title: Speciation of potentially mobile Si in Yangtze Estuary surface sediments: estimates using a modified sequential extraction technique.
abstract: To improve our understanding of the Si-related biogeochemical processes that occur in estuarine ecosystems with large subaqueous deltas (e.g., the Yangtze Estuary; YE), the speciation of Si in the surface sediments of the YE was investigated. The relationships between the different Si species and sediment bulk parameters were also discussed. Based on modified sequential extraction method, we can successfully estimate the following five sedimentary potentially mobile Si pools: weak acid leachable Si (W-Si); Si bound to organic matter (H-Si); Si coprecipitated with amorphous Fe/Al oxides (O-Si); Si coprecipitated with crystalline Fe/Al oxides (Ouv-Si), and biogenic silica (B-Si). The total potentially mobile Si pool (T-Si) ranged between 1689.31 and 5487.10 μg/g, with high values observed in deltaic mud deposits. The Si fractions were closely correlated with grain size compositions, except for O-Si. In deltaic mud deposits, efficient loss of organic matters and recycling of Fe oxides probably resulted in the amorphous or poorly crystalline Fe oxides uncoupled with the clay fractions, and thus leading to the lack of correlation between O-Si and grain size. As compared with Ouv-Si, the O-Si should possess stronger mobility, which highlights the importance of quantifying the O-Si pool in deltaic sediments.
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China.
authors.forename: Huagang
authors.initials: H
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China. pfwang2005@hhu.edu.cn.
authors.forename: Peifang
authors.initials: P
authors.lastname: Wang
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Hou
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Qian
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China.
authors.forename: Yanhui
authors.initials: Y
authors.lastname: Ao
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China.
authors.forename: Cui
authors.initials: C
authors.lastname: Liu
mesh_terms: D017753:Ecosystem; D004784:Environmental Monitoring; D063366:Estuaries; D019015:Geologic Sediments / Q000737:chemistry*; D012822:Silicon Dioxide / Q000032:analysis* / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014877:Water Pollution, Chemical / Q000706:statistics & numerical data*
chemical_list: D014874:Water Pollutants, Chemical; D012822:Silicon Dioxide
keywords: Alluvial sediment; Sequential extraction; Si speciation; The Yangtze Estuary