A Review of the Biogeochemical Cycles of Dissolved Silicon in Rivers |
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| Authors: | Zhang Qianzhu Tao Zhen Gao Quanzhou Ma Zanwen |
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| Institution: | 1. Geography and Planning School of Sun Yat-Sen University, Guangdong Provincial Key Laboratory for Urbanization and Geo-simulation, Guangzhou 510275, China; 2. Key Laboratory of Mineral Resource & Geological Processes of Guangdong Province, Guangzhou 510275, China |
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| Abstract: | The riverine dissolved silicon (DSi) brings environmental information on biogeochemical processes of terrestrial surface, of which the input, transferring, transformation and output are influenced by many factors. Among the weathering of global silicate rocks, 31.53%~64.87% of DSi are intercepted by terrestrial vegetation and only about 12.9% are transferred into rivers. During being transported into ocean, riverine DSi gets impacts from aquatic biological absorption, reverse weathering process and artificial lake effect. The quantity of output is further reduced, which weakens the effect of the oceanic biological pump. According to limited data, the DSi concentration of global rivers has a large variation, ranging from 138 μmol/L to 218μmol/L. It is necessary to quantify contribution rates of influencing factors and establish output models controlled by multiple factors. The δ30Si of riverine DSi ranges from -0.2‰ to 3.4‰. Comparing with the δ30Si of silicate rock, which is about -0.5‰, the fractionation factor is significantly partial to positive from 0.3‰ to 3.9‰. That is because of the occurrence of kinetic fractionation process in river basin including inorganic and organic fractionation. Thus, the key problems, sources and transformation mechanisms of riverine DSi during migration and being transported should be solved in future. |
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| Keywords: | Riverine dissolved silicon Silicon stable isotopic composition Chemical weathering Silicon cycle |
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