Environmental Chemistry and Technology Program, University of Wisconsin─Madison, Madison, Wisconsin 53706, United States.
Department of Civil and Environmental Engineering, University of Wisconsin─Madison, Madison, Wisconsin 53706, United States.
Environ Sci Technol. 2023 Aug 22;57(33):12421-12430. doi: 10.1021/acs.est.3c03343. Epub 2023 Aug 8.
Predicting the fate of organic compounds in the environment is challenging due to the inability of laboratory studies to replicate field conditions. We used the intentionally applied aquatic herbicide florpyrauxifen-benzyl (FPB) as a model compound to investigate the contribution of multiple transformation pathways to organic compound fate in lakes. FPB persisted in five Wisconsin lakes for 5-7 days with an in-lake half-life of <2 days. FPB formed four transformation products, with the bioactive product florpyrauxifen persisting up to 30 days post-treatment. Parallel laboratory experiments showed that FPB degrades to florpyrauxifen via base-promoted hydrolysis. Hydroxy-FPB and hydroxy-florpyrauxifen were identified as biodegradation products, while dechloro-FPB was identified as a photoproduct. Material balance calculations using both laboratory rates and field product concentrations demonstrated that hydrolysis (∼47% of loss), biodegradation (∼20%), sorption (∼13%), and photodegradation (∼4%) occurred on similar timescales. Furthermore, the combined results demonstrated that abiotic and plant-catalyzed hydrolysis of FPB to florpyrauxifen, followed by biodegradation of florpyrauxifen to hydroxy-florpyrauxifen, was the dominant transformation pathway in lakes. This study demonstrates how combined field and laboratory studies can be used to elucidate the role of simultaneous and interacting pathways in the fate of organic compounds in aquatic environments.
由于实验室研究无法复制野外条件，因此预测有机化合物在环境中的命运具有挑战性。我们使用故意施加的水生除草剂氟吡草腙-苄基（FPB）作为模型化合物，研究了多种转化途径对湖泊中有机化合物命运的贡献。FPB 在威斯康星州的五个湖泊中持续存在了 5-7 天，其湖泊内半衰期<2 天。FPB 形成了四种转化产物，其中生物活性产物氟吡草腙在施药后可持续 30 天。平行的实验室实验表明，FPB 通过碱基促进水解转化为氟吡草腙。羟基-FPB 和羟基-氟吡草腙被鉴定为生物降解产物，而脱氯-FPB 被鉴定为光产物。使用实验室速率和野外产物浓度进行的物质平衡计算表明，水解（约 47%的损失）、生物降解（约 20%）、吸附（约 13%）和光降解（约 4%）发生在相似的时间范围内。此外，综合结果表明，FPB 在无机组分和植物催化下水解生成氟吡草腙，随后氟吡草腙生物降解生成羟基-氟吡草腙，是湖泊中有机化合物转化的主要途径。本研究展示了如何结合野外和实验室研究来阐明同时发生和相互作用的途径在水生环境中有机化合物命运中的作用。
