Enhanced particle fluxes in Bay of Bengal inducEd. by injection of freshwater

Abstract

The melting of ice sheets during deglaciation results in the injection of large amounts of fresh water into the oceans. To investigate how such injections might influence particle fluxes in the ocean, and hence the uptake of atmospheric CO2, we deployed three sediment-trap moorings (two traps in each mooring) in the northern, central and southern parts of the Bay of Bengal, respectively. The Bay of Bengal is suitable for such a study, because some of the world's largest rivers supply pulses of fresh water and sediment to the bay, resulting in large seasonal changes in surface salinity. We find that the maximum river discharge, which occurs during the southwest monsoon, coincides with the maximum observed flux of particulate matter. From north to south, the carbonate flux increases, whereas fluxes of opal, organic carbon and particulate matter decrease. The overall flux pattern seems to be controllEd. by the seasonally varying input from the rivers and the accompanying shift in marine biogenic production. We conclude that freshwater pulses during deglaciation may therefore have caused similar shifts in marine biogenic production, resulting in short-term episodes of increased oceanic uptake of atmospheric CO2.