Use of Cl and C Isotopic Fractionation to Identify Degradation and Sources of Polychlorinated Phenols: Mechanistic Study and Field Application
Use of Cl and C Isotopic Fractionation to Identify Degradation and Sources of Polychlorinated Phenols: Mechanistic Study and Field Application
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DOI：
10.1021/es303343u
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发表时间：
2013-01-15
影响因子：
11.4
通讯作者：
Gustafsson, Orjan
中科院分区：
文献类型：
--
作者：
Aeppli, Christoph;Tysklind, Mats;Gustafsson, Orjan
氯化苯酚(CPS)作为木材防腐剂的广泛使用导致了大量受污染的锯木厂场地。然而，评估CPS的原位降解程度仍然具有挑战性。我们评估了使用化合物特有的氯和碳同位素分析(Cl-和C-CSLA)来评估CP的生物转化。在实验室系统中，我们测量了具有代表性的土壤酶(烟熏氯过氧化物酶、辣根过氧化物酶和杂色木霉漆酶)氧化脱氯2，4，6-三氯苯酚过程中的同位素分馏。通过建立数学模型，验证了瑞利法评价表观动力学同位素效应(Akie)的有效性。所有三种酶都观察到一个很小但很明显的Cl-Akie为1.0022+/-0.0006，这与通过阳离子自由基物种的反应途径一致。对于碳，观察到了轻微的反同位素效应(C-Akie=0.9945+/-0.0019)。这种分馏行为与已报道的还原脱氯机理明显不同。根据这些结果，我们随后评估了降解情况，并对两个前锯木厂场地使用的不同类型的技术CP混合物进行了分配。据我们所知，这是第一次利用二元素CSIA研究环境中CPS的来源和转化。
The widespread use of chlorinated phenols (CPs) as a wood preservative has led to numerous contaminated sawmill sites. However, it remains challenging to assess the extent of in situ degradation of CPs. We evaluated the use of compound-specific chlorine and carbon isotope analysis (Cl- and C-CSLA) to assess CP biotransformation. In a laboratory system, we measured isotopic fractionation during oxidative 2,4,6-trichlorophenol dechlorination by representative soil enzymes (C. fumago chloroperoxidase, horseradish peroxidase, and laccase from T. versicolor). Using a mathematical model, the validity of the Rayleigh approach to evaluate apparent kinetic isotope effects (AKIE) was confirmed. A small but significant Cl-AKIE of 1.0022 +/- 0.0006 was observed for all three enzymes, consistent with a reaction pathway via a cationic radical species. For carbon, a slight inverse isotope effect was observed (C-AKIE = 0.9945 +/- 0.0019). This fractionation behavior is clearly distinguishable from reported reductive dechlorination mechanisms. Based on these results we then assessed degradation and apportioned different types of technical CP mixtures used at two former sawmill sites. To our knowledge, this is the first study that makes use of two-element CSIA to study sources and transformation of CPs in the environment.