ABSTRACT
Naturally elevated arsenic concentrations in shallow groundwater across the Bengal Basin threaten the health of millions of people. Deep (>150 m) groundwater low in arsenic is currently the most effective mitigation option in Bangladesh. However, there are both natural and anthropogenic processes in the Bengal basin limiting the use of deep groundwater as the primary arsenic mitigation option in Bangladesh. We have found that in areas where interbedded muds are scarce naturally deep and fast flow system develops resulting in the occurrence of young (<4.0 kyr) groundwater in aquifers as deep as 250 m. Additionally, groundwater model simulation suggests that large-scale pumping for the municipal supply of Dhaka are creating fast flow paths in a highly heterogeneous deltaic aquifer that could contaminate the aquifer within a century. Our findings put emphasis on the nationwide testing of deep groundwater for arsenic as well as setting up systematic monitoring networks around large pumping centers.
