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ORIGINAL ARTICLE
Hydrogeochemistry and quality assessment of groundwateraround chromite-mineralized areas in India
Manohar Kata • Rama Mohan • Keshav Krishna
Received: 30 January 2014 / Accepted: 20 June 2014
� Springer-Verlag Berlin Heidelberg 2014
Abstract The present study aims to assess and under-
stand the chemical characteristics of groundwater and
geochemical processes occurring within the aquifer sys-
tems around chromite-mineralized areas in India. The
water samples are collected from 33 groundwater sources
are analyzed for physicochemical properties as well as
major ion concentrations such as Ca2?, Mg2?, Na?, K?,
CO2�3 , HCO3
-, Cl-, NO3-, F- and SO2�
4 in pre and post-
monsoon. Alkali metal ions (Na?, K?) and alkaline earth
metal ions (Ca2?, Mg2?) data of groundwater showed high
concentration of Ca during pre-monsoon where as high
concentration of Na in post-monsoon than other cations.
The major hydro chemical facies identified as CaHCO3
type of water is predominant during pre-monsoon whereas
the CaHCO3 and mixed CaNaHCO3 type of water in post-
monsoon. The classification based on the total hardness
reveals that a majority of groundwater samples fall in the
hard to very hard category during the pre-monsoon season
that is unfit for drinking. Anions such as bicarbonate 85 %
and nitrate 18 % of the sample locations in pre- monsoon
are exceed the WHO permissible limits, while during post-
monsoon concentrations of bicarbonate decreased (70 %),
nitrate increased (27 %). The suitability of water for irri-
gation by analyzing salinity hazard indicated by sodium
adsorption ratio (SAR) and residual sodium carbonate
(RSC). US Salinity diagram showed the majority of sam-
ples ([50 %) fall in the field of C3-S1, indicating water of
high salinity and low sodium, which can be used for irri-
gation in almost all types of soils with attention.
Keywords Hydro geochemistry � Chromite mining area �Salinity � Piper diagram � Wilcox and Gibbs diagram
Introduction
Rapid decrease in surface water resources due to over-
exploitation and resulted contamination which shifted tre-
mendous pressure on the groundwater resources (Raviku-
mar et al. 2010; Alexakis and Tsakiris 2010;
Srinivasamoorthy et al. 2011) The water quality of the
groundwater is determined predominantly by the geo-
chemical processes, chemical and mineral composition of
the aquifer rocks, residence time and other factors related
to groundwater flow and addition of effluents through
human interference (Divya et al. 2011; Dimitris Alexakis
2011; Klimas 1995; Appelo and Postma 1996; Ibe and
Njemanze 1999; Jeong 2001). A wide range of contami-
nation sources are among the factors contributing to the
complexity of the groundwater quality assessment (Masoud
Eid Al-Ahmadi 2013; Chidambaram et al. 2013).
The quality of surface water and underlying soil/rock
characteristics play a major role in determining the com-
position and quality of the groundwater in a region. In
order to assess the fate and impact of the chemical dis-
charge onto the soil, it is important to understand the Hy-
drogeochemistry of the chemical–soil–groundwater
interactions (Miller 1985; Zuane 1990; Reddy et al. 2010;
Jeevanandan et al. 2012). Further, it is possible to under-
stand the change in quality due to rock water interaction or
any type of anthropogenic influence. Groundwater often
consists of seven major chemical elements- Ca, Mg, Cl,
M. Kata (&) � R. Mohan � K. Krishna
Environmental Geochemistry Division, National Geophysical
Research Institute (Council of Scientific and Industrial
Research), Uppal Road, Hyderabad 500007,
Andhra Pradesh, India
e-mail: chemistry_manohar@yahoo.co.in
123
Environ Earth Sci
DOI 10.1007/s12665-014-3479-z
HCO3, Na, K, and SO4. The chemical parameters of
groundwater play a significant role in classifying and
assessing water quality. Considering the individual and
paired ionic concentration, certain indices are proposed to
find out the hazards by adopting various graphical methods
and interpreting different indices are attempted by many
workers in the recent past (Elango et al. 2003; Kumar et al.
2006; Singh et al. 2006; Rao 2006; Raju 2007; Rashid and
Izrar 2007; Apadaca et al. 2007; Pophare and Dewalkar
2007).
The study area is underlain by crystalline rocks of
Archaean age, consisting of granites gneisses, schist and
chromite bearing ultramafic rocks which are cut across by
quartz, pegmatite veins, and intruded by many dykes. The
crystalline rocks have undergone variable degree of
weathering and fracturing. The thickness of weathered
zone varies with joints are observed in these rocks. Ground
water in the study area occurs under water table conditions
in the weathered and fractured granite and gneissic,
schistose geological environment. Groundwater in this
region is used for domestic, agricultural and industrial
purposes. Therefore, the study of the composition of
groundwater and influence of contaminated in the region
has been considered as of priority importance, in order to
prevent and avoid health risks to the human settlements
located study area. The main objectives of this study are to
evaluate the groundwater quality in the hard rock terrain
region with particular reference to assess its suitability for
various uses and enumerate the influence of nature and
content of the surface water and soil on groundwater
quality.
Materials and methods
Study area
Nuggihalli schist belt is located in Karnataka state. Study
area with co-ordination between 1285500000–1380500000North latitude and 7682500000–7683500000 East
longitudes and covers an area of 400 km2 (Fig. 1). The
major sources of employment are agriculture, horticulture
and animal husbandry, which engage almost 80 % of the
workforce. The major industries are that of mining, stone
crushing, chemicals, oil, cotton, soap, tools, food process-
ing, rice mills, etc. Occurrence, movement and storage of
groundwater are influenced by lithology, thickness and
structure of rock formations. Weathered and fractured
granites, granitic gneiss and chromite bearing ultramafic
rocks form the main aquifer in Nuggihalli. Ground water in
the study area occurs under water table conditions in the
weathered and fractured granite, gneisses. There is no river
in the study area but area very well controlled by drainage
and surface water bodies. The major ion chemistry of
groundwater of Nuggihalli has not been studied earlier.
Water sampling and chemical analysis
Water samples are collected from subsurface in the study
area during May 2011 (pre monsoon) and November 2011
(post monsoon). One liter of water samples is collected using
polythene bottles from various wells. Totally 33 ground-
water samples are collected from study area. The pH, EC and
TDS of water samples are measured in situ using portable
meters (Eutech Instruments- model pHTester10, ECTest-
er11? and TDSTester11?, respectively). With respect to
cation, calcium, magnesium, sodium, potassium and with
respect to anions, chloride, nitrate, sulphate are analyzed by
ion chromatography (Metrohm). Carbonate and bicarbonate
are done by classical volumetric method. The quality of
groundwater is affected by the pump age and natural dis-
charge. The water is also heterogeneous in nature due to
recharge from precipitation and contact with different types
of rocks. Hence in the case of groundwater, the fixations of
suitable sampling sites are not so easy as compared to surface
water because the elements influencing water quality are not
easily known. Some general suggestions can be made for the
selection of sampling sites. In case, where the investigation
does not take into account the changes in groundwater
quality, the key constituents determined in a large number of
samples collected over the entire area is utilized to determine
the water quality of the study area. From this, sites for
selection of samples for comprehensive analysis can be
fixed. If the key constituents are not known at the beginning,
the water quality pattern is arrived at, by first making a
comprehensive analysis and thus partial analysis at other site.
Result and discussion
Groundwater chemistry
The analytical results of different chemical constituents for
pre- and post-monsoon season samples of minimum,
maximum, and average concentrations of physicochemical
parameters of water quality such as pH, EC, TDS, major
anions and major cations are presented in Table 1. During
the investigation, pH value as low as 7 and as high as 8.2
with average value is 7.3 is recorded in pre-monsoon,
whereas pH value as low as 6.8 and as high as 8.1 with
average value is 7.2 is recorded in post monsoon. In gen-
eral, the distribution of pH did not show any specific trend
within study area. Even though pH has no direct effect on
human health, its higher range accelerates the scale for-
mations in water heating apparatus (Ravikumar et al.
2010).
Environ Earth Sci
123
Hydro-chemical facies
Chemical data of the groundwater sample are also pre-
sented by plotting them on a piper tri linear diagram. It
provides a convenient method to classify and compare
water types. Based on the ionic composition of two sea-
sonal (i.e. pre and post monsoon) water samples concen-
tration of major cation and anions plotted in two tri linear
diagrams and one diamond shaped filed of piper diagram.
On the basis of chemical analysis water is divided into six
facies, the graph of groundwater samples. Figure 2
explains the variations or domination of cation and anion
concentrations during the pre-monsoon and post-monsoon.
Groundwater hydrochemistry is primarily controlled by
water–rock interaction and anthropogenic pollution
(Byoung-Young et al. 2005). The CaHCO3 type of water
predominated during pre-monsoon. The CaHCO3 and
CaNaHCO3 type of water predominated during post-mon-
soon. The percentage of samples falling under the CaHCO3
type is 87 % during the pre-monsoon season and CaHCO3
Fig. 1 Location map of the study area and sampling location
Table 1 Summary statistics of
the analytical dataQuality parameter (units) Pre Monsoon Post monsoon
Min Max Average Min Max Average
EC (lS/cm) 370 2,440 1,103.18 313 8,440 1,474.87
pH (mg/L) 7 8.2 7.38 6.8 8.1 7.2
TDS (mg/L) 295 2,040 900.52 200 1,940 883.33
Ca (mg/L) 8.66 224.95 79.36 0.03 99.66 26.08
Mg (mg/L) 6.16 152.76 39.27 7.14 138.12 37.09
Na (mg/L) BDL 92.98 35.49 18.43 268.9 95.42
K (mg/L) BDL 50.48 5.95 1.25 301.96 25.12
HCO3 (mg/L) 85 722 435.55 155.4 670.2 350.2
Cl (mg/L) 22.7 524.7 138.62 12.89 511.75 152.46
NO (mg/L) 0.3 49.9 26.18 2.12 172.69 37.71
SO4 (mg/L) 1.9 1,419 47.27 3.72 219.06 55.93
F (mg/L) 0.8 2 1.18 0.05 1.11 0.6
Environ Earth Sci
123
and CaNaHCO3 type of water predominated during the
post-monsoon season is 33 and 39 % of the water samples.
The CaCl type of water is 6 %, Mixed CaMgCl and
CaNaHCO3 is 3 % each predominated during the Pre-
monsoon. The NaCl type of water is 15 %, Mixed CaMgCl
is 12 % predominated during the Post-monsoon. The
hydrochemical facies of water are summarized in Table 2.
This type of water causes salinity problems, and the
factor of dilution reduces the salinity to some extent.
Increased chloride concentration in the post monsoon
Fig. 2 Piper diagram depicting
hydrochemical facies of
groundwater: a pre monsoon
and b post monsoon
Environ Earth Sci
123
season may be due to the process of the removal of other
ions from the system, either by precipitation or by
adsorption (Chidambaram et al. 2006). In the study area,
the major groundwater type is a mixed category, during the
pre-monsoon is 42 % and the post monsoon is 33 %.
During the pre-monsoon, Ca is the major cation
(Ca [ Mg [ Na) and Pre-monsoon Na is the major cation.
Increased Na concentration and decreased Ca and Mg
concentrations, when compared with the pre -monsoon
values with post-monsoon can be explained by the proba-
bility of the loss of Ca and Mg and gain of Na? by the
cation exchange process (Packialakshmi and Ambujam
2012) HCO3 and Cl are the major anions during the pre-
monsoon and post-monsoon (HCO3 [ Cl [ SO4), HCO3
and Na concentrations come mainly from the weathering of
alkali earth from rocks related to the recharge areas (Pra-
sanna et al. 2011). Calcium and magnesium ions that
combine with bicarbonates and the small amounts of car-
bonates in the groundwater cause the water to be tempo-
rarily hard (Anku et al. 2009). The available carbonates in
the rocks might have been dissolved and added to the
groundwater system during irrigation, rainfall infiltration
and groundwater movement increases the bicarbonate.
There are major significant changes in the hydrochemical
facies during the study period (pre- and post-monsoon).
This indicates the dominance of mineral constituents and
rock weathering, in addition to recharge activities by pre-
cipitation, and induced anthropogenic activities, such as
application of fertilizers, uncontrolled groundwater devel-
opment that influences the groundwater chemistry.
Drinking water quality
The physical and chemical parameters of the analytical
result of pre and post-monsoon ground water are
compared with the standard guideline values recom-
mended by the world health organization (WHO 1993)
for drinking and public health standards in Table 3. The
table shows the most desirable limits and maximum
allowable limits of various parameters. The cations
concentration in pre-monsoon indicates that 6 % of the K
and 3 % Ca and Mg concentration exceed the WHO
limit. For anions bicarbonate 84 %, nitrate 18 % and
fluoride 12 % of the sample location exceed the stan-
dards although cations concentration in post-monsoon
indicates that 15, 6 % of the K and Na, respectively,
concentration exceed the WHO limit. For anions bicar-
bonate 69 % and nitrate 27 % of the sample location
exceed the standards.
Total dissolved solid
To ascertain the suitability of groundwater of any pur-
poses, it is essential to classify the groundwater
depending upon their hydrochemical properties based on
their TDS values of pre-monsoon samples, which are
presented in Table 4 and TDS values of post monsoon
samples presented in Table 5. Based on the groundwater
of the area is fresh water type for 63 and 66 % as well
as the 36 and 33 % of the samples represent brackish
water in pre and post-monsoon respectively. The TDS of
groundwater quality map is prepared for pre-monsoon
and post -monsoon. The study shows that only 18 % in
pre-monsoon and 12 % of the sample in post- monsoon
is below 500 mg/L of TDS which can be used for
drinking without any risk. TDS is mostly due to dis-
solved ionic matter and bear a relationship with the
electrical conductivity of water (Kapil and Bhattacharyya
2008; Sajil Kumar et al. 2013).
Table 2 The hydrochemical
facies for groundwater samplesFacies Pre monsoon Post monsoon
Sample No. of
samples
Percentage
of samples
Samples No. of
samples
Percentage
of samples
CaHCO3 1–9, 14–23, 25,
27, 29, 29–32,
34–3,620
87 87 1, 3, 5, 18, 24, 25,
26, 27, 36, 37
11 33.33
NaCl Nil Nil Nil 6, 8, 17, 32, 33 5 15.15
Mixed
CaNaHCO3
26 1 3.030 2, 4, 9, 14, 15, 16,
19, 21, 22, 30,
31,34, 35
13 39.39
Mixed
CaMgCl
33 1 3.030 7, 23, 28, 29 4 12.12
CaCl 24, 28 2 6.060 Nil Nil Nil
NaHCO3 Nil Nil Nil Nil Nil Nil
Total 33 99.99 33 99.99
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123
Electrical conductivity
Classifications of Electrical conductivity of groundwater in
study area for both the seasons are given in Table 6. It is
found that 81 % in pre -monsoon and 75 % in post-
monsoon of the samples are within the permissible limits
and 18 % each in pre and post- monsoon of the samples fall
in not permissible limit but they are marginally poor in
quality and only 6 % of the sample location in post mon-
soon can be classified as hazardous according to the WHO
standards. The hazardous quality is due to the dissolving of
ions from rocks by weathering and somewhat from
chemical used for the textile processing in the study area.
Total hardness (TH)
The maximum allowable limit of TH for drinking purpose
is 500 mg/L and the most desirable limit is 100 mg/L as
per the WHO international standard. Hardness exhibits a
minimum content of 109.74 and 99.7 mg/L to a maximum
of 837.11 and 632.9 mg/L with the averages of 369.15 and
226.5 mg/L in pre and post- monsoon respectively.
Groundwater exceeding the limit of 300 mg/L is consid-
ered to be very hard (Sawyer and McCarty 1967). The
spatial distribution of hardness in post monsoon samples
shows higher concentrations towards the eastern part. The
classification of the groundwater for the pre-post monsoon
in Table 7 based on total hardness shows that 12 and 24 %
of the ground water samples fall in the moderately high
category, 33 and 57 % of samples fall in the hard category
while 54 and 18 % of the samples fall in very hard category
in pre and post- monsoon season. TH of the groundwater is
calculated using the formula given below (Kuldip-singh
and Singh 2011).
TH ðas CaCO3Þmg=L ¼ ðCa þ MgÞmg=L � 50 ð1Þ
Table 3 Groundwater samples
of the study area exceeding the
permissible limits prescribed by
WHO
a Ec in (uS/cm), all parameter
in mg/L, except pH
Water
quality
WHO (1993) Pre monsoon Post monsoon
Most
desirable
limits
Max.
limits
No. of samples
exceeding
allowable limits
% of samples
exceeding
allowable limits
No. of samples
exceeding
allowable limits
% of samples
exceeding
allowable limits
pH 6.5–8.5
9.2
Nil Nil Nil Nil Nil
EC – 1,500 6 18.18 8 24.24
TDS 500 1,500 3 9.090 4 12.12
Ca 75 200 1 3.030 Nil Nil
Mg 50 150 1 3.030 Nil Nil
K – 12 2 6.060 5 15.15
Na – 200 Nil Nil 2 6.06
Cl 200 600 Nil Nil Nil Nil
HCO3 – 300 28 84.84 23 69.69
NO3 45 – 6 18.18 9 27.27
SO4 200 400 Nil Nil Nil Nil
F – 1.5 4 12.12 Nil Nil
TH 100 500 8 24.24 Nil Nil
Table 4 Groundwater classification of all groundwater
TDS (mg/L) Classification Pre monsoon Post monsoon
Sample no. No. of
samples
% of
samples
Sample no. No. of
samples
% of
samples
\500 Desirables for
drinking
1, 3, 24, 30, 36, 37 6 18.18 1, 3, 24, 36 4 12.12
500–1,000 Permissible for
drinking
4, 5, 9, 14, 16, 18, 19, 21, 22,
23, 25, 27, 31, 33, 34
15 45.45 4, 5, 9, 14–16, 18, 19, 21–23,
25, 27, 29–31, 34, 37
18 54.54
1,000–3,000 Useful for
irrigation
2, 6, 7, 8, 15, 17, 20, 26, 28,
29, 32, 35
12 36.36 2, 6–8, 17, 20, 26 28, 32, 33,
35
11 33.33
[3,000 Unfit for drinking
and irrigation
Nil Nil Nil Nil Nil Nil
Total 33 100 33 100
Environ Earth Sci
123
The climate and geology of the area plays a very
important role in contributing to the total hardness. The
leaching of Ca and Mg from these rocks adds to the
hardness. Further, the agricultural activities directly or
indirectly affect the concentrations of a large number of
inorganic chemicals in groundwater such as NO3-, Cl-,
SO2�4 , HCO3
-, PO3�4 , Na?, K?, Mg2?, Ca2?, etc.
Chloride
Chloride occurs naturally in all types of waters. The
chloride content varies between 22.70 and 524.70 mg/L
(ave. = 138.62 mg/L), of the total samples of pre-mon-
soon whereas 12.89 and 511.75 mg/L (ave. =
152.46 mg/L), of the total samples of post-monsoon,
both seasonal samples are within a permissible limit.
Natural waters, the probable sources of chloride com-
prise the leaching of chloride-containing minerals (like
apatite) and rocks with which the water comes in con-
tact, inland salinity and the discharge of agricultural,
industrial and domestic waste waters (Ravikumar et al.
2010). Agricultural application of K as a plant nutrient
commonly results in chloride contamination of recharg-
ing shallow groundwater.
Nitrate
Nitrate in the study area is found to be high in concentra-
tion in both seasons i.e. pre and post-monsoons. 6 in pre
and 9 in post-monsoon of the ground water samples exceed
the permissible limit of 45 mg/L as per WHO standard. It
varies between 0.30 and 49.90 mg/L with averages
26.18 mg/L in pre monsoon. 115.4–670 mg/L with average
is 350.2 mg/L. The high concentration of nitrate in drink-
ing water is toxic and cause to human beings (Causape
et al. 2004; Jalali 2005). Nitrate content in groundwater is
because of excess use of fertilizer in agricultural land
(Appelo and Postma 2005).
Bicarbonate
Among the anions, bicarbonate is the most dominant one
and shows wide variation in concentrations of both seasons
i.e. pre and post-monsoons. It varies between 85 and
722 mg/L with average 435.55 mg/l in pre monsoon and
115.4 and 670 mg/L with averages 350.2 mg/L in post-
monsoon. The primary source of bicarbonate ions in
groundwater is the dissolution of carbonate minerals in the
study area. The decay of organic matter present in the soil
releases CO2. Water charged with CO2 dissolves carbonate
Table 5 Groundwater classification of all groundwater
TDS (mg/l) Classification Pre monsoon Pre monsoon
Sample no. No. of
samples
% of
samples
Sample no. No. of
samples
% of
samples
\1,000 Fresh water
type
1, 3, 4, 5, 9, 14, 16, 18, 21, 22, 23,
24, 25, 27, 30, 31, 32, 33, 34, 36,
37
21 63.63 1, 3, 24, 36, 4, 5, 9, 14–16, 18,
19, 21–23 25, 27, 29–31, 34,
37
22 66.67
1,000–10,000 Brackish
water type
2, 6, 7, 8, 13, 15, 17, 20, 28, 29,
32, 35
12 36.36 2, 6–8, 17, 20, 26, 28, 32, 33,
35
11 33.33
10,000–100,000 Saline water
type
Nil Nil Nil Nil Nil Nil
[100,000 Brine water
type
Nil Nil Nil Nil Nil Nil
Total 33 100 33 100
Table 6 Groundwater classification based on electrical conductivity
EC us/cm Classification Pre monsoon Post monsoon
Sample no. No. of
samples
% of
samples
Sample no. No. of
samples
% of
samples
\1,500 Permissible 1–5, 7, 9, 14–16, 18, 19, 21–31,
33, 34, 36, 37
27 81.81 1–6, 9, 14–16, 18–27,
29–31, 36, 37
22 75.75
1,500–3,000 Not
permissible
6, 8, 17, 20, 32, 35 6 18.18 07, 17, 28, 32, 34, 35 6 18.18
[3,000 Hazardous Nil Nil Nil 08, 33 2 6.06
Total 33 100 33 100
Environ Earth Sci
123
minerals, as it passes through soils and rocks to give
bicarbonates (Ramesh et al. 1995). The present study too
reveals such positive relationship.
Sulphate
Sulphate in the study area is found to be in the permissible
concentration limit of 400 mg/L as per WHO standard. It
varies between 1.90 and 141.90 mg/L with average
47.27 mg/L in pre monsoon and 3.72 and 219.06 mg/L
with averages 55.93 mg/L in post-monsoon. The high
concentration of sulphate in drinking water is toxic and
causes laxative effective.
Fluoride
Fluoride in the study area is found to be significant in
concentration of pre monsoon samples; where as in post-
monsoon samples are within permissible. The ground water
samples are within a permissible limit of 1.5 mg/L as per
WHO standard. It varies between 0.80 and 2.00 mg/L with
average 1.18 mg/L in pre- monsoon and 0.05 and 1.11 mg/
L with an average 0.60 mg/L in post-monsoon. The high
concentration of fluoride in drinking water is cause to
fluorosis (Srinivasamoorthy et al. 2012).
Calcium
Among the cations, Ca content fall within the permissible
limit (75 mg/L) among the total samples in both seasons
except one sample exceed from pre monsoon. The content
of Ca spreads between 8.66 and 224.95 mg/L with average
79.36 mg/L for pre-monsoon and 0.03 and 99.66 mg/L
averaging 26.08 mg/L for post-monsoon respectively. High
concentration of Ca is not desirable in washing, laundering
and bathing. It is known as the source of Ca in ground-
water, its resources are mainly the crystalline carbonatic
rocks like; limestone, dolomite etc.
Magnesium
The content of Mg is comparatively high than that of Ca.
Although the Mg exhibits within the permissible limit. The
geochemistry of the rock types may have an influence in
the concentration of Mg in groundwater or sometimes
Sewage and industrial wastes are the important sources of
calcium and magnesium (Subrahmanyam and Yadaiah
2001).
Sodium
Na is one of the important naturally occurring cations and its
concentration in fresh waters is generally lower than that of Ca
and Mg. But in the present investigation, the average concen-
tration of Na is comparatively higher than that of Ca and Mg.
For aesthetic reason, the guideline value given by WHO is
200 mg/L. Sodium in pre monsoon are with in permissible limit
however comparatively higher values are recorded from the
north-eastern part of the study area and the values range
between 18.43 and 268.90 mg/L with the average of 95.42 mg/
L in post-monsoon. Sample No 8 and 32 registered value above
the permissible limit. It may be because of geological envi-
ronment covered mainly by granite and gneiss, the geological
influence on the concentration of the cations is well understood
(Ravikumar et al. 2010).
Potassium
The concentration of K shows very high values in two and
five samples in pre and post-monsoon with range are BDL
to 50.48 mg/L and average 5.95 and 1.25–301.96 mg/L
with the average of 25.12 mg/L respectively. Though, most
of the sources of rocks contain K, are released during
weathering, a part of the K go into clay structure and
thereby its concentration gets reduced in water (Ravikumar
et al. 2010). However, sample Nos. 6, 17 in pre and 06, 08,
17, 33 and 35 post-monsoons throughout the study area,
Table 7 Groundwater classification based on hardness (Sawyer and McCarty 1967)
TH as
COCO3
(mg/L)
Classification Pre monsoon Post monsoon
Sample no. No. of
samples
% of
samples
Sample no. No. of
samples
% of
samples
\75 Soft Nil Nil Nil Nil Nil Nil
75–150 Moderately
high
3, 30, 36, 37 4 12.12 1, 2, 4, 21, 24, 31, 33, 36 8 24.24
150–300 Hard 1, 4, 18, 21, 23, 24, 25, 31, 33, 35 11 33.33 3, 6, 8, 9, 14, 15, 16, 17, 18, 19, 22, 23,
25, 27, 29, 30, 30, 34, 34, 35, 37
19 57.57
[300 Very hard 2, 5, 6, 7, 8, 9, 14, 15, 165, 17, 19,
20, 22, 26, 27, 28, 29, 32, 34
18 54.54 7, 20, 21, 28, 32 6 18.18
Total 33 100 33 100
Environ Earth Sci
123
registered values above the drinking water standard of
12 mg/L. K contamination in groundwater can result from
the application of inorganic fertilizer at greater than agro-
nomic rates. Loss of nutrients, including K, from agricul-
tural land have been identified as one of the main causative
factors in reducing water quality in many parts of arid and
semi-arid regions.
Irrigation water quality
Gibbs diagram
The Gibbs (1970) plots illustrate that the water–rock
interaction. The Gibbs ratio for the ions Na ? K/
Na ? K ? Ca of groundwater samples are plotted against
the respective values of TDS for both seasons. The plot
(Fig. 3) indicates that more than 90 % of the groundwater
samples in all the seasons fall in the rock dominant cate-
gory and the rest fall in the evaporation field. Rock dom-
inance of most of the samples are caused by the interaction
between the aquifer rocks and groundwater which is further
influenced by the evaporation process and inappropriate
sources as some sample points scatter between rock dom-
inance to evaporation dominance fields which is more
pronounced in pre-monsoon while in post-monsoon plot
most of the points cluster close to the rock dominance field
(Reddy et al. 2012).
Wilcox diagram
Excessive amount of dissolved ion such as sodium, bicar-
bonate, and carbonate in irrigation water affect plants and
agricultural soil physically and chemically, thus reducing
the productivity. The physical effects of these ions are to
lower the osmotic pressure in the plant structural cells, thus
preventing water from reaching the branches and leaves.
The chemical effects disrupt plant metabolism. It is the
quantity of certain ions, such as sodium and boron, rather
than the total salt concentration that affects plant devel-
opment. Excess salinity reduces the osmotic activity of
plants and thus interferes with the absorption of water and
nutrients from the soil. Sodium adsorption ratio (SAR) is
an important parameter for determining the suitability of
groundwater for irrigation because it is a measure of alkali/
sodium hazard to crops.
SAR = Na/ Ca + Mgð Þ1=2=2 where the concentrations
are represented in meq/L.
The analytical data plotted on the US salinity diagram
proposed by US Salinity Laboratory Staff Fig. 4 and
Table 8 illustrates that;
1. 30 and 27 % of the groundwater’s of pre and post-
monsoon fall in the field of C2-S1, indicating water of
medium salinity and low sodium, which can be used
for irrigation in almost all types of soil with little
danger of exchangeable sodium.
2. 60 and 54 % of the groundwater’s of pre and post-
monsoon fall in the field of C3-S1, indicating water of
high salinity and low sodium, which can be used for
irrigation in almost all types of soil with little danger of
exchangeable sodium.
3. 9 and 3 % of samples of pre and post-monsoon falling
under C4-S1, indicating water of high salinity and low
sodium, which can be used for irrigation in all types of
soils.
4. 9 % of samples of post-monsoon falling under C3-S2,
indicating water of high salinity and medium sodium,
which can be used for irrigation in all types of soils.
5. 6 % sample of post-monsoon are falling under above
3,000 so it’s very high in salinity with the high sodium.
Similarly, a perusal of the diagram of Wilcox relating
sodium percentage and electrical conductivity indicates
Pre Monsoon
1
10
100
1000
10000
0 0.2 0.4 0.6 0.8 1
Na+K:Na+K+Ca (mg/l)
TD
S (m
g/l)
Evaporation
Rock Dominance
Precipitation Dominance
Post Monsoon
1
10
100
1000
10000
0 0.2 0.4 0.6 0.8 1 1.2
Na+K:Na+K+Ca (mg/l)
TD
S (m
g/l)
Evaporation
Rock
Precipitation
(b)(a)Fig. 3 Gibbs plot for a Pre-
monsoon and b Post-monsoon
Environ Earth Sci
123
that all groundwater samples fall in the fields of excellent
too good for irrigation. Sodium concentration plays an
important role in evaluating the groundwater quality for
irrigation because sodium causes an increase in the hard-
ness of soil as well as a reduction in its permeability.
The sodium percentage (Na %) is calculated using the
formula given below
Na % ¼ Na + Kð Þ � 100= Ca + Mg + Na + Kð Þ ð2Þ
where all ionic concentration is expressed in meq/L.
Na % indicates that the 45 % samples of pre monsoon
and 3 % groundwater sample of post-monsoon are
excellent type water, 39 % samples of pre monsoon and
27 % of samples are good in nature, 15 % samples of
pre monsoon and 45 % samples of post-monsoon are
permissible and 8 samples of post-monsoon are doubtful
for the use of irrigation purpose (Table 9). Sodium
concentration plays an important role in evaluating the
groundwater quality for irrigation because sodium causes
an increase in the hardness of soil as well as a reduction
in its permeability. Irrigation qualities of groundwater
based on sodium percentage, where the Na concentration
Fig. 4 USSL diagram for
classification of irrigation water
for a Pre and b Post-monsoon
samples
Environ Earth Sci
123
is high in irrigation water, Na tend to be adsorbed in
clay particles, displacing Mg and Ca cations. Moreover,
the permeability of the soil is reduced due to the
exchange process of Na? in water for Ca and Mg (Saleh
et al. 1999; Subramani et al. 2005; Tank and Chandel
2010).
Table 8 Salinity and alkalinity hazards of irrigation water in US salinity diagram
Classification SAR/EC Pre monsoon Post monsoon
Sample no. No. of
samples
% of
samples
Sample no. No. of
samples
% of
samples
C2-S1 EC
medium
SAR low
01, 3, 04, 18 , 24, 25, 30, 31, 36, 37 10 30.30 01, 03, 04
24, 25, 30, 31, 36, 37
9 27.27
C3-S1 EC high
SAR low
2, 5, 6, 7, 9, 14, 15, 16, 17,19, 20, 21,
22, 23, 26, 27, 28, 29, 33, 34
20 60.60 5, 6, 7, 9, 14, 15, 16, 17, 18, 19,
20, 21, 22, 23, 26, 27, 29, 34
18 54.54
C4-S1 EC very
high
SAR low
8, 32, 35 3 9.09 28 1 3.03
C3-S2 EC high
SAR
medium
Nil Nil Nil 02, 35, 32 3 9.09
[3,000 Very
high
Nil Nil Nil l8, 33 2 6.06
Total 33 100 33 100
Table 9 Irrigation quality of groundwater based on sodium percentage
% Na Classification Pre monsoon Post monsoon
Sample no. No. of
samples
% of
samples
Sample no. No. of
samples
% of
samples
\20 Excellent 2, 5, 7, 8, 15, 16, 17, 19, 20, 21,
22, 26, 28, 32, 35
15 45.45 26 1 3.030
20–40 Good 1, 6, 9, 14, 18, 23, 24, 25,27, 29,
31, 34, 36
13 39.39 5, 18, 23, 24, 25, 27, 9, 36, 37 9 27.27
40–60 Permissible 3, 4, 30, 33, 37 5 15.15 1, 3, 4, 7, 9, 14, 16, 19, 20, 22, 28,
30, 31, 32, 34
15 45.45
60–80 Doutful Nil Nil Nil 2, 6, 8, 15, 17, 21, 33, 35 8 24.24
[80 Unsuitable Nil Nil Nil Nil Nil Nil
Total 33 100 33 100
Table 10 Irrigation quality of groundwater based on residual sodium
RSC Classification Pre monsoon Post monsoon
Sample no. No. of
samples
% of
samples
Sample no. No. of
samples
% of
samples
\1.25 Good 1, 3, 5, 6, 7, 9, 14, 15, 16, 17, 18, 19, 20, 22, 23,
24, 25, 26, 27, 28, 29, 32, 24, 36, 37
25 75.75 3, 5, 7, 22, 23, 24, 26,
27, 28, 29, 32, 36, 37
13 39.39
1.25–2.5 Doubtful 2, 4, 8, 21, 30, 31 6 18.18 1, 6, 14, 21, 25, 30, 31,
34
8 24.24
[2.5 Unsuitable 33, 35 2 6.060 2, 4, 8, 9, 15, 16, 17, 18,
19, 20, 33, 35
12 36.36
Total 33 100 33 100
Environ Earth Sci
123
Residual sodium carbonate
The excess sum of carbonate and bicarbonate in ground
water over the sum of calcium and magnesium also influ-
ence the unsuitability for irrigation. This id denoted as
residual sodium carbonate (RSC) index which is calculated
as
RSC ¼ HCO3 þ CO3ð Þ� CaþMgð Þ ð3Þ
where all the concentrations are expressed in meq/L. the
classification of groundwater based on RSC values are
summarized in Table 10. As concern table 75, 18 and 6 %
of the pre monsoon groundwater samples fall in the cate-
gories of good (RSC [ 1.25), doubtful (125.2.5) and
unsuitable (RSC \ 2.5), respectively for irrigation purpose
where 39, 24 and 36 % of the post-monsoon groundwater
samples fall in the categories of good (RSC [ 1.25),
doubtful (125.2.5) and unsuitable (RSC \ 2.5), respec-
tively for irrigation purpose. The increase of RSC in irri-
gation water is significantly harmful for plant growth
(Kumar et al. 2009; Sivasankar et al. 2013), in study area
RSC value of post-monsoon season are increase it specify
to the weathering of rock and leaching of ions in
groundwater.
Conclusion
Based on the attempt made to study the quality of
groundwater, it is found that Na concentration is dominant
among cations and HCO3 among anions. It is evident from
the higher values of physico-chemical results especially
hardness, alkalinity, bicarbonates, and potassium that most
of the water samples analyzed in the present investigation
are contaminated by geogenic as well as anthropogenic like
sewage and industrial effluents. The groundwater is of
good quality for irrigation purpose, even though high
salinity/low sodium and medium salinity/low sodium type
found to exist that needs better drainage to overcome
salinity problems. Stringent monitoring and control mea-
sures in the regions of low groundwater quality are nec-
essary to ensure sustainable safe use of the resource.
Acknowledgments The authors are thankful to Director, CSIR-
National Geophysical Research Institute, Hyderabad for providing
facilities.
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