Groundwater Geochemistry, Sources Identification and Quality Assessment in Umaria Coalfield, Madhya Pradesh, India

The deterioration of groundwater quality poses a significant concern for inhabitants residing in the mining region. Thus, the present research aimed to assess the geochemistry and suitability of the groundwater for drinking and domestic use in the Umaria coalfield. To accomplish the goals, one hundred groundwater samples were collected on a seasonal basis from various locations in the Umaria coalfield and analysed for pH, electrical conductivity, turbidity, total dissolved solids (TDS), and major ions. The pH of the tested samples ranges from 6.4 to 8.0 in the post-monsoon season and 6.2 to 8.0 in the pre-monsoon season, indicating a slightly acidic to slightly alkaline nature. The post-monsoon season samples have a range of TDS from 74-1,325 mg/L and 87-1,611 mg/L in the pre-monsoon season. The concentration of cations plus anions in the groundwater is 609 mg/L in the post-monsoon season and 765 mg/L in the pre-monsoon season, showing minimal seasonal change in the cationic and anionic chemistry. The groundwater in the studied region shows Ca-Mg-HCO₃ and Ca-Mg-SO₄-Cl hydrogeochemical facies in both seasons. The dominant cations are Ca²⁺ and Na⁺, while the dominant anions are HCO₃^- and SO₄^2- during both seasons. The hydrogeochemical plots, ionic ratios, and multi-statistical analysis suggest that rock weathering, ion exchange processes and human activity are the main factors influencing the chemical composition of Umaria coalfield groundwater. The high SO₄^2- concentration in the groundwater samples is primarily attributed to the oxidative weathering of pyrite, followed by gypsum dissolution, and can have an adverse impact on the human health in the study area. Agricultural practices and residential sewage cause a high NO₃^- concentration in some samples, which can harm the health of the population residing in these areas. The high values of TDS, total hardness (TH), nitrate, sulphate, fluoride, magnesium, calcium, and the water quality index (WQI) indicate that many groundwater samples require proper treatment before being used for drinking and domestic purposes.