State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, 400044, China; Department of Environmental Science, Chongqing University, Chongqing, 400044, China.
State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, 400044, China; Department of Environmental Science, Chongqing University, Chongqing, 400044, China.
Environ Pollut. 2021 Jan 1;268(Pt B):115693. doi: 10.1016/j.envpol.2020.115693. Epub 2020 Sep 21.
An increase in polycyclic aromatic hydrocarbon (PAH) pollution poses significant challenges to human and ecosystem health in the Three Gorges Reservoir (TGR) of the Yangtze River. Based on the combination of PAH analysis with qPCR and high-throughput sequencing of bacteria, 32 topsoil samples collected from 16 sites along the TGR were used to investigate the distribution and biodegradation pathways of PAHs in the water-level-fluctuation zone (WLFZ). The results indicated that the concentrations of PAHs were 43.8-228.2 and 30.8-206.3 ng/g soil (dry weight) under the high- and low-water-level (HWL and LWL) conditions, respectively. The PAH concentration in urban areas was higher than that in rural areas. Under both the HWL and LWL conditions, the abundance of the bamA gene, a biomarker of anaerobic PAH biodegradation, was significantly higher than that of the ring-hydroxylating-dioxygenase (RHD) gene, a biomarker of aerobic PAH biodegradation. The abundance of the bamA gene was significantly positively correlated with PAHs (R = 0.8), and the biodegradation percentage of PAHs incubated anaerobically was greater than that in the aerobically incubated microcosm experiments. These data implicated a key role of the anaerobic pathway in PAH biodegradation. Co-occurrence network analysis suggested that anaerobic Anaerolineaceae, Dechloromonas, Bacteroidetes_vadin HA17 and Geobacter were key participants in the biodegradation of PAHs. The diversity analysis of functional bacteria based on the bamA gene and microcosm experiments further demonstrated that nitrate was the primary electron acceptor for PAH biodegradation. These findings provide a new perspective on the mechanism of PAH biodegradation in the TGR and knowledge that can be used to develop strategies for environmental management.
多环芳烃（PAH）污染的增加对长江三峡水库（TGR）的人类和生态系统健康构成了重大挑战。本研究结合 PAH 分析与 qPCR 以及细菌高通量测序，对 TGR 沿线 16 个地点采集的 32 个表层土壤样本进行了调查，以研究水位波动区（WLFZ）中 PAHs 的分布和生物降解途径。结果表明，高水位（HWL）和低水位（LWL）条件下，PAHs 的浓度分别为 43.8-228.2 和 30.8-206.3 ng/g 土壤（干重）。城市地区的 PAH 浓度高于农村地区。在 HWL 和 LWL 条件下，厌氧 PAH 生物降解标志物 bamA 基因的丰度均明显高于好氧 PAH 生物降解标志物环羟基双加氧酶（RHD）基因的丰度。bamA 基因的丰度与 PAHs 呈显著正相关（R=0.8），并且在厌氧培养微宇宙实验中 PAHs 的生物降解率大于好氧培养的微宇宙实验。这些数据表明，厌氧途径在 PAH 生物降解中起关键作用。共现网络分析表明，厌氧 Anaerolineaceae、Dechloromonas、Bacteroidetes_vadin HA17 和 Geobacter 是 PAHs 生物降解的关键参与者。基于 bamA 基因和微宇宙实验的功能细菌多样性分析进一步证明，硝酸盐是 PAH 生物降解的主要电子受体。这些发现为 TGR 中 PAH 生物降解机制提供了新的视角，并为环境管理策略的制定提供了相关知识。
