Department of Lake Research, UFZ - Helmholtz Centre for Environmental Research, Brückstraße 3a, 39114 Magdeburg, Germany.
Department of Environmental Microbiology, UFZ - Helmholtz Centre for Environmental Research, Permoserstraße 15, 04318 Leipzig, Germany.
Chemosphere. 2015 Nov;138:133-9. doi: 10.1016/j.chemosphere.2015.05.068. Epub 2015 Jun 8.
The extraction of bitumen from oil sands in Alberta (Canada) produces volumes of tailings that are pumped into large anaerobic settling-basins. Beside bitumen, tailings comprise fractions of benzene, toluene, ethylbenzene and xylenes (BTEX) that derive from the application of industrial solvents. Due to their toxicity and volatility, BTEX pose a strong concern for gas- and water-phase environments in the vicinity of the ponds. The examination of two pond profiles showed that concentrations of indigenous BTEX decreased with depth, pointing at BTEX transformation in situ. With depth, the relative contribution of ethylbenzene and xylenes to total BTEX significantly decreased, while benzene increased relatively from 44% to 69%, indicating preferential hydrocarbon degradation. To predict BTEX turnover and residence time, we determined BTEX degradation rates in tailings of different depths in a 180-days microcosm study. In addition, we evaluated the impact of labile organic substrates (e.g. acetate) generally considered to stimulate hydrocarbon degradation and the contribution of sulfate-reducing bacteria (SRB) to BTEX turnover. In all depths, BTEX concentrations significantly decreased due to microbial activity, with degradation rates ranging between 4 and 9 μg kg(-1) d(-1). BTEX biodegradation decreased linearly in correlation with initial concentrations, suggesting a concentration-dependent BTEX transformation. SRB were not significantly involved in BTEX consumption, indicating the importance of methanogenic degradation. BTEX removal decreased to 70-90% in presence of organic substrates presumptively due to an accumulation of acetate that lowered BTEX turnover due to product inhibition. In those assays SRB slightly stimulated BTEX transformation by reducing inhibitory acetate levels.
从加拿大阿尔伯塔省的油砂中提取沥青会产生大量的尾矿，这些尾矿被泵入大型厌氧沉降池中。除了沥青，尾矿中还含有苯、甲苯、乙苯和二甲苯（BTEX）等工业溶剂的馏分。由于 BTEX 的毒性和挥发性，它们对池塘附近的气相与水相环境构成了强烈的威胁。对两个池塘剖面的研究表明，土著 BTEX 的浓度随深度的增加而降低，这表明 BTEX 在原位发生了转化。随着深度的增加，乙苯和二甲苯在总 BTEX 中的相对贡献显著降低，而苯的相对含量从 44%增加到 69%，表明优先降解了烃类化合物。为了预测 BTEX 的周转和停留时间，我们在 180 天的微宇宙研究中确定了不同深度尾矿中的 BTEX 降解速率。此外，我们评估了通常被认为能刺激烃类降解的易生物降解有机底物（如乙酸盐）的影响，以及硫酸盐还原菌（SRB）对 BTEX 周转的贡献。在所有深度下，由于微生物的活性，BTEX 浓度都显著降低，降解速率在 4 到 9μgkg(-1)d(-1)之间。BTEX 的生物降解与初始浓度呈线性相关，表明 BTEX 的转化与浓度有关。SRB 并没有显著参与 BTEX 的消耗，这表明了产甲烷降解的重要性。在有有机底物存在的情况下，BTEX 的去除率下降到 70-90%，这可能是由于乙酸盐的积累降低了 BTEX 的周转率，这是由于产物抑制所致。在这些实验中，SRB 通过降低抑制性乙酸盐水平，略微刺激了 BTEX 的转化。
