Cell Wall Polymers of Higher Plants in Peat Formation: The Role of Microorganisms
C. Exarchos, P. H. Given, 1977. "Cell Wall Polymers of Higher Plants in Peat Formation: The Role of Microorganisms", Interdisciplinary Studies of Peat and Coal Origins, P. H. Given, A. D. Cohen
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Examination of peats and many coals under the microscope shows that considerable amounts of distinguishable woody structures are present, and that cellulose is at least partly retained as a constituent of cell walls. Yet attempts to isolate cellulose chemically from peats afford iittle or none of the polymer. Experiments in which sheets of filter "paper are inserted in peats and left for varying periods of time show that pure cellulose is rapidly destroyed. The variation of destruction.with time and with depth depends upon the site of insertion. In other studies 14C-labelled cellulose, hemicellulose and lignin were inserted in peats in the field for various lengths of time. In 12 days 50% of the 14c activity in the cellulose was eliminated from the system. The rate of destruction of ligrfin was much slower, but still fast enough, one would have thought, to destroy all plant tissues during the period of accumulation of the peat. It is inferred that tissues found in peat must experience some kind of protection against microbial decay from the surface litter stage onward, and that this may well be a coating of a phenolic/humic condensate. Some evidence of the presence in the red mangrove, Rhizophora mangle L, of substances inhibiting cellulose decay has-been found
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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.