Biological and granulometric controls on sedimentary organic matter of an intertidal mudflat |
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Authors: | Lawrence M Mayer Peter T Rahaim William Guerin Stephen A Macko Les Watling Franz E Anderson |
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Affiliation: | 1. Ira C. Darling Center, University of Maine at Orono, Walpole ME 04573, U.S.A.;2. Department of Geology, Memorial University, St. Johns, Newfoundland, Canada;3. Department of Earth Sciences, University of New Hampshire, Durham NH 03824, U.S.A. |
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Abstract: | A variety of measures of organic matter concentration and quality were made on samples collected from the top few mm of intertidal mudflat sediment over the course of a year, in order to assess the relative importance of biological and sedimentological influences on sedimentary organic matter. Winter and summer were times of relatively fine-grained sediment accumulation, caused by biological deposition or stabilization processes and resulting in higher organic matter concentrations. Stable carbon isotope and Br:C ratios indicated a planktonic source of bulk organic matter. Ratios of organic carbon to specific surface area of the sediments were consistent with an organic monolayer coverage of sediment grains. Correction for changing grain size during the year showed no change in the organic concentration per unit surface area, in spite of organic matter inputs by in situ primary production, buildup of heterotroph biomass and mucus coatings, and biodeposition of organic-rich seston. There were also no indications of changes in bulk organic quality, measured as hydrolyzable carbohydrates and amino acids, in response to these biological processes. It is concluded that biological processes on a seasonal time scale affect the bulk organic matter of these sediments via a modulation of grain size rather than creation or decay of organic matter. |
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Keywords: | sediment-water interface sediment texture organic coatings organic matter biogeochemistry mudflats amino acids Maine Coast |
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