INCREASED BIOLOGICAL PRODUCTIVITY AND EXPORT PRODUCTION IN THE GLACIAL SOUTHERN-OCEAN

A range of complementary radionuclide proxies in sediments of the sout hernmost Atlantic Ocean over the past 140,000 years indicate that glac ial periods were characterized by greatly increased fluxes of biogenic detritus out of surface waters. This increase in export production, w hich may have contributed to lower concentrations of carbon dioxide in the glacial atmosphere, was accompanied by more than a fivefold incre ase in accumulation of lithogenic iron transported by winds from Patag onian deserts. These observations support the hypothesis that the iron limitation of today's Southern Ocean productivity was relieved in gla cial periods by a greater supply of iron from wind-blown dust.