US GEOTRACES North Atlantic Section: Sample collection for iron stable isotopes

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).GEOTRACES is a newly initiated international oceanographic program to identify processes and quantify fluxes that control the distributions of key trace elements and isotopes in the oceans and to establish an understanding of the sensitivity of these distributions to changing environmental conditions. Dissolved iron (Fe) is an element that has a profound impact on phytoplankton growth, ecosystem productivity, and carbon sequestration in the ocean. Atmospheric dust deposition, dissolved Fe flux from continental margin sediments, and hydrothermal venting of Fe-rich fluids have all been identified as important sources of biologically utilized Fe to the oceans. However, the relative importance of these sources in supplying Fe to the dissolved phase is not well understood. To address this issue, a scientist from the California Institute of Technology in collaboration with researchers at LEGOS (France) will make Fe stable isotopic measurement on samples collected during the 2010 GEOTRACES cruise along the North Atlantic Ocean basin. Samples will be taken from all physical and biogeochemical processes that influence trace metals and their isotopes, namely strong meridional advection, ocean margin exchange, atmospheric inputs, and hydrothermal sources and sinks. The resultant dataset should help constrain global Fe fluxes to the ocean. As regards broader impacts, the study will yield new insights into the biogeochemical cycle of Fe, an important component needed to resolve the carbon cycle.