Federal Institute of Hydrology, Department of Aquatic Chemistry, 56068, Koblenz, Germany.
Federal Institute of Hydrology, Department of Aquatic Chemistry, 56068, Koblenz, Germany.
Water Res. 2020 May 1;174:115561. doi: 10.1016/j.watres.2020.115561. Epub 2020 Jan 30.
Glucocorticoids (GCs) are one of the most prescribed pharmaceutical classes worldwide. They have reached the focus as environmental pollutants in the current scientific research, due to their potential risks to aquatic organisms even in the lower ng L range. The objective of this study was to determine the kinetic behavior of selected GCs and to identify their main transformation products (TPs) in lab scaled biodegradation experiments. Therefore, we analyzed the removal of 13 GCs in aerated incubation experiments with activated sludge taken from a German municipal wastewater treatment plant (WWTP) as inoculum. For all steroids, an exponential decrease of the concentrations was observed, which was modelled by pseudo-first order kinetics. Overall, the rate constants k ranged from 0.07 L g d (triamcinolone acetonide) to 250 L g d (prednisolone). These results emphasize the broad variation in the biodegradability and recalcitrance of certain GCs. The selection of the studied GCs enabled a deduction of microbiological stability related to functional groups. Based on the identified TPs, a variety of enzymatically mediated reactions were postulated. Moreover, the identified TPs are characterized by an intact steroid core structure. Thus residual endocrine activity cannot be ruled out. The main observed reactions were regioselective hydrogenation of carbon double-bonds, degradation of the steroid C17 side-chain, ester hydrolysis and oxidative hydroxylation. In total, 41 TPs were tentatively identified and 22 of them were unambiguously confirmed via reference standards. Additionally, 12 TPs were detected in the effluents of municipal WWTPs and, to the best of our knowledge, the occurrence of eight of these TPs has been shown for the first time. These TPs might significantly contribute to the detected residual endocrine activities in the aquatic environments. Therefore, there is a strong need for efficient removal strategies, in particular for persistent steroid hormones with elevated potencies.
糖皮质激素（GCs）是全球应用最广泛的药物类别之一。由于其即使在较低的纳克/升范围内也可能对水生生物造成潜在风险，因此在当前的科学研究中，它们已成为环境污染物的焦点。本研究的目的是确定选定 GCs 的动力学行为，并在实验室规模的生物降解实验中鉴定其主要转化产物（TPs）。因此，我们分析了以德国城市污水处理厂（WWTP）活性污泥为接种物的充气培养实验中 13 种 GCs 的去除情况。对于所有类固醇，均观察到浓度呈指数下降，通过拟一级动力学模型进行了建模。总体而言，速率常数 k 范围从 0.07 L g d（曲安奈德乙缩醛）到 250 L g d（泼尼松龙）。这些结果强调了某些 GCs 的生物降解性和难降解性的广泛差异。所选 GC 的研究使与功能基团相关的微生物稳定性得以推断。根据鉴定出的 TPs，推测出多种酶介导的反应。此外，鉴定出的 TPs 具有完整的甾体核心结构。因此，不能排除残留的内分泌活性。主要观察到的反应是碳双键的区域选择性加氢、甾体 C17 侧链的降解、酯水解和氧化羟化。总共暂定鉴定了 41 种 TPs，其中 22 种通过参比标准得到明确确认。此外，在城市 WWTP 的废水中检测到 12 种 TPs，据我们所知，其中 8 种 TPs 的出现尚属首次。这些 TPs 可能会显著促进水生环境中检测到的残留内分泌活性。因此，迫切需要有效的去除策略，特别是对于具有较高效力的持久性甾体激素。
