Arsenic in Bangladesh Groundwater: Focus on Deep Aquifer for Mitigation and Management
The BGS/DPHE National Hydrochemical Survey for the first time reported the occurrences of arsenic safe water at aquifers deeper than 150m. However, most of the deep samples for the survey were collected from the coastal regions. Since then, other surveys came out with findings that depth was not the only criteria for arsenic safe drinking water; rather the local geology plays a vital role in it. It has been found over most of the country that the Pleistocene sediments, irrespective of depth occurrences, provide safe water. Also the localized oxidized sediments at shallower depths provide arsenic safe water. However, this aquifer in many places contains high Manganese. Also in some parts the deeper aquifer contains relatively higher concentrations of other trace elements such as Boron. Apart from quality issues, there are number of other hydrogeological factors which need to be understood well in order to abstract safe water from the deep aquifer on a sustainable basis. The paper would focus on the key hydrogeological and management issues related to deep groundwater in Bangladesh.