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Biogeochemistry of organic matter and associated elements along the river-estuary-ocean continuum
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Comparison of seasonal biogeochemical characteristics of suspended particulate matter in the continental shelf of the southern East China Sea
P-C1-06-S
Qianqian Liu* , State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361102, PR China
Lin Wang, State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361102, PR China
Huawei Wang, State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361102, PR China
Baozhi Lin, State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, PR China
Aiguo Gao, Department of Geological Oceanography, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, PR China
Chen-Tung Arthur Chen, Department of Oceanography, National Sun Yat-sen University, Kaohsiung 80424, Taiwan, R. O. C.
Selvaraj Kandasamy, Department of Geological Oceanography, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, PR China
Presenter Email: liuqq@stu.xmu.edu.cn |
| The compositions of suspended particulate matter (SPM) in marginal seas often vary with seasons due to hydrographic conditions and other localized processes, such as fresh water input, primary productivity and resuspension. As one of the largest river-dominated marginal seas in the western Pacific region, the East China Sea (ECS) receives large quantities of terrestrial material mainly from the Changjiang, which is seasonally varied. However, the coupling between seasonal hydrographic dynamics and the response of the isotopic composition of particulate organic carbon and nitrogen (δ13C and δ15N) in the ECS are less understood. In this study, we compared the organic carbon and nitrogen (POC and PN) and δ13C and δ15N values of SPM investigated from the continental shelf of the southern ECS in summer and autumn 2013 to characterize their seasonal biogeochemical characteristics and to understand the controlling factors of their spatial distribution. The hydrographic parameters of summer SPM revealed that the ECS shelf water was stratified with a distinct deep chlorophyll maximum layer, and the shelf was weakly influenced by fresh water derived from the Changjiang; while in autumn the ECS shelf water was well-mixed and Taiwan warm current water was much weaker. Investigation on organic compositions indicated the dominance of marine-sourced organic matter in both seasons with molar C/N ratios similar to the Redfield ratio (6.63). In contrast to particulate organic matter (POM) in summer that was dominantly sourced from in situ marine productivity, autumn POM was regulated by the cross-shelf mixing and lateral transportation of particles. To summarize, though the marine-sourced POM dominated in summer and autumn 2013, seasonal hydrodynamic forcing plays an essential role in the spatial distribution of elemental and isotopic values of POM in the southern ECS. |
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