Major cations
The order of cation dominance is calcium >
magnesium>potassium > sodium in the study
area. In a study area, sodium range between 12 to 122 mg/L with an
average of 51.4 mg/L. All the sample locations fall under the
permissible level of sodium for drinking purposes (Fig.3e). Calcium and
magnesium are major cations that are highly influencing the quality of
groundwater (Kawo et al., 2018). In a study area, calcium ranges from 20
to 400 mg/L, with an average of 135.93 mg/L. In the spatial analysis,
16.97 sq.km area falls under acceptable, 599.58sq.km area falls under
permissible, and 50.40 sq.km area (Fig.3f) falls under the undesirable
limit recommended by WHO (2011) and BIS (2012). A concentration of
magnesium ion ranges from 6.07 mg/L to 194.4 mg/L, with a mean of 76.14
mg/L. About 3.22 sq.km area is acceptable, 599.46 sq.km area is
permissible, and 64.27 sq.km area (Fig.4a) is recorded as an undesirable
limit as per standards. An excess concentration of calcium and magnesium
causes severe health issues on human and water used for irrigation
purposes (Aravinthasamy et al., 2019). Potassium range between 2 to 18
mg/L with a mean of 9.66 mg/L and 26.67 % of the sample locations
(Fig.4b) are highly affected due to the presence of higher
concentration. The weathering of feldspars, microcline, orthoclase, and
biotite are the major mineral causes the excess concentration of
potassium in groundwater.