State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
Environ Sci Technol. 2021 Feb 2;55(3):2132-2142. doi: 10.1021/acs.est.0c05204. Epub 2021 Jan 12.
Solid-gas-water phase partitioning of mercury (Hg) and the processes governing its diffusivity within soils are poorly studied. In this study, landscape and forest species dependences of gaseous elemental Hg (Hg(0)) in soil profiles (0-50 cm) were investigated over four seasons in eight subtropical (130 days) and temperate (96 days) forest plots. The vertical soil pore Hg(0) concentrations differed between subtropical (Masson pine, broad-leaved forest, and open field) and temperate (Chinese pine, larch, mixed broad-leaf forests, and open field) catchments, with annual averages ranging from 6.73 to 15.8 and 0.95 to 2.08 ng m, respectively. The highest Hg(0) concentrations in soil gas consistently occurred in the upper mineral or organic horizons, indicating immobilization of Hg(0) in mineral soils. A strongly positive relationship between pore Hg(0) concentrations and ratios of Hg to organic matter (SOM) in soils suggests that the vertical distribution of Hg(0) is related to soil Hg(0) formation by Hg(II) reduction and sorption to SOM. Temperature was also an important driver of Hg(0) production in soil pores. Based on measurements of soil-air Hg(0) exchange, diffusion coefficients () of Hg(0) between soil and atmosphere were calculated for field sites, providing a foundation for future development and validation of terrestrial Hg models.
汞（Hg）的固-气-水三相分配以及其在土壤中扩散的过程研究较少。本研究在亚热带（130 天）和温带（96 天）森林样地中，四个季节分别调查了土壤剖面（0-50cm）中气态元素汞（Hg(0)）的景观和森林物种依赖性。亚热带（马尾松、阔叶林和开阔地）和温带（华山松、落叶松、混交阔叶林和开阔地）集水区的土壤孔隙Hg(0)浓度存在差异，年平均值分别为 6.73-15.8 和 0.95-2.08ng/m。土壤气体中 Hg(0)浓度最高的始终出现在矿物或有机上层，这表明 Hg(0)在矿物土壤中被固定。土壤孔隙 Hg(0)浓度与土壤中 Hg 与有机质（SOM）比值之间呈强正相关关系，这表明 Hg(0)的垂直分布与 Hg(II)还原和对 SOM 的吸附形成土壤中的 Hg(0)有关。温度也是土壤孔隙中 Hg(0)产生的重要驱动因素。根据土壤-空气 Hg(0)交换的测量结果，为现场站点计算了 Hg(0)在土壤和大气之间的扩散系数（D），为未来陆地 Hg 模型的开发和验证提供了基础。
