| Peatmire is a kind of special ecosystem, in which a great quantity of organic carbon has accumulated, and therefore, plenty of information about climate and environment change records was kept in it. The study of carbon cycle and organic geochemistry plays an important role in the research of global change. In this paper, the author disclosed the process of organic carbon conversion in the key stage of carbon cycle in peatlands by means of the analyse to the profile in typical stratums of peatland The purpose of this paper is to reconstruct the environment since late Holocene using the records of molecular fossils in organic compounds and to provide new viewpoints to the research of global change.Drill cores were collected in Hani peatmire located in the west slope of Changbeishan Mountain. By analyzing the organic components of the samples, total organic carbon and analyzing of the lipids extraction with the GC-MS, and using the methods and principles in peat-geology,organic geochemistry, and statistics, the author studied the carbon cycle mechanism of the peatlands and the reliability of new proxy of the environmental change with the biomarkers. The study has shown:(1) With increasing sediment depth and the woody giblets, the total organic carbon(TOC), the extraction of benzene , the total humic acids and the unhydrolyte are enhanced, while the hydrolyte is decreasing.(2) According to the GC-MS analysis, n-alkane,n-alkan-2-ones and n-alkanones are composed mainly of long-chains,such a result is thought to be characteristic of a herbaceous input from 2300a.B.P. n-alkanones exist in the samples may be considered as the evidence of microorganisms activity. (3) It is showed that the lipids is more sensitive to the climate change than the floristic. The proxy of the pollen spore of the peat stratum is different from the normal environment proxy. It is one of the main reasons that the sensitivity difference of the bog vegetation reacting to the climate isn't accordant with the log of the fat molecule fossil and biology fossil.(4) The transformation of the peat organic carbon is under the influence of temperature,acidity,organic material constituting, etc, and it showed the up-trend with the depth. In the short-term scale, the conversion of the peat organic carbon is effected by seasonal water,regional climate and vegetations; while in the long-term scale, it is controlled mainly by the climate (especially the temperature). (5) According to the comparing the orderliness of organic compound,vegetation giblets with the depth to the characteristics of the peat molecule fossil with the section, in the development of this peatmire, 1500a B.P(210cm)is regard as the borderline of the late Holocene, the keynote of the front period is warm with several cold fluctuations, and the trend of the back period is dry and cold although there were several fluctuations. |
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