Atrazine is a frequently detected groundwater contaminant. It can be microbially degraded by oxidative dealkylation or by hydrolytic dechlorination. Compound-specific isotope analysis is a powerful tool to assess its transformation. In previous work, carbon and nitrogen isotope effects were found to reflect these different transformation pathways. However, chlorine isotope fractionation could be a particularly sensitive indicator of natural transformation since chlorine isotope effects are fully represented in the molecular average while carbon and nitrogen isotope effects are diluted by non-reacting atoms. Therefore, this study explored chlorine isotope effects during atrazine hydrolysis with Arthrobacter aurescens TC1 and oxidative dealkylation with Rhodococcus sp. NI86/21. Dual element isotope slopes of chlorine vs. carbon isotope fractionation (ΛArthroCl/C = 1.7 ± 0.9 vs. ΛRhodoCl/C = 0.6 ± 0.1) and chlorine vs. nitrogen isotope fractionation (ΛArthroCl/N = -1.2 ± 0.7 vs. ΛRhodoCl/N = 0.4 ± 0.2) provided reliable indicators of different pathways. Observed chlorine isotope effects in oxidative dealkylation (εCl = -4.3 ± 1.8‰) were surprisingly large, whereas in hydrolysis (εCl = -1.4 ± 0.6‰) they were small, indicating that C-Cl bond cleavage was not the rate-determining step. This demonstrates the importance of constraining expected isotope effects of new elements before using the approach in the field. Overall, the triple element isotope information brought forward here enables a more reliable identification of atrazine sources and degradation pathways.

中文翻译：

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at去津生物降解中化合物特异性的氯同位素分级分离。

阿特拉津是一种经常被发现的地下水污染物。它可以通过氧化脱烷基或水解脱氯进行微生物降解。化合物特异性同位素分析是评估其转化的有力工具。在以前的工作中，发现碳和氮同位素效应反映了这些不同的转化途径。但是，氯同位素分馏可能是自然转化的一个特别敏感的指标，因为氯同位素效应在分子平均值中得到了充分体现，而碳和氮同位素效应则被未反应的原子稀释了。因此，本研究探讨了用金节杆菌TC1水解at去津和氯红球菌sp氧化脱烷基过程中氯同位素的作用。NI86 / 21。氯的双元素同位素斜率与 碳同位素分馏（ArthroCl / C = 1.7±0.9 vs.ΛRhodoCl/ C = 0.6±0.1）和氯vs.氮同位素分馏（ΛArthroCl/ N = -1.2±0.7 vs.ΛRhodoCl/ N = 0.4±0.2）提供了可靠的指标不同的途径。氧化脱烷基反应中观察到的氯同位素效应（εCl= -4.3±1.8‰）出乎意料地大，而在水解反应（εCl= -1.4±0.6‰）中则很小，表明C-Cl键断裂不是决定速率的步骤。这证明了在现场使用该方法之前限制新元素的预期同位素效应的重要性。总体而言，此处提出的三元素同位素信息可以更可靠地鉴定at去津来源和降解途径。氮同位素分馏（ΛArthroCl / N = -1.2±0.7相对于ΛRhodoCl/ N = 0.4±0.2）提供了不同途径的可靠指标。氧化脱烷基反应中观察到的氯同位素效应（εCl= -4.3±1.8‰）出乎意料地大，而在水解反应（εCl= -1.4±0.6‰）中则很小，表明C-Cl键断裂不是决定速率的步骤。这证明了在现场使用该方法之前限制新元素的预期同位素效应的重要性。总体而言，此处提出的三元素同位素信息可以更可靠地鉴定at去津来源和降解途径。氮同位素分馏（ΛArthroCl / N = -1.2±0.7相对于ΛRhodoCl/ N = 0.4±0.2）提供了不同途径的可靠指标。氧化脱烷基反应中观察到的氯同位素效应（εCl= -4.3±1.8‰）出乎意料地大，而在水解反应（εCl= -1.4±0.6‰）中则很小，表明C-Cl键断裂不是决定速率的步骤。这证明了在现场使用该方法之前限制新元素的预期同位素效应的重要性。总体而言，此处提出的三元素同位素信息可以更可靠地鉴定at去津来源和降解途径。而在水解过程中（εCl= -1.4±0.6‰）它们很小，表明C-Cl键的裂解不是决定速率的步骤。这证明了在现场使用该方法之前限制新元素的预期同位素效应的重要性。总体而言，此处提出的三元素同位素信息可以更可靠地鉴定at去津来源和降解途径。而在水解过程中（εCl= -1.4±0.6‰）它们很小，表明C-Cl键的裂解不是决定速率的步骤。这证明了在现场使用该方法之前限制新元素的预期同位素效应的重要性。总体而言，此处提出的三元素同位素信息可以更可靠地鉴定at去津来源和降解途径。