Institute of Groundwater Ecology, Helmholtz Zentrum Munchen - German Research Center for Environmental Health, Ingolstadter Landstrasse 1, Neuherberg, Germany.
Environ Sci Technol. 2010 Apr 1;44(7):2372-8. doi: 10.1021/es9031858.
The fate of pesticides in the subsurface is of great interest to the public, industry, and regulatory authorities. Compound-specific isotope analysis (CSIA) is a promising tool complementary to existing methods for elucidating pesticide degradation reactions. Here, we address three different initial biotransformation reactions of the phenylurea herbicide isoproturon (3-(4-isopropylphenyl)-1,1-dimethylurea) in pure culture experiments with bacterial and fungal strains. When analyzing isotopic changes in different parts of the isoproturon molecule, hydroxylation of the isopropyl group by fungi was found to be associated with C and H isotope fractionation. In contrast, hydrolysis by Arthrobacter globiformis D47 caused strong C and N isotope fractionation, albeit in a different manner than abiotic hydrolysis so that isotope measurements can distinguish between both modes of transformation. No significant isotope fractionation was observed during N-demethylation by Sphingomonas sp. SRS2. The observed isotope fractionation patterns were in agreement with the type of reactions and elements involved. Moreover, their substantially different nature suggests that isotope changes in natural samples may be uniquely attributed to either pathway, allowing even to distinguish the abiotic versus biotic nature of hydrolysis. Our investigations show how characteristic isotope patterns may significantly add to the present understanding of the environmental fate of pesticides.
地下水中农药的命运引起了公众、工业界和监管机构的极大兴趣。化合物特异性同位素分析（CSIA）是一种很有前途的工具，可以补充现有方法，用于阐明农药降解反应。在这里，我们在纯培养实验中研究了苯基脲类除草剂异丙隆（3-（4-异丙基苯基）-1,1-二甲基脲）的三种不同初始生物转化反应，涉及细菌和真菌菌株。在分析异丙隆分子不同部位的同位素变化时，发现真菌的异丙基羟化与 C 和 H 同位素分馏有关。相比之下，球形节杆菌 D47 的水解导致强烈的 C 和 N 同位素分馏，尽管与非生物水解的方式不同，因此同位素测量可以区分两种转化模式。在 Sphingomonas sp. SRS2 进行的 N-脱甲基过程中没有观察到明显的同位素分馏。观察到的同位素分馏模式与涉及的反应和元素类型一致。此外，它们性质的显著差异表明，天然样品中的同位素变化可能仅归因于任一途径，甚至可以区分水解的非生物和生物性质。我们的研究表明，特征性的同位素模式如何极大地增加了对农药环境命运的现有理解。
