Geochemical Characteristics Of Silicon In The Dah And Wuliangsuhai Lake

Silicon, which represents 27% of the lithosphere, is an important component in the lake eeosystem.About 80% inputs of silicic aeid to the world ocean come from rivers.Estuarine Environments are Potential locations for labile silica burial due to removal of dissolved silica during mixing proeesses of fresh and brackish water and deposition of biogenic opal, where commonly supporting abundant diatom blooms.A Tessier sequential chemical extraction methods have been introduced to studythe distribution of species of silica bioavailability in lake sediment of inner Mongolia :Ⅰ-exchangeable,Ⅱ-bound to carbonates,Ⅲ-bound to Fe-Mn oxides andⅣ-bound toorganic matter and sulfide.Ⅲ-is predominant over the rest of other species.Thecontent of four different species in sediment core isⅢ>Ⅵ>Ⅱ>ⅠBased on the basis of the research of silicon forms, systematically carry out the silicon cycling of plateau lakes in west Inner Mongolia for first, reveals the distribution difference mechanism of silicon forms in two lakes , expounds the contribution of silicon forms to lake ecosystems, which provide valuable database for the studies of environmental geochemical cycle and function transformation of source/sink of silicon in lakes sediment. For sediment on the carbon cycle silicon cycle econonmy provides basic data. The results are described as follows:1. The dominant form of silicon is IMOF - Si, accounts for about 80% of the total silicon biological effectiveness. Each point in sediments have the sequence of IMOF-Si>OSF-Si>CF-Si≈IEF-Si.2. Through analysis the transfer of CF - Si mode, in vertical direction, CF - Si diagenesis have kept the mineralized organic precipitation, and transfer function of mineral silicate dissolved.3. In the release experiment,vibration helps to release silica within a certain period;the influence of salinity on the release of silica is relatively complex,in low salinity scope(about within 5‰),the content of released silica varies negatively with the increase of salinity,subsequently dissolved silica tend to increase in line with ascending salinity,but relatively high salinity have little influence on silica release.While pH places an significantly opposite role on the release of silica with the increase of pH between 3～9. Release test also show that, except the successive extraction in the five kinds of confirmation, sediment deposition silicon forms exist in deionized water extraction can be used with the normal silicon loose. If using successive extraction of IEF - Si combined with CF - to estimate the biological can give a state silicon content, so will the quantitative analysis of natural water environment generate obvious undervalued.4. Through the shengyuan silicon and N, P, OC ratio, can discover that a large part of the buried, cannot participate BSi recycling. Also on the other hand provide theoretical basis for silicon restrictions.5. Through correlation analysis , the various forms of silicon has very good homology transformation;The nutrient which N, P, OC were the primary productivity of has very good correlation between the various forms, compared to the contribution of silicon.