Institute of Organic Contaminant Control and Soil Remediation, Nanjing Agricultural University
Supported by the National Science Fund for Distinguished Young Scholars, China ( No. 41925029 ) and the Jiangsu Provincial Special Fund for S&T Innovation in Carbon Emission Peak and Neutrality, China ( No. 20220013 )
Minerals are critical active components of soils, which can drive the chemical transformation of toxic organic pollutants in the soil environment and reduce the risk of environmental contamination. Previous studies of the interface behavior of toxic organic pollutants on soil mineral surfaces mainly focused on the water environment or mineral suspension systems. Natural soils, especially surface soils, are usually under water-unsaturated conditions. In recent years, the transformation mechanism of toxic organic pollutants on water-unsaturated soil mineral surfaces has attracted considerable attention, and a series of fascinating discoveries have been made. The water-unsaturated iron and manganese minerals, clay minerals and metal ion-saturated clay minerals drive the transformation of the hydrophobic toxic organic pollutants such as polycyclic aromatic hydrocarbons and antibiotics. Water molecules at the interface of water-unsaturated minerals have weak competition with toxic organic pollutants for active sites, and the dehydration process of minerals also makes them change to highly active structures. However, an appropriate increase in the moisture of dry soil minerals can enhance the transformation of toxic organic pollutants. A small amount of water molecules can improve mass transfer and promote the transfer of toxic organic pollutants to the active sites of soil minerals. The different moisture state of soil minerals leads to the formation of various products. The water-unsaturated condition is more conducive to the formation and stability of persistent free radicals and halogenated dioxins. Also, the transformation of toxic organic pollutants is influenced by the catalytic activity of soil minerals and the physical and chemical properties of toxic organic pollutants. In previous studies, electron transfer reaction was considered as the transformation mechanism of toxic organic pollutants on soil minerals. However, free radical catalysis and hydrolysis mechanisms have been gradually discovered. Transition metal elements in iron manganese minerals and metal ion-saturated clay minerals can receive or give electrons during the transformation of toxic organic pollutants. The defects of soil minerals tend to induce the generation of active free radicals. While, the active hydroxyl, Br?nsted acid sites, and Lewis acid sites in soil minerals can accelerate the hydrolysis of toxic organic pollutants. The development of detection technology and theoretical calculation has made the relevant mechanisms precise to the mineral crystal type and plane structure. Additionally, Soil, a complex system, is mainly composed of minerals, organic matter, and microorganisms. And organic matter and microorganisms have an important effect on the transformation of toxic organic pollutants at the mineral interface. Most notably, they can promote the reduction of mineral dissolution, and improve the reduction of toxic organic pollutants. Although the transformation and mechanism of toxic organic pollutants at the interface of water-unsaturated minerals have been gradually evident, the breadth and depth of the research need to be further expanded and deepened. It is suggested that future research focus on the following aspects: reveal the transformation of toxic organic pollutants in the natural soil systems, strengthen the research on the reduction and transformation processes, develop the in situ reaction devices and detection methods, and analyze the transformation mechanism of toxic organics at the mineral interface from micro and nanoscale and molecular level.
程鹏飞,赵旭强,高彦征.水分非饱和条件下土壤矿物界面有毒有机物转化机制研究进展[J].土壤学报,2024,61(3). DOI:10.11766/trxb202212180694 CHENG Pengfei, ZHAO Xuqiang, GAO Yanzheng. Research Progress on the Transformation Mechanism of Toxic Organic Pollutants on Soil Mineral Interface Under Water-unsaturated Conditions[J]. Acta Pedologica Sinica,2024,61(3).复制