Utrecht University, Princetonplein 9, Utrecht 3584 CC, Netherlands; Deltares, Princetonlaan 8, Utrecht 3584 CB, Netherlands.
Utrecht University, Princetonplein 9, Utrecht 3584 CC, Netherlands; KWR Water Cycle Research Institute, Groningenhaven 7, Nieuwegein 3433 PE, Netherlands.
Sci Total Environ. 2020 Jun 20;722:137797. doi: 10.1016/j.scitotenv.2020.137797. Epub 2020 Mar 8.
Source zones containing tar, a dense non-aqueous phase liquid (DNAPL), can contaminate groundwater for centuries. A common occurrence of tar is at former Pintsch gas factories. Little is known about the composition and fate of contaminants dissolving from Pintsch gas tar DNAPL. In this study, we determined the composition and water-soluble characteristics of mobile aromatic hydrocarbons and their biodegradation metabolites in the DNAPL contaminated groundwater at a former Pintsch gas tar plant. We assessed the factors that determine the fate of observed groundwater contaminants. Measured values of density (1.03-1.06 kg/m) and viscosity (18.6-39.4 cP) were found to be relatively low compared to common coal tars. Analysis showed that unlike common coal tars phenanthrene is the primary component rather than naphthalene. Moreover, it was found that Pintsch gas tar contains a relatively high amount of light molecular aromatic hydrocarbon compounds, such as benzene, toluene, ethylbenzene and xylenes (BTEX). Less commonly reported components, such as styrene, ethyltoluenes, di-ethylbenzene, 1,2,4,5-tetramethylbenzene, were also detected in water extracts from Pintsch gas tar. Moreover, 46 relatively hydrophilic metabolites were found within the tar samples. Metabolites present within the tar suggest biodegradation of mobile aromatic Pintsch gas tar compounds occurred near the DNAPL. Based on eleven detected suspect metabolites, a novel anaerobic biodegradation pathway is proposed for indene. Overall, our findings indicate that Pintsch gas tar has higher invasive and higher flux properties than most coal tars due to its relatively low density, low viscosity and, high content of water-soluble compounds. The partitioning of contaminants from multi-component DNAPL into the aqueous phase and re-dissolution of their slightly less hydrophobic metabolites back from the aqueous phase into the DNAPL is feasible and demonstrates the complexity of assessing degradation processes within a source zone.
含焦油（一种致密非水相液体（DNAPL））的源区可能会污染地下水数百年。焦油的常见污染源是前 Pintsch 煤气厂。关于从 Pintsch 煤气焦油 DNAPL 中溶解的污染物的组成和命运，人们知之甚少。在这项研究中，我们确定了前 Pintsch 煤气焦油厂污染地下水中可移动芳烃及其生物降解代谢物的组成和水溶性特征。我们评估了决定观察到的地下水污染物命运的因素。与常见的煤焦油相比，测量得到的密度（1.03-1.06 kg/m）和粘度（18.6-39.4 cP）相对较低。分析表明，不同于常见的煤焦油，菲是主要成分而不是萘。此外，还发现 Pintsch 煤气焦油含有相对较高量的轻分子芳烃化合物，如苯、甲苯、乙苯和二甲苯（BTEX）。较少报道的成分，如苯乙烯、乙基甲苯、二乙基苯、1,2,4,5-四甲苯，也在从 Pintsch 煤气焦油中提取的水提取物中检测到。此外，在焦油样品中还发现了 46 种相对亲水的代谢物。焦油中存在的代谢物表明，靠近 DNAPL 的可移动芳烃 Pintsch 煤气焦油化合物发生了生物降解。基于检测到的 11 种可疑代谢物，提出了茚的一种新型厌氧生物降解途径。总的来说，我们的研究结果表明，由于相对较低的密度、较低的粘度和较高的水溶性化合物含量，Pintsch 煤气焦油比大多数煤焦油具有更高的侵入性和更高的通量特性。多组分 DNAPL 中的污染物分配到水相，以及其疏水性稍低的代谢物从水相重新溶解到 DNAPL 中，是可行的，这表明在源区评估降解过程的复杂性。
