土壤-水稻系统Cd-As同步钝化与吸收阻控研究进展

我国稻田土壤镉-砷(Cd-As)复合污染形势严峻,是实现农田安全利用的难点。相较于其他粮食作物,水稻积累Cd/As的能力更强,对人类健康危害更大,因此,修复Cd-As复合污染稻田土壤,降低稻米Cd/As含量,对保障我国食品安全意义重大。原位钝化技术是目前应用最广泛且治理效率较高的重金属污染土壤修复技术,本文重点阐述了针对稻田土壤Cd-As复合污染的典型钝化剂及其钝化机理,主要包括铁(Fe)+碱性无机材料复合钝化剂、Fe+有机材料复合钝化剂、Fe+有机+碱性无机材料复合钝化剂、有机+碱性无机材料复合钝化剂等;在此基础上,从根际稳定固持和体内运移阻控两方面,探讨原位钝化技术同步降低水稻Cd-As吸收的作用机制。最后,提出未来Cd-As复合钝化剂的研发方向,强调了土壤友好型Fe-Si复合钝化剂可有效从土壤钝化和生理阻隔两方面同步降低Cd/As生物毒害,应用前景广阔。

Synchronous passivation and absorption inhibition of Cd-As co-contamination in soil-rice system: A review

In recent years, paddy soil co-contaminated with cadmium and arsenic(Cd-As) in China has become increasingly common. Due to the completely opposite chemical properties of Cd and As in soil, Cd-As compound pollution is increasingly considered to be of significance in the remediation of heavy metal contamination in farmland. Compared with other cereal crops, rice has been subjected to growing threats from Cd and As contamination in the soil. Therefore, the remediation of Cd-As co-contaminated paddy soil and the control of the accumulation of Cd and As in rice grains are of great importance to ensure food safety. In situ immobilization technology for soil heavy metal pollution is a widely-applied remediation measure due to its high efficiency. Here, the common compound passivation materials of paddy soil Cd-As pollution, including Fe + alkaline inorganic passivators, Fe + organic passivators, Fe + alkaline inorganic + organic passivators, and organic + alkaline inorganic passivators, along with their remediation mechanisms were summarized. Based on this, the principles of mitigating Cd and As accumulation in rice were also explored. This review suggests that to better inhibit the uptake of Cd and As by rice, passivators should have good ability in soil heavy metal solidification and inhibit heavy metal transport to rice grains through physiological barrier. Considering the broad application prospects of soil-friendly Fe-silicon compound passivators in remediating Cd-As co-contaminated paddy soil, it is critical to develop novel Fe-silicon compound passivators in the future.