Terrigenous input and paleoproductivity in the Southern Ocean

The geochemistry of several sites along the Polar Front Zone of the Southern Ocean revealed significant changes in terrigenous input and productivity on glacial timescales. Our records indicate concentrations and fluxes of terrigenous elements (i.e., Fe, Al, and Ti) are low during interglacials and increase tenfold to twentyfold during glacials. Phosphorus accumulation, reactive P concentrations, and P/Ti ratios exhibit similar trends as the terrigenous components, suggesting increased export production during glacials. In all cores, elemental ratios remain relatively constant, indicating terrigenous sources at each site have not likely varied over the past similar to 250 kyr. Iron accumulation rates for these sites are 10 times higher during glacials than interglacials and exceed the estimated regional eolian fluxes by similar to 50 times. The source of this terrigenous material is thus likely to be hemipelagic rather than direct eolian input or ice rafting, and we speculate Fe upwelled from this source may have stimulated glacial productivity in the Southern Ocean.