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首页> 外文期刊>Estuarine Coastal and Shelf Science >Seasonal variations in the nitrogen isotopic composition of dissolved nitrate in the Changjiang River estuary, China
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Seasonal variations in the nitrogen isotopic composition of dissolved nitrate in the Changjiang River estuary, China

机译：长江口溶解硝酸盐氮同位素组成的季节变化

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摘要

The Changjiang River estuary is the most eutrophic estuary in China. Although anthropogenic input from the Changjiang River (the third-largest river in the world) is considered the main source of nitrogen, the contributions of newly regenerated nitrogen from deep waters may be underestimated, in part due to the lack of information on the nitrogen biogeochemical processes that are occurring. The nitrogen stable isotope ratio is widely used as an indicator of the source of nitrogen and nitrogen transformation processes including assimilation, nitrification, nitrogen fixation and mineralization. To study the biogeochemical processes in the Changjiang River estuary, seasonal variations in the nitrogen stable isotope ratio of nitrate (delta(NO3)-N-15), salinity, temperature, dissolved oxygen concentration, chlorophyll a (Chl a) concentration, and the composition of dissolved inorganic nitrogen were investigated along two transects in the estuary in 2010. In the surface waters, assimilation between May and November was suggested by high Chl a and delta(NO3)-N-15 and supported by the mixing behavior of the nitrate and delta(NO3)-N-15. From February to November, the mean nitrate content in the deep waters gradually increased (from similar to 8 to similar to 15 mu mol l(-1)), whereas the mean delta(NO3)-N-15 decreased (from similar to 2 parts per thousand to similar to-2 parts per thousand). Particularly in November, most of the delta(NO3)-N-15 values in the deep waters were negative (similar to-5 parts per thousand -0 parts per thousand, which is much lower than the similar to 3 parts per thousand riverine input from delta(NO3)-N-15), indicating that most of the nitrates in the deep water were newly regenerated from nitrification rather than originating from riverine input Additionally, the mean ammonium abruptly increased (from similar to 2 to similar to 20 mu mol l(-1)) in the deep waters during November when the delta(NO3)-N-15 values were negative, whereas in August, high Chl a values were observed in the deep waters. These results indicate that remineralization and nitrification occurred in the deep waters of the Changjiang River estuary, implying that regenerated nitrogen may also be an important nitrogen source for uptake by phytoplankton. (C) 2015 Elsevier Ltd. All rights reserved.
机译：长江口是中国最富营养的河口。尽管长江（世界第三大河）的人为输入被认为是氮的主要来源，但深水中新再生氮的贡献可能被低估了，部分原因是缺乏关于氮生物地球化学的信息正在发生的过程。氮稳定同位素比被广泛用作氮和氮转化过程（包括同化，硝化，固氮和矿化）来源的指标。为了研究长江口的生物地球化学过程，分析了硝酸盐（δ（NO3）-N-15）的氮稳定同位素比，盐度，温度，溶解氧浓度，叶绿素a（Chl a）浓度和在2010年沿河口两个断面调查了溶解态无机氮的组成。在地表水中，高Chla和δ（NO3）-N-15表示5月至11月之间的同化作用，并受硝酸盐的混合行为的支持。和δ（NO3）-N-15。从2月到11月，深水区的平均硝酸盐含量逐渐增加（从大约8到大约15μmol l（-1）），而平均δ（NO3）-N-15下降（从大约2千分之二类似于千分之二。特别是在11月，深水区的大多数δ（NO3）-N-15值均为负值（大约为每千份中有-5份-每千份中有-0份，这远低于每千份河流中有3份的输入量。从delta（NO3）-N-15中得出），表明深水中的大部分硝酸盐是硝化作用新生成的，而不是源自河流的输入。此外，平均铵盐突然增加（从2摩尔增加到20摩尔）当del（NO3）-N-15值为负值时，在深水域的l（-1））发生变化，而在8月，在深水域则观察到了较高的Chla值。这些结果表明，长江口深水区发生了再矿化和硝化作用，这意味着再生氮也可能是浮游植物吸收氮的重要来源。 （C）2015 Elsevier Ltd.保留所有权利。

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  • 来源
    《Estuarine Coastal and Shelf Science》 |2015年第20期|148-155|共8页
  • 作者

    Yu Haiyan; Yu Zhiming; Song Xiuxian; Cao Xihua; Yuan Yongquan; Lu Guangyuan;

  • 作者单位

    Chinese Acad Sci, Inst Oceanol, Key Lab Marine Ecol & Environm Sci, Qingdao 266071, Peoples R China;

    Chinese Acad Sci, Inst Oceanol, Key Lab Marine Ecol & Environm Sci, Qingdao 266071, Peoples R China;

    Chinese Acad Sci, Inst Oceanol, Key Lab Marine Ecol & Environm Sci, Qingdao 266071, Peoples R China;

    Chinese Acad Sci, Inst Oceanol, Key Lab Marine Ecol & Environm Sci, Qingdao 266071, Peoples R China;

    Chinese Acad Sci, Inst Oceanol, Key Lab Marine Ecol & Environm Sci, Qingdao 266071, Peoples R China;

    Chinese Acad Sci, Inst Oceanol, Key Lab Marine Ecol & Environm Sci, Qingdao 266071, Peoples R China;

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  • 原文格式 PDF
  • 正文语种 eng
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  • 关键词

    nitrogen isotopes; nitrification; mineralization; assimilation; eutrophication;

    机译：氮同位素;硝化;矿化;同化;富营养化;

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