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Arsenic enrichment in the shallow aquifer, contaminating groundwater source, has been envisaged as a serious health concern in parts of the Brahmaputra floodplains (BFP), Assam, India. In 68 groundwater samples were collected from the adjoining regions of Brahmaputra river (< 70 m depth) 78% of the samples had shown As concentration above 10 μ g L-1. Highest arsenic concentrations, at three different selected regions were found to be 85, 67 and 22 μ g L-1. Semi-quantitative XRF analysis of sediment depicted that average high As concentration 61 mg kg-1 in shallow depth (< 15 m) whereas average low As concentration of 8.2 mg kg-1 was found in deeper (> 50 m) aquifer sediments. The combined results of shallow aquifer groundwater suggested that the rate of weathering (eg silicate), dissolution (eg carbonate, Fe, Mn) and precipitation of solid phase minerals (viz. As, Fe, Ca, Cu and Pb) were the …