244
The total oxidation state of arsenic (As), magnesium (Mg), sodium (Na), potassium
(K), calcium (Ca), phosphorus (P), manganese (Mn), copper (Cu), nickel (Ni),
cobalt (Co), iron (Fe), zinc (Zn) and lead (Pb) was analyzed by inductively coupled
plasma-mass spectrometry (ICP-MS) (Agilent 7500 CX). The equipment was linearly calibrated from 1 to 100 μg/l, using a certified standard solution (Sigma ICP
Multielement Standard Solution). Linearity was checked after every ten samples.
Accuracy has been tested by analyzing a certified reference material, NIST SRM
1643c “trace elements in water.” Bias ranged from 2% to 10%.
8.2.2.3 Statistical Analysis
Descriptive statistics analysis was used to perform analysis of data, including mean,
median, maximum and minimums, 25th and 75th percentile, standard deviation,
variance, and Box-Cox transformed values of mean, skewness, and kurtosis for
shallow and deep groundwater. Piper diagram was used for the identification of
chemical processes in groundwater using the statistical program Grapher 16.2.354
(2020). Since the quality of groundwater can change at different depths even in the
same aquifer, differences between the quality of shallow and deep groundwater
were investigated using Welch’s t-test for unequal variances and unequal sample
sizes. The power of the analysis was performed calculating the type II error. Factor
analysis was performed to investigate the relationship between investigated ions
using statistical program Statistica, version 10 (StatSoft. Inc. 2011). Varimax normalized type of rotation and multiple R-squared method were used for the extraction of the loadings.
8.3 Results and Discussion
8.3.1 Groundwater Chemistry
The average temperature of the groundwater was 16 °C during sampling. pH values
varied from slightly acidic to alkaline (6.84–8.67) with a median value of 7.86.
Almost 12.4% of investigated samples were classified as very hard groundwater
with total hardness greater than 300 mg/l CaCO 3 , 36% were hard (total hardness
150–300), 42.5% were moderately hard (total hardness 75–150), and only 9.1%
were classified as soft water (0–75) suitable for domestic use.
Based on the borehole depth and the pollution vulnerability, groundwater in the
investigated region was classified into two categories: (1) shallow groundwater
(6–70 m) where almost 73% of investigated boreholes belong and (2) deep groundwater (72–130 m) where the rest 27% investigated boreholes belong. Literature data
showed that groundwater is generally supplied by precipitation, irrigation, infiltration, reservoir seepage, canal seepage, or lateral recharge (Luo et al. 2018). In the
B. Kovacevik et al.
The total oxidation state of arsenic (As), magnesium (Mg), sodium (Na), potassium
(K), calcium (Ca), phosphorus (P), manganese (Mn), copper (Cu), nickel (Ni),
cobalt (Co), iron (Fe), zinc (Zn) and lead (Pb) was analyzed by inductively coupled
plasma-mass spectrometry (ICP-MS) (Agilent 7500 CX). The equipment was linearly calibrated from 1 to 100 μg/l, using a certified standard solution (Sigma ICP
Multielement Standard Solution). Linearity was checked after every ten samples.
Accuracy has been tested by analyzing a certified reference material, NIST SRM
1643c “trace elements in water.” Bias ranged from 2% to 10%.
8.2.2.3 Statistical Analysis
Descriptive statistics analysis was used to perform analysis of data, including mean,
median, maximum and minimums, 25th and 75th percentile, standard deviation,
variance, and Box-Cox transformed values of mean, skewness, and kurtosis for
shallow and deep groundwater. Piper diagram was used for the identification of
chemical processes in groundwater using the statistical program Grapher 16.2.354
(2020). Since the quality of groundwater can change at different depths even in the
same aquifer, differences between the quality of shallow and deep groundwater
were investigated using Welch’s t-test for unequal variances and unequal sample
sizes. The power of the analysis was performed calculating the type II error. Factor
analysis was performed to investigate the relationship between investigated ions
using statistical program Statistica, version 10 (StatSoft. Inc. 2011). Varimax normalized type of rotation and multiple R-squared method were used for the extraction of the loadings.
8.3 Results and Discussion
8.3.1 Groundwater Chemistry
The average temperature of the groundwater was 16 °C during sampling. pH values
varied from slightly acidic to alkaline (6.84–8.67) with a median value of 7.86.
Almost 12.4% of investigated samples were classified as very hard groundwater
with total hardness greater than 300 mg/l CaCO 3 , 36% were hard (total hardness
150–300), 42.5% were moderately hard (total hardness 75–150), and only 9.1%
were classified as soft water (0–75) suitable for domestic use.
Based on the borehole depth and the pollution vulnerability, groundwater in the
investigated region was classified into two categories: (1) shallow groundwater
(6–70 m) where almost 73% of investigated boreholes belong and (2) deep groundwater (72–130 m) where the rest 27% investigated boreholes belong. Literature data
showed that groundwater is generally supplied by precipitation, irrigation, infiltration, reservoir seepage, canal seepage, or lateral recharge (Luo et al. 2018). In the
B. Kovacevik et al.