Elucidating mechanisms of pesticide sorption and degradation by compound specific isotope analysis in conjunction with advanced mathematical transport modelling

通过化合物特定同位素分析结合先进的数学传输模型阐明农药吸附和降解的机制

• 批准号: 40956159
• 负责人: Professor Dr. Martin Elsner
• 金额: --
• 依托单位: Institut für Grundwasserökologie (IGOE) (aufgelöst)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2007
• 资助国家: 德国
• 起止时间: 2006-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/40956159?language=en
• 关键词: Elucidating; mechanisms; pesticide; sorption; degradation

Biogeochemical interfaces play a key role for retardation and elimination of organic pesticides: (i) as sorption medium for retention; (ii) by harbouring microorganisms that facilitate degradation. Tracing these processes under natural conditions in the absence of mass balances is difficult. Of particular concern are polar and anionic pesticides because they are highly mobile. This proposal aims to provide two important, new contributions towards a better process understanding, each focussed in one Ph.D. project:(1) Measurements of compound-specific 13C and 15N isotope fractionation to investigate pesticide sorption and degradation. We will for the first time (a) measure degradation-associated isotope fractionation for bentazone and MCPA, as a new approach to detecting their transformation in natural systems; (b) use the isotope effect between the neutral and anionic form of bentazone to characterize directly which form (neutral versus ionic) is preferentially retained at geochemical surfaces (pure minerals, artificial and natural soils).(2) Column studies in conjunction with cutting-edge mathematical modelling to assess the role of immobile water on sorption and degradation. We aim to test the hypotheses that (a) surface interactions of pesticides are more pronounced when more of the substances are present in immobile (= stagnant, near-surface) water, and (b) that this proportion is greater under unsaturated conditions. To this end, (i) tracer tests (3H, bromide) at different degrees of water content will quantify the proportions of mobile versus immobile water at different degrees of saturation; (ii) an advanced mathematical model including slow, irreversible sorption, and rapid sorption equilibrium in the immobile water zone will be developed to describe for the first time the influence of immobile water on pesticide sorption and degradation.

生物地球化学界面在延缓和消除有机农药方面发挥着关键作用：（i）作为吸附介质进行保留;（ii）通过窝藏促进降解的微生物。在没有质量平衡的自然条件下追踪这些过程是困难的。特别令人关注的是极性和阴离子农药，因为它们具有高度移动的性。该提案旨在为更好地理解过程提供两个重要的新贡献，每个贡献都集中在一个博士学位上。项目：（1）测量化合物特定的13 C和15 N同位素分馏，以研究农药的吸附和降解。我们将首次（a）测量苯达松和2甲4氯的降解相关同位素分馏，作为检测其在自然系统中转化的新方法;（B）利用苯达松中性和阴离子形式之间的同位素效应，直接表征哪种形式（中性与离子）优先保留在地球化学表面（纯矿物、人造和天然土壤）。(2)柱研究结合先进的数学建模，以评估固定水对吸附和降解的作用。我们的目标是测试的假设，（a）农药的表面相互作用是更明显的，当更多的物质存在于不流动（=停滞，近表面）的水，和（B），这一比例是在不饱和条件下更大。为此，（一）在不同程度的水含量的示踪剂测试（3 H，溴化物）将量化的比例移动的与不移动的水在不同程度的饱和;（二）一个先进的数学模型，包括缓慢，不可逆的吸附，快速吸附平衡在不移动的水区将开发描述的影响，第一次不移动的水对农药的吸附和降解。