Nature 351, 385 - 387 (30 May 1991); doi:10.1038/351385a0

Enhanced particle fluxes in Bay of Bengal induced by injection of fresh water

V. Ittekkot^*, R. R. Nair^†, S. Honjo^‡, V. Ramaswamy^†, M. Bartsch^*, S. Manganini^‡ & B. N. Desai^†

^* Institute of Biogeochemistry and Marine Chemistry, University of Hamburg, Bundesstrasse 55, 2000 Hamburg 13, Germany
^† National Institute of Oceanography, Dona Paula, Goa 403004, India
^‡ Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA

THE melting of ice sheets during deglaciation results in the injection of large amounts of fresh water into the oceans¹. 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 rivers² supply pulses of fresh water and sediment to the bay, resulting in large seasonal changes in surface salinity³. We find that the maximum river discharge, which occurs during the southwest monsoon, coincides with the maximum observed flux of participate 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 fresh-water 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.

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