Connotea
CiteULike
del.ico.us
BibSonomyAbstract
Diatom-bound 15N/14N: New support for enhanced nutrient consumption in the ice age subantarctic
Department of Geosciences, Princeton University, Princeton, New Jersey, USA
Department of Geosciences, Princeton University, Princeton, New Jersey, USA
Department of Geosciences, Princeton University, Princeton, New Jersey, USA
Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, Canada
Byrd Polar Research Center, Columbus, Ohio, USA
Department of Geological Sciences and Marine Science Institute, University of California, Santa Barbara, California, USA
Diatom-bound 15N/14N was used to reconstruct the glacial nutrient status of the Subantarctic Zone in the Southern Ocean. Down-core records from both the Pacific and Indian sectors show δ15N of 5 to 6‰ during the Last Glacial Maximum and a decrease, coincident with the glacial termination, to values as low as 2‰. The effect of either diatom assemblage or physiological change on the diatom-bound 15N/14N is unknown and cannot yet be ruled out as a possible explanation for the observed change. However, the consistency between Indian and Pacific sector records and with other paleoceanographic data suggests that the glacial-interglacial difference in diatom-bound 15N/14N was driven by higher consumption of nitrate in the subantarctic surface during the last ice age. Such a change in nutrient consumption may have resulted from atmospheric iron fertilization and/or decreased glacial mixed layer depths associated with sea ice melting. Enhanced nutrient consumption in the glacial subantarctic would have worked to lower the concentration of CO2 in the ice age atmosphere. It also would have reduced the preformed nutrient content of the low-latitude thermocline, leading to decreases in low-latitude productivity, suboxia, and denitrification.
Received 9 November 2004; accepted 28 March 2005; published 22 July 2005.
Citation: (2005), Diatom-bound 15N/14N: New support for enhanced nutrient consumption in the ice age subantarctic, Paleoceanography, 20, PA3003, doi:10.1029/2004PA001114.
Cited By