Biological response to millennial variability of dust and nutrient supply in the Subantarctic South Atlantic Ocean

Robert F. Anderson, Stephen Barker, Martin Fleisher, Rainer Gersonde, Steven L. Goldstein, Gerhard Kuhn, P. Graham Mortyn, Katharina Pahnke, Julian P. Sachs

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    Abstract

    Fluxes of lithogenic material and fluxes of three palaeo-productivity proxies (organic carbon, biogenic opal and alkenones) over the past 100 000 years were determined using the 230Th-normalization method in three sediment cores from the Subantarctic South Atlantic Ocean. Features in the lithogenic flux record of each core correspond to similar features in the record of dust deposition in the EPICA Dome C ice core. Biogenic fluxes correlate with lithogenic fluxes in each sediment core. Our preferred interpretation is that South American dust, most probably from Patagonia, constitutes a major source of lithogenic material in Subantarctic South Atlantic sediments, and that past biological productivity in this region responded to variability in the supply of dust, probably due to biologically available iron carried by the dust. Greater nutrient supply as well as greater nutrient utilization (stimulated by dust) contributed to Subantarctic productivity during cold periods, in contrast to the region south of the Antarctic Polar Front (APF), where reduced nutrient supply during cold periods was the principal factor limiting productivity. The anti-phased patterns of productivity on opposite sides of the APF point to shifts in the physical supply of nutrients and to dust as cofactors regulating productivity in the Southern Ocean. © 2014 The Author(s) Published by the Royal Society.
    Original languageEnglish
    Article number20130054
    JournalPhilosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
    Volume372
    Issue number2019
    DOIs
    Publication statusPublished - 13 Jul 2014

    Keywords

    • Biological productivity
    • Dust
    • Iron
    • Southern Ocean

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