Abstract:

Remediation of Cd-contaminated soil has become a critical issue in the world today. Phytoremediation, a sustainable and low-cost remediation technology, plays a significant role in reducing or eliminating the toxicity of heavy metals. In recent years, research on chelating agent-assisted phytoremediation of Cd-contaminated soils has garnered widespread attention. This paper reviews the effects and mechanisms of single chelating agents, combinations of multiple chelating agents, and chelating agents synergized with other substances (such as plant growth regulators, nutrients, surfactants, and microorganisms) to enhance the phytoremediation of Cd-contaminated soil. The findings indicate that a single chelating agent can activate insoluble heavy metals by lowering soil pH and disrupting the balance between metal ions and soil colloids. It can also promote the production of glutathione in plant cells, limiting the transfer of heavy metal ions in the cytoplasm, thereby reducing Cd toxicity. Additionally, it can form stable and easily absorbable metal chelates with Cd ions, enhancing heavy metal uptake by plants. Combining chelating agents with other substances improves the bioavailability of Cd, enhances soil biological activity and microbial community composition, and significantly mitigates the inhibitory effects of single chelating agents on plant growth, which further strengthens the effectiveness of phytoremediation. When selecting chelating agents, it is essential to consider not only their ability to activate Cd but also their degradability, economic feasibility, and the type of contaminated soil. This ensures the selection of the most suitable chelating agent or combination of agents, thereby improving phytoremediation efficiency. Finally, future research directions for chelator-enhanced phytoremediation are proposed.

Key words: chelating agent, phytoremediation, heavy metal contaminated soil, Cd enrichment, joint repair

摘要：

镉（Cd）污染土壤的修复已成为当今世界十分关注的问题。植物修复是一种可持续、低成本的修复技术，对降低或消除重金属的毒性具有重要意义。近年来，利用螯合剂辅助植物修复Cd污染土壤的研究得到了广泛关注。本文综述了单一螯合剂、多种螯合剂联用及螯合剂协同其他物质（植物生长调节剂、营养元素、表面活性剂和微生物）强化植物修复Cd污染土壤的作用效果和机制。结果表明，单一螯合剂可通过降低土壤pH、破坏金属离子与土壤胶体间平衡来活化难溶重金属；能促进植物细胞产生谷胱甘肽、限制重金属离子在细胞质中转移，从而降低Cd毒性；还可以与Cd离子形成稳定且易被植物吸收的金属螯合物，促进植物吸收重金属。螯合剂联合其他物质会提高Cd的生物有效性、改善土壤生物活性和微生物群落组成，并显著缓解单一螯合剂对植物生长的抑制作用，进一步强化植物修复效果。选择螯合剂时，不仅需要考虑螯合剂对Cd的活化能力，还需要考虑其降解性、经济效益以及污染土壤的类型，选出最合适的螯合剂及螯合剂组合，从而提高植物修复效率。最后，提出了螯合剂强化植物修复未来研究的重点。

关键词: 螯合剂, 植物修复, 重金属污染土壤, Cd富集, 联合修复