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www.biogeosciences-discuss.net/6/7481/2009/
doi:10.5194/bgd-6-7481-2009
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under the Creative Commons Attribution 3.0 License.
Natural iron enrichment around the Antarctic Peninsula in the Southern Ocean
1Norwegian University of Science and Technology (NTNU), Department of Biology, Trondheim, 7491, Norway
2Polar Research Program, Marine Biology Research Division, Scripps Institution of Oceanography, University of California-San Diego, La Jolla, Ca 92093-0202, USA
3NOAA Fisheries, Antarctic Ecosystem Research Division, La Jolla, CA 92037, USA
4Pontificia Universidad Católica de Valparaíso, Escuela de Ciencias del Mar, Chile
5Woods Hole Oceanographic Institution, Department of Marine Chemistry and Geochemistry, Woods Hole, MA 02543, USA
6Norwegian University of Science and Technology, Department of Chemistry, Trondheim, 7491, Norway
Abstract. As part of the US-AMLR program that occupied 99 hydrographic stations in the South Shetland Islands-Antarctic Peninsula region in January–February of 2006, concentrations of dissolved iron (DFe) and total acid-leachable iron (TaLFe) were measured in the upper 150 m at 16 stations (both coastal and pelagic waters). The concentrations in the upper mixed layer (UML) of DFe and TaLFe were relatively high in Weddell Sea Shelf Waters (~0.6 nM and 15 nM, respectively) and lowest in Drake Passage waters (~0.2 nM and 0.9 nM, respectively). In the Bransfield Strait, representing a mixture of waters from the Weddell Sea and the Antarctic Circumpolar Current (ACC), concentrations of DFe were ~0.4 nM and of TaLFe ~1.7 nM. The highest concentrations of DFe and TaLFe in the UML were found at shallow coastal stations close to Livingston Island (~1.6 nM and 100 nM, respectively). The ratio of TaLFe:DFe varied with the distance to land: ~45 at the shallow coastal stations, ~15 in the high-salinity waters of Bransfield Strait, and ~4 in ACC waters. Concentrations of DFe increased slightly with depth in the water column, while that of TaLFe did not show any consistent trend with depth. Our data are consistent with the hypothesis that the relatively high rates of primary production known from the central regions of the Scotia Sea are partially sustained by natural iron enrichment resulting from a northeasterly flow of iron-rich coastal waters originating in the South Shetland Islands-Antarctic Peninsula region.
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Citation: Ardelan, M. V., Holm-Hansen, O., Hewes, C. D., Reiss, C. S., Silva, N. S., Dulaiova, H., Steinnes, E., and Sakshaug, E.: Natural iron enrichment around the Antarctic Peninsula in the Southern Ocean, Biogeosciences Discuss., 6, 7481-7515, doi:10.5194/bgd-6-7481-2009, 2009. Bibtex EndNote Reference Manager XML
