9400069 Cooper Research supported by this grant is under the auspices of the Arctic Systems Science (ARCSS) Global Change Research Program and is jointly sponsored by the Division of Ocean Sciences and the Office of Polar Programs. The research will be centered around a unique and intensive, multidisciplinary research expedition to parts of the Arctic Ocean that have never been extensively studied. The 1994 U.S./Canada Arctic Ocean Section is a collaborative effort with Canada that will involve approximately 60 scientists on a Canadian and a U.S. icebreaker during summer 1994. NSF-funded projects will focus on hydrography, biology, paleo-, and sea-ice studies. Data collected will be amongst the first ever from several regions of the Arctic Ocean and will be highly relevant to improving our understanding of how the Arctic is an indicator of changing global climate conditions and how it affects the physical, chemical, and biological features of the more temperate oceans and regions. This work will identify trends in elemental and isotopic ratios of artificial radioactive contaminants particularly iodine-129, technetium, and several transuranics. Sources of these contaminants may be river-borne and associated with accidental releases or fuel re-processing activities, or marine in origin and associated with breached reactors, weapons, and/or disposed wastes. Although this work will contribute to on-going assessments of radionuclide contamination of the Arctic Ocean, the distributions of the radioisotopes chosen for study will also improve understanding of Arctic Ocean circulation and its hydrologic cycle, particularly the role of the major Siberian rivers in influencing physical, biological, and chemical mixing processes. The chemical behavior of the radioisotopes selected for study will permit a "fingerprint" identification of the provenance of contaminants due to the variability in isotope or elemental ratios in each potential source. The parallel use of other radioisotope, conservati ve tracer (delta^18O and delta D), and biologically modified tracer distributions (nutrients, dissolved oxygen, and by extension, NO and PO), will contribute to defining particle transport and water mixing mechanisms, in addition to describing the propagation patterns of contaminants. ***
