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Free Drifting Icebergs as Proliferation Sites of Iron Enrichment, Organic Carbon Production and Export in the Southern Ocean

Atmospheric warming has been associated with retreating glaciers, disintegrating ice shelves, and the increasing prevalence of icebergs in the Southern Ocean over the last decade. Our preliminary study of two icebergs in the NW Weddell Sea, an area of high iceberg concentration, showed significant delivery of terrestrial material accompanied by significant enhancement of phytoplankton and zooplankton/micronekton abundance, and primary production surrounding the icebergs. We hypothesize that nutrient enrichment by free-drifting icebergs will increase primary production and sedimentation of organic carbon, thus increasing the draw-down and sequestration of CO2 in the Southern Ocean and impacting the global carbon cycle. Our research addresses the following questions:1) What is the relationship between the physical dynamics of free-drifting icebergs and the Fe and nutrient distributions of the surrounding water column? 2) What is the relationship between Fe and nutrient distributions associated with free-drifting icebergs and the organic carbon dynamics of the ice-attached and surrounding pelagic communities (microbes, zooplankton, micronekton)? 3) What is impact on the export flux of particulate organic carbon from the mixed layer? An interdisciplinary approach is proposed to examine iceberg structure and dynamics, biogeochemical processes, and carbon cycling that includes measurement of trace element, nutrient and radionuclide distributions; organic carbon dynamics mediated by microbial, ice-attached and zooplankton communities; and particulate organic carbon export fluxes. Results from this project will further our understanding of the relationship between climate change and carbon sequestration in the Southern Ocean. Our findings will be incorporated into the Antarctic Research division of the Ocean Exploration Center (OEC) as part of the SIOExplorer: Digital Library Project. The OEC allows users to access content, which is classified to one of four levels: entry (grade K-6), student (grade 6-12), college, and research. Graduate students, undergraduates, teachers, and volunteers are important participants in the proposed field and laboratory work. For the K-12 level, a professional writer of children's books will participate in cruises to produce an account of the expedition and a daily interactive website.

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