Hydrogeochemical investigation and qualitative assessment of surface water resources in West Bokaro coalfield, India

A hydrogeochemical study of surface water of the West Bokaro coalfield has been undertaken to assess its quality and suitability for drinking, domestic and irrigation purposes. For this purpose, fourteen samples collected from rivers and ponds of the coalfield were analysed for pH, conductivity, total dissolved solids (TDS), major cations (Ca2+, Mg2+, Na+ and K+), major anions (HCO3 (-), F-, Cl-, SO4 (2-) and NO3 (-)) and trace metals. The pH of the analysed water samples varied from 7.3 to 8.2, indicating slightly alkaline in nature. The electrical conductivity (EC) value varied from 93 mu s cm(-1) to 906 mu s cm(-1) while the TDS varied from 76 mg L-1 to 658 mg L-1. HCO3 (-) and SO4 (2-) are the dominant anion and Ca2+ and Na+ the cation in the surface water. The concentration of alkaline earth metals (Ca2+ + Mg2+) exceed the alkali metals (Na+ + K+) and HCO3 (-) dominates over SO4 (2-) + Cl- concentrations in the majority of the surface water samples. Ca2+ -Mg2+ -HCO3 (-) and Ca2+ -Mg2+ -Cl- are the dominant hydrogeochemical facies in the surface water of the area. The water chemistry is mainly controlled by rock weathering with secondary contribution from anthropogenic sources. For quality assessment, analyzed water parameter values compared with Indian and WHO water quality standard. In majority of the samples, the analyzed parameters are well within the desirable limits and water is potable for drinking purposes. However, concentrations of TDS, TH, Ca2+, Mg2+ and Fe are exceeding the desirable limits in some water samples and needs treatment before its utilization. The calculated parameters such as sodium absorption ration, percent sodium, residual sodium carbonate, permeability index and magnesium hazard revealed good to permissible quality and suitable for irrigation purposes, however, higher salinity, permeability index and Mg-ratio restrict its suitability for irrigation at few sites.