toryrdquo LEAD Action News vol 12 no 2 2011 httpwwwleadorgaunlhtml
[40] P-C Huang P-H Su H-Y Chen et al ldquoChildhood bloodlead levels and intellectual development after ban of leadedgasoline in Taiwan a 9-year prospective studyrdquo EnvironmentInternational vol 40 no 1 pp 88ndash96 2012
[41] C W Rankin J O Nriagu J K Aggarwal T A ArowoloK Adebayo and A R Flegal ldquoLead contamination in cocoaand cocoa products isotopic evidence of global contaminationrdquoEnvironmental Health Perspectives vol 113 no 10 pp 1344ndash1348 2005
[42] E Schelle BG Rawlins RM Lark RWebster I Staton andCW McLeod ldquoMapping aerial metal deposition in metropolitanareas from tree bark a case study in Sheffield EnglandrdquoEnvironmental Pollution vol 155 no 1 pp 164ndash173 2008
[43] M Catinon S Ayrault O Boudouma J Asta M Tissut andP Ravanel ldquoAtmospheric element deposit on tree barks theopposite effects of rain and transpirationrdquo Ecological Indicatorsvol 14 no 1 pp 170ndash177 2012
[44] K O Soetan C O Olaiya and O E Oyewole ldquoThe importanceof mineral elements for humans domestic animals and plantsa reviewrdquo African Journal of Food Science vol 4 no 5 pp 200ndash222 2010
[45] J C Tan D L Burns and H R Jones ldquoSevere ataxiamyelopathy and peripheral neuropathy due to acquired copperdeficiency in a patient with history of gastrectomyrdquo Journal ofParenteral and Enteral Nutrition vol 30 no 5 pp 446ndash4502006
[46] A L Al-Khlaifat and O A Al-Khashman ldquoAtmospheric heavymetal pollution in Aqaba city Jordan using Phoenix dactyliferaL leavesrdquo Atmospheric Environment vol 41 no 39 pp 8891ndash8897 2007
[47] M A Nwachukwu H Feng and J Alinnor ldquoAssessment ofheavy metal pollution in soil and their implications within andaround mechanic villagesrdquo International Journal of Environ-mental Science and Technology vol 7 no 2 pp 347ndash358 2010
[48] N M Karaaslan and M Yaman ldquoDetermination of Nickel andChromium in Pinus nigra L Cedrus Libani and CupressusArizonica leaves to monitor the effects of pollution in Elazig(Turkey)rdquo Instrumentation Science amp Technology vol 41 no 3pp 335ndash348 2013
[49] C-Y Kuo R-H Wong J-Y Lin J-C Lai and H LeeldquoAccumulation of chromium and nickel metals in lung tumorsfrom lung cancer patients in Taiwanrdquo Journal of Toxicology and
Environmental HealthmdashPart A Current Issues vol 69 no 14pp 1337ndash1344 2006
[50] I Koturbash F A Beland and I P Pogribny ldquoRole of epigeneticevents in chemical carcinogenesis-a justification for incorporat-ing epigenetic evaluations in cancer risk assessmentrdquoToxicologyMechanisms and Methods vol 21 no 4 pp 289ndash297 2011
[51] M Gałazyn-Sidorczuk M M Brzoska M Jurczuk and JMoniuszko-Jakoniuk ldquoOxidative damage to proteins and DNAin rats exposed to cadmiumandor ethanolrdquoChemico-BiologicalInteractions vol 180 no 1 pp 31ndash38 2009
[52] P R Shakya P Shrestha C S Tamrakar and P K BhattaraildquoStudies and determination of heavy metals in waste tyresand their impacts on the environmentrdquo Pakistan Journal ofAnalytical and Environmental Chemistry vol 7 no 2 pp 70ndash76 2006
[53] H Spikes ldquoLow- and zero-sulphated ash phosphorus andsulphur anti-wear additives for engine oilsrdquo Lubrication Sciencevol 20 no 2 pp 103ndash136 2008
biomonitoring to evaluate air quality has been investigatedone alternative is to characterize gradients of air pollutionon a small scale by the use of biological monitors [21 22]In San Luis Potosi one of the most industrially developedcities in Mexico Beramendi-Orosco et al [23] studied thecorrelations between Zn Pb and Cu in tree-ring sequencesof Prosopis juliflora a tree species native to arid environ-ments The results suggested that the smelterrsquos emissionsare dispersed to longer distances through the tall chimneysthereby confirming Prosopis juliflora as a good bioindicatorthus providing information on the chronology and sources ofheavy metal pollution in urban and industrial areas Turkishred pine (Pinus brutia) a widespread evergreen tree hasbeen investigated by Baslar et al [14] in Mediterraneanand Aegean regions of Turkey The barks were examinedas biomonitor of Zn and Mn accumulation in the studiedarea Many studies have focused on the use of different treebark species as biomonitor However in some studies onlypine species were investigated to decide whether pine speciescan be used as a biomonitor for the determination of heavymetals Results of such studies showed that the barks ofthe pine trees are good adsorbents of airborne pollutantsincluding anthropogenic heavy metals Different authorshave reported the atmospheric pollutants bioaccumulationof pine tree species due to their widespread with evergreenneedle normally 3ndash5 inches haphazardly warped [19 22]including Turkish red pine (Pinus brutiaTen) [14]This studyrelates to a seasonal study in the city of Ibadan with the aimto determine the levels of heavy metals using tree barks asindicators of atmospheric trace metal pollution The metalsinvestigated are Pb Zn Cd Cu Co and Cr based on theirenvironmental concerns
2 Materials and Methods
21 Study Area Ibadan located in southwestern Nigeria isan ancient city categorized by urban sprawl and moderniza-tion [24] it falls within the basement complex of the geolog-ical setting of southern Nigeria which lies between latitude7∘151015840Nndash7∘301015840 and longitude 3∘451015840ndash4∘601015840E which possessestwo seasonal climates (wet and dry) andmoderately the sametemperatures in a given season of the year There has beenincreased industrialization and urbanization in Ibadan lead-ing to progressively increased discharges of heavymetals intothe atmosphere [24] The samples of tree backs with differentbark morphology were collected from 65 locations withinIbadan city (Figure 1) involving seven different speciesnamely Terminalia catappa Azadirachta indica Gmelinaarborea Mangifera indica Gliricidia sepium Prosopisjuliflora and Murraya species Decision on sampling zoneswas made after a careful survey of the traffic densities indus-trial distribution pattern covering the whole city of IbadanThe sampling points designated and number of samples col-lected include industrial zone (INZ
1ndash20) high traffic commer-cial zone (HTZ
1ndash14) residential high traffic zone (RHZ1ndash16)
and residential low traffic zone (RLZ1ndash11) The university
botanical garden (CTZ1ndash5) aided in the uncontaminated
reference point (control) being far-flung from traffic flowThetrees that were closer to the highways (about 5m) about same
age were chosen and the barks were cautiously detachedwith a clean stainless knife at a height of about 18ndash20mabove the ground level [25 26] The samples were collectedin duplicates and thereafter mixed to obtain whole sample
22 Experiment The samples were dried in the oven at atemperature of 60∘C for 3-4 hours to a constant weight Thedried samples were pulverized to uniform size with a labora-tory mill thoroughly cleaned and dried after each grindingto circumvent cross contamination Samples were kept inclean plastic bags until the time analysis About 2 g of thepowdered sample was weighed accurately into a precleanednumbered Vitreosil crucible They were then transportedinto the muffle furnace and were preashed in the furnacefor about 15 minutes at 150∘C until the fumes vanishedand ashed at the temperature of about 450ndash500∘C [27] Thecooled ashed samples were then liquefied with 10mL of 10HNO
3
solution and transfer to precleaned labelled centrifugetube The crucible was again rinsed with portions of acidsolution to make a total volume of 20mL and vortexed forproper mixing The samples were centrifuged for 30 minutesat 3000 rpm using HERMLE-Z323 Model The supernatantswere decanted into 100mL calibrated volumetric flasks madeup to the mark with the acid solution and evaluated formetal concentrations with the Buck Scientific Model 210VGP Atomic Absorption Spectrophotometer possessing air-acetylene flame (functioned in line with the instrumentrsquosguidebook) and calibrated using mixed calibration standardsolutions prepared asmandated [14 28] Blank solutions wereprepared without the samples using the same procedure
A spike recovery was used to verify the acid digestionprocedure used in this study by spiking portions of previouslyanalyzed samples six samples including onewith a high back-ground or low background These samples were oven-driedat 105∘C homogenized and passed through the extractionand analytical steps [29] The accuracy and validation ofmethod were determined by analyzing spiked samples usingthe same reagents apparatus and method as those used forthe samples Percentage recovery of Cr 9420 plusmn 840 Zinc9710 plusmn 891 Pb 9358 plusmn 1587 Cu 9493 plusmn 1150 Co8840 plusmn 467 and Cd 9732 plusmn 1029 was obtained Thefinal concentrations of the metals measured in the tree barksamples byAAS technique are likely to be the correspondingpercentages as the true values since 100 plusmn 20 recoveryis acceptable and all the metal concentrations were withinthe recovery range value [29ndash31] The format used for thecalculation of recovery is as follows Percent recovery (Recovery) = (119860 minus 119861)119862 times 100119860 is concentration of the spiked sample 119861 is concentra-
tion of the unspiked sample and 119862 is spike added
3 Result and Discussion
The extractable heavy metal concentrations in the sevenspecies of tree barks sampled from four zones (industrialhigh traffic commercial and residential high and low trafficzones) in addition to the control samples (botanical gardenUniversity of Ibadan) in Ibadan are presented in Table 1
Journal of Analytical Methods in Chemistry 3
Table 1 Summary of results for tree bark metal concentration (mean plusmn SD mg kgminus1 dry weight) in all zones
Metal Parameter Industrial zoneHigh trafficcommercial
Figure 1 Ibadan City map showing the various sampling points
Various heavy metals accumulation in different plant parts isdependent on the amount of metals present in the ecosystemand the metal accumulation levels differ within and betweenspecies of plants [9 32] Generally the same trend for metalconcentration as found in the control zone was also observed
in the industrial zone residential high traffic zone andresidential low traffic zone that is Zn gt Pb gt Cu gt Cr gt Co gtCd However Zn showed the highest metal concentrationwith mean magnitude of 4597 plusmn 4388mgkgminus1 amongall zones (Figures 2(a)ndash2(f)) Overall mean concentrations
4 Journal of Analytical Methods in Chemistry
Pb
0
2
4
6
8
10
INZ
HTZ
CTZ
RHZRLZ
Locations
INZHTZRHZ
RLZCTZ
Con
cent
ratio
ns (m
g kgminus
1 )
(a)
Cd
Con
cent
ratio
ns (m
g kgminus
1 )
INZ
HTZ
CTZ
RHZRLZ
Locations
INZHTZRHZ
RLZCTZ
0
002
004
006
008
01
012
014
(b)
Zn
Con
cent
ratio
ns (m
g kgminus
1 )
INZ
HTZ
CTZ
RHZRLZ
Locations
INZHTZRHZ
RLZCTZ
0
10
20
30
40
50
(c)
Cu
Con
cent
ratio
ns (m
g kgminus
1 )
INZ
HTZ
CTZ
RHZRLZ
Locations
INZHTZRHZ
RLZCTZ
55
6
65
7
75
(d)
Co
Con
cent
ratio
ns (m
g kgminus
1 )
INZ
HTZ
CTZ
RHZRLZ
Locations
INZHTZRHZ
RLZCTZ
0
02
04
06
08
1
(e)
Cr
Con
cent
ratio
ns (m
g kgminus
1 )
INZ
HTZ
CTZ
RHZRLZ
Locations
INZHTZRHZ
RLZCTZ
0
05
1
15
2
25
3
35
(f)
Figure 2 Metal concentrations in tree backs collected from all sampling zones INZ industrial zone HTZ high traffic commercial zoneRHZ residential high traffic zone RLZ residential low traffic zone CTZ control zone
(mg kgminus1 dry weight) of metals in tree bark samples obtainedfrom this study were found to be Pb 599 plusmn 525 Cd 009 plusmn007 Zn 2764 plusmn 2966 Cu 690 plusmn 554 Co 087 plusmn 045and Cr 284 plusmn 158 which varied from 075 to 2974 lt001to 026 370 to 16613 181 to 3912 023 to 235 and lt001
to 834mg kgminus1 respectively (Table 2) Abundance of metalconcentrations follows the order Zn gt Cu gt Pb gt Cr gt Co gtCdThe results indicate the presence of zinc copper and leadin high concentrations in samples taken from industrial hightraffic commercial and residential high traffic areas relative to
Journal of Analytical Methods in Chemistry 5
Table 2 Overall mean metal concentrations (mg kgminus1 dry weight) in tree bark samples
Range 75ndash2974 lt001ndash026 370ndash16613 181ndash3912 023ndash235 lt001ndash834
residential low traffic and control areas The concentrationsof the heavy metal investigated in this study when comparedwith metal levels reported by Mleczek et al [33] revealedthat the concentrations obtained in this study were higher formetals like Pb Zn Cu and Cr while the concentrations of Coand Cd were lower than those reported in another study thiscould be due to the addition of these metals in trace amountin Nigeria petrol as a means of enhancing the octane numberof gasoline [34 35]
The results for themetal concentrations showed amarkedvariation for samples obtained from the industrial zoneOpposite Procter amp Gamble Limited (INZ
5
) high trafficcommercial zone Iwo Roundabout (HTZ
13
) residential hightraffic zone Opposite Coca-Cola Mini Depot (RHZ
1
) andresidential low traffic zone Adeyi AvenueOld Bodija (RLZ
3
)this generally has the highest value of metal levels Zincconcentration varied widely in all zones with the residen-tial low traffic zone having the lowest level 1641mg kgminus1and the highly trafficked commercial zone possessing thehighest level with mean value of 4597mg kgminus1 The highestconcentration of Zn (16616mg kgminus1) was observed in thesample collected at Iwo Road Roundabout (Alakia axis)(HTZ
14
) within high traffic commercial zone The resultsshowed that there is a significant difference in the zincconcentration at 120588 lt 005 among the zones However nosignificant difference was observed in the zinc concentrationof high traffic commercial zone as compared to industrialzone This indication connotes emission and tyre wear frommotor vehicle pointers as a source of the environmentalzinc contamination Also zinc could be added to the envi-ronment during industrial activities like engine wear wastecombustion exhaust emission and the use of sewage sludgefrom industrial areas as fertilizer Zn promotes growth anddevelopment in the human body but its excessiveness maybe an indication of metal poisoning and growth impedance[36]
The concentration of lead in samples obtained from hightraffic commercial residential high traffic and residential lowtraffic zones varied slightly with average concentrations of962 670 and 596mg kgminus1 respectively However possiblecradles of metal contaminants in the environment are acrucial part of environmental pollution studies The chiefsource of lead (Pb) is the use of leaded gasoline in the20th century [37ndash40] which inevitably brings about leadpollutant in the ecosystem Lead content of Nigeria petrol[06ndash08 g Lminus1] ranks among the world highest content [41]Concentrations of lead reported in other studies showedhigher values than that obtained in this study except forlead concentration reported by [29 33 42 43] Humanexposure to lead brings about reproductive dysfunction
that exhibits biochemical-morphological features includingdecreased sperm quality disorganized epithelia and alteredsperm morphology [44] The analysis of variance showedno significant difference between the levels of copper in allzones at 120588 gt 005 Copper as a crucial micronutrient isessential for bone growth and formation neurologic systemsand nervous systems myelin sheaths [45] The high level(3912mg kgminus1) of copper concentration in samples sampledfrom Aworawo along Ojoo road (HTZ
9
) high traffic com-mercial zones could result from various human activitiesClose look at the results of copper level in residential highand low traffic zones suggests common source Increasedlevels could lead to cirrhosis rheumatoid arthritis mal-nutrition irregular hair growth and depigmentation furgrowth impairment and reproductive performance failureof the heart and disturbances in gastrointestinal systems[44]
Mean concentration of cobalt in the zones was found tofollow the trend high traffic commercial gt residential hightraffic gt industrial gt control gt residential low traffic (Figures2(a)ndash2(f)) with ranges There is no significant differenceobserved for the level of cobalt in all investigated zones at120588 gt 005 The highest cobalt concentration was found in theMangifera indica sample from behind Sumal Foods (chewinggum) (INZ
3
) industrial zone Chromium levels were largelylow in the study (Figures 2(a)ndash2(f)) and the residentiallow traffic zone posed the lowest level of chromium whichcould be attributed to natural sources In various zoneschromium pollution could be due to automobile engineand body erosion yellow lead chromate paint for roadpattern and few steel and glass industry activities [46ndash48] Chromium is known as a ubiquitous pollutant fromthe industrial and environmental activities also a knownhuman carcinogen with specificity in cancer of the lungs[49 50] There is no definite gradient in the concentration ofcadmium present in the investigated zones The residentiallow traffic zone gave 010mg kgminus1 and the lowest meanlevel of cadmium (Cd) was found in residential high trafficzone (006mg kgminus1) ranging from 001 to 015mg kgminus1 Theslight increase in the mean level of cadmium in the controlzone (014mg kgminus1) with the highest concentration foundin the Gmelina arborea species (025mg kgminus1) could belinked to the use of phosphate fertilizer which has cadmiumas a trace element for growing crops When cadmium isaccumulated above the recommended threshold limit itbrings about liver acute and chronic poisoning and also thereplacement of calciumwithin bonematrix of young children[44] it inhibits increased oxidative stress resulting in thedamage of membrane and membrane-enzymes bound losses[51]
6 Journal of Analytical Methods in Chemistry
Table 3 Correlation coefficient among metals in tree bark samplesfrom all zones (bold correlations are significant at 120588 lt 005)
Pb Cd Zn Cu Co CrPb 1Cd 040 1Zn 070 031 1Cu 027 050 079 1Co 024 020 054 077 1Cr 067 024 055 063 069 1
31 Correlation Matrix A coefficient matrix among PbCd Zn Cu Co and Cr concentrations in samples fromthe studied locations are presented in Table 3 The resultsshowed that the elements investigated in this study are highlycorrelated with one another suggesting common source andother possible uncommon sources of metal fallout There isrelatively high correlations amongst metals such as Zn andCu and Co and Cu Positive moderate correlation coefficientwas observed between Pb and Zn and Zn and Co The highcorrelation found between Pb andZn andZn andCu suggestsa common source and other possible well-mixed constituentsinitiating from different sources Positive moderate correla-tion coefficient was also observed between Cr versus Pb andZn and Cr versus Cu and Co Zn level in all the zones wasseen to be in high concentration followed by Cu and Pb Highvalues of Cu and Zn obtained indicate that emission and tyrewear from motor vehicle as a source of the environmentalzinc contamination high level of copper could come fromthe fabrication of brass alloy brake linings and electrical andmechanical working while lead could be the use of leadedgasoline in the Nigeria petrol This is because lead additivesin the form of tetraethyl lead (TEL[Pb(C
2
H5
)4
]) are added togasoline as the cheapestmeans of boasting the octane numberof Nigeria petrol and zinc in the form of organometalliccompounds such as zinc dialkyl dithiophosphate (ZDDP)lubricating oils and tyres [46 52 53]
4 Conclusion
The results of this survey demonstrate the suitability ofTerminalia catappa Azadirachta indica Gmelina arboreaMangifera indica Prosopis juliflora andMurraya species andGliricidia sepium bark species as potential bioindicators forCu Pb Zn Cr and possibly Co and Cd as well as the pointersof some degree of temporal heavy metals contaminationThe levels of the metals were higher in bark samples fromhighly trafficked commercial zone than in other zones Thedeviation in metal concentrations amongst the studied sitescould be due to various anthropogenic activitiesWith respectto the high contribution factors of Zn Cu and Pb to thepotential ecological risk of the area thorough study shouldbe piloted to determine the actual route of the metals entry tothe environment It is imperative that the environmental tracemetal levels be constantly examined to diagnose the stateand trend of environmental atmospheric pollution Furthermonitoring of plant barks species as well as the surrounding
lower epiphytes higher epiphytes and vascular plants isneeded in order to determine whether any temporal trendsexist in metal concentration among biological indicatorsPotential risk assessment of these heavy metals to cropsanimals and humans in the area is recommended Furtherfarming activities within the diameter of 15ndash10Km of thevicinity of the industries and high human activities should bediscouraged as there will be every possibility of heavy metalsuptake by planted crops which will in turn reach up thefood chain and finally to humans Furthermore interspeciesvariation of heavymetal concentrations in plants barks is alsorecommended
Conflict of Interests
Regarding the publication of this paper the authors declareno conflict of interests
Authorsrsquo Contribution
The authors contributed equally to the achievement of theresearch
Acknowledgments
Theauthors wish to acknowledge GovanMbeki Research andDevelopmentCentre (GMRDC)University of FortHare andNRF-Sasol Inzalo Fundation for financial support receivedThe authors acknowledge Eyitayo Fadipe and Ayoade Folukewho assisted in the sample collection
References
[1] T Abbasi and S A Abbasi ldquoIs the use of renewable energysources an answer to the problems of global warming andpollutionrdquo Critical Reviews in Environmental Science and Tech-nology vol 42 no 2 pp 99ndash154 2012
[2] K Ravindra R Sokhi and R Van Grieken ldquoAtmosphericpolycyclic aromatic hydrocarbons source attribution emissionfactors and regulationrdquo Atmospheric Environment vol 42 no13 pp 2895ndash2921 2008
[3] C Woodford Air Pollution 2010 httpwwwexplainthatstuffcomair-pollution-introductionhtml
[4] U Makkonen H Hellen P Anttila and M Ferm ldquoSizedistribution and chemical composition of airborne particlesin south-eastern Finland during different seasons and wildfireepisodes in 2006rdquo Science of the Total Environment vol 408 no3 pp 644ndash651 2010
[5] J Wang Z Hu Y Chen Z Chen and S Xu ldquoContaminationcharacteristics and possible sources of PM10 and PM25 indifferent functional areas of Shanghai Chinardquo AtmosphericEnvironment vol 68 pp 221ndash229 2013
[6] G Qingjie D Jun X Yunchuan W Qingfei and Y LiqiangldquoCalculating pollution indices by heavy metals in ecologicalgeochemistry assessment and a case study in parks of BeijinrdquoJournal of ChinaUniversity of Geosciences vol 19 no 3 pp 230ndash241 2008
[7] C O Ogunkunle and P O Fatoba ldquoPollution loads andthe ecological risk assessment of soil heavy metals around
Journal of Analytical Methods in Chemistry 7
a mega cement factory in Southwest Nigeriardquo Polish Journal ofEnvironmental Studies vol 22 no 2 pp 487ndash493 2013
[8] H A Sani A I Tsafe B U Bagudo and A U ItodoldquoToxic metals uptake by spinach (Spinacea oleracea) and lettuce(Lactuca sativa) cultivated in sokoto a comparative studyrdquoPakistan Journal of Nutrition vol 10 no 6 pp 572ndash576 2011
[9] D Satpathy andMVReddy ldquoPhytoextraction ofCd Pb ZnCuandmn by Indian mustard (Brassica juncea L) grown on loamysoil amended with heavy metal contaminated municipal solidwaste compostrdquo Applied Ecology and Environmental Researchvol 11 no 4 pp 661ndash679 2013
[10] D R Hashmi S Ismail and G H Shaikh ldquoAssessment ofthe level of trace metals in commonly edible vegetables locallyavailable in the markets of Karachi cityrdquo Pakistan Journal ofBotany vol 39 no 3 pp 747ndash751 2007
[11] G N Lion and J O Olowoyo ldquoPopulation health risk dueto dietary intake of toxic heavy metals from Spinacia oleraceaharvested from soils collected in and around Tshwane SouthAfricardquo South African Journal of Botany vol 88 pp 178ndash1822013
[12] B A Anhwange J A Kagbu E B Agbaji and C E GimbaldquoTrace metal contents of some common vegetables grown onirrigated farms along the banks of river Benue within MakurdiMetropolisrdquo Electronic Journal of Environmental Agriculturaland Food Chemistry vol 8 no 11 pp 1150ndash1155 2009
[13] S Baytak R Mert and A R Turker ldquoDetermination ofCu(II) Fe(III) Mn(II) and Zn(II) in various samples afterpreconcentrationwithRhizopus oryzae loaded natural cellulose(almond bark)rdquo International Journal of Environmental Analyt-ical Chemistry vol 94 no 10 pp 975ndash987 2014
[14] S Baslar Y Dogan N Durkan and H Bag ldquoBiomonitoringof zinc and manganese in bark of Turkish red pine of westernAnatoliardquo Journal of Environmental Biology vol 30 no 5 pp831ndash834 2009
[15] A Celik A A Kartal A Akdogan and Y Kaska ldquoDeterminingthe heavy metal pollution in Denizli (Turkey) by using Robiniopseudo-acacia Lrdquo Environment International vol 31 no 1 pp105ndash112 2005
[16] G Nabulo H Oryem Origa G W Nasinyama and D ColeldquoAssessment of Zn Cu Pb and Ni contamination in wetlandsoils and plants in the LakeVictoria basinrdquo International Journalof Environmental Science and Technology vol 5 no 1 pp 65ndash742008
[17] BWolterbeek S Sarmento andTVerburg ldquoIs there a future forbiomonitoring of elemental air pollutionA review focused on alarger-scaled health-related (epidemiological) contextrdquo Journalof Radioanalytical and Nuclear Chemistry vol 286 no 1 pp195ndash210 2010
[18] P K Rai ldquoEnvironmental magnetic studies of particulates withspecial reference to biomagnetic monitoring using roadsideplant leavesrdquo Atmospheric Environment vol 72 pp 113ndash1292013
[19] B Kord A Mataji and S Babaie ldquoPine (Pinus Eldarica Medw)needles as indicator for heavy metals pollutionrdquo InternationalJournal of Environmental Science and Technology vol 7 no 1pp 79ndash84 2010
[20] I Rodrıguez-Germade K J Mohamed D Rey B Rubio and AGarcıa ldquoThe influence of weather and climate on the reliabilityof magnetic properties of tree leaves as proxies for air pollutionmonitoringrdquo Science of the Total Environment vol 468-469 pp892ndash902 2014
[21] L Mulligan An assessment of epiphytic lichens lichen diversityand environmental quality in the semi-natural woodlands ofKnocksink Wood Nature Reserve Enniskerry County Wicklow[PhD thesis] Dublin Institute of Technology 2009
[22] B Kord and B Kord ldquoHeavymetal levels in pine (Pinus eldaricaMedw) tree barks as indicators of atmospheric pollutionrdquoBioResources vol 6 no 2 pp 927ndash935 2011
[23] L E Beramendi-Orosco M L Rodriguez-Estrada O Morton-Bermea F M Romero G Gonzalez-Hernandez and EHernandez-Alvarez ldquoCorrelations between metals in tree-ringsof Prosopis julifora as indicators of sources of heavy metalcontaminationrdquo Applied Geochemistry vol 39 pp 78ndash84 2013
[24] D G Shendell and G R E E Ana ldquoPromoting environmentalpublic health in rapidly urbanizing areas of less-developedcountries in Africa a collaborative interdisciplinary training inIbadan Nigeriardquo Journal of Environmental Health vol 74 no 1pp 26ndash35 2011
[25] M Zhiyanski M Sokolovska J Bech A Clouvas I Penev andV Badulin ldquoCesium-137 contamination of oak (Quercus petraeLiebl) from sub-mediterranean zone in South Bulgariardquo Journalof Environmental Radioactivity vol 101 no 10 pp 864ndash8682010
[26] I Suchara P Rulık J Hulka and H Pilatova ldquoRetrospectivedetermination of 137Cs specific activity distribution in sprucebark and bark aggregated transfer factor in forests on the scaleof the Czech Republic ten years after the Chernobyl accidentrdquoScience of the Total Environment vol 409 no 10 pp 1927ndash19342011
[27] T Sawidis J BreusteMMitrovic P Pavlovic andK TsigaridasldquoTrees as bioindicator of heavy metal pollution in three Euro-pean citiesrdquo Environmental Pollution vol 159 no 12 pp 3560ndash3570 2011
[28] S Leshe and M Tessema ldquoDetermination of levels of essentialand toxic heavy metals in lentil (lens culinaris medik) by flameatomic absorption spectroscopyrdquo African Journal of ChemicalEducation vol 4 no 4 pp 16ndash34 2014
[29] F G Fujiwara D R Gomez L Dawidowski P Perelman andA Faggi ldquoMetals associated with airborne particulate matter inroad dust and tree bark collected in a megacity (Buenos AiresArgentina)rdquo Ecological Indicators vol 11 no 2 pp 240ndash2472011
[30] P C Ogbonna C Odukaesieme and J A Teixeira da SilvaldquoDistribution of heavymetals in soil and accumulation in plantsat an agricultural area of Umudike Nigeriardquo Chemistry andEcology vol 29 no 7 pp 595ndash603 2013
[31] A I Ajai S SOchigbo ZAbdullahi andP I Anigboro ldquoDeter-mination of trace metals and essential minerals in selected fruitjuices in Minna Nigeriardquo International Journal of Food Sciencevol 2014 Article ID 462931 5 pages 2014
[32] A R Ipeaiyeda and M Dawodu ldquoAssessment of toxic metalpollution in soil leaves and tree barks bio-indicators of atmo-spheric particulate deposition within a University communityin Nigeriardquo AES Bioflux vol 6 no 2 pp 101ndash110 2014
[33] M Mleczek I Rissmann P Rutkowski Z Kaczmarek and PGolinski ldquoAccumulation of selected heavy metals by differentgenotypes of Salixrdquo Environmental and Experimental Botanyvol 66 no 2 pp 289ndash296 2009
[34] S E Kakulu ldquoTracemetal concentration in roadside surface soiland tree back a measurement of local atmospheric pollution inAbuja Nigeriardquo Environmental Monitoring and Assessment vol89 no 3 pp 233ndash242 2003
8 Journal of Analytical Methods in Chemistry
[35] J G SpeightThe Chemistry and Technology of Petroleum CRCPress Taylor amp Francis Boca Raton Fla USA 5th edition 2010
[36] K B Singh and S K Taneja ldquoConcentration of Zn Cu andMn in vegetables and meat food stuff commonly available inManipur a North Eastern state of Indiardquo Electronic Journal ofEnvironmental Agricultural and Food Chemistry vol 9 no 3pp 610ndash616 2010
[37] A E Kelly M K Reuer N F Goodkin and E A Boyle ldquoLeadconcentrations and isotopes in corals and water near Bermuda1780ndash2000rdquo Earth and Planetary Science Letters vol 283 no 1ndash4 pp 93ndash100 2009
[38] N Robbins Z-F Zhang J Sun M E Ketterer J ALalumandier and R A Shulze ldquoChildhood lead exposure anduptake in teeth in the Cleveland area during the era of leadedgasolinerdquo Science of the Total Environment vol 408 no 19 pp4118ndash4127 2010
[39] A Roberts ldquoChronology of leaded gasolineleaded petrol his-toryrdquo LEAD Action News vol 12 no 2 2011 httpwwwleadorgaunlhtml
[40] P-C Huang P-H Su H-Y Chen et al ldquoChildhood bloodlead levels and intellectual development after ban of leadedgasoline in Taiwan a 9-year prospective studyrdquo EnvironmentInternational vol 40 no 1 pp 88ndash96 2012
[41] C W Rankin J O Nriagu J K Aggarwal T A ArowoloK Adebayo and A R Flegal ldquoLead contamination in cocoaand cocoa products isotopic evidence of global contaminationrdquoEnvironmental Health Perspectives vol 113 no 10 pp 1344ndash1348 2005
[42] E Schelle BG Rawlins RM Lark RWebster I Staton andCW McLeod ldquoMapping aerial metal deposition in metropolitanareas from tree bark a case study in Sheffield EnglandrdquoEnvironmental Pollution vol 155 no 1 pp 164ndash173 2008
[43] M Catinon S Ayrault O Boudouma J Asta M Tissut andP Ravanel ldquoAtmospheric element deposit on tree barks theopposite effects of rain and transpirationrdquo Ecological Indicatorsvol 14 no 1 pp 170ndash177 2012
[44] K O Soetan C O Olaiya and O E Oyewole ldquoThe importanceof mineral elements for humans domestic animals and plantsa reviewrdquo African Journal of Food Science vol 4 no 5 pp 200ndash222 2010
[45] J C Tan D L Burns and H R Jones ldquoSevere ataxiamyelopathy and peripheral neuropathy due to acquired copperdeficiency in a patient with history of gastrectomyrdquo Journal ofParenteral and Enteral Nutrition vol 30 no 5 pp 446ndash4502006
[46] A L Al-Khlaifat and O A Al-Khashman ldquoAtmospheric heavymetal pollution in Aqaba city Jordan using Phoenix dactyliferaL leavesrdquo Atmospheric Environment vol 41 no 39 pp 8891ndash8897 2007
[47] M A Nwachukwu H Feng and J Alinnor ldquoAssessment ofheavy metal pollution in soil and their implications within andaround mechanic villagesrdquo International Journal of Environ-mental Science and Technology vol 7 no 2 pp 347ndash358 2010
[48] N M Karaaslan and M Yaman ldquoDetermination of Nickel andChromium in Pinus nigra L Cedrus Libani and CupressusArizonica leaves to monitor the effects of pollution in Elazig(Turkey)rdquo Instrumentation Science amp Technology vol 41 no 3pp 335ndash348 2013
[49] C-Y Kuo R-H Wong J-Y Lin J-C Lai and H LeeldquoAccumulation of chromium and nickel metals in lung tumorsfrom lung cancer patients in Taiwanrdquo Journal of Toxicology and
Environmental HealthmdashPart A Current Issues vol 69 no 14pp 1337ndash1344 2006
[50] I Koturbash F A Beland and I P Pogribny ldquoRole of epigeneticevents in chemical carcinogenesis-a justification for incorporat-ing epigenetic evaluations in cancer risk assessmentrdquoToxicologyMechanisms and Methods vol 21 no 4 pp 289ndash297 2011
[51] M Gałazyn-Sidorczuk M M Brzoska M Jurczuk and JMoniuszko-Jakoniuk ldquoOxidative damage to proteins and DNAin rats exposed to cadmiumandor ethanolrdquoChemico-BiologicalInteractions vol 180 no 1 pp 31ndash38 2009
[52] P R Shakya P Shrestha C S Tamrakar and P K BhattaraildquoStudies and determination of heavy metals in waste tyresand their impacts on the environmentrdquo Pakistan Journal ofAnalytical and Environmental Chemistry vol 7 no 2 pp 70ndash76 2006
[53] H Spikes ldquoLow- and zero-sulphated ash phosphorus andsulphur anti-wear additives for engine oilsrdquo Lubrication Sciencevol 20 no 2 pp 103ndash136 2008
Figure 1 Ibadan City map showing the various sampling points
Various heavy metals accumulation in different plant parts isdependent on the amount of metals present in the ecosystemand the metal accumulation levels differ within and betweenspecies of plants [9 32] Generally the same trend for metalconcentration as found in the control zone was also observed
in the industrial zone residential high traffic zone andresidential low traffic zone that is Zn gt Pb gt Cu gt Cr gt Co gtCd However Zn showed the highest metal concentrationwith mean magnitude of 4597 plusmn 4388mgkgminus1 amongall zones (Figures 2(a)ndash2(f)) Overall mean concentrations
4 Journal of Analytical Methods in Chemistry
Pb
0
2
4
6
8
10
INZ
HTZ
CTZ
RHZRLZ
Locations
INZHTZRHZ
RLZCTZ
Con
cent
ratio
ns (m
g kgminus
1 )
(a)
Cd
Con
cent
ratio
ns (m
g kgminus
1 )
INZ
HTZ
CTZ
RHZRLZ
Locations
INZHTZRHZ
RLZCTZ
0
002
004
006
008
01
012
014
(b)
Zn
Con
cent
ratio
ns (m
g kgminus
1 )
INZ
HTZ
CTZ
RHZRLZ
Locations
INZHTZRHZ
RLZCTZ
0
10
20
30
40
50
(c)
Cu
Con
cent
ratio
ns (m
g kgminus
1 )
INZ
HTZ
CTZ
RHZRLZ
Locations
INZHTZRHZ
RLZCTZ
55
6
65
7
75
(d)
Co
Con
cent
ratio
ns (m
g kgminus
1 )
INZ
HTZ
CTZ
RHZRLZ
Locations
INZHTZRHZ
RLZCTZ
0
02
04
06
08
1
(e)
Cr
Con
cent
ratio
ns (m
g kgminus
1 )
INZ
HTZ
CTZ
RHZRLZ
Locations
INZHTZRHZ
RLZCTZ
0
05
1
15
2
25
3
35
(f)
Figure 2 Metal concentrations in tree backs collected from all sampling zones INZ industrial zone HTZ high traffic commercial zoneRHZ residential high traffic zone RLZ residential low traffic zone CTZ control zone
(mg kgminus1 dry weight) of metals in tree bark samples obtainedfrom this study were found to be Pb 599 plusmn 525 Cd 009 plusmn007 Zn 2764 plusmn 2966 Cu 690 plusmn 554 Co 087 plusmn 045and Cr 284 plusmn 158 which varied from 075 to 2974 lt001to 026 370 to 16613 181 to 3912 023 to 235 and lt001
to 834mg kgminus1 respectively (Table 2) Abundance of metalconcentrations follows the order Zn gt Cu gt Pb gt Cr gt Co gtCdThe results indicate the presence of zinc copper and leadin high concentrations in samples taken from industrial hightraffic commercial and residential high traffic areas relative to
Journal of Analytical Methods in Chemistry 5
Table 2 Overall mean metal concentrations (mg kgminus1 dry weight) in tree bark samples
Range 75ndash2974 lt001ndash026 370ndash16613 181ndash3912 023ndash235 lt001ndash834
residential low traffic and control areas The concentrationsof the heavy metal investigated in this study when comparedwith metal levels reported by Mleczek et al [33] revealedthat the concentrations obtained in this study were higher formetals like Pb Zn Cu and Cr while the concentrations of Coand Cd were lower than those reported in another study thiscould be due to the addition of these metals in trace amountin Nigeria petrol as a means of enhancing the octane numberof gasoline [34 35]
The results for themetal concentrations showed amarkedvariation for samples obtained from the industrial zoneOpposite Procter amp Gamble Limited (INZ
5
) high trafficcommercial zone Iwo Roundabout (HTZ
13
) residential hightraffic zone Opposite Coca-Cola Mini Depot (RHZ
1
) andresidential low traffic zone Adeyi AvenueOld Bodija (RLZ
3
)this generally has the highest value of metal levels Zincconcentration varied widely in all zones with the residen-tial low traffic zone having the lowest level 1641mg kgminus1and the highly trafficked commercial zone possessing thehighest level with mean value of 4597mg kgminus1 The highestconcentration of Zn (16616mg kgminus1) was observed in thesample collected at Iwo Road Roundabout (Alakia axis)(HTZ
14
) within high traffic commercial zone The resultsshowed that there is a significant difference in the zincconcentration at 120588 lt 005 among the zones However nosignificant difference was observed in the zinc concentrationof high traffic commercial zone as compared to industrialzone This indication connotes emission and tyre wear frommotor vehicle pointers as a source of the environmentalzinc contamination Also zinc could be added to the envi-ronment during industrial activities like engine wear wastecombustion exhaust emission and the use of sewage sludgefrom industrial areas as fertilizer Zn promotes growth anddevelopment in the human body but its excessiveness maybe an indication of metal poisoning and growth impedance[36]
The concentration of lead in samples obtained from hightraffic commercial residential high traffic and residential lowtraffic zones varied slightly with average concentrations of962 670 and 596mg kgminus1 respectively However possiblecradles of metal contaminants in the environment are acrucial part of environmental pollution studies The chiefsource of lead (Pb) is the use of leaded gasoline in the20th century [37ndash40] which inevitably brings about leadpollutant in the ecosystem Lead content of Nigeria petrol[06ndash08 g Lminus1] ranks among the world highest content [41]Concentrations of lead reported in other studies showedhigher values than that obtained in this study except forlead concentration reported by [29 33 42 43] Humanexposure to lead brings about reproductive dysfunction
that exhibits biochemical-morphological features includingdecreased sperm quality disorganized epithelia and alteredsperm morphology [44] The analysis of variance showedno significant difference between the levels of copper in allzones at 120588 gt 005 Copper as a crucial micronutrient isessential for bone growth and formation neurologic systemsand nervous systems myelin sheaths [45] The high level(3912mg kgminus1) of copper concentration in samples sampledfrom Aworawo along Ojoo road (HTZ
9
) high traffic com-mercial zones could result from various human activitiesClose look at the results of copper level in residential highand low traffic zones suggests common source Increasedlevels could lead to cirrhosis rheumatoid arthritis mal-nutrition irregular hair growth and depigmentation furgrowth impairment and reproductive performance failureof the heart and disturbances in gastrointestinal systems[44]
Mean concentration of cobalt in the zones was found tofollow the trend high traffic commercial gt residential hightraffic gt industrial gt control gt residential low traffic (Figures2(a)ndash2(f)) with ranges There is no significant differenceobserved for the level of cobalt in all investigated zones at120588 gt 005 The highest cobalt concentration was found in theMangifera indica sample from behind Sumal Foods (chewinggum) (INZ
3
) industrial zone Chromium levels were largelylow in the study (Figures 2(a)ndash2(f)) and the residentiallow traffic zone posed the lowest level of chromium whichcould be attributed to natural sources In various zoneschromium pollution could be due to automobile engineand body erosion yellow lead chromate paint for roadpattern and few steel and glass industry activities [46ndash48] Chromium is known as a ubiquitous pollutant fromthe industrial and environmental activities also a knownhuman carcinogen with specificity in cancer of the lungs[49 50] There is no definite gradient in the concentration ofcadmium present in the investigated zones The residentiallow traffic zone gave 010mg kgminus1 and the lowest meanlevel of cadmium (Cd) was found in residential high trafficzone (006mg kgminus1) ranging from 001 to 015mg kgminus1 Theslight increase in the mean level of cadmium in the controlzone (014mg kgminus1) with the highest concentration foundin the Gmelina arborea species (025mg kgminus1) could belinked to the use of phosphate fertilizer which has cadmiumas a trace element for growing crops When cadmium isaccumulated above the recommended threshold limit itbrings about liver acute and chronic poisoning and also thereplacement of calciumwithin bonematrix of young children[44] it inhibits increased oxidative stress resulting in thedamage of membrane and membrane-enzymes bound losses[51]
6 Journal of Analytical Methods in Chemistry
Table 3 Correlation coefficient among metals in tree bark samplesfrom all zones (bold correlations are significant at 120588 lt 005)
Pb Cd Zn Cu Co CrPb 1Cd 040 1Zn 070 031 1Cu 027 050 079 1Co 024 020 054 077 1Cr 067 024 055 063 069 1
31 Correlation Matrix A coefficient matrix among PbCd Zn Cu Co and Cr concentrations in samples fromthe studied locations are presented in Table 3 The resultsshowed that the elements investigated in this study are highlycorrelated with one another suggesting common source andother possible uncommon sources of metal fallout There isrelatively high correlations amongst metals such as Zn andCu and Co and Cu Positive moderate correlation coefficientwas observed between Pb and Zn and Zn and Co The highcorrelation found between Pb andZn andZn andCu suggestsa common source and other possible well-mixed constituentsinitiating from different sources Positive moderate correla-tion coefficient was also observed between Cr versus Pb andZn and Cr versus Cu and Co Zn level in all the zones wasseen to be in high concentration followed by Cu and Pb Highvalues of Cu and Zn obtained indicate that emission and tyrewear from motor vehicle as a source of the environmentalzinc contamination high level of copper could come fromthe fabrication of brass alloy brake linings and electrical andmechanical working while lead could be the use of leadedgasoline in the Nigeria petrol This is because lead additivesin the form of tetraethyl lead (TEL[Pb(C
2
H5
)4
]) are added togasoline as the cheapestmeans of boasting the octane numberof Nigeria petrol and zinc in the form of organometalliccompounds such as zinc dialkyl dithiophosphate (ZDDP)lubricating oils and tyres [46 52 53]
4 Conclusion
The results of this survey demonstrate the suitability ofTerminalia catappa Azadirachta indica Gmelina arboreaMangifera indica Prosopis juliflora andMurraya species andGliricidia sepium bark species as potential bioindicators forCu Pb Zn Cr and possibly Co and Cd as well as the pointersof some degree of temporal heavy metals contaminationThe levels of the metals were higher in bark samples fromhighly trafficked commercial zone than in other zones Thedeviation in metal concentrations amongst the studied sitescould be due to various anthropogenic activitiesWith respectto the high contribution factors of Zn Cu and Pb to thepotential ecological risk of the area thorough study shouldbe piloted to determine the actual route of the metals entry tothe environment It is imperative that the environmental tracemetal levels be constantly examined to diagnose the stateand trend of environmental atmospheric pollution Furthermonitoring of plant barks species as well as the surrounding
lower epiphytes higher epiphytes and vascular plants isneeded in order to determine whether any temporal trendsexist in metal concentration among biological indicatorsPotential risk assessment of these heavy metals to cropsanimals and humans in the area is recommended Furtherfarming activities within the diameter of 15ndash10Km of thevicinity of the industries and high human activities should bediscouraged as there will be every possibility of heavy metalsuptake by planted crops which will in turn reach up thefood chain and finally to humans Furthermore interspeciesvariation of heavymetal concentrations in plants barks is alsorecommended
Conflict of Interests
Regarding the publication of this paper the authors declareno conflict of interests
Authorsrsquo Contribution
The authors contributed equally to the achievement of theresearch
Acknowledgments
Theauthors wish to acknowledge GovanMbeki Research andDevelopmentCentre (GMRDC)University of FortHare andNRF-Sasol Inzalo Fundation for financial support receivedThe authors acknowledge Eyitayo Fadipe and Ayoade Folukewho assisted in the sample collection
References
[1] T Abbasi and S A Abbasi ldquoIs the use of renewable energysources an answer to the problems of global warming andpollutionrdquo Critical Reviews in Environmental Science and Tech-nology vol 42 no 2 pp 99ndash154 2012
[2] K Ravindra R Sokhi and R Van Grieken ldquoAtmosphericpolycyclic aromatic hydrocarbons source attribution emissionfactors and regulationrdquo Atmospheric Environment vol 42 no13 pp 2895ndash2921 2008
[3] C Woodford Air Pollution 2010 httpwwwexplainthatstuffcomair-pollution-introductionhtml
[4] U Makkonen H Hellen P Anttila and M Ferm ldquoSizedistribution and chemical composition of airborne particlesin south-eastern Finland during different seasons and wildfireepisodes in 2006rdquo Science of the Total Environment vol 408 no3 pp 644ndash651 2010
[5] J Wang Z Hu Y Chen Z Chen and S Xu ldquoContaminationcharacteristics and possible sources of PM10 and PM25 indifferent functional areas of Shanghai Chinardquo AtmosphericEnvironment vol 68 pp 221ndash229 2013
[6] G Qingjie D Jun X Yunchuan W Qingfei and Y LiqiangldquoCalculating pollution indices by heavy metals in ecologicalgeochemistry assessment and a case study in parks of BeijinrdquoJournal of ChinaUniversity of Geosciences vol 19 no 3 pp 230ndash241 2008
[7] C O Ogunkunle and P O Fatoba ldquoPollution loads andthe ecological risk assessment of soil heavy metals around
Journal of Analytical Methods in Chemistry 7
a mega cement factory in Southwest Nigeriardquo Polish Journal ofEnvironmental Studies vol 22 no 2 pp 487ndash493 2013
[8] H A Sani A I Tsafe B U Bagudo and A U ItodoldquoToxic metals uptake by spinach (Spinacea oleracea) and lettuce(Lactuca sativa) cultivated in sokoto a comparative studyrdquoPakistan Journal of Nutrition vol 10 no 6 pp 572ndash576 2011
[9] D Satpathy andMVReddy ldquoPhytoextraction ofCd Pb ZnCuandmn by Indian mustard (Brassica juncea L) grown on loamysoil amended with heavy metal contaminated municipal solidwaste compostrdquo Applied Ecology and Environmental Researchvol 11 no 4 pp 661ndash679 2013
[10] D R Hashmi S Ismail and G H Shaikh ldquoAssessment ofthe level of trace metals in commonly edible vegetables locallyavailable in the markets of Karachi cityrdquo Pakistan Journal ofBotany vol 39 no 3 pp 747ndash751 2007
[11] G N Lion and J O Olowoyo ldquoPopulation health risk dueto dietary intake of toxic heavy metals from Spinacia oleraceaharvested from soils collected in and around Tshwane SouthAfricardquo South African Journal of Botany vol 88 pp 178ndash1822013
[12] B A Anhwange J A Kagbu E B Agbaji and C E GimbaldquoTrace metal contents of some common vegetables grown onirrigated farms along the banks of river Benue within MakurdiMetropolisrdquo Electronic Journal of Environmental Agriculturaland Food Chemistry vol 8 no 11 pp 1150ndash1155 2009
[13] S Baytak R Mert and A R Turker ldquoDetermination ofCu(II) Fe(III) Mn(II) and Zn(II) in various samples afterpreconcentrationwithRhizopus oryzae loaded natural cellulose(almond bark)rdquo International Journal of Environmental Analyt-ical Chemistry vol 94 no 10 pp 975ndash987 2014
[14] S Baslar Y Dogan N Durkan and H Bag ldquoBiomonitoringof zinc and manganese in bark of Turkish red pine of westernAnatoliardquo Journal of Environmental Biology vol 30 no 5 pp831ndash834 2009
[15] A Celik A A Kartal A Akdogan and Y Kaska ldquoDeterminingthe heavy metal pollution in Denizli (Turkey) by using Robiniopseudo-acacia Lrdquo Environment International vol 31 no 1 pp105ndash112 2005
[16] G Nabulo H Oryem Origa G W Nasinyama and D ColeldquoAssessment of Zn Cu Pb and Ni contamination in wetlandsoils and plants in the LakeVictoria basinrdquo International Journalof Environmental Science and Technology vol 5 no 1 pp 65ndash742008
[17] BWolterbeek S Sarmento andTVerburg ldquoIs there a future forbiomonitoring of elemental air pollutionA review focused on alarger-scaled health-related (epidemiological) contextrdquo Journalof Radioanalytical and Nuclear Chemistry vol 286 no 1 pp195ndash210 2010
[18] P K Rai ldquoEnvironmental magnetic studies of particulates withspecial reference to biomagnetic monitoring using roadsideplant leavesrdquo Atmospheric Environment vol 72 pp 113ndash1292013
[19] B Kord A Mataji and S Babaie ldquoPine (Pinus Eldarica Medw)needles as indicator for heavy metals pollutionrdquo InternationalJournal of Environmental Science and Technology vol 7 no 1pp 79ndash84 2010
[20] I Rodrıguez-Germade K J Mohamed D Rey B Rubio and AGarcıa ldquoThe influence of weather and climate on the reliabilityof magnetic properties of tree leaves as proxies for air pollutionmonitoringrdquo Science of the Total Environment vol 468-469 pp892ndash902 2014
[21] L Mulligan An assessment of epiphytic lichens lichen diversityand environmental quality in the semi-natural woodlands ofKnocksink Wood Nature Reserve Enniskerry County Wicklow[PhD thesis] Dublin Institute of Technology 2009
[22] B Kord and B Kord ldquoHeavymetal levels in pine (Pinus eldaricaMedw) tree barks as indicators of atmospheric pollutionrdquoBioResources vol 6 no 2 pp 927ndash935 2011
[23] L E Beramendi-Orosco M L Rodriguez-Estrada O Morton-Bermea F M Romero G Gonzalez-Hernandez and EHernandez-Alvarez ldquoCorrelations between metals in tree-ringsof Prosopis julifora as indicators of sources of heavy metalcontaminationrdquo Applied Geochemistry vol 39 pp 78ndash84 2013
[24] D G Shendell and G R E E Ana ldquoPromoting environmentalpublic health in rapidly urbanizing areas of less-developedcountries in Africa a collaborative interdisciplinary training inIbadan Nigeriardquo Journal of Environmental Health vol 74 no 1pp 26ndash35 2011
[25] M Zhiyanski M Sokolovska J Bech A Clouvas I Penev andV Badulin ldquoCesium-137 contamination of oak (Quercus petraeLiebl) from sub-mediterranean zone in South Bulgariardquo Journalof Environmental Radioactivity vol 101 no 10 pp 864ndash8682010
[26] I Suchara P Rulık J Hulka and H Pilatova ldquoRetrospectivedetermination of 137Cs specific activity distribution in sprucebark and bark aggregated transfer factor in forests on the scaleof the Czech Republic ten years after the Chernobyl accidentrdquoScience of the Total Environment vol 409 no 10 pp 1927ndash19342011
[27] T Sawidis J BreusteMMitrovic P Pavlovic andK TsigaridasldquoTrees as bioindicator of heavy metal pollution in three Euro-pean citiesrdquo Environmental Pollution vol 159 no 12 pp 3560ndash3570 2011
[28] S Leshe and M Tessema ldquoDetermination of levels of essentialand toxic heavy metals in lentil (lens culinaris medik) by flameatomic absorption spectroscopyrdquo African Journal of ChemicalEducation vol 4 no 4 pp 16ndash34 2014
[29] F G Fujiwara D R Gomez L Dawidowski P Perelman andA Faggi ldquoMetals associated with airborne particulate matter inroad dust and tree bark collected in a megacity (Buenos AiresArgentina)rdquo Ecological Indicators vol 11 no 2 pp 240ndash2472011
[30] P C Ogbonna C Odukaesieme and J A Teixeira da SilvaldquoDistribution of heavymetals in soil and accumulation in plantsat an agricultural area of Umudike Nigeriardquo Chemistry andEcology vol 29 no 7 pp 595ndash603 2013
[31] A I Ajai S SOchigbo ZAbdullahi andP I Anigboro ldquoDeter-mination of trace metals and essential minerals in selected fruitjuices in Minna Nigeriardquo International Journal of Food Sciencevol 2014 Article ID 462931 5 pages 2014
[32] A R Ipeaiyeda and M Dawodu ldquoAssessment of toxic metalpollution in soil leaves and tree barks bio-indicators of atmo-spheric particulate deposition within a University communityin Nigeriardquo AES Bioflux vol 6 no 2 pp 101ndash110 2014
[33] M Mleczek I Rissmann P Rutkowski Z Kaczmarek and PGolinski ldquoAccumulation of selected heavy metals by differentgenotypes of Salixrdquo Environmental and Experimental Botanyvol 66 no 2 pp 289ndash296 2009
[34] S E Kakulu ldquoTracemetal concentration in roadside surface soiland tree back a measurement of local atmospheric pollution inAbuja Nigeriardquo Environmental Monitoring and Assessment vol89 no 3 pp 233ndash242 2003
8 Journal of Analytical Methods in Chemistry
[35] J G SpeightThe Chemistry and Technology of Petroleum CRCPress Taylor amp Francis Boca Raton Fla USA 5th edition 2010
[36] K B Singh and S K Taneja ldquoConcentration of Zn Cu andMn in vegetables and meat food stuff commonly available inManipur a North Eastern state of Indiardquo Electronic Journal ofEnvironmental Agricultural and Food Chemistry vol 9 no 3pp 610ndash616 2010
[37] A E Kelly M K Reuer N F Goodkin and E A Boyle ldquoLeadconcentrations and isotopes in corals and water near Bermuda1780ndash2000rdquo Earth and Planetary Science Letters vol 283 no 1ndash4 pp 93ndash100 2009
[38] N Robbins Z-F Zhang J Sun M E Ketterer J ALalumandier and R A Shulze ldquoChildhood lead exposure anduptake in teeth in the Cleveland area during the era of leadedgasolinerdquo Science of the Total Environment vol 408 no 19 pp4118ndash4127 2010
[39] A Roberts ldquoChronology of leaded gasolineleaded petrol his-toryrdquo LEAD Action News vol 12 no 2 2011 httpwwwleadorgaunlhtml
[40] P-C Huang P-H Su H-Y Chen et al ldquoChildhood bloodlead levels and intellectual development after ban of leadedgasoline in Taiwan a 9-year prospective studyrdquo EnvironmentInternational vol 40 no 1 pp 88ndash96 2012
[41] C W Rankin J O Nriagu J K Aggarwal T A ArowoloK Adebayo and A R Flegal ldquoLead contamination in cocoaand cocoa products isotopic evidence of global contaminationrdquoEnvironmental Health Perspectives vol 113 no 10 pp 1344ndash1348 2005
[42] E Schelle BG Rawlins RM Lark RWebster I Staton andCW McLeod ldquoMapping aerial metal deposition in metropolitanareas from tree bark a case study in Sheffield EnglandrdquoEnvironmental Pollution vol 155 no 1 pp 164ndash173 2008
[43] M Catinon S Ayrault O Boudouma J Asta M Tissut andP Ravanel ldquoAtmospheric element deposit on tree barks theopposite effects of rain and transpirationrdquo Ecological Indicatorsvol 14 no 1 pp 170ndash177 2012
[44] K O Soetan C O Olaiya and O E Oyewole ldquoThe importanceof mineral elements for humans domestic animals and plantsa reviewrdquo African Journal of Food Science vol 4 no 5 pp 200ndash222 2010
[45] J C Tan D L Burns and H R Jones ldquoSevere ataxiamyelopathy and peripheral neuropathy due to acquired copperdeficiency in a patient with history of gastrectomyrdquo Journal ofParenteral and Enteral Nutrition vol 30 no 5 pp 446ndash4502006
[46] A L Al-Khlaifat and O A Al-Khashman ldquoAtmospheric heavymetal pollution in Aqaba city Jordan using Phoenix dactyliferaL leavesrdquo Atmospheric Environment vol 41 no 39 pp 8891ndash8897 2007
[47] M A Nwachukwu H Feng and J Alinnor ldquoAssessment ofheavy metal pollution in soil and their implications within andaround mechanic villagesrdquo International Journal of Environ-mental Science and Technology vol 7 no 2 pp 347ndash358 2010
[48] N M Karaaslan and M Yaman ldquoDetermination of Nickel andChromium in Pinus nigra L Cedrus Libani and CupressusArizonica leaves to monitor the effects of pollution in Elazig(Turkey)rdquo Instrumentation Science amp Technology vol 41 no 3pp 335ndash348 2013
[49] C-Y Kuo R-H Wong J-Y Lin J-C Lai and H LeeldquoAccumulation of chromium and nickel metals in lung tumorsfrom lung cancer patients in Taiwanrdquo Journal of Toxicology and
Environmental HealthmdashPart A Current Issues vol 69 no 14pp 1337ndash1344 2006
[50] I Koturbash F A Beland and I P Pogribny ldquoRole of epigeneticevents in chemical carcinogenesis-a justification for incorporat-ing epigenetic evaluations in cancer risk assessmentrdquoToxicologyMechanisms and Methods vol 21 no 4 pp 289ndash297 2011
[51] M Gałazyn-Sidorczuk M M Brzoska M Jurczuk and JMoniuszko-Jakoniuk ldquoOxidative damage to proteins and DNAin rats exposed to cadmiumandor ethanolrdquoChemico-BiologicalInteractions vol 180 no 1 pp 31ndash38 2009
[52] P R Shakya P Shrestha C S Tamrakar and P K BhattaraildquoStudies and determination of heavy metals in waste tyresand their impacts on the environmentrdquo Pakistan Journal ofAnalytical and Environmental Chemistry vol 7 no 2 pp 70ndash76 2006
[53] H Spikes ldquoLow- and zero-sulphated ash phosphorus andsulphur anti-wear additives for engine oilsrdquo Lubrication Sciencevol 20 no 2 pp 103ndash136 2008
Figure 2 Metal concentrations in tree backs collected from all sampling zones INZ industrial zone HTZ high traffic commercial zoneRHZ residential high traffic zone RLZ residential low traffic zone CTZ control zone
(mg kgminus1 dry weight) of metals in tree bark samples obtainedfrom this study were found to be Pb 599 plusmn 525 Cd 009 plusmn007 Zn 2764 plusmn 2966 Cu 690 plusmn 554 Co 087 plusmn 045and Cr 284 plusmn 158 which varied from 075 to 2974 lt001to 026 370 to 16613 181 to 3912 023 to 235 and lt001
to 834mg kgminus1 respectively (Table 2) Abundance of metalconcentrations follows the order Zn gt Cu gt Pb gt Cr gt Co gtCdThe results indicate the presence of zinc copper and leadin high concentrations in samples taken from industrial hightraffic commercial and residential high traffic areas relative to
Journal of Analytical Methods in Chemistry 5
Table 2 Overall mean metal concentrations (mg kgminus1 dry weight) in tree bark samples
Range 75ndash2974 lt001ndash026 370ndash16613 181ndash3912 023ndash235 lt001ndash834
residential low traffic and control areas The concentrationsof the heavy metal investigated in this study when comparedwith metal levels reported by Mleczek et al [33] revealedthat the concentrations obtained in this study were higher formetals like Pb Zn Cu and Cr while the concentrations of Coand Cd were lower than those reported in another study thiscould be due to the addition of these metals in trace amountin Nigeria petrol as a means of enhancing the octane numberof gasoline [34 35]
The results for themetal concentrations showed amarkedvariation for samples obtained from the industrial zoneOpposite Procter amp Gamble Limited (INZ
5
) high trafficcommercial zone Iwo Roundabout (HTZ
13
) residential hightraffic zone Opposite Coca-Cola Mini Depot (RHZ
1
) andresidential low traffic zone Adeyi AvenueOld Bodija (RLZ
3
)this generally has the highest value of metal levels Zincconcentration varied widely in all zones with the residen-tial low traffic zone having the lowest level 1641mg kgminus1and the highly trafficked commercial zone possessing thehighest level with mean value of 4597mg kgminus1 The highestconcentration of Zn (16616mg kgminus1) was observed in thesample collected at Iwo Road Roundabout (Alakia axis)(HTZ
14
) within high traffic commercial zone The resultsshowed that there is a significant difference in the zincconcentration at 120588 lt 005 among the zones However nosignificant difference was observed in the zinc concentrationof high traffic commercial zone as compared to industrialzone This indication connotes emission and tyre wear frommotor vehicle pointers as a source of the environmentalzinc contamination Also zinc could be added to the envi-ronment during industrial activities like engine wear wastecombustion exhaust emission and the use of sewage sludgefrom industrial areas as fertilizer Zn promotes growth anddevelopment in the human body but its excessiveness maybe an indication of metal poisoning and growth impedance[36]
The concentration of lead in samples obtained from hightraffic commercial residential high traffic and residential lowtraffic zones varied slightly with average concentrations of962 670 and 596mg kgminus1 respectively However possiblecradles of metal contaminants in the environment are acrucial part of environmental pollution studies The chiefsource of lead (Pb) is the use of leaded gasoline in the20th century [37ndash40] which inevitably brings about leadpollutant in the ecosystem Lead content of Nigeria petrol[06ndash08 g Lminus1] ranks among the world highest content [41]Concentrations of lead reported in other studies showedhigher values than that obtained in this study except forlead concentration reported by [29 33 42 43] Humanexposure to lead brings about reproductive dysfunction
that exhibits biochemical-morphological features includingdecreased sperm quality disorganized epithelia and alteredsperm morphology [44] The analysis of variance showedno significant difference between the levels of copper in allzones at 120588 gt 005 Copper as a crucial micronutrient isessential for bone growth and formation neurologic systemsand nervous systems myelin sheaths [45] The high level(3912mg kgminus1) of copper concentration in samples sampledfrom Aworawo along Ojoo road (HTZ
9
) high traffic com-mercial zones could result from various human activitiesClose look at the results of copper level in residential highand low traffic zones suggests common source Increasedlevels could lead to cirrhosis rheumatoid arthritis mal-nutrition irregular hair growth and depigmentation furgrowth impairment and reproductive performance failureof the heart and disturbances in gastrointestinal systems[44]
Mean concentration of cobalt in the zones was found tofollow the trend high traffic commercial gt residential hightraffic gt industrial gt control gt residential low traffic (Figures2(a)ndash2(f)) with ranges There is no significant differenceobserved for the level of cobalt in all investigated zones at120588 gt 005 The highest cobalt concentration was found in theMangifera indica sample from behind Sumal Foods (chewinggum) (INZ
3
) industrial zone Chromium levels were largelylow in the study (Figures 2(a)ndash2(f)) and the residentiallow traffic zone posed the lowest level of chromium whichcould be attributed to natural sources In various zoneschromium pollution could be due to automobile engineand body erosion yellow lead chromate paint for roadpattern and few steel and glass industry activities [46ndash48] Chromium is known as a ubiquitous pollutant fromthe industrial and environmental activities also a knownhuman carcinogen with specificity in cancer of the lungs[49 50] There is no definite gradient in the concentration ofcadmium present in the investigated zones The residentiallow traffic zone gave 010mg kgminus1 and the lowest meanlevel of cadmium (Cd) was found in residential high trafficzone (006mg kgminus1) ranging from 001 to 015mg kgminus1 Theslight increase in the mean level of cadmium in the controlzone (014mg kgminus1) with the highest concentration foundin the Gmelina arborea species (025mg kgminus1) could belinked to the use of phosphate fertilizer which has cadmiumas a trace element for growing crops When cadmium isaccumulated above the recommended threshold limit itbrings about liver acute and chronic poisoning and also thereplacement of calciumwithin bonematrix of young children[44] it inhibits increased oxidative stress resulting in thedamage of membrane and membrane-enzymes bound losses[51]
6 Journal of Analytical Methods in Chemistry
Table 3 Correlation coefficient among metals in tree bark samplesfrom all zones (bold correlations are significant at 120588 lt 005)
Pb Cd Zn Cu Co CrPb 1Cd 040 1Zn 070 031 1Cu 027 050 079 1Co 024 020 054 077 1Cr 067 024 055 063 069 1
31 Correlation Matrix A coefficient matrix among PbCd Zn Cu Co and Cr concentrations in samples fromthe studied locations are presented in Table 3 The resultsshowed that the elements investigated in this study are highlycorrelated with one another suggesting common source andother possible uncommon sources of metal fallout There isrelatively high correlations amongst metals such as Zn andCu and Co and Cu Positive moderate correlation coefficientwas observed between Pb and Zn and Zn and Co The highcorrelation found between Pb andZn andZn andCu suggestsa common source and other possible well-mixed constituentsinitiating from different sources Positive moderate correla-tion coefficient was also observed between Cr versus Pb andZn and Cr versus Cu and Co Zn level in all the zones wasseen to be in high concentration followed by Cu and Pb Highvalues of Cu and Zn obtained indicate that emission and tyrewear from motor vehicle as a source of the environmentalzinc contamination high level of copper could come fromthe fabrication of brass alloy brake linings and electrical andmechanical working while lead could be the use of leadedgasoline in the Nigeria petrol This is because lead additivesin the form of tetraethyl lead (TEL[Pb(C
2
H5
)4
]) are added togasoline as the cheapestmeans of boasting the octane numberof Nigeria petrol and zinc in the form of organometalliccompounds such as zinc dialkyl dithiophosphate (ZDDP)lubricating oils and tyres [46 52 53]
4 Conclusion
The results of this survey demonstrate the suitability ofTerminalia catappa Azadirachta indica Gmelina arboreaMangifera indica Prosopis juliflora andMurraya species andGliricidia sepium bark species as potential bioindicators forCu Pb Zn Cr and possibly Co and Cd as well as the pointersof some degree of temporal heavy metals contaminationThe levels of the metals were higher in bark samples fromhighly trafficked commercial zone than in other zones Thedeviation in metal concentrations amongst the studied sitescould be due to various anthropogenic activitiesWith respectto the high contribution factors of Zn Cu and Pb to thepotential ecological risk of the area thorough study shouldbe piloted to determine the actual route of the metals entry tothe environment It is imperative that the environmental tracemetal levels be constantly examined to diagnose the stateand trend of environmental atmospheric pollution Furthermonitoring of plant barks species as well as the surrounding
lower epiphytes higher epiphytes and vascular plants isneeded in order to determine whether any temporal trendsexist in metal concentration among biological indicatorsPotential risk assessment of these heavy metals to cropsanimals and humans in the area is recommended Furtherfarming activities within the diameter of 15ndash10Km of thevicinity of the industries and high human activities should bediscouraged as there will be every possibility of heavy metalsuptake by planted crops which will in turn reach up thefood chain and finally to humans Furthermore interspeciesvariation of heavymetal concentrations in plants barks is alsorecommended
Conflict of Interests
Regarding the publication of this paper the authors declareno conflict of interests
Authorsrsquo Contribution
The authors contributed equally to the achievement of theresearch
Acknowledgments
Theauthors wish to acknowledge GovanMbeki Research andDevelopmentCentre (GMRDC)University of FortHare andNRF-Sasol Inzalo Fundation for financial support receivedThe authors acknowledge Eyitayo Fadipe and Ayoade Folukewho assisted in the sample collection
References
[1] T Abbasi and S A Abbasi ldquoIs the use of renewable energysources an answer to the problems of global warming andpollutionrdquo Critical Reviews in Environmental Science and Tech-nology vol 42 no 2 pp 99ndash154 2012
[2] K Ravindra R Sokhi and R Van Grieken ldquoAtmosphericpolycyclic aromatic hydrocarbons source attribution emissionfactors and regulationrdquo Atmospheric Environment vol 42 no13 pp 2895ndash2921 2008
[3] C Woodford Air Pollution 2010 httpwwwexplainthatstuffcomair-pollution-introductionhtml
[4] U Makkonen H Hellen P Anttila and M Ferm ldquoSizedistribution and chemical composition of airborne particlesin south-eastern Finland during different seasons and wildfireepisodes in 2006rdquo Science of the Total Environment vol 408 no3 pp 644ndash651 2010
[5] J Wang Z Hu Y Chen Z Chen and S Xu ldquoContaminationcharacteristics and possible sources of PM10 and PM25 indifferent functional areas of Shanghai Chinardquo AtmosphericEnvironment vol 68 pp 221ndash229 2013
[6] G Qingjie D Jun X Yunchuan W Qingfei and Y LiqiangldquoCalculating pollution indices by heavy metals in ecologicalgeochemistry assessment and a case study in parks of BeijinrdquoJournal of ChinaUniversity of Geosciences vol 19 no 3 pp 230ndash241 2008
[7] C O Ogunkunle and P O Fatoba ldquoPollution loads andthe ecological risk assessment of soil heavy metals around
Journal of Analytical Methods in Chemistry 7
a mega cement factory in Southwest Nigeriardquo Polish Journal ofEnvironmental Studies vol 22 no 2 pp 487ndash493 2013
[8] H A Sani A I Tsafe B U Bagudo and A U ItodoldquoToxic metals uptake by spinach (Spinacea oleracea) and lettuce(Lactuca sativa) cultivated in sokoto a comparative studyrdquoPakistan Journal of Nutrition vol 10 no 6 pp 572ndash576 2011
[9] D Satpathy andMVReddy ldquoPhytoextraction ofCd Pb ZnCuandmn by Indian mustard (Brassica juncea L) grown on loamysoil amended with heavy metal contaminated municipal solidwaste compostrdquo Applied Ecology and Environmental Researchvol 11 no 4 pp 661ndash679 2013
[10] D R Hashmi S Ismail and G H Shaikh ldquoAssessment ofthe level of trace metals in commonly edible vegetables locallyavailable in the markets of Karachi cityrdquo Pakistan Journal ofBotany vol 39 no 3 pp 747ndash751 2007
[11] G N Lion and J O Olowoyo ldquoPopulation health risk dueto dietary intake of toxic heavy metals from Spinacia oleraceaharvested from soils collected in and around Tshwane SouthAfricardquo South African Journal of Botany vol 88 pp 178ndash1822013
[12] B A Anhwange J A Kagbu E B Agbaji and C E GimbaldquoTrace metal contents of some common vegetables grown onirrigated farms along the banks of river Benue within MakurdiMetropolisrdquo Electronic Journal of Environmental Agriculturaland Food Chemistry vol 8 no 11 pp 1150ndash1155 2009
[13] S Baytak R Mert and A R Turker ldquoDetermination ofCu(II) Fe(III) Mn(II) and Zn(II) in various samples afterpreconcentrationwithRhizopus oryzae loaded natural cellulose(almond bark)rdquo International Journal of Environmental Analyt-ical Chemistry vol 94 no 10 pp 975ndash987 2014
[14] S Baslar Y Dogan N Durkan and H Bag ldquoBiomonitoringof zinc and manganese in bark of Turkish red pine of westernAnatoliardquo Journal of Environmental Biology vol 30 no 5 pp831ndash834 2009
[15] A Celik A A Kartal A Akdogan and Y Kaska ldquoDeterminingthe heavy metal pollution in Denizli (Turkey) by using Robiniopseudo-acacia Lrdquo Environment International vol 31 no 1 pp105ndash112 2005
[16] G Nabulo H Oryem Origa G W Nasinyama and D ColeldquoAssessment of Zn Cu Pb and Ni contamination in wetlandsoils and plants in the LakeVictoria basinrdquo International Journalof Environmental Science and Technology vol 5 no 1 pp 65ndash742008
[17] BWolterbeek S Sarmento andTVerburg ldquoIs there a future forbiomonitoring of elemental air pollutionA review focused on alarger-scaled health-related (epidemiological) contextrdquo Journalof Radioanalytical and Nuclear Chemistry vol 286 no 1 pp195ndash210 2010
[18] P K Rai ldquoEnvironmental magnetic studies of particulates withspecial reference to biomagnetic monitoring using roadsideplant leavesrdquo Atmospheric Environment vol 72 pp 113ndash1292013
[19] B Kord A Mataji and S Babaie ldquoPine (Pinus Eldarica Medw)needles as indicator for heavy metals pollutionrdquo InternationalJournal of Environmental Science and Technology vol 7 no 1pp 79ndash84 2010
[20] I Rodrıguez-Germade K J Mohamed D Rey B Rubio and AGarcıa ldquoThe influence of weather and climate on the reliabilityof magnetic properties of tree leaves as proxies for air pollutionmonitoringrdquo Science of the Total Environment vol 468-469 pp892ndash902 2014
[21] L Mulligan An assessment of epiphytic lichens lichen diversityand environmental quality in the semi-natural woodlands ofKnocksink Wood Nature Reserve Enniskerry County Wicklow[PhD thesis] Dublin Institute of Technology 2009
[22] B Kord and B Kord ldquoHeavymetal levels in pine (Pinus eldaricaMedw) tree barks as indicators of atmospheric pollutionrdquoBioResources vol 6 no 2 pp 927ndash935 2011
[23] L E Beramendi-Orosco M L Rodriguez-Estrada O Morton-Bermea F M Romero G Gonzalez-Hernandez and EHernandez-Alvarez ldquoCorrelations between metals in tree-ringsof Prosopis julifora as indicators of sources of heavy metalcontaminationrdquo Applied Geochemistry vol 39 pp 78ndash84 2013
[24] D G Shendell and G R E E Ana ldquoPromoting environmentalpublic health in rapidly urbanizing areas of less-developedcountries in Africa a collaborative interdisciplinary training inIbadan Nigeriardquo Journal of Environmental Health vol 74 no 1pp 26ndash35 2011
[25] M Zhiyanski M Sokolovska J Bech A Clouvas I Penev andV Badulin ldquoCesium-137 contamination of oak (Quercus petraeLiebl) from sub-mediterranean zone in South Bulgariardquo Journalof Environmental Radioactivity vol 101 no 10 pp 864ndash8682010
[26] I Suchara P Rulık J Hulka and H Pilatova ldquoRetrospectivedetermination of 137Cs specific activity distribution in sprucebark and bark aggregated transfer factor in forests on the scaleof the Czech Republic ten years after the Chernobyl accidentrdquoScience of the Total Environment vol 409 no 10 pp 1927ndash19342011
[27] T Sawidis J BreusteMMitrovic P Pavlovic andK TsigaridasldquoTrees as bioindicator of heavy metal pollution in three Euro-pean citiesrdquo Environmental Pollution vol 159 no 12 pp 3560ndash3570 2011
[28] S Leshe and M Tessema ldquoDetermination of levels of essentialand toxic heavy metals in lentil (lens culinaris medik) by flameatomic absorption spectroscopyrdquo African Journal of ChemicalEducation vol 4 no 4 pp 16ndash34 2014
[29] F G Fujiwara D R Gomez L Dawidowski P Perelman andA Faggi ldquoMetals associated with airborne particulate matter inroad dust and tree bark collected in a megacity (Buenos AiresArgentina)rdquo Ecological Indicators vol 11 no 2 pp 240ndash2472011
[30] P C Ogbonna C Odukaesieme and J A Teixeira da SilvaldquoDistribution of heavymetals in soil and accumulation in plantsat an agricultural area of Umudike Nigeriardquo Chemistry andEcology vol 29 no 7 pp 595ndash603 2013
[31] A I Ajai S SOchigbo ZAbdullahi andP I Anigboro ldquoDeter-mination of trace metals and essential minerals in selected fruitjuices in Minna Nigeriardquo International Journal of Food Sciencevol 2014 Article ID 462931 5 pages 2014
[32] A R Ipeaiyeda and M Dawodu ldquoAssessment of toxic metalpollution in soil leaves and tree barks bio-indicators of atmo-spheric particulate deposition within a University communityin Nigeriardquo AES Bioflux vol 6 no 2 pp 101ndash110 2014
[33] M Mleczek I Rissmann P Rutkowski Z Kaczmarek and PGolinski ldquoAccumulation of selected heavy metals by differentgenotypes of Salixrdquo Environmental and Experimental Botanyvol 66 no 2 pp 289ndash296 2009
[34] S E Kakulu ldquoTracemetal concentration in roadside surface soiland tree back a measurement of local atmospheric pollution inAbuja Nigeriardquo Environmental Monitoring and Assessment vol89 no 3 pp 233ndash242 2003
8 Journal of Analytical Methods in Chemistry
[35] J G SpeightThe Chemistry and Technology of Petroleum CRCPress Taylor amp Francis Boca Raton Fla USA 5th edition 2010
[36] K B Singh and S K Taneja ldquoConcentration of Zn Cu andMn in vegetables and meat food stuff commonly available inManipur a North Eastern state of Indiardquo Electronic Journal ofEnvironmental Agricultural and Food Chemistry vol 9 no 3pp 610ndash616 2010
[37] A E Kelly M K Reuer N F Goodkin and E A Boyle ldquoLeadconcentrations and isotopes in corals and water near Bermuda1780ndash2000rdquo Earth and Planetary Science Letters vol 283 no 1ndash4 pp 93ndash100 2009
[38] N Robbins Z-F Zhang J Sun M E Ketterer J ALalumandier and R A Shulze ldquoChildhood lead exposure anduptake in teeth in the Cleveland area during the era of leadedgasolinerdquo Science of the Total Environment vol 408 no 19 pp4118ndash4127 2010
[39] A Roberts ldquoChronology of leaded gasolineleaded petrol his-toryrdquo LEAD Action News vol 12 no 2 2011 httpwwwleadorgaunlhtml
[40] P-C Huang P-H Su H-Y Chen et al ldquoChildhood bloodlead levels and intellectual development after ban of leadedgasoline in Taiwan a 9-year prospective studyrdquo EnvironmentInternational vol 40 no 1 pp 88ndash96 2012
[41] C W Rankin J O Nriagu J K Aggarwal T A ArowoloK Adebayo and A R Flegal ldquoLead contamination in cocoaand cocoa products isotopic evidence of global contaminationrdquoEnvironmental Health Perspectives vol 113 no 10 pp 1344ndash1348 2005
[42] E Schelle BG Rawlins RM Lark RWebster I Staton andCW McLeod ldquoMapping aerial metal deposition in metropolitanareas from tree bark a case study in Sheffield EnglandrdquoEnvironmental Pollution vol 155 no 1 pp 164ndash173 2008
[43] M Catinon S Ayrault O Boudouma J Asta M Tissut andP Ravanel ldquoAtmospheric element deposit on tree barks theopposite effects of rain and transpirationrdquo Ecological Indicatorsvol 14 no 1 pp 170ndash177 2012
[44] K O Soetan C O Olaiya and O E Oyewole ldquoThe importanceof mineral elements for humans domestic animals and plantsa reviewrdquo African Journal of Food Science vol 4 no 5 pp 200ndash222 2010
[45] J C Tan D L Burns and H R Jones ldquoSevere ataxiamyelopathy and peripheral neuropathy due to acquired copperdeficiency in a patient with history of gastrectomyrdquo Journal ofParenteral and Enteral Nutrition vol 30 no 5 pp 446ndash4502006
[46] A L Al-Khlaifat and O A Al-Khashman ldquoAtmospheric heavymetal pollution in Aqaba city Jordan using Phoenix dactyliferaL leavesrdquo Atmospheric Environment vol 41 no 39 pp 8891ndash8897 2007
[47] M A Nwachukwu H Feng and J Alinnor ldquoAssessment ofheavy metal pollution in soil and their implications within andaround mechanic villagesrdquo International Journal of Environ-mental Science and Technology vol 7 no 2 pp 347ndash358 2010
[48] N M Karaaslan and M Yaman ldquoDetermination of Nickel andChromium in Pinus nigra L Cedrus Libani and CupressusArizonica leaves to monitor the effects of pollution in Elazig(Turkey)rdquo Instrumentation Science amp Technology vol 41 no 3pp 335ndash348 2013
[49] C-Y Kuo R-H Wong J-Y Lin J-C Lai and H LeeldquoAccumulation of chromium and nickel metals in lung tumorsfrom lung cancer patients in Taiwanrdquo Journal of Toxicology and
Environmental HealthmdashPart A Current Issues vol 69 no 14pp 1337ndash1344 2006
[50] I Koturbash F A Beland and I P Pogribny ldquoRole of epigeneticevents in chemical carcinogenesis-a justification for incorporat-ing epigenetic evaluations in cancer risk assessmentrdquoToxicologyMechanisms and Methods vol 21 no 4 pp 289ndash297 2011
[51] M Gałazyn-Sidorczuk M M Brzoska M Jurczuk and JMoniuszko-Jakoniuk ldquoOxidative damage to proteins and DNAin rats exposed to cadmiumandor ethanolrdquoChemico-BiologicalInteractions vol 180 no 1 pp 31ndash38 2009
[52] P R Shakya P Shrestha C S Tamrakar and P K BhattaraildquoStudies and determination of heavy metals in waste tyresand their impacts on the environmentrdquo Pakistan Journal ofAnalytical and Environmental Chemistry vol 7 no 2 pp 70ndash76 2006
[53] H Spikes ldquoLow- and zero-sulphated ash phosphorus andsulphur anti-wear additives for engine oilsrdquo Lubrication Sciencevol 20 no 2 pp 103ndash136 2008
Range 75ndash2974 lt001ndash026 370ndash16613 181ndash3912 023ndash235 lt001ndash834
residential low traffic and control areas The concentrationsof the heavy metal investigated in this study when comparedwith metal levels reported by Mleczek et al [33] revealedthat the concentrations obtained in this study were higher formetals like Pb Zn Cu and Cr while the concentrations of Coand Cd were lower than those reported in another study thiscould be due to the addition of these metals in trace amountin Nigeria petrol as a means of enhancing the octane numberof gasoline [34 35]
The results for themetal concentrations showed amarkedvariation for samples obtained from the industrial zoneOpposite Procter amp Gamble Limited (INZ
5
) high trafficcommercial zone Iwo Roundabout (HTZ
13
) residential hightraffic zone Opposite Coca-Cola Mini Depot (RHZ
1
) andresidential low traffic zone Adeyi AvenueOld Bodija (RLZ
3
)this generally has the highest value of metal levels Zincconcentration varied widely in all zones with the residen-tial low traffic zone having the lowest level 1641mg kgminus1and the highly trafficked commercial zone possessing thehighest level with mean value of 4597mg kgminus1 The highestconcentration of Zn (16616mg kgminus1) was observed in thesample collected at Iwo Road Roundabout (Alakia axis)(HTZ
14
) within high traffic commercial zone The resultsshowed that there is a significant difference in the zincconcentration at 120588 lt 005 among the zones However nosignificant difference was observed in the zinc concentrationof high traffic commercial zone as compared to industrialzone This indication connotes emission and tyre wear frommotor vehicle pointers as a source of the environmentalzinc contamination Also zinc could be added to the envi-ronment during industrial activities like engine wear wastecombustion exhaust emission and the use of sewage sludgefrom industrial areas as fertilizer Zn promotes growth anddevelopment in the human body but its excessiveness maybe an indication of metal poisoning and growth impedance[36]
The concentration of lead in samples obtained from hightraffic commercial residential high traffic and residential lowtraffic zones varied slightly with average concentrations of962 670 and 596mg kgminus1 respectively However possiblecradles of metal contaminants in the environment are acrucial part of environmental pollution studies The chiefsource of lead (Pb) is the use of leaded gasoline in the20th century [37ndash40] which inevitably brings about leadpollutant in the ecosystem Lead content of Nigeria petrol[06ndash08 g Lminus1] ranks among the world highest content [41]Concentrations of lead reported in other studies showedhigher values than that obtained in this study except forlead concentration reported by [29 33 42 43] Humanexposure to lead brings about reproductive dysfunction
that exhibits biochemical-morphological features includingdecreased sperm quality disorganized epithelia and alteredsperm morphology [44] The analysis of variance showedno significant difference between the levels of copper in allzones at 120588 gt 005 Copper as a crucial micronutrient isessential for bone growth and formation neurologic systemsand nervous systems myelin sheaths [45] The high level(3912mg kgminus1) of copper concentration in samples sampledfrom Aworawo along Ojoo road (HTZ
9
) high traffic com-mercial zones could result from various human activitiesClose look at the results of copper level in residential highand low traffic zones suggests common source Increasedlevels could lead to cirrhosis rheumatoid arthritis mal-nutrition irregular hair growth and depigmentation furgrowth impairment and reproductive performance failureof the heart and disturbances in gastrointestinal systems[44]
Mean concentration of cobalt in the zones was found tofollow the trend high traffic commercial gt residential hightraffic gt industrial gt control gt residential low traffic (Figures2(a)ndash2(f)) with ranges There is no significant differenceobserved for the level of cobalt in all investigated zones at120588 gt 005 The highest cobalt concentration was found in theMangifera indica sample from behind Sumal Foods (chewinggum) (INZ
3
) industrial zone Chromium levels were largelylow in the study (Figures 2(a)ndash2(f)) and the residentiallow traffic zone posed the lowest level of chromium whichcould be attributed to natural sources In various zoneschromium pollution could be due to automobile engineand body erosion yellow lead chromate paint for roadpattern and few steel and glass industry activities [46ndash48] Chromium is known as a ubiquitous pollutant fromthe industrial and environmental activities also a knownhuman carcinogen with specificity in cancer of the lungs[49 50] There is no definite gradient in the concentration ofcadmium present in the investigated zones The residentiallow traffic zone gave 010mg kgminus1 and the lowest meanlevel of cadmium (Cd) was found in residential high trafficzone (006mg kgminus1) ranging from 001 to 015mg kgminus1 Theslight increase in the mean level of cadmium in the controlzone (014mg kgminus1) with the highest concentration foundin the Gmelina arborea species (025mg kgminus1) could belinked to the use of phosphate fertilizer which has cadmiumas a trace element for growing crops When cadmium isaccumulated above the recommended threshold limit itbrings about liver acute and chronic poisoning and also thereplacement of calciumwithin bonematrix of young children[44] it inhibits increased oxidative stress resulting in thedamage of membrane and membrane-enzymes bound losses[51]
6 Journal of Analytical Methods in Chemistry
Table 3 Correlation coefficient among metals in tree bark samplesfrom all zones (bold correlations are significant at 120588 lt 005)
Pb Cd Zn Cu Co CrPb 1Cd 040 1Zn 070 031 1Cu 027 050 079 1Co 024 020 054 077 1Cr 067 024 055 063 069 1
31 Correlation Matrix A coefficient matrix among PbCd Zn Cu Co and Cr concentrations in samples fromthe studied locations are presented in Table 3 The resultsshowed that the elements investigated in this study are highlycorrelated with one another suggesting common source andother possible uncommon sources of metal fallout There isrelatively high correlations amongst metals such as Zn andCu and Co and Cu Positive moderate correlation coefficientwas observed between Pb and Zn and Zn and Co The highcorrelation found between Pb andZn andZn andCu suggestsa common source and other possible well-mixed constituentsinitiating from different sources Positive moderate correla-tion coefficient was also observed between Cr versus Pb andZn and Cr versus Cu and Co Zn level in all the zones wasseen to be in high concentration followed by Cu and Pb Highvalues of Cu and Zn obtained indicate that emission and tyrewear from motor vehicle as a source of the environmentalzinc contamination high level of copper could come fromthe fabrication of brass alloy brake linings and electrical andmechanical working while lead could be the use of leadedgasoline in the Nigeria petrol This is because lead additivesin the form of tetraethyl lead (TEL[Pb(C
2
H5
)4
]) are added togasoline as the cheapestmeans of boasting the octane numberof Nigeria petrol and zinc in the form of organometalliccompounds such as zinc dialkyl dithiophosphate (ZDDP)lubricating oils and tyres [46 52 53]
4 Conclusion
The results of this survey demonstrate the suitability ofTerminalia catappa Azadirachta indica Gmelina arboreaMangifera indica Prosopis juliflora andMurraya species andGliricidia sepium bark species as potential bioindicators forCu Pb Zn Cr and possibly Co and Cd as well as the pointersof some degree of temporal heavy metals contaminationThe levels of the metals were higher in bark samples fromhighly trafficked commercial zone than in other zones Thedeviation in metal concentrations amongst the studied sitescould be due to various anthropogenic activitiesWith respectto the high contribution factors of Zn Cu and Pb to thepotential ecological risk of the area thorough study shouldbe piloted to determine the actual route of the metals entry tothe environment It is imperative that the environmental tracemetal levels be constantly examined to diagnose the stateand trend of environmental atmospheric pollution Furthermonitoring of plant barks species as well as the surrounding
lower epiphytes higher epiphytes and vascular plants isneeded in order to determine whether any temporal trendsexist in metal concentration among biological indicatorsPotential risk assessment of these heavy metals to cropsanimals and humans in the area is recommended Furtherfarming activities within the diameter of 15ndash10Km of thevicinity of the industries and high human activities should bediscouraged as there will be every possibility of heavy metalsuptake by planted crops which will in turn reach up thefood chain and finally to humans Furthermore interspeciesvariation of heavymetal concentrations in plants barks is alsorecommended
Conflict of Interests
Regarding the publication of this paper the authors declareno conflict of interests
Authorsrsquo Contribution
The authors contributed equally to the achievement of theresearch
Acknowledgments
Theauthors wish to acknowledge GovanMbeki Research andDevelopmentCentre (GMRDC)University of FortHare andNRF-Sasol Inzalo Fundation for financial support receivedThe authors acknowledge Eyitayo Fadipe and Ayoade Folukewho assisted in the sample collection
References
[1] T Abbasi and S A Abbasi ldquoIs the use of renewable energysources an answer to the problems of global warming andpollutionrdquo Critical Reviews in Environmental Science and Tech-nology vol 42 no 2 pp 99ndash154 2012
[2] K Ravindra R Sokhi and R Van Grieken ldquoAtmosphericpolycyclic aromatic hydrocarbons source attribution emissionfactors and regulationrdquo Atmospheric Environment vol 42 no13 pp 2895ndash2921 2008
[3] C Woodford Air Pollution 2010 httpwwwexplainthatstuffcomair-pollution-introductionhtml
[4] U Makkonen H Hellen P Anttila and M Ferm ldquoSizedistribution and chemical composition of airborne particlesin south-eastern Finland during different seasons and wildfireepisodes in 2006rdquo Science of the Total Environment vol 408 no3 pp 644ndash651 2010
[5] J Wang Z Hu Y Chen Z Chen and S Xu ldquoContaminationcharacteristics and possible sources of PM10 and PM25 indifferent functional areas of Shanghai Chinardquo AtmosphericEnvironment vol 68 pp 221ndash229 2013
[6] G Qingjie D Jun X Yunchuan W Qingfei and Y LiqiangldquoCalculating pollution indices by heavy metals in ecologicalgeochemistry assessment and a case study in parks of BeijinrdquoJournal of ChinaUniversity of Geosciences vol 19 no 3 pp 230ndash241 2008
[7] C O Ogunkunle and P O Fatoba ldquoPollution loads andthe ecological risk assessment of soil heavy metals around
Journal of Analytical Methods in Chemistry 7
a mega cement factory in Southwest Nigeriardquo Polish Journal ofEnvironmental Studies vol 22 no 2 pp 487ndash493 2013
[8] H A Sani A I Tsafe B U Bagudo and A U ItodoldquoToxic metals uptake by spinach (Spinacea oleracea) and lettuce(Lactuca sativa) cultivated in sokoto a comparative studyrdquoPakistan Journal of Nutrition vol 10 no 6 pp 572ndash576 2011
[9] D Satpathy andMVReddy ldquoPhytoextraction ofCd Pb ZnCuandmn by Indian mustard (Brassica juncea L) grown on loamysoil amended with heavy metal contaminated municipal solidwaste compostrdquo Applied Ecology and Environmental Researchvol 11 no 4 pp 661ndash679 2013
[10] D R Hashmi S Ismail and G H Shaikh ldquoAssessment ofthe level of trace metals in commonly edible vegetables locallyavailable in the markets of Karachi cityrdquo Pakistan Journal ofBotany vol 39 no 3 pp 747ndash751 2007
[11] G N Lion and J O Olowoyo ldquoPopulation health risk dueto dietary intake of toxic heavy metals from Spinacia oleraceaharvested from soils collected in and around Tshwane SouthAfricardquo South African Journal of Botany vol 88 pp 178ndash1822013
[12] B A Anhwange J A Kagbu E B Agbaji and C E GimbaldquoTrace metal contents of some common vegetables grown onirrigated farms along the banks of river Benue within MakurdiMetropolisrdquo Electronic Journal of Environmental Agriculturaland Food Chemistry vol 8 no 11 pp 1150ndash1155 2009
[13] S Baytak R Mert and A R Turker ldquoDetermination ofCu(II) Fe(III) Mn(II) and Zn(II) in various samples afterpreconcentrationwithRhizopus oryzae loaded natural cellulose(almond bark)rdquo International Journal of Environmental Analyt-ical Chemistry vol 94 no 10 pp 975ndash987 2014
[14] S Baslar Y Dogan N Durkan and H Bag ldquoBiomonitoringof zinc and manganese in bark of Turkish red pine of westernAnatoliardquo Journal of Environmental Biology vol 30 no 5 pp831ndash834 2009
[15] A Celik A A Kartal A Akdogan and Y Kaska ldquoDeterminingthe heavy metal pollution in Denizli (Turkey) by using Robiniopseudo-acacia Lrdquo Environment International vol 31 no 1 pp105ndash112 2005
[16] G Nabulo H Oryem Origa G W Nasinyama and D ColeldquoAssessment of Zn Cu Pb and Ni contamination in wetlandsoils and plants in the LakeVictoria basinrdquo International Journalof Environmental Science and Technology vol 5 no 1 pp 65ndash742008
[17] BWolterbeek S Sarmento andTVerburg ldquoIs there a future forbiomonitoring of elemental air pollutionA review focused on alarger-scaled health-related (epidemiological) contextrdquo Journalof Radioanalytical and Nuclear Chemistry vol 286 no 1 pp195ndash210 2010
[18] P K Rai ldquoEnvironmental magnetic studies of particulates withspecial reference to biomagnetic monitoring using roadsideplant leavesrdquo Atmospheric Environment vol 72 pp 113ndash1292013
[19] B Kord A Mataji and S Babaie ldquoPine (Pinus Eldarica Medw)needles as indicator for heavy metals pollutionrdquo InternationalJournal of Environmental Science and Technology vol 7 no 1pp 79ndash84 2010
[20] I Rodrıguez-Germade K J Mohamed D Rey B Rubio and AGarcıa ldquoThe influence of weather and climate on the reliabilityof magnetic properties of tree leaves as proxies for air pollutionmonitoringrdquo Science of the Total Environment vol 468-469 pp892ndash902 2014
[21] L Mulligan An assessment of epiphytic lichens lichen diversityand environmental quality in the semi-natural woodlands ofKnocksink Wood Nature Reserve Enniskerry County Wicklow[PhD thesis] Dublin Institute of Technology 2009
[22] B Kord and B Kord ldquoHeavymetal levels in pine (Pinus eldaricaMedw) tree barks as indicators of atmospheric pollutionrdquoBioResources vol 6 no 2 pp 927ndash935 2011
[23] L E Beramendi-Orosco M L Rodriguez-Estrada O Morton-Bermea F M Romero G Gonzalez-Hernandez and EHernandez-Alvarez ldquoCorrelations between metals in tree-ringsof Prosopis julifora as indicators of sources of heavy metalcontaminationrdquo Applied Geochemistry vol 39 pp 78ndash84 2013
[24] D G Shendell and G R E E Ana ldquoPromoting environmentalpublic health in rapidly urbanizing areas of less-developedcountries in Africa a collaborative interdisciplinary training inIbadan Nigeriardquo Journal of Environmental Health vol 74 no 1pp 26ndash35 2011
[25] M Zhiyanski M Sokolovska J Bech A Clouvas I Penev andV Badulin ldquoCesium-137 contamination of oak (Quercus petraeLiebl) from sub-mediterranean zone in South Bulgariardquo Journalof Environmental Radioactivity vol 101 no 10 pp 864ndash8682010
[26] I Suchara P Rulık J Hulka and H Pilatova ldquoRetrospectivedetermination of 137Cs specific activity distribution in sprucebark and bark aggregated transfer factor in forests on the scaleof the Czech Republic ten years after the Chernobyl accidentrdquoScience of the Total Environment vol 409 no 10 pp 1927ndash19342011
[27] T Sawidis J BreusteMMitrovic P Pavlovic andK TsigaridasldquoTrees as bioindicator of heavy metal pollution in three Euro-pean citiesrdquo Environmental Pollution vol 159 no 12 pp 3560ndash3570 2011
[28] S Leshe and M Tessema ldquoDetermination of levels of essentialand toxic heavy metals in lentil (lens culinaris medik) by flameatomic absorption spectroscopyrdquo African Journal of ChemicalEducation vol 4 no 4 pp 16ndash34 2014
[29] F G Fujiwara D R Gomez L Dawidowski P Perelman andA Faggi ldquoMetals associated with airborne particulate matter inroad dust and tree bark collected in a megacity (Buenos AiresArgentina)rdquo Ecological Indicators vol 11 no 2 pp 240ndash2472011
[30] P C Ogbonna C Odukaesieme and J A Teixeira da SilvaldquoDistribution of heavymetals in soil and accumulation in plantsat an agricultural area of Umudike Nigeriardquo Chemistry andEcology vol 29 no 7 pp 595ndash603 2013
[31] A I Ajai S SOchigbo ZAbdullahi andP I Anigboro ldquoDeter-mination of trace metals and essential minerals in selected fruitjuices in Minna Nigeriardquo International Journal of Food Sciencevol 2014 Article ID 462931 5 pages 2014
[32] A R Ipeaiyeda and M Dawodu ldquoAssessment of toxic metalpollution in soil leaves and tree barks bio-indicators of atmo-spheric particulate deposition within a University communityin Nigeriardquo AES Bioflux vol 6 no 2 pp 101ndash110 2014
[33] M Mleczek I Rissmann P Rutkowski Z Kaczmarek and PGolinski ldquoAccumulation of selected heavy metals by differentgenotypes of Salixrdquo Environmental and Experimental Botanyvol 66 no 2 pp 289ndash296 2009
[34] S E Kakulu ldquoTracemetal concentration in roadside surface soiland tree back a measurement of local atmospheric pollution inAbuja Nigeriardquo Environmental Monitoring and Assessment vol89 no 3 pp 233ndash242 2003
8 Journal of Analytical Methods in Chemistry
[35] J G SpeightThe Chemistry and Technology of Petroleum CRCPress Taylor amp Francis Boca Raton Fla USA 5th edition 2010
[36] K B Singh and S K Taneja ldquoConcentration of Zn Cu andMn in vegetables and meat food stuff commonly available inManipur a North Eastern state of Indiardquo Electronic Journal ofEnvironmental Agricultural and Food Chemistry vol 9 no 3pp 610ndash616 2010
[37] A E Kelly M K Reuer N F Goodkin and E A Boyle ldquoLeadconcentrations and isotopes in corals and water near Bermuda1780ndash2000rdquo Earth and Planetary Science Letters vol 283 no 1ndash4 pp 93ndash100 2009
[38] N Robbins Z-F Zhang J Sun M E Ketterer J ALalumandier and R A Shulze ldquoChildhood lead exposure anduptake in teeth in the Cleveland area during the era of leadedgasolinerdquo Science of the Total Environment vol 408 no 19 pp4118ndash4127 2010
[39] A Roberts ldquoChronology of leaded gasolineleaded petrol his-toryrdquo LEAD Action News vol 12 no 2 2011 httpwwwleadorgaunlhtml
[40] P-C Huang P-H Su H-Y Chen et al ldquoChildhood bloodlead levels and intellectual development after ban of leadedgasoline in Taiwan a 9-year prospective studyrdquo EnvironmentInternational vol 40 no 1 pp 88ndash96 2012
[41] C W Rankin J O Nriagu J K Aggarwal T A ArowoloK Adebayo and A R Flegal ldquoLead contamination in cocoaand cocoa products isotopic evidence of global contaminationrdquoEnvironmental Health Perspectives vol 113 no 10 pp 1344ndash1348 2005
[42] E Schelle BG Rawlins RM Lark RWebster I Staton andCW McLeod ldquoMapping aerial metal deposition in metropolitanareas from tree bark a case study in Sheffield EnglandrdquoEnvironmental Pollution vol 155 no 1 pp 164ndash173 2008
[43] M Catinon S Ayrault O Boudouma J Asta M Tissut andP Ravanel ldquoAtmospheric element deposit on tree barks theopposite effects of rain and transpirationrdquo Ecological Indicatorsvol 14 no 1 pp 170ndash177 2012
[44] K O Soetan C O Olaiya and O E Oyewole ldquoThe importanceof mineral elements for humans domestic animals and plantsa reviewrdquo African Journal of Food Science vol 4 no 5 pp 200ndash222 2010
[45] J C Tan D L Burns and H R Jones ldquoSevere ataxiamyelopathy and peripheral neuropathy due to acquired copperdeficiency in a patient with history of gastrectomyrdquo Journal ofParenteral and Enteral Nutrition vol 30 no 5 pp 446ndash4502006
[46] A L Al-Khlaifat and O A Al-Khashman ldquoAtmospheric heavymetal pollution in Aqaba city Jordan using Phoenix dactyliferaL leavesrdquo Atmospheric Environment vol 41 no 39 pp 8891ndash8897 2007
[47] M A Nwachukwu H Feng and J Alinnor ldquoAssessment ofheavy metal pollution in soil and their implications within andaround mechanic villagesrdquo International Journal of Environ-mental Science and Technology vol 7 no 2 pp 347ndash358 2010
[48] N M Karaaslan and M Yaman ldquoDetermination of Nickel andChromium in Pinus nigra L Cedrus Libani and CupressusArizonica leaves to monitor the effects of pollution in Elazig(Turkey)rdquo Instrumentation Science amp Technology vol 41 no 3pp 335ndash348 2013
[49] C-Y Kuo R-H Wong J-Y Lin J-C Lai and H LeeldquoAccumulation of chromium and nickel metals in lung tumorsfrom lung cancer patients in Taiwanrdquo Journal of Toxicology and
Environmental HealthmdashPart A Current Issues vol 69 no 14pp 1337ndash1344 2006
[50] I Koturbash F A Beland and I P Pogribny ldquoRole of epigeneticevents in chemical carcinogenesis-a justification for incorporat-ing epigenetic evaluations in cancer risk assessmentrdquoToxicologyMechanisms and Methods vol 21 no 4 pp 289ndash297 2011
[51] M Gałazyn-Sidorczuk M M Brzoska M Jurczuk and JMoniuszko-Jakoniuk ldquoOxidative damage to proteins and DNAin rats exposed to cadmiumandor ethanolrdquoChemico-BiologicalInteractions vol 180 no 1 pp 31ndash38 2009
[52] P R Shakya P Shrestha C S Tamrakar and P K BhattaraildquoStudies and determination of heavy metals in waste tyresand their impacts on the environmentrdquo Pakistan Journal ofAnalytical and Environmental Chemistry vol 7 no 2 pp 70ndash76 2006
[53] H Spikes ldquoLow- and zero-sulphated ash phosphorus andsulphur anti-wear additives for engine oilsrdquo Lubrication Sciencevol 20 no 2 pp 103ndash136 2008
Table 3 Correlation coefficient among metals in tree bark samplesfrom all zones (bold correlations are significant at 120588 lt 005)
Pb Cd Zn Cu Co CrPb 1Cd 040 1Zn 070 031 1Cu 027 050 079 1Co 024 020 054 077 1Cr 067 024 055 063 069 1
31 Correlation Matrix A coefficient matrix among PbCd Zn Cu Co and Cr concentrations in samples fromthe studied locations are presented in Table 3 The resultsshowed that the elements investigated in this study are highlycorrelated with one another suggesting common source andother possible uncommon sources of metal fallout There isrelatively high correlations amongst metals such as Zn andCu and Co and Cu Positive moderate correlation coefficientwas observed between Pb and Zn and Zn and Co The highcorrelation found between Pb andZn andZn andCu suggestsa common source and other possible well-mixed constituentsinitiating from different sources Positive moderate correla-tion coefficient was also observed between Cr versus Pb andZn and Cr versus Cu and Co Zn level in all the zones wasseen to be in high concentration followed by Cu and Pb Highvalues of Cu and Zn obtained indicate that emission and tyrewear from motor vehicle as a source of the environmentalzinc contamination high level of copper could come fromthe fabrication of brass alloy brake linings and electrical andmechanical working while lead could be the use of leadedgasoline in the Nigeria petrol This is because lead additivesin the form of tetraethyl lead (TEL[Pb(C
2
H5
)4
]) are added togasoline as the cheapestmeans of boasting the octane numberof Nigeria petrol and zinc in the form of organometalliccompounds such as zinc dialkyl dithiophosphate (ZDDP)lubricating oils and tyres [46 52 53]
4 Conclusion
The results of this survey demonstrate the suitability ofTerminalia catappa Azadirachta indica Gmelina arboreaMangifera indica Prosopis juliflora andMurraya species andGliricidia sepium bark species as potential bioindicators forCu Pb Zn Cr and possibly Co and Cd as well as the pointersof some degree of temporal heavy metals contaminationThe levels of the metals were higher in bark samples fromhighly trafficked commercial zone than in other zones Thedeviation in metal concentrations amongst the studied sitescould be due to various anthropogenic activitiesWith respectto the high contribution factors of Zn Cu and Pb to thepotential ecological risk of the area thorough study shouldbe piloted to determine the actual route of the metals entry tothe environment It is imperative that the environmental tracemetal levels be constantly examined to diagnose the stateand trend of environmental atmospheric pollution Furthermonitoring of plant barks species as well as the surrounding
lower epiphytes higher epiphytes and vascular plants isneeded in order to determine whether any temporal trendsexist in metal concentration among biological indicatorsPotential risk assessment of these heavy metals to cropsanimals and humans in the area is recommended Furtherfarming activities within the diameter of 15ndash10Km of thevicinity of the industries and high human activities should bediscouraged as there will be every possibility of heavy metalsuptake by planted crops which will in turn reach up thefood chain and finally to humans Furthermore interspeciesvariation of heavymetal concentrations in plants barks is alsorecommended
Conflict of Interests
Regarding the publication of this paper the authors declareno conflict of interests
Authorsrsquo Contribution
The authors contributed equally to the achievement of theresearch
Acknowledgments
Theauthors wish to acknowledge GovanMbeki Research andDevelopmentCentre (GMRDC)University of FortHare andNRF-Sasol Inzalo Fundation for financial support receivedThe authors acknowledge Eyitayo Fadipe and Ayoade Folukewho assisted in the sample collection
References
[1] T Abbasi and S A Abbasi ldquoIs the use of renewable energysources an answer to the problems of global warming andpollutionrdquo Critical Reviews in Environmental Science and Tech-nology vol 42 no 2 pp 99ndash154 2012
[2] K Ravindra R Sokhi and R Van Grieken ldquoAtmosphericpolycyclic aromatic hydrocarbons source attribution emissionfactors and regulationrdquo Atmospheric Environment vol 42 no13 pp 2895ndash2921 2008
[3] C Woodford Air Pollution 2010 httpwwwexplainthatstuffcomair-pollution-introductionhtml
[4] U Makkonen H Hellen P Anttila and M Ferm ldquoSizedistribution and chemical composition of airborne particlesin south-eastern Finland during different seasons and wildfireepisodes in 2006rdquo Science of the Total Environment vol 408 no3 pp 644ndash651 2010
[5] J Wang Z Hu Y Chen Z Chen and S Xu ldquoContaminationcharacteristics and possible sources of PM10 and PM25 indifferent functional areas of Shanghai Chinardquo AtmosphericEnvironment vol 68 pp 221ndash229 2013
[6] G Qingjie D Jun X Yunchuan W Qingfei and Y LiqiangldquoCalculating pollution indices by heavy metals in ecologicalgeochemistry assessment and a case study in parks of BeijinrdquoJournal of ChinaUniversity of Geosciences vol 19 no 3 pp 230ndash241 2008
[7] C O Ogunkunle and P O Fatoba ldquoPollution loads andthe ecological risk assessment of soil heavy metals around
Journal of Analytical Methods in Chemistry 7
a mega cement factory in Southwest Nigeriardquo Polish Journal ofEnvironmental Studies vol 22 no 2 pp 487ndash493 2013
[8] H A Sani A I Tsafe B U Bagudo and A U ItodoldquoToxic metals uptake by spinach (Spinacea oleracea) and lettuce(Lactuca sativa) cultivated in sokoto a comparative studyrdquoPakistan Journal of Nutrition vol 10 no 6 pp 572ndash576 2011
[9] D Satpathy andMVReddy ldquoPhytoextraction ofCd Pb ZnCuandmn by Indian mustard (Brassica juncea L) grown on loamysoil amended with heavy metal contaminated municipal solidwaste compostrdquo Applied Ecology and Environmental Researchvol 11 no 4 pp 661ndash679 2013
[10] D R Hashmi S Ismail and G H Shaikh ldquoAssessment ofthe level of trace metals in commonly edible vegetables locallyavailable in the markets of Karachi cityrdquo Pakistan Journal ofBotany vol 39 no 3 pp 747ndash751 2007
[11] G N Lion and J O Olowoyo ldquoPopulation health risk dueto dietary intake of toxic heavy metals from Spinacia oleraceaharvested from soils collected in and around Tshwane SouthAfricardquo South African Journal of Botany vol 88 pp 178ndash1822013
[12] B A Anhwange J A Kagbu E B Agbaji and C E GimbaldquoTrace metal contents of some common vegetables grown onirrigated farms along the banks of river Benue within MakurdiMetropolisrdquo Electronic Journal of Environmental Agriculturaland Food Chemistry vol 8 no 11 pp 1150ndash1155 2009
[13] S Baytak R Mert and A R Turker ldquoDetermination ofCu(II) Fe(III) Mn(II) and Zn(II) in various samples afterpreconcentrationwithRhizopus oryzae loaded natural cellulose(almond bark)rdquo International Journal of Environmental Analyt-ical Chemistry vol 94 no 10 pp 975ndash987 2014
[14] S Baslar Y Dogan N Durkan and H Bag ldquoBiomonitoringof zinc and manganese in bark of Turkish red pine of westernAnatoliardquo Journal of Environmental Biology vol 30 no 5 pp831ndash834 2009
[15] A Celik A A Kartal A Akdogan and Y Kaska ldquoDeterminingthe heavy metal pollution in Denizli (Turkey) by using Robiniopseudo-acacia Lrdquo Environment International vol 31 no 1 pp105ndash112 2005
[16] G Nabulo H Oryem Origa G W Nasinyama and D ColeldquoAssessment of Zn Cu Pb and Ni contamination in wetlandsoils and plants in the LakeVictoria basinrdquo International Journalof Environmental Science and Technology vol 5 no 1 pp 65ndash742008
[17] BWolterbeek S Sarmento andTVerburg ldquoIs there a future forbiomonitoring of elemental air pollutionA review focused on alarger-scaled health-related (epidemiological) contextrdquo Journalof Radioanalytical and Nuclear Chemistry vol 286 no 1 pp195ndash210 2010
[18] P K Rai ldquoEnvironmental magnetic studies of particulates withspecial reference to biomagnetic monitoring using roadsideplant leavesrdquo Atmospheric Environment vol 72 pp 113ndash1292013
[19] B Kord A Mataji and S Babaie ldquoPine (Pinus Eldarica Medw)needles as indicator for heavy metals pollutionrdquo InternationalJournal of Environmental Science and Technology vol 7 no 1pp 79ndash84 2010
[20] I Rodrıguez-Germade K J Mohamed D Rey B Rubio and AGarcıa ldquoThe influence of weather and climate on the reliabilityof magnetic properties of tree leaves as proxies for air pollutionmonitoringrdquo Science of the Total Environment vol 468-469 pp892ndash902 2014
[21] L Mulligan An assessment of epiphytic lichens lichen diversityand environmental quality in the semi-natural woodlands ofKnocksink Wood Nature Reserve Enniskerry County Wicklow[PhD thesis] Dublin Institute of Technology 2009
[22] B Kord and B Kord ldquoHeavymetal levels in pine (Pinus eldaricaMedw) tree barks as indicators of atmospheric pollutionrdquoBioResources vol 6 no 2 pp 927ndash935 2011
[23] L E Beramendi-Orosco M L Rodriguez-Estrada O Morton-Bermea F M Romero G Gonzalez-Hernandez and EHernandez-Alvarez ldquoCorrelations between metals in tree-ringsof Prosopis julifora as indicators of sources of heavy metalcontaminationrdquo Applied Geochemistry vol 39 pp 78ndash84 2013
[24] D G Shendell and G R E E Ana ldquoPromoting environmentalpublic health in rapidly urbanizing areas of less-developedcountries in Africa a collaborative interdisciplinary training inIbadan Nigeriardquo Journal of Environmental Health vol 74 no 1pp 26ndash35 2011
[25] M Zhiyanski M Sokolovska J Bech A Clouvas I Penev andV Badulin ldquoCesium-137 contamination of oak (Quercus petraeLiebl) from sub-mediterranean zone in South Bulgariardquo Journalof Environmental Radioactivity vol 101 no 10 pp 864ndash8682010
[26] I Suchara P Rulık J Hulka and H Pilatova ldquoRetrospectivedetermination of 137Cs specific activity distribution in sprucebark and bark aggregated transfer factor in forests on the scaleof the Czech Republic ten years after the Chernobyl accidentrdquoScience of the Total Environment vol 409 no 10 pp 1927ndash19342011
[27] T Sawidis J BreusteMMitrovic P Pavlovic andK TsigaridasldquoTrees as bioindicator of heavy metal pollution in three Euro-pean citiesrdquo Environmental Pollution vol 159 no 12 pp 3560ndash3570 2011
[28] S Leshe and M Tessema ldquoDetermination of levels of essentialand toxic heavy metals in lentil (lens culinaris medik) by flameatomic absorption spectroscopyrdquo African Journal of ChemicalEducation vol 4 no 4 pp 16ndash34 2014
[29] F G Fujiwara D R Gomez L Dawidowski P Perelman andA Faggi ldquoMetals associated with airborne particulate matter inroad dust and tree bark collected in a megacity (Buenos AiresArgentina)rdquo Ecological Indicators vol 11 no 2 pp 240ndash2472011
[30] P C Ogbonna C Odukaesieme and J A Teixeira da SilvaldquoDistribution of heavymetals in soil and accumulation in plantsat an agricultural area of Umudike Nigeriardquo Chemistry andEcology vol 29 no 7 pp 595ndash603 2013
[31] A I Ajai S SOchigbo ZAbdullahi andP I Anigboro ldquoDeter-mination of trace metals and essential minerals in selected fruitjuices in Minna Nigeriardquo International Journal of Food Sciencevol 2014 Article ID 462931 5 pages 2014
[32] A R Ipeaiyeda and M Dawodu ldquoAssessment of toxic metalpollution in soil leaves and tree barks bio-indicators of atmo-spheric particulate deposition within a University communityin Nigeriardquo AES Bioflux vol 6 no 2 pp 101ndash110 2014
[33] M Mleczek I Rissmann P Rutkowski Z Kaczmarek and PGolinski ldquoAccumulation of selected heavy metals by differentgenotypes of Salixrdquo Environmental and Experimental Botanyvol 66 no 2 pp 289ndash296 2009
[34] S E Kakulu ldquoTracemetal concentration in roadside surface soiland tree back a measurement of local atmospheric pollution inAbuja Nigeriardquo Environmental Monitoring and Assessment vol89 no 3 pp 233ndash242 2003
8 Journal of Analytical Methods in Chemistry
[35] J G SpeightThe Chemistry and Technology of Petroleum CRCPress Taylor amp Francis Boca Raton Fla USA 5th edition 2010
[36] K B Singh and S K Taneja ldquoConcentration of Zn Cu andMn in vegetables and meat food stuff commonly available inManipur a North Eastern state of Indiardquo Electronic Journal ofEnvironmental Agricultural and Food Chemistry vol 9 no 3pp 610ndash616 2010
[37] A E Kelly M K Reuer N F Goodkin and E A Boyle ldquoLeadconcentrations and isotopes in corals and water near Bermuda1780ndash2000rdquo Earth and Planetary Science Letters vol 283 no 1ndash4 pp 93ndash100 2009
[38] N Robbins Z-F Zhang J Sun M E Ketterer J ALalumandier and R A Shulze ldquoChildhood lead exposure anduptake in teeth in the Cleveland area during the era of leadedgasolinerdquo Science of the Total Environment vol 408 no 19 pp4118ndash4127 2010
[39] A Roberts ldquoChronology of leaded gasolineleaded petrol his-toryrdquo LEAD Action News vol 12 no 2 2011 httpwwwleadorgaunlhtml
[40] P-C Huang P-H Su H-Y Chen et al ldquoChildhood bloodlead levels and intellectual development after ban of leadedgasoline in Taiwan a 9-year prospective studyrdquo EnvironmentInternational vol 40 no 1 pp 88ndash96 2012
[41] C W Rankin J O Nriagu J K Aggarwal T A ArowoloK Adebayo and A R Flegal ldquoLead contamination in cocoaand cocoa products isotopic evidence of global contaminationrdquoEnvironmental Health Perspectives vol 113 no 10 pp 1344ndash1348 2005
[42] E Schelle BG Rawlins RM Lark RWebster I Staton andCW McLeod ldquoMapping aerial metal deposition in metropolitanareas from tree bark a case study in Sheffield EnglandrdquoEnvironmental Pollution vol 155 no 1 pp 164ndash173 2008
[43] M Catinon S Ayrault O Boudouma J Asta M Tissut andP Ravanel ldquoAtmospheric element deposit on tree barks theopposite effects of rain and transpirationrdquo Ecological Indicatorsvol 14 no 1 pp 170ndash177 2012
[44] K O Soetan C O Olaiya and O E Oyewole ldquoThe importanceof mineral elements for humans domestic animals and plantsa reviewrdquo African Journal of Food Science vol 4 no 5 pp 200ndash222 2010
[45] J C Tan D L Burns and H R Jones ldquoSevere ataxiamyelopathy and peripheral neuropathy due to acquired copperdeficiency in a patient with history of gastrectomyrdquo Journal ofParenteral and Enteral Nutrition vol 30 no 5 pp 446ndash4502006
[46] A L Al-Khlaifat and O A Al-Khashman ldquoAtmospheric heavymetal pollution in Aqaba city Jordan using Phoenix dactyliferaL leavesrdquo Atmospheric Environment vol 41 no 39 pp 8891ndash8897 2007
[47] M A Nwachukwu H Feng and J Alinnor ldquoAssessment ofheavy metal pollution in soil and their implications within andaround mechanic villagesrdquo International Journal of Environ-mental Science and Technology vol 7 no 2 pp 347ndash358 2010
[48] N M Karaaslan and M Yaman ldquoDetermination of Nickel andChromium in Pinus nigra L Cedrus Libani and CupressusArizonica leaves to monitor the effects of pollution in Elazig(Turkey)rdquo Instrumentation Science amp Technology vol 41 no 3pp 335ndash348 2013
[49] C-Y Kuo R-H Wong J-Y Lin J-C Lai and H LeeldquoAccumulation of chromium and nickel metals in lung tumorsfrom lung cancer patients in Taiwanrdquo Journal of Toxicology and
Environmental HealthmdashPart A Current Issues vol 69 no 14pp 1337ndash1344 2006
[50] I Koturbash F A Beland and I P Pogribny ldquoRole of epigeneticevents in chemical carcinogenesis-a justification for incorporat-ing epigenetic evaluations in cancer risk assessmentrdquoToxicologyMechanisms and Methods vol 21 no 4 pp 289ndash297 2011
[51] M Gałazyn-Sidorczuk M M Brzoska M Jurczuk and JMoniuszko-Jakoniuk ldquoOxidative damage to proteins and DNAin rats exposed to cadmiumandor ethanolrdquoChemico-BiologicalInteractions vol 180 no 1 pp 31ndash38 2009
[52] P R Shakya P Shrestha C S Tamrakar and P K BhattaraildquoStudies and determination of heavy metals in waste tyresand their impacts on the environmentrdquo Pakistan Journal ofAnalytical and Environmental Chemistry vol 7 no 2 pp 70ndash76 2006
[53] H Spikes ldquoLow- and zero-sulphated ash phosphorus andsulphur anti-wear additives for engine oilsrdquo Lubrication Sciencevol 20 no 2 pp 103ndash136 2008
a mega cement factory in Southwest Nigeriardquo Polish Journal ofEnvironmental Studies vol 22 no 2 pp 487ndash493 2013
[8] H A Sani A I Tsafe B U Bagudo and A U ItodoldquoToxic metals uptake by spinach (Spinacea oleracea) and lettuce(Lactuca sativa) cultivated in sokoto a comparative studyrdquoPakistan Journal of Nutrition vol 10 no 6 pp 572ndash576 2011
[9] D Satpathy andMVReddy ldquoPhytoextraction ofCd Pb ZnCuandmn by Indian mustard (Brassica juncea L) grown on loamysoil amended with heavy metal contaminated municipal solidwaste compostrdquo Applied Ecology and Environmental Researchvol 11 no 4 pp 661ndash679 2013
[10] D R Hashmi S Ismail and G H Shaikh ldquoAssessment ofthe level of trace metals in commonly edible vegetables locallyavailable in the markets of Karachi cityrdquo Pakistan Journal ofBotany vol 39 no 3 pp 747ndash751 2007
[11] G N Lion and J O Olowoyo ldquoPopulation health risk dueto dietary intake of toxic heavy metals from Spinacia oleraceaharvested from soils collected in and around Tshwane SouthAfricardquo South African Journal of Botany vol 88 pp 178ndash1822013
[12] B A Anhwange J A Kagbu E B Agbaji and C E GimbaldquoTrace metal contents of some common vegetables grown onirrigated farms along the banks of river Benue within MakurdiMetropolisrdquo Electronic Journal of Environmental Agriculturaland Food Chemistry vol 8 no 11 pp 1150ndash1155 2009
[13] S Baytak R Mert and A R Turker ldquoDetermination ofCu(II) Fe(III) Mn(II) and Zn(II) in various samples afterpreconcentrationwithRhizopus oryzae loaded natural cellulose(almond bark)rdquo International Journal of Environmental Analyt-ical Chemistry vol 94 no 10 pp 975ndash987 2014
[14] S Baslar Y Dogan N Durkan and H Bag ldquoBiomonitoringof zinc and manganese in bark of Turkish red pine of westernAnatoliardquo Journal of Environmental Biology vol 30 no 5 pp831ndash834 2009
[15] A Celik A A Kartal A Akdogan and Y Kaska ldquoDeterminingthe heavy metal pollution in Denizli (Turkey) by using Robiniopseudo-acacia Lrdquo Environment International vol 31 no 1 pp105ndash112 2005
[16] G Nabulo H Oryem Origa G W Nasinyama and D ColeldquoAssessment of Zn Cu Pb and Ni contamination in wetlandsoils and plants in the LakeVictoria basinrdquo International Journalof Environmental Science and Technology vol 5 no 1 pp 65ndash742008
[17] BWolterbeek S Sarmento andTVerburg ldquoIs there a future forbiomonitoring of elemental air pollutionA review focused on alarger-scaled health-related (epidemiological) contextrdquo Journalof Radioanalytical and Nuclear Chemistry vol 286 no 1 pp195ndash210 2010
[18] P K Rai ldquoEnvironmental magnetic studies of particulates withspecial reference to biomagnetic monitoring using roadsideplant leavesrdquo Atmospheric Environment vol 72 pp 113ndash1292013
[19] B Kord A Mataji and S Babaie ldquoPine (Pinus Eldarica Medw)needles as indicator for heavy metals pollutionrdquo InternationalJournal of Environmental Science and Technology vol 7 no 1pp 79ndash84 2010
[20] I Rodrıguez-Germade K J Mohamed D Rey B Rubio and AGarcıa ldquoThe influence of weather and climate on the reliabilityof magnetic properties of tree leaves as proxies for air pollutionmonitoringrdquo Science of the Total Environment vol 468-469 pp892ndash902 2014
[21] L Mulligan An assessment of epiphytic lichens lichen diversityand environmental quality in the semi-natural woodlands ofKnocksink Wood Nature Reserve Enniskerry County Wicklow[PhD thesis] Dublin Institute of Technology 2009
[22] B Kord and B Kord ldquoHeavymetal levels in pine (Pinus eldaricaMedw) tree barks as indicators of atmospheric pollutionrdquoBioResources vol 6 no 2 pp 927ndash935 2011
[23] L E Beramendi-Orosco M L Rodriguez-Estrada O Morton-Bermea F M Romero G Gonzalez-Hernandez and EHernandez-Alvarez ldquoCorrelations between metals in tree-ringsof Prosopis julifora as indicators of sources of heavy metalcontaminationrdquo Applied Geochemistry vol 39 pp 78ndash84 2013
[24] D G Shendell and G R E E Ana ldquoPromoting environmentalpublic health in rapidly urbanizing areas of less-developedcountries in Africa a collaborative interdisciplinary training inIbadan Nigeriardquo Journal of Environmental Health vol 74 no 1pp 26ndash35 2011
[25] M Zhiyanski M Sokolovska J Bech A Clouvas I Penev andV Badulin ldquoCesium-137 contamination of oak (Quercus petraeLiebl) from sub-mediterranean zone in South Bulgariardquo Journalof Environmental Radioactivity vol 101 no 10 pp 864ndash8682010
[26] I Suchara P Rulık J Hulka and H Pilatova ldquoRetrospectivedetermination of 137Cs specific activity distribution in sprucebark and bark aggregated transfer factor in forests on the scaleof the Czech Republic ten years after the Chernobyl accidentrdquoScience of the Total Environment vol 409 no 10 pp 1927ndash19342011
[27] T Sawidis J BreusteMMitrovic P Pavlovic andK TsigaridasldquoTrees as bioindicator of heavy metal pollution in three Euro-pean citiesrdquo Environmental Pollution vol 159 no 12 pp 3560ndash3570 2011
[28] S Leshe and M Tessema ldquoDetermination of levels of essentialand toxic heavy metals in lentil (lens culinaris medik) by flameatomic absorption spectroscopyrdquo African Journal of ChemicalEducation vol 4 no 4 pp 16ndash34 2014
[29] F G Fujiwara D R Gomez L Dawidowski P Perelman andA Faggi ldquoMetals associated with airborne particulate matter inroad dust and tree bark collected in a megacity (Buenos AiresArgentina)rdquo Ecological Indicators vol 11 no 2 pp 240ndash2472011
[30] P C Ogbonna C Odukaesieme and J A Teixeira da SilvaldquoDistribution of heavymetals in soil and accumulation in plantsat an agricultural area of Umudike Nigeriardquo Chemistry andEcology vol 29 no 7 pp 595ndash603 2013
[31] A I Ajai S SOchigbo ZAbdullahi andP I Anigboro ldquoDeter-mination of trace metals and essential minerals in selected fruitjuices in Minna Nigeriardquo International Journal of Food Sciencevol 2014 Article ID 462931 5 pages 2014
[32] A R Ipeaiyeda and M Dawodu ldquoAssessment of toxic metalpollution in soil leaves and tree barks bio-indicators of atmo-spheric particulate deposition within a University communityin Nigeriardquo AES Bioflux vol 6 no 2 pp 101ndash110 2014
[33] M Mleczek I Rissmann P Rutkowski Z Kaczmarek and PGolinski ldquoAccumulation of selected heavy metals by differentgenotypes of Salixrdquo Environmental and Experimental Botanyvol 66 no 2 pp 289ndash296 2009
[34] S E Kakulu ldquoTracemetal concentration in roadside surface soiland tree back a measurement of local atmospheric pollution inAbuja Nigeriardquo Environmental Monitoring and Assessment vol89 no 3 pp 233ndash242 2003
8 Journal of Analytical Methods in Chemistry
[35] J G SpeightThe Chemistry and Technology of Petroleum CRCPress Taylor amp Francis Boca Raton Fla USA 5th edition 2010
[36] K B Singh and S K Taneja ldquoConcentration of Zn Cu andMn in vegetables and meat food stuff commonly available inManipur a North Eastern state of Indiardquo Electronic Journal ofEnvironmental Agricultural and Food Chemistry vol 9 no 3pp 610ndash616 2010
[37] A E Kelly M K Reuer N F Goodkin and E A Boyle ldquoLeadconcentrations and isotopes in corals and water near Bermuda1780ndash2000rdquo Earth and Planetary Science Letters vol 283 no 1ndash4 pp 93ndash100 2009
[38] N Robbins Z-F Zhang J Sun M E Ketterer J ALalumandier and R A Shulze ldquoChildhood lead exposure anduptake in teeth in the Cleveland area during the era of leadedgasolinerdquo Science of the Total Environment vol 408 no 19 pp4118ndash4127 2010
[39] A Roberts ldquoChronology of leaded gasolineleaded petrol his-toryrdquo LEAD Action News vol 12 no 2 2011 httpwwwleadorgaunlhtml
[40] P-C Huang P-H Su H-Y Chen et al ldquoChildhood bloodlead levels and intellectual development after ban of leadedgasoline in Taiwan a 9-year prospective studyrdquo EnvironmentInternational vol 40 no 1 pp 88ndash96 2012
[41] C W Rankin J O Nriagu J K Aggarwal T A ArowoloK Adebayo and A R Flegal ldquoLead contamination in cocoaand cocoa products isotopic evidence of global contaminationrdquoEnvironmental Health Perspectives vol 113 no 10 pp 1344ndash1348 2005
[42] E Schelle BG Rawlins RM Lark RWebster I Staton andCW McLeod ldquoMapping aerial metal deposition in metropolitanareas from tree bark a case study in Sheffield EnglandrdquoEnvironmental Pollution vol 155 no 1 pp 164ndash173 2008
[43] M Catinon S Ayrault O Boudouma J Asta M Tissut andP Ravanel ldquoAtmospheric element deposit on tree barks theopposite effects of rain and transpirationrdquo Ecological Indicatorsvol 14 no 1 pp 170ndash177 2012
[44] K O Soetan C O Olaiya and O E Oyewole ldquoThe importanceof mineral elements for humans domestic animals and plantsa reviewrdquo African Journal of Food Science vol 4 no 5 pp 200ndash222 2010
[45] J C Tan D L Burns and H R Jones ldquoSevere ataxiamyelopathy and peripheral neuropathy due to acquired copperdeficiency in a patient with history of gastrectomyrdquo Journal ofParenteral and Enteral Nutrition vol 30 no 5 pp 446ndash4502006
[46] A L Al-Khlaifat and O A Al-Khashman ldquoAtmospheric heavymetal pollution in Aqaba city Jordan using Phoenix dactyliferaL leavesrdquo Atmospheric Environment vol 41 no 39 pp 8891ndash8897 2007
[47] M A Nwachukwu H Feng and J Alinnor ldquoAssessment ofheavy metal pollution in soil and their implications within andaround mechanic villagesrdquo International Journal of Environ-mental Science and Technology vol 7 no 2 pp 347ndash358 2010
[48] N M Karaaslan and M Yaman ldquoDetermination of Nickel andChromium in Pinus nigra L Cedrus Libani and CupressusArizonica leaves to monitor the effects of pollution in Elazig(Turkey)rdquo Instrumentation Science amp Technology vol 41 no 3pp 335ndash348 2013
[49] C-Y Kuo R-H Wong J-Y Lin J-C Lai and H LeeldquoAccumulation of chromium and nickel metals in lung tumorsfrom lung cancer patients in Taiwanrdquo Journal of Toxicology and
Environmental HealthmdashPart A Current Issues vol 69 no 14pp 1337ndash1344 2006
[50] I Koturbash F A Beland and I P Pogribny ldquoRole of epigeneticevents in chemical carcinogenesis-a justification for incorporat-ing epigenetic evaluations in cancer risk assessmentrdquoToxicologyMechanisms and Methods vol 21 no 4 pp 289ndash297 2011
[51] M Gałazyn-Sidorczuk M M Brzoska M Jurczuk and JMoniuszko-Jakoniuk ldquoOxidative damage to proteins and DNAin rats exposed to cadmiumandor ethanolrdquoChemico-BiologicalInteractions vol 180 no 1 pp 31ndash38 2009
[52] P R Shakya P Shrestha C S Tamrakar and P K BhattaraildquoStudies and determination of heavy metals in waste tyresand their impacts on the environmentrdquo Pakistan Journal ofAnalytical and Environmental Chemistry vol 7 no 2 pp 70ndash76 2006
[53] H Spikes ldquoLow- and zero-sulphated ash phosphorus andsulphur anti-wear additives for engine oilsrdquo Lubrication Sciencevol 20 no 2 pp 103ndash136 2008
[35] J G SpeightThe Chemistry and Technology of Petroleum CRCPress Taylor amp Francis Boca Raton Fla USA 5th edition 2010
[36] K B Singh and S K Taneja ldquoConcentration of Zn Cu andMn in vegetables and meat food stuff commonly available inManipur a North Eastern state of Indiardquo Electronic Journal ofEnvironmental Agricultural and Food Chemistry vol 9 no 3pp 610ndash616 2010
[37] A E Kelly M K Reuer N F Goodkin and E A Boyle ldquoLeadconcentrations and isotopes in corals and water near Bermuda1780ndash2000rdquo Earth and Planetary Science Letters vol 283 no 1ndash4 pp 93ndash100 2009
[38] N Robbins Z-F Zhang J Sun M E Ketterer J ALalumandier and R A Shulze ldquoChildhood lead exposure anduptake in teeth in the Cleveland area during the era of leadedgasolinerdquo Science of the Total Environment vol 408 no 19 pp4118ndash4127 2010
[39] A Roberts ldquoChronology of leaded gasolineleaded petrol his-toryrdquo LEAD Action News vol 12 no 2 2011 httpwwwleadorgaunlhtml
[40] P-C Huang P-H Su H-Y Chen et al ldquoChildhood bloodlead levels and intellectual development after ban of leadedgasoline in Taiwan a 9-year prospective studyrdquo EnvironmentInternational vol 40 no 1 pp 88ndash96 2012
[41] C W Rankin J O Nriagu J K Aggarwal T A ArowoloK Adebayo and A R Flegal ldquoLead contamination in cocoaand cocoa products isotopic evidence of global contaminationrdquoEnvironmental Health Perspectives vol 113 no 10 pp 1344ndash1348 2005
[42] E Schelle BG Rawlins RM Lark RWebster I Staton andCW McLeod ldquoMapping aerial metal deposition in metropolitanareas from tree bark a case study in Sheffield EnglandrdquoEnvironmental Pollution vol 155 no 1 pp 164ndash173 2008
[43] M Catinon S Ayrault O Boudouma J Asta M Tissut andP Ravanel ldquoAtmospheric element deposit on tree barks theopposite effects of rain and transpirationrdquo Ecological Indicatorsvol 14 no 1 pp 170ndash177 2012
[44] K O Soetan C O Olaiya and O E Oyewole ldquoThe importanceof mineral elements for humans domestic animals and plantsa reviewrdquo African Journal of Food Science vol 4 no 5 pp 200ndash222 2010
[45] J C Tan D L Burns and H R Jones ldquoSevere ataxiamyelopathy and peripheral neuropathy due to acquired copperdeficiency in a patient with history of gastrectomyrdquo Journal ofParenteral and Enteral Nutrition vol 30 no 5 pp 446ndash4502006
[46] A L Al-Khlaifat and O A Al-Khashman ldquoAtmospheric heavymetal pollution in Aqaba city Jordan using Phoenix dactyliferaL leavesrdquo Atmospheric Environment vol 41 no 39 pp 8891ndash8897 2007
[47] M A Nwachukwu H Feng and J Alinnor ldquoAssessment ofheavy metal pollution in soil and their implications within andaround mechanic villagesrdquo International Journal of Environ-mental Science and Technology vol 7 no 2 pp 347ndash358 2010
[48] N M Karaaslan and M Yaman ldquoDetermination of Nickel andChromium in Pinus nigra L Cedrus Libani and CupressusArizonica leaves to monitor the effects of pollution in Elazig(Turkey)rdquo Instrumentation Science amp Technology vol 41 no 3pp 335ndash348 2013
[49] C-Y Kuo R-H Wong J-Y Lin J-C Lai and H LeeldquoAccumulation of chromium and nickel metals in lung tumorsfrom lung cancer patients in Taiwanrdquo Journal of Toxicology and
Environmental HealthmdashPart A Current Issues vol 69 no 14pp 1337ndash1344 2006
[50] I Koturbash F A Beland and I P Pogribny ldquoRole of epigeneticevents in chemical carcinogenesis-a justification for incorporat-ing epigenetic evaluations in cancer risk assessmentrdquoToxicologyMechanisms and Methods vol 21 no 4 pp 289ndash297 2011
[51] M Gałazyn-Sidorczuk M M Brzoska M Jurczuk and JMoniuszko-Jakoniuk ldquoOxidative damage to proteins and DNAin rats exposed to cadmiumandor ethanolrdquoChemico-BiologicalInteractions vol 180 no 1 pp 31ndash38 2009
[52] P R Shakya P Shrestha C S Tamrakar and P K BhattaraildquoStudies and determination of heavy metals in waste tyresand their impacts on the environmentrdquo Pakistan Journal ofAnalytical and Environmental Chemistry vol 7 no 2 pp 70ndash76 2006
[53] H Spikes ldquoLow- and zero-sulphated ash phosphorus andsulphur anti-wear additives for engine oilsrdquo Lubrication Sciencevol 20 no 2 pp 103ndash136 2008
