Arsenic contamination in Rapti River Basin, Terai region of India

Ingestion of Arsenic (As) through groundwater has become a severe public health concern around the world. In >70 countries groundwater with elevated concentrations of As has been reported. The present study estimates the As concentration as high as 399 μg/L in Rapti River Basin which lies in Terai region of Uttar Pradesh, India. The villages on the left bank showed As contamination whereas villages on the right bank does not show As concentration above WHO standards of 10 μg/L. High concentration of iron (Fe) along with bicarbonate (HCO3−) and As indicates reductive dissolution of FeOOH leading enrichment of As in groundwater. Highly reducing conditions are also indicated by low values of SO4/Cl ratio (ranges between 0 and 3.57). Topography, geology and river dynamics seem to govern the As contamination as depressions/low lying areas shows presence of high As in the aquifers.