State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China; School of Environmental Studies, China University of Geosciences, Wuhan 430074, China; Laboratory of Basin Hydrology and Wetland Eco-restoration, China University of Geosciences, Wuhan 430074, China.
State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China; School of Environmental Studies, China University of Geosciences, Wuhan 430074, China.
J Hazard Mater. 2016 May 5;308:187-91. doi: 10.1016/j.jhazmat.2016.01.044. Epub 2016 Jan 21.
Understanding the magnitude and variability in isotope fractionation with respect to specific processes is crucial to the application of stable isotopic analysis as a tool to infer and quantify transformation processes. The variability of carbon isotope fractionation during Fenton-like degradation of trichloroethene (TCE) in the presence of different inorganic ions (nitrate, sulfate, and chloride), was investigated to evaluate the potential effects of inorganic anions on carbon isotope enrichment factor (ε value). A comparison of ε values obtained in deionized water, nitrate solution, and sulfate solution demonstrated that the ε values were identical and not affected by the presence of nitrate and sulfate. In the presence of chloride, however, the ε values (ranging from -6.3±0.8 to 10±1.3‰) were variable and depended on the chloride concentration, indicating that chloride could significantly affect carbon isotope fractionation during Fenton-like degradation of TCE. Thus, caution should be exercised in selecting appropriate ε values for the field application of stable isotope analysis, as various chloride concentrations may be present due to naturally present or introduced with pH adjustment and iron salts during Fenton-like remediation. Furthermore, the effects of chloride on carbon isotope fractionation may be able to provide new insights about reaction mechanisms of Fenton-like processes.
了解特定过程中同位素分馏的幅度和可变性对于将稳定同位素分析作为推断和量化转化过程的工具的应用至关重要。本研究考察了芬顿样降解三氯乙烯（TCE）过程中不同无机离子（硝酸盐、硫酸盐和氯离子）存在时碳同位素分馏的变化，以评估无机阴离子对碳同位素富集因子（ε 值）的潜在影响。在去离子水、硝酸盐溶液和硫酸盐溶液中获得的 ε 值的比较表明，ε 值相同，不受硝酸盐和硫酸盐的存在影响。然而，在氯离子存在的情况下，ε 值（范围为-6.3±0.8 至 10±1.3‰）是可变的，并且取决于氯离子浓度，这表明氯离子可能会显著影响芬顿样降解 TCE 过程中的碳同位素分馏。因此，在稳定同位素分析的现场应用中选择合适的 ε 值时应谨慎，因为由于自然存在或在芬顿修复过程中 pH 调节和铁盐引入，可能存在各种氯离子浓度。此外，氯离子对碳同位素分馏的影响可能能够为芬顿样过程的反应机制提供新的见解。
