(微)塑料污染对土壤生态系统的影响:进展与思考

近年来土壤重金属污染已经成为全球性的环境问题。而汞作为五大毒性重金属元素之一，其在土壤中的迁移转化不仅会影响作物的正常生长，还会对农产品质量和安全造成严重威胁。土壤pH是影响汞迁移转化的重要因素之一，对其作用机理的不断探索已经成为近年来的研究热点。本文在前人的研究基础上，概述了土壤中汞的来源、危害及存在形态，并从汞的生物有效性及迁移转化过程两个方面详细阐述了土壤pH对汞迁移转化的影响机制。研究表明，酸性条件可能会使土壤中有效态汞的含量增加，进而导致其生物有效性提高，迁移能力增强；土壤pH对汞迁移转化过程中吸附-解吸的影响较大；土壤pH对汞迁移转化过程中络合-螯合、氧化-还原及甲基化反应的影响机理分别体现在离子竞争吸附、价态变化及甲基化促使因子的合成等方面。最后对今后的研究方向作出展望，旨在为汞污染土壤的修复与治理及汞污染扩散模型的建立提供参考依据。

Impacts of(micro)plastics on soil ecosystem: Progress and perspective

With the rapid development of industrialization, soil heavy metal pollution has become a global environmental problem. Mercury, as one of the five most toxic environment pollutants, not only affects the normal growth of crops, but also poses a serious threat to the quality and safety of agricultural products. Soil pH is one of the most important factors affecting mercury migration and transformation. The mechanism of interaction between soil pH and mercury has become a focus of environmental science research in recent years. Therefore, this paper summarized the source, hazard and forms of mercury in soil, and the mechanism of the effect of soil pH on mercury migration and transformation was elaborated from the aspects of mercury bioavailability and migration and transformation process. Several conclusions were drawn based on these analyses. Acidic conditions might increase the amount of available mercury, resulting in increase of mercury bioavailability and migration capacity. Adsorption-desorption of mercury was greatly affected by the soil pH. The effects of soil pH on complexation-chelation reaction, redox reactions and methylation reaction in mercury migration and transformation were reflected in ion competitive adsorption, valence change and methylation-promoting factor synthesis, respectively. In addition, the further research of mercury was proposed, which could provide reference for the remediation of mercury contaminated soil and the establishment of mercury pollution diffusion model.