The lignin geochemistry of marine sediments from the southern Washington coast |
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| Authors: | John I Hedges Dale C Mann |
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| Institution: | Department of Oceanography, WB-10, University of Washington Seattle, WA 98195, U.S.A. |
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| Abstract: | Lignin oxidation products and stable carbon isotope distributions are used to investigate the sources, transport, and chemical stability of land-derived organic matter in dated cores of modern sediment from the southern Washington State continental shelf and slope. There is no evidence for significant chemical alteration of lignin compounds in these sediments for time periods of up to 400 yr. Gymnosperm woods and nonwoody angiosperm tissues account for most of the land-derived organic matter in the deposits. These land plant remains have an average δ13C of approximately ?25.5% and are concentrated in a narrow band of silty sediment which extends northward from the Columbia River mouth along the mid-shelf. Marine organic matter having an approximate δ13C of ?21.5%, strongly predominates in most other shelf and slope environments. Net fluxes of land-derived organic matter into the surface 5 cm of the cores vary directly with sediment accumulation rates. Net fluxes of marine organic material into the surface sediments are highest in environments which favor the preservation of organic matter, but correspond to less than 1% of the primary productivity in the overlying waters. |
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