GEOTRACES Arctic Section: Improving understanding of controls on the distributions of selected anthropogenic radionuclides in the Amerasian Basin

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In this project, a group of investigators participating in the 2015 U.S. GEOTRACES Arctic expedition will determine the concentrations of a suite of anthropogenic (human-made) radioisotopes in the Arctic Ocean. Anthropogenic radioisotopes are unstable forms of elements that have a human-made origin; they may leak into the environment as by-products of nuclear weapons testing or nuclear energy production. In common with other multinational initiatives in the International GEOTRACES program, the goals of the U.S. Arctic expedition are to identify processes and quantify fluxes that control the distributions of key trace elements and isotopes in the ocean, and to establish the sensitivity of these distributions to changing environmental conditions. Results from this research will help to characterize distinct contaminant sources for anthropogenic radioisotopes and identify the influence of important mechanisms that lead to their observed distributions in the Arctic. Researchers will collaborate with the NSF-funded Polar Learning and Responding Climate Change Education Partnership in order to develop web-based spatial tools for sharing results of their work with students and the general public.Although a significant amount of work has been done in the Arctic, data sets on radionuclides are entirely lacking in some cases or limited with respect to particular elements or isotopes of interest including characterization of different sources, water column, sea ice, and sediments. The U.S. GEOTRACES Arctic section offers an unprecedented opportunity to study the sources, fate and transport of anthropogenic radionuclides in the Arctic, a region that has been heavily impacted by nuclear industrial activities and exhibiting dramatic and rapid responses to global climate change. Using a comprehensive, multi-tracer approach, these researchers will determine the concentrations of a suite of anthropogenic radionuclides, including cesium-137, cesium-134, plutonium-239, plutonium-240, and neptunium-237 in a variety of different types of samples from the Arctic. This study will provide information on the horizontal and vertical distributions of the anthropogenic radionuclides of interest, which will substantially add to the global data set, constrain the budgets of several anthropogenic radionuclides through collaboration with European colleagues, and address not only the transport and fate of these contaminants in the Arctic, but also provide insight into the dominant processes that affect them. The data will support efforts in data modeling, which will integrate the dissolved and particulate anthropogenic radionuclides data on a basin-wide basis, and then compare and evaluate the contributions from different oceanic processes as well as the influence of sources of contamination.