| Both Erhai lake and Aha lake are lie in Yunnan-Guizhou plateau, but there are so many different between them, such as climate, illumination, oxygen, sulfate and their origin and so on. So they give us good samples to study the micro — biogeochemistry sulfur cycle in the lake sediment. Using spectrophotometry , ICS, HPLC and fluorescence in situ hybridization (FISH) we have determined the sulfur speciation(S2-, SO32-, S2O32-, SO42-, AVS, S0, FeS2) and the sulfate reduction bacteria content in the sediment of Ehai lake and Aha lake in spring autumn and winter. Searched the coupling relationship in their location, from all we got the later result.1.Because of the detection limit of H-2S is too low, we cannot detect it in Erhai lake in spring autumn and winter, only we can get litter of H2S in Aha lake in autumn. The reason is Fe2+ was using up then, residual H2Scombine with Mn2+ and turn into MnS, the solubility of MnS is bigger (than that of FeS), some of MnS hydrolyzes and produce S2-2.Among spring autumn and winter, In winter, the sulfate in sediment is much higher but unconstantly in vertical distribution. Show both anaerobic and aerobic characters, but in spring the sulfate is much lower, showed the anaerobic character. We take it as the result of the biological film on the surface of the sediment, and we built up the model of adhesive sedimentation process: In spring and winter the upper lake water was colder than that of bottom So the convection was take place in this two seasons, and the microorganism move with the convection of water, when it arrived the surface of the sediment, not only some of adhesive ones will adhere to the sediment but also the former ones will adhere latter ones more, this action will keeping on till the convection stopped. This process builds up the heavy biological film on the surface of the sediment. In winter the biological film does not build up completely, so it shows both anaerobic and aerobic characters, but in spring the film...
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