| Summary: | CDOM has been identified as a major factor in the absorption of solar energy into Arctic surface waters, controlling the vertical partitioning of solar energy and directly impacting the degree of solar heating, ice melt and thermal stratification. The source of this material on Western Arctic shelf seas is ambiguous. A positive correlation between CDOM absorption and salinity argues against a terrestrial source. High concentrations observed within sea ice cores point towards this medium as a potentially important substrate for production and storage of marine derived CDOM. Projected sea ice retreat will eliminate this CDOM pool, reducing the influx of optically active material to surface waters during the critical ice-melting phase. Warming on land could result in an increased flux of terrestrial CDOM into the Arctic Ocean, although the contribution of this influx is uncertain in terms of the timing of the spring ice melt. Here knowledge of the time scales over which CDOM remains optically active is crucial for understanding the role it plays in the warming of surface waters. The source of the material will affect the reactivity, with fresh marine CDOM being highly labile and quickly removed from the system, and older terrestrial material being more refractory and long lasting. The PI and an associate participated in a spring 2011 ice camp off Ellesmere Island in order to investigate these questions. The objectives of the project were; 1) Determine the sources of CDOM in the surface mixed layer of the western Arctic -- does it come from rivers, is it produced by phytoplankton, or by ice algae? 2) Investigate how quickly and by what mechanism (photochemical or biological) the CDOM degrades 3) Determine the impact of the CDOM on solar heating, thermal stratification, and ice melt. Funding Source: Arctic Natural Sciences (ANS) Sponsor: Old Dominion University Research Foundation, 4111 Monarch Way, Norfolk, VA 23508-2561
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