Center for Hydrogeology, University of Neuchâtel, Rue Emile Argand 11, 2009 Neuchâtel, Switzerland.
Water Res. 2011 Oct 1;45(15):4459-69. doi: 10.1016/j.watres.2011.05.040. Epub 2011 Jun 14.
Three independent techniques were used to assess the biodegradation of monoaromatic hydrocarbons and low-molecular weight polyaromatic hydrocarbons in the alluvial aquifer at the site of a former cokery (Flémalle, Belgium). Firstly, a stable carbon isotope-based field method allowed quantifying biodegradation of monoaromatic compounds in situ and confirmed the degradation of naphthalene. No evidence could be deduced from stable isotope shifts for the intrinsic biodegradation of larger molecules such as methylnaphthalenes or acenaphthene. Secondly, using signature metabolite analysis, various intermediates of the anaerobic degradation of (poly-) aromatic and heterocyclic compounds were identified. The discovery of a novel metabolite of acenaphthene in groundwater samples permitted deeper insights into the anaerobic biodegradation of almost persistent environmental contaminants. A third method, microcosm incubations with 13C-labeled compounds under in situ-like conditions, complemented techniques one and two by providing quantitative information on contaminant biodegradation independent of molecule size and sorption properties. Thanks to stable isotope labels, the sensitivity of this method was much higher compared to classical microcosm studies. The 13C-microcosm approach allowed the determination of first-order rate constants for 13C-labeled benzene, naphthalene, or acenaphthene even in cases when degradation activities were only small. The plausibility of the third method was checked by comparing 13C-microcosm-derived rates to field-derived rates of the first approach. Further advantage of the use of 13C-labels in microcosms is that novel metabolites can be linked more easily to specific mother compounds even in complex systems. This was achieved using alluvial sediments where 13C-acenaphthyl methylsuccinate was identified as transformation product of the anaerobic degradation of acenaphthene.
采用三种独立技术评估了前炼焦厂（比利时弗拉芒勒）冲积含水层中单环芳烃和低分子量多环芳烃的生物降解情况。首先，基于稳定碳同位素的现场方法可定量原位测定单环芳烃化合物的生物降解情况，并证实萘的降解。稳定同位素位移未提供证据表明较大分子如甲基萘或苊的内在生物降解。其次，采用特征代谢物分析，鉴定了（多）芳烃和杂环化合物厌氧降解的各种中间产物。在地下水样本中发现了苊的一种新型代谢物，可深入了解几乎持久存在的环境污染物的厌氧生物降解。第三种方法是在类似于原位的条件下用 13C 标记化合物进行微宇宙培养，通过提供与分子大小和吸附特性无关的污染物生物降解的定量信息，补充了技术 1 和 2。由于稳定同位素标记，与传统微宇宙研究相比，该方法的灵敏度要高得多。13C-微宇宙方法可测定 13C 标记苯、萘或苊的一级速率常数，即使降解活性很小也是如此。通过将 13C-微宇宙衍生的速率与第一种方法的现场衍生的速率进行比较，可以检查第三种方法的合理性。在微宇宙中使用 13C 标记的另一个优点是，即使在复杂系统中，也可以更容易地将新型代谢物与特定的母体化合物联系起来。这是在冲积沉积物中实现的，在那里，13C-苊基甲基琥珀酸被鉴定为苊厌氧降解的转化产物。
