Chu Kung-Hui, Mahendra Shaily, Song Donald L, Conrad Mark E, Alvarez-Cohen Lisa
Department of Civil and Environmental Engineering, 110B Perkins Hall, University of Tennessee, Knoxville, Tennessee 37996-2010, USA.
Environ Sci Technol. 2004 Jun 1;38(11):3126-30. doi: 10.1021/es035238c.
Stable isotope analysis is recognized as a powerful tool for monitoring, assessing, and validating in-situ bioremediation processes. In this study, kinetic carbon isotope fractionation factors (epsilon) associated with the aerobic biodegradation of vinyl chloride (VC), cis-1,2-dichloroethylene (cDCE), and trichloroethylene (TCE) were examined. Of the three solvents, the largest fractionation effects were observed for biodegradation of VC. Both metabolic and cometabolic VC degradation were studied using Mycobacterium aurum L1 (grown on VC), Methylosinus trichosporium OB3b (grown on methane), Mycobacterium vaccae JOB5 (grown on propane), and two VC enrichment cultures seeded from contaminated soils of Alameda Point and Travis Air Force Base, CA. M. aurum L1 caused the greatest fractionation (epsilon = -5.7) while for the cometabolic cultures, epsilon values ranged from -3.2 to -4.8. VC fractionation patterns for the enrichment cultures were within the range of those observed for the metabolic and cometabolic cultures (epsilon = -4.5 to -5.5). The fractionation for cometabolic degradation of TCE by Me. trichosporium OB3b was low (epsilon = -1.1), while no quantifiable carbon isotopic fractionation was observed during the cometabolic degradation of cDCE. For all three of the tested chlorinated ethenes, isotopic fractionation measured during aerobic degradation was significantly smaller than that reported for anaerobic reductive dechlorination. This study suggests that analysis of compound-specific isotopic fractionation could assist in determining whether aerobic or anaerobic degradation of VC and cDCE predominates in field applications of in-situ bioremediation. In contrast, isotopic fractionation effects associated with metabolic and cometabolic reactions are not sufficiently dissimilar to distinguish these processes in the field.
稳定同位素分析被认为是监测、评估和验证原位生物修复过程的有力工具。在本研究中，研究了与氯乙烯（VC）、顺式-1,2-二氯乙烯（cDCE）和三氯乙烯（TCE）的好氧生物降解相关的动力学碳同位素分馏因子（ε）。在这三种溶剂中，观察到VC生物降解的分馏效应最大。使用金黄色分枝杆菌L1（在VC上生长）、嗜甲基孢囊菌OB3b（在甲烷上生长）、母牛分枝杆菌JOB5（在丙烷上生长）以及从加利福尼亚州阿拉米达角和特拉维斯空军基地受污染土壤中接种的两种VC富集培养物，对代谢和共代谢VC降解进行了研究。金黄色分枝杆菌L1引起的分馏最大（ε = -5.7），而对于共代谢培养物，ε值范围为-3.2至-4.8。富集培养物的VC分馏模式在代谢和共代谢培养物观察到的范围内（ε = -4.5至-5.5）。嗜甲基孢囊菌OB3b对TCE共代谢降解的分馏较低（ε = -1.1），而在cDCE共代谢降解过程中未观察到可量化的碳同位素分馏。对于所有三种测试的氯代乙烯，好氧降解过程中测量的同位素分馏明显小于厌氧还原脱氯报道的分馏。本研究表明，化合物特异性同位素分馏分析有助于确定在原位生物修复的现场应用中，VC和cDCE的好氧或厌氧降解是否占主导。相比之下，与代谢和共代谢反应相关的同位素分馏效应差异不足以在现场区分这些过程。
