Groundwater Arsenic Contamination in Brahmaputra River Basin: A GIS Based Water Quality Assessment with Seasonal Variation in Dhemaji (Assam), India

Abstract

Distribution of arsenic and its compound and related toxicology are serious concerns nowadays. Millions of individuals worldwide are suffering from arsenic toxic effect due to drinking of arsenic –contaminated groundwater. The Bengal delta plain, which is formed by the Ganga–Padma–Meghna–Brahmaputra river basin, covering several districts of West Bengal, India, and Bangladesh is considered as the worst arsenic –affected alluvial basin. The present study was carried out to investigate the seasonal variations of arsenic in groundwater of Dhemaji district of Assam, an adjoining region of the West Bengal and Bangladesh borders. Sixty groundwater samples were collected from tubewells of five development blocks of dhemaji district (Assam) in one year period, during December 2016 to November 2017 using GIS technique. The present study showed that out of the 60 groundwater samples, 37%, were found contaminated with higher arsenic contents (WHO, arsenic 10 μg/L for potable water). The most badly affected area was the Sissiborgaon development block, where 75% of the samples had arsenic concentration above the WHO drinking water guideline values. In this block, the highest arsenic concentration was recorded 19.45 μg/L at sampling point, B-7. Significant variation was observed between premonsoon (October to April) and post-monsoon (May to September). Arsenic concentration is sufficiently higher in post-monsoon than in pre-monsoon season.