Iron in ice cores from Law Dome: A record of atmospheric iron deposition for maritime East Antarctica during the Holocene and Last Glacial Maximum

• Published in: Geochemistry, Geophysics, Geosystems
• Main Authors: Edwards, Ross, Sedwick, Peter, Morgan, Vin, Boutron, Claude
• Other Authors: Desert Research Institute (DRI), Bermuda Biological Station for Research (BBSR), Bermuda Biological Station for Research, Institute of Antarctic and Southern Ocean Studies (IASOS), University of Tasmania Hobart, Australia (UTAS), Antarctic Climate and Ecosystems Cooperative Research Centre (ACE-CRC), Australian Antarctic Division (AAD), Australian Government, Department of the Environment and Energy, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2006
• Subjects: atmospheric iron deposition; Antarctica; Southern Ocean; Last Glacial Maximum 0414 Biogeosciences: Biogeochemical cycles; processes; [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology; Antarctic; The Antarctic; East Antarctica; Wilkes Land; Law Dome; Antarc*; EPICA; ice core
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-00375459; https://hal-insu.archives-ouvertes.fr/insu-00375459/document; https://hal-insu.archives-ouvertes.fr/insu-00375459/file/2006GC001307.pdf; https://doi.org/10.1029/2006GC001307

International audience Total dissolvable iron (TDFe) was measured in sections of ice cores recovered from Law Dome on the coast of Wilkes Land, East Antarctica. These samples include ice dating from the Last Glacial Maximum (LGM), the Last Deglaciation, and the early and mid Holocene as well as samples from the Anthropocene that have been dated with seasonal to annual resolution. Combining our TDFe concentration data with estimates of the ice accumulation rate, we estimate the atmospheric iron deposition for Law Dome and the adjacent Southern Ocean during these periods. Our results indicate that the atmospheric iron deposition flux to this region during the LGM (∼8 μmol Fe m−2 yr−1) was an order of magnitude higher than the average Holocene deposition flux (∼0.8 μmol Fe m−2 yr−1). This Holocene flux estimate is significantly higher than recent estimates of atmospheric iron deposition based on the analysis of iron in samples of the Dome C EPICA ice core, implying that there are significant meridional gradients in eolian iron flux to the Antarctic region. Our data also suggest that there have been significant variations in atmospheric iron deposition to Law Dome and adjacent ocean waters over seasonal to decadal timescales during the past century. Analysis of ice samples dating from calendar years 1927 to 1928 indicates an anomalously high flux of TDFe to the Law Dome region, amounting to around half the maximum LGM flux, possibly as a result of severe drought conditions on the Australian continent. Given that chronic iron deficiency is thought to limit phytoplankton production in much of the ocean around Antarctica, such large secular variations in atmospheric iron supply are likely to have had profound impacts on year-to-year primary production and ecosystem structure in Antarctic waters.