Assessment of groundwater quality from Bankura I and II Blocks, Bankura District, West Bengal, India

Abstract

Hydrochemical evaluation of groundwater has been conducted in Bankura I and II Blocks to analyze and determining groundwater quality in the area. Thirty-six groundwater samples were analyzed for their physical and chemical properties using standard laboratory methods. The constituents have the following ranges in the water: pH 6.4–8.6, electrical conductivity 80–1900 μS/cm, total hardness 30–730 mg/l, TDS 48–1001 mg/l, Ca2+ 4.2–222.6 mg/l, Na+ 2.33–103.33 mg/l, Mg2+ 1.56–115.36 mg/l, K+ 0.67–14 mg/l and Fe BDL–2.53 mg/l, {text{HCO}}_{3}^{ - } 48.8–1000.4 mg/l, Cl− 5.6–459.86 mg/l and {text{SO}}_{4}^{ = } BDL–99.03 mg/l. Results also show that bicarbonate ions ( {text{HCO}}_{3}^{ - } ) dominate the other anions (Cl− and {text{SO}}_{4}^{2 - } ). Sodium adsorption ratio (SAR), soluble sodium percentage (SSP), residual sodium carbonate (RSC), magnesium adsorption ratio (MAR), total hardness (TH), and permeability index (PI) were calculated as derived parameters, to investigate the ionic toxicity. Concerned chemical parameters when plotted in the U.S. Salinity diagram indicate that waters are of C1–S1, C2–S1 and C3–S1 types, i.e., low salinity and low sodium which is good for irrigation. The values of Sodium Adsorption Ratio indicate that the groundwater of the area falls under the category of low sodium hazard. So, there is neither salinity nor toxicity problem of irrigation water, and hence the ground water can safely be used for long-term irrigation. The chemical parameters when plotted in Piper’s trilinear diagram are found to concentrate in the central and west central part of the diamond-shaped field. Based on the analytical results, groundwater in the area is found to be generally fresh and hard to very hard. The abundance of the major ions is as follows: HCO3 > Cl > SO4 and Ca > Na > Mg > K > Fe. Results also show that bicarbonate ions ( {text{HCO}}_{3}^{ - } ) dominate the other anions (Cl− and {text{SO}}_{4}^{2 - } ). According to Gibbs diagrams samples fall in the rock dominance field and the chemical quality of groundwater is related to the lithology of the area. The alkaline earth elements (Ca and Mg) occur in greater abundance than alkaline elements (Na and K). A comparative study of our analytical results with the WHO standards of drinking water indicate that the present waters are also good for drinking purposes.