Title: Impacts of pumping on the distribution of arsenic concentrations in Bangladesh groundwater
Speaker: Dr. Rajib Mozumder
Environmental Engineer & Hydrogeologist, GRADIENT, Boston, MA.
Abstract: Many of the world’s megacities rely on groundwater from aquifers that are over-exploited and threatened by contamination. Here, we demonstrate how groundwater exploitation in the Mega-City of Dhaka, Bangladesh, may exacerbate groundwater arsenic (As) contamination on a regional- to local-scale. Using long-term hydrogeochemical
measurements and groundwater flow modeling we show that, overpumping has altered groundwater dynamics and the distribution of As. To understand the sustainability of long-term pumping from low-As aquifers, we examined to what extent adsorption of As could delay the rate of As transport relative to groundwater flow. The results indicated
that As is adsorbed rather strongly by aquifer sediments, irrespective of their age and/or oxidation status. By and large, groundwater As concentrations declined or remained stable over the last 12-15 years, suggesting low-As aquifers are more likely than not protected against the intrusion of high-As groundwater.