ABSTRACT
Alluvial sands in the delta and flood plains of Ganga-Bahmaputra-Meghna river systems are usually rich in mica (5-30% of suspended sediment) and biotite constitutes about 65-75% of the total mica. It is transported to the alluvium by the river system from source terrain, and therefore weathering of biotite (both physical and chemical) is often noticed during transportation. Biotite is also known to be good adsorbent of As (Chakraborty et al., 2007) and the association between As and weathered biotite was reported in the As-rich
1 INTRODUCTION
Arsenic (As) mobilization in groundwater is widely reported in the sedimentary aquifers of the Bengal Delta Plain, BDP (West Bengal, India and Bangladesh), and is a major threat to the supply of safe drinking water for roughly 80 million people. Serious skin lesions, cancer, and related internal toxic exposures are manifested among populations consuming As contaminated groundwater over a prolonged period of time.
