Department of Agronomy, Purdue University, West Lafayette, IN 47907-2054, USA.
Department of Agronomy, Purdue University, West Lafayette, IN 47907-2054, USA.
Chemosphere. 2016 Feb;144:2482-8. doi: 10.1016/j.chemosphere.2015.11.021. Epub 2015 Dec 6.
Aerobic soil biodegradation of toluene-2,4-di(8:2 fluorotelomer urethane) (FTU) and hexamethylene-1,6-di(8:2 fluorotelomer urethane) (HMU) in a forest soil and FTU in an agricultural silty clay loam soil was monitored for up to 6 months. Fluorotelomer alcohols were measured in headspace and parent monomers and all metabolites in soil extracts. Negligible degradation of FTU biodegradation occurred in the agricultural soil with 94 ± 15% recovered at day 180. However, in the forest soil, both FTU and HMU degradation was evident with significant losses of 24% (117 d) and 27% (180 day), respectively, and concomitant increases in the terminal metabolite, perfluorooctanoic acid (PFOA) concentrations were well above what could result from residual 8:2 FTOH. Kinetic modeling estimated half-lives for FTU (aromatic backbone) and HMU (aliphatic backbone) in the forest soil to be 3-5 months and 15.9-22.2 months, respectively. The addition of a structurally similar non-fluorinated FTU analog, toluene-2,4-dicarbamic acid diethyl ester (TDAEE) enhanced production of terminal end products from 8:2 FTOH degradation. However, there was no clear evidence that TDAEE enhanced cleavage of the urethane bond, thus TDAEE appeared to just serve as an additional carbon source. TDAEE's half-life was ∼ one week. A second addition of TDAEE appeared to retard subsequent degradation of FTU exemplifying the microbial dynamics and diversity impacting degradation of polyfluoroalkyl substances. Enhanced degradation of HMU was observed upon re-aeration indicating oxygen may have been limiting during some periods although degradation of intermediate metabolites to terminal metabolites was still occurring, albeit at slower rates.
在森林土壤中监测了甲苯-2,4-双（8:2 氟代四氢呋喃基）脲（FTU）和六亚甲基-1,6-双（8:2 氟代四氢呋喃基）脲（HMU）的有氧土壤生物降解，以及在农业粉质粘壤土中 FTU 的生物降解，最长可达 6 个月。在顶空和母体单体中测量了氟代四氢呋喃醇，并在土壤提取物中测量了所有代谢物。在农业土壤中，FTU 生物降解几乎没有发生，在 180 天回收了 94±15%。然而，在森林土壤中，FTU 和 HMU 的降解都很明显，分别损失了 24%（117 天）和 27%（180 天），并且末端代谢物全氟辛酸（PFOA）的浓度显著增加，远高于残留 8:2 FTOH 所致的浓度。动力学模型估计 FTU（芳环骨架）和 HMU（脂肪族骨架）在森林土壤中的半衰期分别为 3-5 个月和 15.9-22.2 个月。添加结构相似的非氟代 FTU 类似物，甲苯-2,4-二氨基甲酸二乙酯（TDAEE），增强了 8:2 FTOH 降解产生末端产物的能力。然而，没有明显证据表明 TDAEE 增强了氨基甲酸酯键的断裂，因此 TDAEE 似乎只是作为额外的碳源。TDAEE 的半衰期约为一周。第二次添加 TDAEE 似乎会延缓 FTU 的后续降解，这说明了微生物动力学和多样性对全氟烷基物质降解的影响。重新通气后观察到 HMU 的降解增强，表明在某些时期可能缺氧，尽管中间代谢物向末端代谢物的降解仍在继续，但速度较慢。
