Biogeochemical properties and potential risk of shallow arsenic-rich sediment layers to groundwater quality in Western Bangladesh.

The arsenic-contaminated groundwater has attracted attention in much south and southeast Asian deltas, however, mainly on the deep aquifers. Here, arsenic (As) concentration and its fractionation of the sediment cores in a shallow aquifer in Bangladesh were investigated using ICP-MS, FE-EPMA, XRD and C-AMS chronology techniques. The results of the present study indicated that the peak concentrations of As (54.