土壤中持久性自由基诱导产生ROS氧化As(III)的微观机制研究

Persistent free radicals (PFRs) are widely present in the environment, which can produce reactive oxygen species (ROS) to elicit environmental toxicity and mediate the degradation of pollutants. However, the relevant researches on the generation of ROS mediated by PFRs in soils and their environmental effect are very limited. Therefore, this project intends to investigate the oxidation of As(III) mediated by PFRs and ROS. The effects of factors such as Fe (II), organic matter content, pH and Eh on the species and concentration of PFRs will be investigated by means of free radical extraction experiments, and the PFRs will be quantitatively and quantitatively analyzed by EPR. The mechanism of the formation of PFRs in soils will be elucidated by studying the interaction between the clay minerals and the quinone components in the humus. Finally, PFRs and ROS will be used to oxidize As(III) in soils. EPR technique will be used to determine the relationships between PFRs conversion and ROS production (such as •OH and H2O2), and the factors for controlling the ROS generation and As(III) oxidation efficiency will be examined in these experiments. The results of this study will provide significant theoretical value for potential risk assessment of the PRFs and the prevention of arsenic pollution in the environment.

持久性自由基（PFRs）广泛存在于环境中，其能够产生活性氧基团（ROS）引发环境毒性和介导污染物降解，但是关于土壤中PFRs诱导产生ROS的机制及其所产生的环境效应尚不明确。基于此，本项目拟开展土壤中PFRs介导氧化As(III)的研究。通过自由基提取实验，借助电子顺磁共振技术（EPR）对土壤中形成的PFRs进行定性和定量分析，探究土壤中Fe(II)、有机质含量、pH和Eh等因素对PFRs种类和浓度的影响。模拟研究土壤中粘土矿物与腐殖质中醌类组分的相互作用，揭示土壤中PFRs的形成机制及诱导产生ROS的过程。以As(III)为模式污染物，研究PFRs还原氧气产生ROS（如羟基自由基、过氧化氢）氧化As(III)的作用机制，阐明影响ROS产生和As(III)氧化的各项环境因素。通过上述研究，以期为土壤中PRFs的潜在风险评估及环境中砷污染的防治提供理论依据。

环境中的持久性自由基（PFRs）广泛存在，其能够产生活性氧基团（ROS）引发环境毒性和介导污染物转化，但是关于土壤中PFRs诱导产生ROS的机制及其所产生的环境效应尚不明确。基于此，本项目借助电子顺磁共振技术（EPR）对土壤中醌类物质形成的PFRs进行了定性和定量分析，发现酚酸以及还原性的氢醌和氧化性的苯醌均可以产生半醌类持久性自由基，揭示了此类PFRs的形成机制及诱导产生ROS的过程。考察了所产生ROS对As(III)的氧化作用，发现在好氧条件下，半醌类自由基（SQ•–）能够通过类芬顿反应生成H2O2和•OH，将As(III)氧化为As(V)。通过自由基淬灭反应和自由基探针技术发现产生的•OH和H2O2是通过O2•–介导的。进一步的研究表明在自由基的产生过程中氢醌和苯醌之间会发生相互转化。通过上述研究为醌类持久性自由基的潜在风险评估及环境中砷污染的防治提供理论依据。在项目研究期间，共发表8篇SCI论文；先后参与本项目的研究生共有7人，其中4人已毕业。