| Fe, Mn and S are all redox sensitive elements,so they are active during diagenetic process in lake sediments acting as oxides in the degradation of organic matters. Fe, Mn and S control the redox zone and the distribution of phosphorus and trace elements.This paper is based on three typical lakes, which are Erhai Lake, Yangzong Lake and Aha Lake on Yun-gui Plateau in China. Through Fe, Mn and S various vertical profiles, we expatiate on the difference of redox process in these lakes, the control of redox boundary to Fe and Mn cycle and the connection of Fe, Mn and trace elements. These studies give evidences for understanding degradation of organic matter and early diagenesis.①In Aha Lake Fe and Mn present seasonal release and the cycle of Mn is more drastic than that of Fe. Fe-Mn accumulate in surface layer of sediments.Surface sediments change black in summer from filemot in winter which indicates Fe-Mn oxide layer changes into FeS.②The diffusion and deposition flux of Fe-Mn show difference in these lakes, and the extent of re-migration of Mn is more remarkable than that of Fe. Fe-Mn forms redox cycle surrouding sediment-water interface with the force of organic matters degradation in lakes and its cycle is doubly controlled by redox boundary layer and sediment-water interface.③In the three lakes sulfate reduction all occur in sediment-water interface. In Erhai it's not main oxide because of its low content and the oxic interface, but in Yangzong and Aha Lake the situation is opposite. The distribution of SRB affirms in sediments of Aha Lake the severe sulfate reduction .Downward diffusion from the overlying water to the sediments is key process in lakes with high content sulfate, while biological adsorption is key process in lakes with low content sulfate.④In these sediments a majority of S is FeS2.The content of AVS is a little high in Yangzong Lake which affirm the drastic reduction of sulfate furthmore.In Aha Lake the reduction of sulfate is irrelative to season and its range remove with the migration of redox boundary. Feo is superior to react with H2S, however Fec can be changed into Feo.⑤In these lakes organic carbon all presents typical degradation form and it proves early diagenesis in sediments. In Erhai Lake organic carbon presents deposition, degradation and accumulation stages, but in Yangzong and Aha Lake it only presents degradition and accumulation stages. The difference of these three lakes is tightly realated to the sedimental deposition speed. The C/N in Erhai Lake indicates the organic matters are mainly from fasciculi plants. The C/N in Aha Lake exceeds 20 which indicates the organic matters are mainly from islands and they contain low and easily degraded nitrogen and high carbon.⑥The post-depositional remobility of trace elements is a universal phenomenon in lake sediments. In Erhai Lake the migration of Pb and Cu is mainly controlled by Fe-Mn cycle,but adsorption-desorption of particles is main controlling factor to Cd.⑦In Yangzong Lake trace elements show the covariance with iron and manganese so the reduction of Fe-Mn oxides causes their accumulation in pore-water.The release trend of Pb and Cd is strong so their re-migration is severe,and they deposit and accumulate in sediments surface combining with some organic matters. In a word, the migration of trace elements is mainly controlled by Fe-Mn cycle, degradation of organic matters and deposition of sulfide, but in different lakes the importance of these factors isn't different either.
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