Soil Hg(0) emissions are an important source of atmospheric mercury (Hg), but the Hg isotopic signatures of this source remain poorly characterized. In this study, the fractionation of Hg isotopes during Hg (0) emissions from Hg‐enriched agricultural and forest soils in Wanshan Hg mining area were investigated through laboratory experiments. Significant mass‐dependent fractionation (MDF) of Hg isotopes and mass independent fractionation of odd Hg isotopes (odd‐MIF) were observed. Mean MDF enrichment factors (ε²⁰²Hg_Hg(0)‐soil) of agricultural soil were in the range of −2.03‰ to −1.34‰ for agricultural soil in light‐, light moisture‐, and temperature‐controlled experiments, which were higher than those of forest soil in similar controls (means = −3.38‰ to −1.98‰). Temperature‐controlled experiments exhibited a larger MDF compared to light‐ and light moisture‐controlled experiments. Photoreduction of Hg in agricultural soil in the presence and absence of soil water generated a larger positive odd‐MIF (mean E¹⁹⁹Hg_{Hg(0)­‐soil} = 0.67‰ to 0.76‰, n = 2) than the temperature‐controlled experiments (mean E¹⁹⁹Hg_{Hg(0)‐­soil} = 0.18 ± 0.04‰, 1 SD), whereas the E¹⁹⁹Hg_{Hg(0)‐­soil} of forest soil in temperature controls (mean = 0.23 ± 0.03‰, 1 SD) were higher than that in light (mean = 0.18 ± 0.06‰, 1 SD) and light moisture‐controlled experiments (mean = −0.03 ± 0.06‰, 1 SD). It is speculated that photoreducible Hg (II) likely dominantly bound to S‐containing ligands in agricultural soil but to both S‐containing and sulfurless ligands in forest soil, resulting in significant positive odd‐MIF in Hg(0) product during photoreduction in the former case and a small magnitude of positive to some negative odd‐MIF in the latter case.

中文翻译：

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万山汞矿区富汞土壤中汞（0）同位素组成的室内研究

土壤Hg（0）的排放是大气中汞（Hg）的重要来源，但是该来源的Hg同位素特征仍然不明确。在这项研究中，通过实验室试验研究了万山汞矿区富汞农业和森林土壤中汞（0）排放过程中的汞同位素分馏。观察到Hg同位素的显着质量相关分馏（MDF）和奇数Hg同位素（odd-MIF）的质量独立分馏。平均数MDF富集因子（ε ²⁰²汞_{汞（0） -土壤}）在光，轻度水分和温度控制的实验中，农业土壤的农业土壤含量在−2.03‰至−1.34‰的范围内，高于类似对照中的森林土壤（平均值= −3.38‰）至-1.98‰）。与光和光湿度控制的实验相比，温度控制的实验显示出更大的MDF。在有水和无水条件下，农业土壤中汞的光还原产生的正奇-MIF（平均E ¹⁹⁹ Hg _{Hg（0）-土壤} = 0.67‰至0.76‰，n  = 2）大于温控实验（平均E ¹⁹⁹ Hg _{Hg（0）-土壤} = 0.18±0.04‰，1 SD），而E ¹⁹⁹ Hg _{Hg（0）-土壤}温度控制下的森林土壤（平均值= 0.23±0.03‰，1 SD）高于轻度（平均值= 0.18±0.06‰，1 SD）和轻度水分控制的实验（平均值= -0.03±0.06‰，1 SD） SD）。据推测，光还原性Hg（II）可能主要与农业土壤中的含S配体结合，但同时与森林土壤中的S和无硫配体结合，导致Hg（0）产品中的Hg（0）产物在光还原过程中具有显着的正奇MIF值。前一种情况，而在后一种情况下，小到正数到负数的奇数MIF。