Surface Mediated Transformation of Pesticides

矿物-水界面强烈影响土壤环境的整体地球化学。矿物质为有机和无机溶质、胶体或微生物的吸附提供反应性表面，而且还促进山梨酸盐的水解或电子转移反应。与非极性相反，过去的现代有机农用化学品的疏水农药通常是高度官能化的。对于这些农药，与矿物表面的特定相互作用有助于甚至可能主导其在土壤中的命运。拟议的研究的总体目标是阐明的矿物表面（氧化物，粘土）的影响，代表那些存在于A和B层的天然土壤表面介导的农药的热化学反应的机械基础。为此，我们选择了一组农药（环酰菌胺、苯达松、甲霜灵），这些农药含有现代农用化学品典型的反应性结构特征。更具体地说，我们建议在实验室批量模型系统中评估在何种程度上吸附和/或与矿物表面的相互作用i）影响农药水解的速率，反应机制和产物谱。ii）可能是立体选择性的，因此可能影响手性农药的转化速率和产物谱（异构体比率）除了水解，我们还将考虑iii）农药中存在的氨基部分的表面介导的氧化转化反应和iv）农药中存在的硫部分的表面介导的还原转化反应。我们期望本研究的结果将有助于预测非生物转化反应的意义，农药在土壤中的整体降解速率和机制。

The mineral-water interface strongly influences the overall biogeochemistry of soil environments. Minerals provide reactive surfaces for the adsorption of organic and inorganic solutes, colloids or microorganisms, but also facilitate hydrolysis or electron transfer reactions of the sorbates. In contrast to non-polar, hydrophobic pesticides of the past modern organic agrochemicals typically are highly functionalized. For such pesticides, specific interactions with mineral surfaces contribute to or even may dominate their fate in soils. The overall goal of the proposed research is to elucidate on a mechanistic basis the effects of mineral surfaces (oxides, clays) representative of those present in A and B horizons of natural soils on surface mediated thermochemical reactions of pesticides. To this end, we have chosen a set of pesticides (Fenhexamid, Bentazone, Metalaxyl) that contain reactive structural features typical for modern agrochemicals. More specifically, we propose to evaluate in laboratory batch model systems to what extent sorption to and/or interactions with mineral surfaces i) affects the rates, reaction mechanisms and product spectrum of pesticide hydrolysis. ii) may be stereoselective and thus may affect the transformation rates and the product spectrum (isomer ratios) of chiral pesticides Besides hydrolysis , we will also consider iii) surface mediated oxidative transformation reactions of amino moieties present in pesticides and iv) surface mediated reductive transformation reactions of sulfur moieties present in pesticides. We expect that the results of this research will help to predict the significance of abiotic transformation reactions to the overall degradation rates and mechanisms of pesticides in soil.