Stable Strontium Isotopic Compositions of River Water, Groundwater and Sediments From the Ganges–Brahmaputra–Meghna River System in Bangladesh

The Sr isotopic composition of rivers and groundwaters in the Bengal Plain is a major contributor to global oceanic inventory. stable strontium isotope ratios (? 88 Sr) provide new tool identify chemical weathering reactions terrestrial water. In this study, we investigated spatiotemporal variations ? samples river water, bedload sediment, groundwater collected from Ganges–Brahmaputra–Meghna drainage basin Bangladesh, which known strongly influence 87 Sr/ 86 ratio seawater. average values waters Ganges, Brahmaputra, Meghna were 0.269, 0.316, 0.278‰, respectively. Our data showed little difference between seasons high low discharge. measured sequential leaching fractions sediments varied –0.258 0.516‰ highest silicate fraction, followed turn by carbonate fraction exchangeable fraction. Both these are primarily controlled inputs products Himalayan (Ganges Brahmaputra). Values Sr/Ca higher Brahmaputra River than Ganges River, attribute greater input weathering. waters. Mineral sorting effects dissolution kinetics can account for large scatter values. depth profile wide variation at shallow depths convergence narrow range about 0.31‰ 70 m, reflects more complete equilibration interactions ambient owing longer residence time deeper groundwater. We found that Bangladesh almost identical those water lower downstream its confluence with Ganges–Brahmaputra system, thus confirming discharge Bay very similar