Tracing recharge to aquifers beneath an Asian megacity with Cl/Br and stable isotopes: the example of Dhaka, Bangladesh

摘要: Dhaka, the capital of Bangladesh, is home to a population 15 million people, whose water supply 85% drawn from groundwater in aquifers that underlie city. Values Cl/Br >500 are common beneath western Dhaka areas <3 km river, and rivers sewers around within The study shows strongly influenced by infiltration effluent leaking unsewered sanitation, river-bank Turag-Buriganga river system which bounds limit River-bank other minor. Cl concentrations reveal 23 % wells sampled saline connate amounts up 1%. This residual natural salinity compromises use electrical conductivity as method for defining pathways recharge contaminated surface waters. Concentrations As, B, Ba, Cd, Cu, F, Ni, NO3, Pb, Sb, Se U samples less than WHO health-based guideline values drinking water.