Fig. 8.

Known areas with elevated arsenic in the IGB aquifer system. Very high arsenic concentrations (>100 μg/L) are mostly restricted to groundwater in the uppermost 100-m alluvium in the southern Bengal Basin. Less extreme arsenic concentrations, though still >10 μg/L, are known to occur in other areas of the aquifer, including: Assam, southern Nepal, the Sylhet trough in eastern Bangladesh, and within Holocene sediments along the course of the Ganges and Indus river systems (figure modified from MacDonald et al. 2016). (Coastline outline provided by ESRI)