Particle Size Distribution and 13C Content of Dissolved Organic Matter in a Salt Marsh
John A. Calder, Fie Kearsley, 1977. "Particle Size Distribution and 13C Content of Dissolved Organic Matter in a Salt Marsh", Interdisciplinary Studies of Peat and Coal Origins, P. H. Given, A. D. Cohen
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The dissolved organic carbon (DOC) in a stream flowing through a Florida coastal salt marsh, populated by Spartina and Juncus, undergoes continuous modification as it .is transported over the salinity gradient. High molecular weight organics of terrestrial origin are lost from the dissolved fraction at mid-salinity and large quantities of low molecular weight (less than T 1,000 MW) dissolved organics are- added to the water. The water leaving the salt marsh contains about the same concentration of total DOC as the water entering the marsh, but the effluent waters contain a much greater proportion of low molecular weight material. This material may have greater biological activity than the high molecular weight material that it replaced, and therefore be.an important input to the estuarine food chain. The implications of the changing composition for processes of peat accumulation are noted.
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This publication represents the proceedings, of a symposium on The Geology, Paleobotany, Geochemistry, and Microbiology of Peats." The symposium was held during the Annual Meeting of the Geological Society of America and associated societies, which took place in Miami, 18-20 November, 1974, and was jointly sponsored by the Coal Geology Division of the Society and the Organic Geochemistry Division of the Geochemical Society. Fourteen papers were presented, and nine are included in this publication. Five authors elected to make other arrangements for publishing their work; but the abstracts of these five papers, as submitted for inclusion in Abstracts with Programs, volume 6, number 7, 1974, are included here for completeness. Peats are of interest to scientists in a variety of disciplines: coal geology, organic geochemistry, soil science, plant ecology, the general ecology of food chains, agronomy, and environmental studies. Workers in many of these fields contributed to this symposium, but it is perhaps fair to say that the central unifying core is the consideration of peat as the precursor of coal. From a broad and general earth science point of view, peats and coals are of special interest because (a) such sediments contain higher concentrations of organic matter than any other common sedimentary deposits, and (b) in most peat beds and coal seams, the greater part of the organic matter and part of the mineral matter are autochthonous in the strictest sense, so that the many biological and chemical fossils that they contain are valid indicators of the organisms from which the organic matter was derived or of the environment of deposition. By contrast, although the reservoir and source rocks of petroleum do contain chemical fossils indicating their origin, reservoir rocks at least, cannot, of their nature, contain relevant fossils in the ordinary biological sense.