生物炭钝化沉积物中汞的间接作用机制研究

Biochar is often applied to contaminated sediments to control mercury release, thus reducing its environmental exposure risk. At present, most researches focus on the direct interaction mechanism between biochar and mercury in aqueous medium. However, in addition to physical adsorption, biochar can also release soluble components, which can have an indirect impact on the speciation and bioavailability of mercury in sediments. However, due to the limitation of technical methods and the complexity of practical operation, the indirect mechanism of mercury immobilized by biochar remains to be further explored. The project focuses on the anaerobic sediment environment, and analyzes the effects of biochar application on different parameters of the system, and explores the correlation between these changes and mercury bioavailability to clarify the indirect mechanism of biochar immobilization of mercury. In addition, by controlling the key environmental factors of sediment systems, the effects of biochar on mercury morphology and water-soil interface distribution are discussed in sediment, and the main driving force of biochar immobilization of mercury is revealed. By clarifying the indirect mechanism and influencing factors of biochar immobilization of mercury, it provides a reference for scientific and rational selection of biochar and efficient regulation of its mercury-contaminated sediments.

生物炭常被施用于污染沉积物以控制汞的释放，从而降低其暴露风险。目前研究多关注于水相介质中生物炭对汞产生的直接作用机制。然而，除物理吸附外，生物炭还能够释放可溶性组分，可对沉积物汞形态及生物有效性产生间接影响。但由于技术手段的局限性及实际操作上的复杂性，生物炭钝化沉积物汞的间接作用机制还有待深入探索。本项目聚焦厌氧沉积物环境，通过分析生物炭施用对体系不同参数的影响，探究上述变化与汞生物有效性的关联，以阐明生物炭钝化汞的间接作用机制；此外，通过调控沉积物体系关键环境因子，探究其对沉积物汞形态及水土界面分配规律的影响，揭示生物炭钝化汞的主要驱动力。通过明确生物炭钝化汞的间接作用机制和影响因素，为科学合理选择生物炭、高效调控其修复汞污染沉积物提供参考。

生物炭常被施用于污染土壤以控制汞的释放，在汞污染农业土壤原位修复方面具有极大的潜力。然而生物炭具有实际施用量较大、施用成本较高、刺激土壤汞甲基化等原因，阻碍了其在田间的大规模推广使用。为了进一步提高生物质资源的利用效率，本项目致力于探讨共热解生物炭在汞污染土壤中的应用效果及潜力，探索研发基于生物炭的稻田土壤甲基汞阻断新技术。本研究主要发现600 oC水稻和浒苔共热解生物炭（1:1）在减少水稻根系对甲基汞的吸收，降低水稻籽粒甲基汞含量等方面具有较大的优势；并系统考察了共热解生物炭对水稻不同组织中甲基汞累积的影响。此外，炭包实验结果表明，其主要通过间接作用影响汞在土壤中的迁移转化过程。通过明确共热解生物炭钝化汞的间接作用机制和影响因素，为科学合理选择生物炭、高效调控其修复汞污染土壤提供参考。