有机磷农药（OPPs）作为一种通过抑制生物体神经系统中乙酰胆碱酶活性从而杀灭害虫的高效杀虫剂，在农业生产中被广泛使用。OPPs在世界范围内多种环境介质中均存在，甚至在北极等偏远地区也被检出，OPPs残留在环境中并通过食物链在人体富集，给生态环境及人体健康带来潜在危害。本文通过环境介质本身存在的化合物构建反应体系，降解地下水中有机磷农药，对地下水污染控制与修复具有重要理论意义和应用价值。

本文针对北方某灌区在地下水中OPPs的分布、时空变化、潜在风险研究的基础上，分析了利用含水介质中天然二氧化锰矿物构建氧化还原反应体系降解地下水中OPPs的途径，通过制备α-MnO₂和δ-MnO₂，构建了α-MnO₂/HSO₃^-反应体系及δ-MnO₂/草酸反应体系，研究了两种反应体系对不同结构OPPs的氧化还原降解特征，进而揭示了两种MnO₂反应体系对OPPs的降解机理。取得的主要成果如下：

1、北方某灌区地下水中的OPPs主要为乐果、敌敌畏、甲基对硫磷、马拉硫磷，地下水中OPPs主要来源于OPPs的施用，地下水中OPPs的时空分布差异性明显，主要受地下水流场与OPPs施用的影响。地下水中OPPs威胁地下水水质和人体健康，利用含水介质中高锰的特点，构建基于二氧化锰反应体系降解OPPs的途径，对保障地下水水质安全具有重要意义。

2、以高锰酸钾（KMnO₄）和硫酸锰（MnSO₄）为主要原料，通过水热合成法制备了α-MnO₂，α-MnO₂主要是由细小片状颗粒聚集形成的直径在1-15 μm类球状结构，并形成直径为10nm左右，长度可达几百纳米的空隙通道，具锰钾矿结构特征；以高锰酸钾（KMnO₄）、氢氧化钾（KOH）和氯化锰（MnCl₂）为主要原料，通过水热合成法制备了δ-MnO₂，δ-MnO₂主要是由细小颗粒组成的不规则粉末结构并形成网状结构，具水锰矿结构特征。

3、利用合成的α-MnO₂和δ-MnO₂分别构建了α-MnO₂/HSO₃^-反应体系和δ-MnO₂/草酸反应体系；实验研究了pH、MnO₂含量、HSO₃^-含量、草酸含量、Mn²⁺含量、氧气及初始浓度等因素对甲基对硫磷降解的影响特征，得到两种MnO₂反应体系的最佳反应条件；两种MnO₂反应体系对不同结构有机磷农药的降解效果表明：α-MnO₂/HSO₃^-反应体系对含有P=S键的有机磷农药的降解效果优于含P=O键的有机磷农药；δ-MnO₂/草酸反应体系对含有硝基结构（-NO₂）的有机磷农药的降解效果优于不含硝基结构（-NO₂）的有机磷农药。

4、通过活性物质捕获剂或络合剂对两种MnO₂反应体系可能产生的活性物质进行定性分析表明：α-MnO₂/HSO₃^-反应体系生成具有很强氧化活性的Mn(III)，Mn(III)可通过一系列反应氧化OPPs，尤其对含有P=S键的OPPs效果更佳，是该反应体系的主要降解机理。δ-MnO₂/草酸反应体系首先产生Mn(III)，Mn(III)与过量草酸形成螯合物，再与OPPs形成三元配合物，促进OPPs还原降解，尤其对含硝基（-NO₂）的OPPs效果更佳，是该反应体系主要降解机理。

5、根据LC-HRMS对甲基对硫磷和甲基对氧磷降解产物的分析，甲基对硫磷和甲基对氧磷在α-MnO₂/HSO₃^-反应体系下转化路径为：两种有机磷农药在α-MnO₂和HSO₃^-作用下会发生S_N@P和S_N@C取代反应而被水解→甲基对硫磷及水解产物中的P=S键会被反应系统产生的Mn(III)氧化成P=O键→甲基对氧磷和甲基对硫磷水解产物—对硝基苯酚会通过一系列反应最终被氧化，进一步促进两者的水解过程。甲基对硫磷和甲基对氧磷在δ-MnO₂/草酸反应体系下转化路径：两种有机磷农药在δ-MnO₂和草酸作用下会发生S_N@P和S_N@C取代反应而被水解→甲基对硫磷和甲基对氧磷及两者水解产物中的硝基（-NO₂）会被还原成氨基（-NH₂）。

Organophosphorus pesticides (OPPs) are highly effective insecticides that kill pests by inhibiting the activity of acetylcholinase in the nervous system of organisms, and are widely used in agriculture. OPPs have been detected in many environmental medias worldwide, even in remote areas such as the Arctic. OPPs residues in the environment and accumulate in the human body through the food chain, bringing potential harm to the ecological environment and human health. In this paper, a reaction system was constructed to degrade organophosphorus pesticides in groundwater through compounds existing in environmental media, which has important theoretical significance and application value for groundwater pollution control and remediation.

Based on the study of OPPs distribution, spatio-temporal variation and potential risk in groundwater of a sewage irrigation area in north China, this paper study the way of degradation of OPPs in groundwater by using natural manganese dioxide in water-bearing media to construct oxidation and reduction reaction systems. By preparing α-MnO₂ and δ-MnO₂, α-MnO₂/HSO₃^- reaction system and δ-MnO₂/Oxalic acid reaction system were constructed to study the degradation characteristics of OPPs with different structures, and further reveal the degradation mechanism of OPPs. The main achievements are as follows:

1. The OPPs in groundwater of a sewage irrigation area in north China are mainly dimethoate, dichlorvos, methyl parathion and malathion. The OPPs in groundwater mainly come from the application of OPPs, and have obvious spatial and temporal distribution characteristics. OPPs in groundwater have posed a threat to groundwater quality and human health. Therefore, it is of great significance to construct a degradation pathway of OPPs based on manganese dioxide reaction system by utilizing the characteristics of high manganese content in water-bearing media.

2. α-MnO₂ was prepared by hydrothermal synthesis method with potassium permanganate (KMnO₄) and manganese sulfate (MnSO₄). α-MnO₂ is mainly composed of fine columnar particles that form spherical structures with diameters ranging from 1-15 μm and form pore channels of different sizes，which has the structure characteristics of cryptomelane. δ-MnO₂ was prepared by comproportionation with potassium permanganate (KMnO₄), potassium hydroxide (KOH) and manganese chloride (MnCl₂). δ-MnO₂ is mainly composed of fine particles with irregular powder structure and formed a network structure, which has the structure characteristics of manganite.

3. The α-MnO₂/HSO₃^- reaction system and δ-MnO₂/Oxalic acid reaction system were constructed by using the synthesized α-MnO₂ and δ-MnO₂, respectively. The effects of pH, MnO₂ content, HSO₃^- content, oxalic acid content, Mn²⁺ content, oxygen and initial concentration on the degradation of methyl parathion were studied experimentally, and the optimal reaction conditions of two MnO₂ reaction systems were obtained. The degradation effects of two MnO₂ reaction systems on OPPs with different structures showed that α-MnO₂/HSO₃^- reaction system had better degradation effects on OPPs containing P=S bond than OPPs containing P=O bond.  δ-MnO₂/Oxalic acid reaction system had better degradation effects on OPPs containing nitro (-NO₂) than OPPs without nitro (-NO₂).

4. Qualitative analysis of the possible active substances produced by the two MnO₂ reaction systems through active substance trapping agent or complexing agent shows that: The α-MnO₂/HSO₃^- reaction system generates Mn(III) with strong oxidation activity. Mn(III) can oxidize OPPs through a series of reactions, especially for the OPPs containing P=S bonds, which is the main degradation mechanism of this reaction system. The δ-MnO₂/Oxalic acid reaction system firstly produces Mn(III), which forms chelates with excess oxalic acid, and then forms ternary complexes with OPPs to promote the reduction of OPPs, especially the OPPs containing nitro (-NO₂), which is the main degradation mechanism of this reaction system.

5. According to the analysis of degradation products of methyl parathion and methyl paraoxon by LC-HRMS, the transformation path of methyl parathion and methyl paraoxon in α-MnO₂/HSO₃^- reaction system is as follows:The two OPPs are hydrolyzed by SN@P and SN@C substitution reactions under the action of α-MnO₂ and HSO₃^- → The P=S bonds in methyl parathion and the hydrolyzed product are oxidized to P=O bonds by Mn(III) generated by the reaction system → The hydrolyzed product of methyl parathion and methyl paraoxon — p-nitrophenol are oxidized eventually through a series of reactions. The transformation path of methyl parathion and methyl paraoxon in the reaction system of δ-MnO₂/Oxalic acid is as follows: The two OPPs are hydrolyzed by SN@P and SN@C substitution reactions in the reaction of δ-MnO₂ and oxalic acid → The nitro (-NO₂) in methyl parathion and methyl paraoxon and their hydrolyzed products are reduced to amino (-NH₂).