Test of a Model of Organic Matter Preservation in Marine Sediments

点击翻译按钮获取中文摘要

9530280 Heinrichs This research will test a new model which explains sedimentary organic matter preservation in terms of strong adsorption to mineral particles in sediments. In the model, preservation depends on the concentration and solubilization rate of labile organic matter, the adsorption coefficient of dissolved organic substances, the sediment accumulation and bioturbation rates, and the decomposition rates of adsorbed and dissolved organic matter. The model not only explains global patterns of organic matter preservation, but also the general lack of preservation of terrigenous organic matter and kerogen in the marine environment. The test of the model will involve: (1) measurement of adsorption and desorption of proteins, polyamino acids, and melanoidins by clay minerals and iron oxide, (2) studies of the decomposition of these adsorbed substances in coastal sediments, and (3) measurements of the adsorption of natural sediment hydrolyzable amino acids and organic matter. If supported by results of this research, the proposed model would explain the large differences in organic matter preservation in different sedimentary environments, a key process in the long-term global carbon, nitrogen, and phosphorous cycles. This would aid interpretation of the sedimentary record of organic matter accumulation in both recent and ancient sediments. The model could improve predictions of the effects of changes in ocean productivity and sedimentation, due to human activities or natural phenomena, on sedimentary carbon accumulation in continental margins.