Hydrodynamics Mediates Biogeochemical Dynamics of Particulate Organic Matter in the Shelf of the Northern South China Sea During Summer

文献类型： 外文期刊

第一作者： Jiang, Zhiqin

作者： Jiang, Zhiqin;Shi, Zhen;Chen, Dawei;Li, Xiangfu;Jiang, Zhiqin;Chen, Dawei;Li, Ruihuan;Xu, Jie;Xu, Jie

作者机构：

关键词： particulate organic matter; stable isotopes of carbon and nitrogen; phytoplankton community; the Pearl River Dilution Water; upwelling; anticyclonic eddy

期刊名称：JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS （ 影响因子：3.4； 五年影响因子：4.0 ）

ISSN： 2169-9275

年卷期： 2024 年 129 卷 10 期

页码：

收录情况： SCI

摘要： Environmental conditions, physiology and community composition of phytoplankton and the carbon and nitrogen isotope signature (delta C-13(POC) and delta N-15(PN)) of particulate organic matter (POM) often covary across marine environments. However, little was known on the link of delta C-13(POC) and delta N-15(PN) and the community and biochemical composition of phytoplankton. In this study, particulate organic carbon (POC) and nitrogen (PN), delta C-13(POC), delta N-15(PN), phytoplankton community composition and biomass were determined during summer, along with environmental variables, in the shelf of the northern South China Sea influenced by the Pearl River plume, upwelling and anticyclonic eddy. Our results show that variability in delta C-13(POC) and delta N-15(PN) along an environmental gradient is coupled with shifts in phytoplankton community composition and carbon to chlorophyll a (C:Chl a) ratio of phytoplankton. Low delta C-13(POC) values (-28.4 to -27.0 parts per thousand) at nearshore stations (salinity <21) were primarily due to terrestrial POM input. High delta C-13(POC) (>-21.0 parts per thousand) and delta N-15(PN) (>5.6 parts per thousand) values are most likely attributed to high abundance of diatoms induced by riverine nutrients in the plume-impacted waters with intermediate salinity (21< salinity <33). Low delta C-13(POC) (<-22.0 parts per thousand) and delta N-15(PN) (-1.1-3.7 parts per thousand) values are associated with high abundance of slow-growing cyanobacteria in the oligotrophic area (salinity >33), where the lowest delta N-15(PN) is most likely attributed to high abundance of N-2-fixing Trichodesmium spp., due to the influence of the anticyclonic eddy. Therefore, hydrodynamics modulates the biochemical composition and community composition of phytoplankton, leading to changes in delta C-13(POC) and delta N-15(PN). Our findings advance our understanding of the coupling of physical and biogeochemical processes in marginal seas.

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