Groundwater Quality and Arsenic

Water Pollution is an alarm at the global level. The groundwater is continuously decreasing, in anthropogenic pressure as well as naturally. Arsenic is one of the prominent contaminant, which is degrading the quality of groundwater naturally. In India, arsenic pollution in groundwater is mainly reported from West Bengal. Since its first reported case in early eighties, there are 1312 affected villages, 15 non-municipal and 9 municipalities in 8 districts in the State till date. On an approximation 34000 sq km area in the State is reported with high concentration of arsenic in drinking water abstracted from tube wells. The pollution is mostly reported from the intermediate water depth of 20-80 meter below ground level. The arsenic anomaly in the State is associated with high iron, calcium, magnesium and bicarbonates with low sulphate, fluoride and chloride. The problem of arsenic pollution has been reported to be due to the geological formations of the source material. Occurrence of ‘arseno-pyrite’ and the change of geochemical environment due to over-exploitation of groundwater or excessive fluctuation of groundwater table.