Studies on Toxic Level of Some Trace Elements in the Groundwater of Bhagalpur District

Bhagalpur is in eastern Bihar state of Indian subcontinent is mostly famous for silk products. After silk production, rice, maize, and banana are mostly produced end-products from this city. Bhagalpur stands on the banks of Ganga basin, where the location lies at 25°15'N latitude and 87°0'E longitude. This city is situated at the height of 141 feet above the measurement of sea level. Groundwater  from well, hand pumps, submersible is main drinking water in this area. The quality  of groundwater varies area to area and season to season which is a natural phenomena. Some of the toxic trace elements are also observed during sampling. Groundwater samples were collected from the different locations of Bhagalpur district, to assess the presence of toxic trace elements viz. arsenic (As), boron (B), barium (Ba), chromium (Cr), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), and uranium (U)  by using water quality index (WQI). Based on global positioning system (GPS) 100 groundwater samples were collected from the different sources at different depths. A single mathematical approach was identified using several parameters integrated to represent a single value for evaluating groundwater quality called as WQI. Chronic exposure to groundwater containing elevated concentrations of geogenic contaminants such as arsenic (As) and uranium (U) can lead to detrimental health impacts. In this study, we have undertaken a groundwater survey of representative sites across Bhagalpur districts of the State of Bihar, in the Middle Gangetic Plain of north-eastern India. The aim is to characterize the inorganic major and trace element aqueous geochemistry in groundwater sources widely used for drinking in Bihar, with a particular focus on the spatial distribution and associated geochemical controls on groundwater As and U. Concentrations of As and U are highly heterogeneous across Bihar, exceeding (provisional) guideline values in ~16% and 7% of samples (n = 273), respectively. The strongly inverse correlation between As and U is consistent with the contrasting redox controls on As and U mobility. High As is associated with Fe, Mn, lower Eh and is depth-dependent; in contrast, high U is associated with HCO3, NO3, and higher Eh. The improved understanding of the distribution and geochemical controls on trace elements in groundwater in Bhagalpur has important implications on remediation priorities and selection, and may contribute to informing further monitoring and/or representative characterization in Bihar and elsewhere in India.