Vegetation uptake of mercury and impacts on global cycling
Vegetation uptake of mercury and impacts on global cycling
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DOI：
10.1038/s43017-021-00146-y
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发表时间：
2021-03
影响因子：
42.1
通讯作者：
Jun Zhou;D. Obrist;A. Dastoor;M. Jiskra;A. Ryjkov
中科院分区：
文献类型：
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作者：
Jun Zhou;D. Obrist;A. Dastoor;M. Jiskra;A. Ryjkov
汞（Hg）是一种全球性污染物，通过人为活动、生物质燃烧、地质脱气以及陆地和海洋的遗留排放，向大气中大量排放（每年约6000 - 8000毫克汞）。高达三分之二的陆地汞排放主要通过植被对汞的吸收沉积在陆地上。在本综述中，我们收集了一个全球数据库，其中包括440个地点的35000多个汞测量数据，并综合了树叶和植被生态系统中汞的来源、分布和汇。地衣和苔藓显示出比维管植物更高的汞浓度，而地上生物量中的汞主要来自大气吸收，根系中的汞则来自土壤和大气的联合吸收。植被从大气中吸收汞并向土壤转移是所有生物群系中主要的汞源，在全球范围内占陆地汞沉积的60-90%，并使全球大气汞库减少约660 Mg。此外，它减少了向全球海洋的汞沉积，在没有植被的情况下，全球海洋每年可能额外接收960毫克的汞沉积。为了更好地理解植被循环，需要更好地约束植被吸收机制；为了量化全球植被影响，需要改进植被汞循环的模型表示。
Mercury (Hg) is a global pollutant that emits in large quantities to the atmosphere (>6,000–8,000 Mg Hg per year) through anthropogenic activities, biomass burning, geogenic degassing and legacy emissions from land and oceans. Up to two-thirds of terrestrial Hg emissions are deposited back onto land, predominantly through vegetation uptake of Hg. In this Review, we assemble a global database of over 35,000 Hg measurements taken across 440 sites and synthesize the sources, distributions and sinks of Hg in foliage and vegetated ecosystems. Lichen and mosses show higher Hg concentrations than vascular plants, and, whereas Hg in above-ground biomass is largely from atmospheric uptake, root Hg is from combined soil and atmospheric uptake. Vegetation Hg uptake from the atmosphere and transfer to soils is the major Hg source in all biomes, globally accounting for 60–90% of terrestrial Hg deposition and decreasing the global atmospheric Hg pool by approximately 660 Mg. Moreover, it reduces the Hg deposition to global oceans, which, in the absence of vegetation, might receive an additional Hg deposition of 960 Mg per year. Vegetation uptake mechanisms need to be better constrained to understand vegetation cycling, and model representation of vegetation Hg cycling should be improved to quantify global vegetation impacts.