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首页> 外文期刊>Environmental Science & Technology >Stable Mercury Isotope Transition during Postdepositional Decomposition of Biomass in a Forest Ecosystem over Five Centuries
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Stable Mercury Isotope Transition during Postdepositional Decomposition of Biomass in a Forest Ecosystem over Five Centuries

机译：稳定的水星同位素在森林生态系统中的森林生物量后期分解过程中的转变

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摘要

Organic soil is an important transient reservoir of mercury (Hg) in terrestrial ecosystems, but the fate of deposited Hg in organic forest soil is poorly understood. To understand the dynamic changes of deposited Hg on forest floor, the composition of stable Hg and carbon (C) isotopes in decomposing litters and organic soil layer was measured to construct the 500 year history of postdepositional Hg transformation in a subtropical evergreen broad-leaf forest in Southwest China. Using the observational data and a multiprocess isotope model, the contributions of microbial reduction, photoreduction, and dark reduction mediated by organic matter to the isotopic transition were estimated. Microbial reduction and photoreduction play a dominant role in the initial litter decomposition during first 2 years. Dark redox reactions mediated by organic matter become the predominant process in the subsequent 420 years. After that, the values of Hg mass dependent fractionation (MDF), mass independent fractionation (MIF), and Δ~(199)Hg/Δ~(201)Hg ratio do not change significantly, indicating sequestration and immobilization of Hg in soil. The linear correlations between the isotopic signatures of Hg and C suggest that postdepositional transformation of Hg is closely linked to the fate of natural organic matter (NOM). Our findings are consistent with the abiotic dark reduction driven by nuclear volume effect reported in boreal and tropical forests. We recommend that the dark reduction process be incorporated in future model assessment of the giobal Hg biogeochemical cycle.
机译：有机土壤是陆地生态系统中汞（HG）的重要瞬态储层，但有机林土中沉积的Hg的命运尚不清楚。为了了解沉积的Hg对森林地板的动态变化，测量稳定的Hg和碳（c）同位素在分解窝和有机土壤层中的组成，构建亚热带常绿宽叶森林中的后定位Hg转化的500年历史在中国西南。利用观察数据和多处理同位素模型，估计通过有机物质介导的微生物还原，光电和暗影减少对同位素转变的贡献。微生物减少和拍摄在前2年期间在最初的凋落物分解中起着显性作用。有机物质介导的深氧化还原反应成为后续420年的主要过程。之后，Hg质量依赖性分馏（MDF），质量独立分级（MIF）的值，以及δ〜（199）Hg /δ〜（201）Hg比不会显着变化，表明Hg在土壤中的螯合和固定。 HG和C同位素之间的线性相关性表明Hg的后置定转化与天然有机物的命运密切相关（NOM）。我们的研究结果与北方和热带林中报告的核体积效应驱动的非生物暗减少。我们建议在GIOBAL HG生物地球化学循环的未来模型评估中纳入黑暗还原过程。

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  • 来源
    《Environmental Science & Technology》 |2020年第14期|8739-8749|共11页
  • 作者

    Wei Yuan; Xun Wang; Che-Jen Lin; Chuansheng Wu; Leiming Zhang; Bo Wang; Jonas Sommar; Zhiyun Lu; Xinbin Feng;

  • 作者单位

    State Key Laboratory of Environmental Geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang 550081 China University of Chinese Academy of Sciences Beijing 100049 China;

    College of Resources and Environment Southwest University Chongqing 400715 China;

    Center for Advances in Water and Air Quality Lamar University Beaumont Texas 77710 United States;

    Anhui Province Key Laboratory of Environmental Hormone and Reproduction Fuyang Normal University Anhui 236037 China;

    Air Quality Research Division Science and Technology Branch Environment and Climate Change Canada Toronto Ontario M3H 5T4 Canada;

    State Key Laboratory of Environmental Geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang 550081 China University of Chinese Academy of Sciences Beijing 100049 China;

    State Key Laboratory of Environmental Geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang 550081 China;

    National Forest Ecosystem Research Station at Ailaoshan Yunnan 676209 China;

    State Key Laboratory of Environmental Geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang 550081 China Center for Excellence in Quaternary Science and Global Change Chinese Academy of Sciences Xian 710061 China;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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