Seasonal changes in groundwater composition in an industrial center of south India and quality evaluation for consumption and health risk using geospatial methods

Effluents from leather tanneries and other small-scale industries have caused groundwater contamination in one of the biggest industrial centers (i.e. Vellore) of south India. This study evaluated quality of 70 different open and tube wells for consumption and health risks by collecting groundwater samples in four different seasons between 2017-2018. We compared physicochemical parameters of the groundwater samples with international drinking water standards (World Health Organization) to know their suitability for human consumption. Piper's trilinear diagram classified most of them as Ca-Cl and mixed Ca-Mg-Cl types. Inverse Distance Weighted (IDW) spatial interpolation showed the spatial distributions of different groundwater quality parameters. These parameters, including the Water Quality Index (WQI), indicated that most of the samples collected during the non-rainfall seasons (post-NE monsoon: 82.8 %; pre-SW monsoon: 78.6 %) were 'poor' for consumption. However, the qualities of 40-44.3 % of samples collected during both the rainfall seasons (NE and SW monsoon) were "good". We evaluated non-carcinogenic health risks for children and adults from consumption of the nitrate-rich groundwater by estimating the Hazard Quotient (HQ). Our results did not suggest any health risk for children and adults during both the rainfall seasons. In the non-rainfall seasons, about 59-63 % of samples posed health risk to children and 37-39 % caused possible health risk to the adult population.