State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China.
State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China.
J Environ Sci (China). 2022 Mar;113:311-321. doi: 10.1016/j.jes.2021.06.016. Epub 2021 Jul 6.
Continuing permafrost degradation is increasing the risk of mercury (Hg) exposure in the permafrost regions on the Qinghai-Tibetan Plateau (QTP), but related studies are still limited, especially the ones on the detailed Hg migration processes in permafrost. The vertical distribution characteristics of soil Hg were investigated in three ecosystems in the Beiluhe area on the QTP, and its influencing factors and formation mechanism were investigated. The results indicate that the total soil mercury (THg) concentration in the Beiluhe area remains at an extremely low level (6.33 ± 2.45 ng/g). In the vertical profile, the THg concentration of the shallow soil layer (0-50 cm) (5.96 ± 2.22 ng/g) is significantly lower than that of the deep layer (50-400 cm) (7.44 ± 2.71 ng/g) (p < 0.05). Within the upper 50 cm, the THg concentration decreases with soil depth, and the peak THg concentration occurs at 100-300 cm on the entire profile. Although the THg concentration is slightly affected by the organic matter in the shallow soil layer, in general, the soil parent material is the dominant factor affecting the THg concentration. Intense weathering results in a low THg concentration in the shallow soil layer because the soil Hg is carried downward with the soil moisture. To a certain depth, the impermeable frozen soil layer intercepts the flow of the soil Hg, and it forms a Hg enrichment layer. This paper presents the distinctive pattern of the soil Hg distribution in the permafrost regions of the QTP.
持续的永久冻土退化增加了青藏高原（QTP）永久冻土地区汞（Hg）暴露的风险，但相关研究仍然有限，特别是关于永久冻土中 Hg 迁移过程的详细研究。本研究调查了青藏高原北麓河地区三种生态系统中土壤 Hg 的垂直分布特征及其影响因素和形成机制。结果表明，北麓河地区土壤总汞（THg）浓度仍处于极低水平（6.33±2.45ng/g）。在垂直剖面中，浅层土壤层（0-50cm）（5.96±2.22ng/g）的 THg 浓度明显低于深层土壤层（50-400cm）（7.44±2.71ng/g）（p<0.05）。在 50cm 以上范围内，THg 浓度随土壤深度的增加而降低，整个剖面的 THg 浓度峰值出现在 100-300cm 处。尽管浅层土壤中有机质对 THg 浓度有一定影响，但总体而言，土壤母质是影响 THg 浓度的主要因素。强烈的风化作用导致浅层土壤中 THg 浓度较低，因为土壤 Hg 随土壤水分向下迁移。在一定深度上，不透水的冻土层阻止了土壤 Hg 的流动，从而形成了 Hg 富集层。本文提出了青藏高原永久冻土区土壤 Hg 分布的独特模式。
