农田土壤砷、镉协同钝化修复的研究进展

由于砷和镉的化学行为不同,为使用化学法实现农田土壤中两元素协同钝化修复增加了难度。本文综述了近几年来砷、镉协同钝化修复的材料和使用效果,其中应用较多的是复合钝化剂和改性钝化剂。复合钝化剂在施加方式上略微复杂,但制备工艺较为简单,钝化效果比单一钝化剂更胜一筹;从钝化剂的性质上看,改性钝化剂效果好且施加量少,但其制备工艺比不改性钝化剂复杂,限制其大面积推广使用,因而简化改性材料的制备流程是砷、镉协同钝化修复的一大突破口。此外,文章从吸附、化学沉淀、络合、螯合作用等方面,归纳了砷、镉协同钝化的机理,并介绍了田间砷、镉协同钝化修复的案例;最后,对目前农田土壤砷、镉协同钝化修复研究提出了5个亟待解决的科学问题——钝化剂的有效性、持久性、安全性、普适性和经济性,并对该领域今后的发展趋势如深入研究如何提高钝化修复材料的普适性,重点关注钝化剂的施用量、持久性和对土壤生态系统的风险评价以及针对不同类型污染土壤的模式化、规范化和规程化钝化修复等方面进行了展望。

Advances in Synergistic Passivation Remediation of Arsenic and Cadmium in Farmland Soil

Due to the different chemical behaviors of arsenic and cadmium, it is more difficult to use chemical methods to achieve the synergistic passivation of the two elements in farmland soil. This review summarizes the remediation materials and their efficiency during the synergistic passivation of arsenic and cadmium in recent years. Combined passivators and modified passivators are widely applied, and the combined passivators have a better passivative efficiency compared with the single ones due to their simple preparation process, although the application of them is slightly complex. In the case of the nature of the passivative agents, the modified passivative agents have a good passivative effect with low concentration of application, but their preparation process is more complicated than that of the unmodified passivative agents, which restricts their use in large areas. Therefore, it is a breakthrough to simplify the preparation process of modified passivative agents during the synergistic passivation remediation of arsenic and cadmium in farmland soil. Additionally, the mechanisms regarding the synergistic passivation of arsenic and cadmium are summarized in terms of adsorption, chemical precipitation, complexation and chelation. Moreover, a case study related to synergistic passivation remediation of arsenic and cadmium in soil is introduced. At last, five scientific questions concerning the synergistic passivation remediation of arsenic and cadmium in farmland soil are proposed, including the effectiveness, persistence, safety, universality and economy of passivative agents. The future prospects, including the promotion of universality in application of passivative materials, their application amount, persistence and the ecological risk to soil ecosystem, as well as the remediation pattern, standardization and regulation during the application of passivative materials, are also addressed.