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Based on gas chromatography and gas chromatography-mass spectrometry analyses, an amazing amount of hopanoids were detected in the peat deposits in the Dajiuhu National Wetland Park in Central China. The hopanoids identified included hopanes (C27–C31 αβ, C27–C32 ββ, C29 βα), hopenes (hop-22(29)-ene, 22,29,30-trinorhop-17(21)-ene, hop-17(21)-ene, hop-13(18)-ene, etc.), hopanoic acids (C31–C34 ββ, C32–C33 βα, C32 αβ), hopanols (C32 ββ and αβ) and hopanone (22,29,30-trinor-hop-21-one). C31 αβ-22R hopane was found to be the dominant hopanoid, more abundant than individual n-alkanes derived from higher plants. These hopanoids, exclusive of some hopenes, are proposed to be primarily from bacteria. The dominant C31 αβ-22R hopane in young sediments, without any thermal maturation, might be formed through microbial epimerization under acidic conditions in the peatland as suggested before, or directly from aerobic bacteria. This finding highlights the importance of microbes in the formation of peatland as well as in the reconstruction of paleoenvironments. |
