Contamination of Arsenic in Groundwater of Bara District, Nepal

Abstract

Groundwater is the major source of water for drinking and household purposes in Nepal’s Tarai districts. This study was conducted to evaluate the concentration of arsenic (As) in deep and shallow groundwater and its association with iron, manganese, depth and age of the tube wells/dug wells in Bara District. Groundwater samples (36) were collected from randomly chosen wells (dug wells and tube wells) of Bara District, in 2017. As concentrations of water were measured by hydride generation atomic absorption spectrometry (AAS). About 50% of tube wells/dug wells exceeded permissible value 10 ppb of WHO drinking water guideline, but 16% tube wells/dug wells exceeded permissible values of Nepal Interim Standard of arsenic (50 ppb). As concentrations were highly correlated with iron and manganese. The higher concentrations of As in some of the sites of the study area were attributed to the groundwater geochemistry in the study area. As contamination was found high at the depth range of tube wells <20 m, which was constructed in last 10–15 years. The risk of As contamination to the people living in and around study area is high because the contaminated water has been used daily for household purposes such as cooking, drinking and other purposes.