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.

生物地球化学界面对于有机农药的阻滞和消除发挥着关键作用：（i）作为保留的吸附介质； (ii) 通过藏匿促进降解的微生物。在没有质量平衡的情况下，在自然条件下追踪这些过程是很困难的。特别值得关注的是极性和阴离子农药，因为它们具有很高的流动性。该提案旨在为更好地理解流程提供两项重要的新贡献，每一项都集中在一名博士论文中。项目：(1) 测量化合物特异性 13C 和 15N 同位素分馏，以研究农药的吸附和降解。我们将首次 (a) 测量苯达松和二甲氯苯与降解相关的同位素分馏，作为检测它们在自然系统中转化的新方法； (b) 利用苯达松的中性和阴离子形式之间的同位素效应来直接表征哪种形式（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) 与切割相结合的柱研究- 边缘数学模型，用于评估固定水对吸附和降解的作用。我们的目的是测试以下假设：(a) 当更多物质存在于不流动的（=停滞的、近地表）水中时，农药的表面相互作用更加明显；(b) 在不饱和条件下这一比例更大。为此，(i) 不同含水量下的示踪剂测试（3H、溴化物）将量化不同饱和度下流动水与固定水的比例； (ii) 将开发一种先进的数学模型，包括不动水区域的慢速、不可逆吸附和快速吸附平衡，以首次描述不动水对农药吸附和降解的影响。