Science Serving Maryland's Coasts
Rodger Harvey, Ph.D.
Chesapeake Biological Laboratory
The Use of 210Pb Chronology and Amino Acid Analysis to Understand Organic Matter Cycling in the Arctic
Organic matter cycling is a central process taking place in all types of ecosystems. The Arctic Ocean is no exception. In this study, sediments which represent one specific sector of the organic matter reservoir, in the Arctic were investigated. Two analysis methods were combined; the distribution of amino acids downcore to examine the history of organic matter inputs and processing together with 210Pb to establish an age chronology. Three sediment cores (2, 4, and 7) crossing the continental shelf East of Barrow (EB), Alaska were analyzed. Results for sediment chronology found that the two near shore stations (EB-2 or EB-4) were well mixed over the sampling range (0-20cm) due it intense benthic activity and 210Pb chronologies were not useful. The average sedimentation rate calculated for the EB-7 core collected in deeper waters was 0.0411 cm/year or 41.1 cm/1000 years.
Our results show that amino acids varied among all three cores. The three most abundant amino acids in the EB-2 sediment core included, glycine, serine, and valine; in the EB-4 core the most abundant amino acids were alanine, glycine, and serine; while in the deep water EB-7 sediment core showed glycine, serine, and aspartic acid with the highest concentrations. The percent total organic carbon was shown to remain stable through the intervals measured in the cores while the THAA concentrations showed fluctuation, suggesting varied carbon sources over the sediment accumulation history.
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