title: Biogenic silica composition and δ13C abundance in the Changjiang (Yangtze) and Huanghe (Yellow) Rivers with implications for the silicon cycle.
abstract: The study was carried out to address a method for separation of terrestrial and marine biogenic silica (BSi) in estuaries based on BSi compositions and δ13C values in BSi associated organic matter (δ13CBSi). We used two world-class major rivers - the Changjiang (Yangtze) and Huanghe (Yellow) Rivers as examples to illustrate our approach. Our results for these rivers indicate that riverine BSi is comprised mainly of phytoliths and diatoms. River BSi concentrations vary with terrestrial inputs and in-stream primary production. Although the fluvial BSi sources are complex, the terrestrial δ13CBSisignals are quite unique (-24.7±0.8), significantly lower than the marine δ13CBSivalues (-21.3±0.07, central Yellow Sea) (p<0.01). Thus, the variation of δ13C within BSi organic matter can provide terrestrial source information on the biogeochemistry of silicon in estuaries and the adjacent shelf. The δ13CBSicombination could potentially act as an efficient tool to study environmental change in coastal areas on decadal time-scales since this index may respond to variable terrestrial fluxes from land, as well as to changed phytoplankton assemblages in the coastal ocean.
authors.affiliation: Research Center for Marine Ecology, First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, PR China. Electronic address: rxb@fio.org.cn.
authors.forename: Xiangbin
authors.initials: X
authors.lastname: Ran
authors.affiliation: Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, PR China.
authors.forename: Bochao
authors.initials: B
authors.lastname: Xu
authors.affiliation: Research Center for Marine Ecology, First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, PR China.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.affiliation: Research Center for Marine Ecology, First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, PR China.
authors.forename: Chenying
authors.initials: C
authors.lastname: Zhao
authors.affiliation: Research Center for Marine Ecology, First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, PR China; Tianjin Marine Environmental Monitoring Central Station, State Oceanic Administration, Tianjin 300450, PR. China.
authors.forename: Sen
authors.initials: S
authors.lastname: Liu
authors.affiliation: Research Center for Marine Ecology, First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, PR China.
authors.forename: Jiaye
authors.initials: J
authors.lastname: Zang
keywords: Biogenic silica; Carbon isotope; Changjiang River (Yangtze River); Composition; Huanghe River (Yellow River); Source