Assessment of Groundwater Quality for Drinking Purpose in Rural Areas Surrounding a Defunct Copper Mine

The suitability of groundwater quality of 22 wells located in the rural areas surrounding Ingaldhal defunct copper mine in Chithradurga district of Karnataka state was assessed for drinking purpose based on the various water quality parameters. Standard methods for physicochemical analysis of groundwater samples were employed. The results of analysis carried out showed the following concentration ranges: pH (7.61-8.34), EC (950-3120 mu S/cm), TH (410-1400mg/l), TDS (594-1913mg/l), F- (0.15-1.43mg/l), NO3- (14-162mg/l), HCO3- (417-574mg/l), SO42- (68-286mg/l) and Ca2+ (59-150mg/l), Mg2+ (49-250mg/l), Na+ (38-290mg/l), K+ (6-58mg/l). The ionic dominance for the major cations and the anions respectively were in the order of Mg2+ > Na+ > Ca2+ > K+ and HCO3- > Cl- > SO42- > NO3- > Fe- > F- > CO3-. Most of the samples analyzed were above the Guidelines set by both national (BIS) and international (WHO, 2011) bodies for drinking water. Geographical Information System (GIS) capabilities are used to classify zones with acceptable groundwater quality for drinking purpose. The Gibbs diagrams show that the groundwater samples fall both in the rock and evaporation dominance fields as well as about 18% samples fall outside the defined fields indicating integrated mechanisms for hydrochemistry such as high weathering and low rates of evaporation in addition to input from the anthropogenic activities. According to plots on the piper diagram the groundwater of the Ingaldhal and surrounding regions consists of 4 hydrochemical types, viz., Ca-Mg-HCO3 type (n=9), Ca-Mg-SO4 (n=6), mixed Ca-Na-HCO3 (n=6) and Na-Cl type (n=1). Assessment of groundwater samples from various parameters indicates that groundwater in most part of the study area is chemically unsuitable for drinking purpose. (C) 2015 The Authors. Published by Elsevier B.V.