Identification of Groundwater Arsenic Contaminated Vulnerability Zones in Alluvial Tract of West Bengal, India

Rolee Kanchan

doi:10.37591/joeecc.v2i1-3.5981

Abstract

Underground water is regarded to be free from all types of pollutants hence it is considered to be safefor drinking. Consequentially, it is a predominant source of drinking water in several parts of the worldparticularly in the developing countries. Regrettably, empirical studies have also been conducted inother parts of the World and it is found that in twenty countries the subsurface water is contaminatedwith arsenic. Serious arsenic contamination is reported along the River Bhagirathi in Ganga–Brahmaputra delta in the linear tract of 470 km. The occurrence of arsenic in groundwater is mainlyin the shallow and intermediate aquifer, the deeper aquifers are free from contamination. Arsenicmobilization in water is favoured by desorption of arsenic from iron and other metals oxides. In BengalPlains such conditions tend to occur in shallow aquifers in quaternary strata underlying the regionslarge alluvial and deltaic plains. The occurrence of arsenic in groundwater is influenced by localgeology, geo-chemistry and hydrology of the alluvial aquifers. The present study envisages studying thespatial pattern of groundwater contamination in West Bengal and identifies the arsenic contaminatedvulnerability zones. Spatial variation in respect to the depth and proximity to river Bhagirathi is noticedin the alluvial tract.