Biochemical composition and size distribution of organic matter at the Pacific and Atlantic time-series stations |
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| Authors: | Karl Kaiser Ronald Benner |
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| Institution: | 1. Department of Marine Earth and Atmospheric Sciences, North Carolina State University, 2800 Faucette Drive, Raleigh, NC 27607, United States;2. Institute of Marine Sciences, University of North Carolina at Chapel Hill, 3431 Arendell St, Morehead City, NC 28557, United States;3. Chemistry Division, US Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, District of Columbia 20375, United States;4. Department of Marine Sciences, University of North Carolina at Chapel Hill, 123 South Road, Chapel Hill, NC 27599, United States;1. Department Geological Sciences, University of Florida, Gainesville, FL 32611, USA;2. Department of Earth and Environmental Sciences Tulane University, New Orleans, LA 70118, USA;3. Department of Biology, University of Nevada, Reno, NV 89557, USA;4. Department of Geology, Texas A&M University, TX 77843, USA;2. Earth Research Institute, University of California Santa Barbara, California, USA;1. Department of Marine Sciences, University of Georgia, Athens, GA 30602, USA;2. Research Group for Marine Geochemistry (ICBM-MPI Bridging Group), Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University of Oldenburg, 26129 Oldenburg, Germany;3. School of Oceanography, University of Washington, Seattle, WA 98195, USA;4. Romberg Tiburon Center, San Francisco State University, Tiburon, CA 94920, USA;5. Lamont–Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA;6. Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, Piracicaba, SP 13400–970, Brazil;1. State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 511 Kehuajie, Guangzhou 510640, China;2. Department of Biological Sciences and Marine Science Program, University of South Carolina, 700 Sumter Street, Columbia 29208, United States;3. College of Ocean and Earth Science, Tongji University, 1239 Sipinglu, Shanghai 200092, China;4. University of Chinese Academy of Sciences, 19A Yuquanlu, Beijing 100049, China;1. Earth System Science, University of California, Irvine, CA, USA;2. Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, FL, USA;3. Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA, USA;4. Horn Point Laboratory, University of Maryland Center for Environmental Science, Cambridge, MD, USA;5. Rosenstiel School of Marine and Atmospheric Science, University of Miami, FL, USA |
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| Abstract: | Amino acids, neutral sugars and amino sugars were analyzed to investigate the chemical composition and diagenetic processing of suspended particulate organic matter (POM, > 100 nm), high-molecular-weight dissolved organic matter (HMW DOM, 1–100 nm) and low-molecular-weight dissolved organic matter (LMW DOM, < 1 nm) at the time-series stations near Bermuda (BATS) and Hawaii (HOT). Differences between BATS and HOT were principally related to location-specific biogeochemical processes and water mass ventilation ages. Concentrations of amino acids, neutral sugar and amino sugars in unfiltered seawater sharply declined with depth at both stations, indicating an upper ocean source and rapid turnover of these components. The size distribution of organic matter was heavily skewed to smaller molecular sizes. Depth comparisons showed that larger size classes of organic matter were more efficiently removed than smaller size classes. Carbon-normalized yields of amino acids, neutral sugars and amino sugars decreased rapidly with depth and molecular size. Together these biochemicals accounted for 55% of organic carbon in surface POM but only 2% of the organic carbon in LMW DOM in deep water. Chemical compositions showed distinct differences between organic matter size classes indicating the extent of diagenetic processing increased with decreasing molecular size. These findings are consistent with the size-reactivity continuum model for organic matter in which bioreactivity decreases with decreasing molecular size and diagenetic processes lead to the formation of smaller components that are resistant to biodegradation. The data also provided evidence for a size-composition continuum. Carbon-normalized yields of amino acids, neutral sugars and amino sugars were sensitive indicators of diagenetic alterations. Diagenetic indicators based on amino acid compositions revealed distinct patterns for the North Pacific and Sargasso Sea possibly indicating the influence of varying sources or diagenetic processing. |
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