Key Laboratory of Prevention and Control for Aquatic Invasive Alien Species, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Aquatic Animal Immunology and Sustainable Aquaculture, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510380, China.
Guangdong Provincial Key Laboratory of Chemical Measurement and Emergency Test Technology, Guangdong Provincial Engineering Research Center for Ambient Mass Spectrometry, Institute of Analysis, Guangdong Academy of Sciences (China National Analytical Center, Guangzhou), Guangzhou 510070, China.
Sci Total Environ. 2022 Dec 20;853:158617. doi: 10.1016/j.scitotenv.2022.158617. Epub 2022 Sep 7.
Currently, the specific mechanism generating seasonal variation in polycyclic aromatic hydrocarbons (PAHs) via bacterial biodegradation remains unclear, and whether this alteration affects PAH bioaccumulation is unknown. Therefore, we performed a study between 2015 and 2020 to investigate the effects of seasonal variation on bacterial communities and PAH bioaccumulation in the Pearl River Estuary. Significantly high PAH concentrations in both aquatic and fishery species were determined in dry seasons (the mean ∑PAH concentration: water, 37.24 ng/L (2015), 30.83 ng/L (2020); fish, 51.01 ng/L (2015) and 72.60 ng/L (2020)) compared to wet seasons (the mean ∑PAH concentration: water, 22.38 ng/L (2015), 19.40 ng/L(2020); fish, 25.28 ng/L (2015) and 32.59 ng/L (2020)). Distinct differences in taxonomic and functional composition of bacterial communities related to biodegradation of low molecular weight PAHs (LMW-PAHs) were observed between seasons, and the concentrations of PAHs were negatively correlated with seasonal variation in temperature. Temperature-related specific bacterial taxa (e.g., Stenotrophomonas) directly or indirectly participated in LMW-PAH degradation via encoding PAH degradation enzymes (e.g., protocatechuate 4,5-dioxygenase) that subsequently led to bioaccumulation of high molecular weight PAHs (HMW-PAHs) in wild and fishery species due to LMW-PAHs in the water. Based on this alteration, the ecological risk posed by PAHs decreased in wet seasons, and an unbalanced spatio-temporal distribution of PAHs was observed in this estuary. These results suggest that seasonal variation of temperature affects HMW-PAH accumulation in fishery species via bacterially mediated LMW-PAH biodegradation.
目前，通过细菌生物降解产生多环芳烃（PAHs）季节性变化的具体机制尚不清楚，这种变化是否会影响 PAH 的生物积累也不清楚。因此，我们在 2015 年至 2020 年期间进行了一项研究，以调查季节性变化对珠江口细菌群落和 PAH 生物积累的影响。结果发现，无论是在水体还是在渔业生物体内，PAHs 的浓度在枯水期（∑PAH 浓度：水，37.24ng/L（2015 年），30.83ng/L（2020 年）；鱼，51.01ng/L（2015 年）和 72.60ng/L（2020 年））都明显高于丰水期（∑PAH 浓度：水，22.38ng/L（2015 年），19.40ng/L（2020 年）；鱼，25.28ng/L（2015 年）和 32.59ng/L（2020 年））。不同季节之间与低分子量 PAHs（LMW-PAHs）生物降解相关的细菌群落的分类和功能组成存在明显差异，并且 PAHs 的浓度与温度的季节性变化呈负相关。温度相关的特定细菌类群（如 Stenotrophomonas）通过编码 PAH 降解酶（如原儿茶酸 4,5-双加氧酶）直接或间接参与 LMW-PAH 降解，随后由于水体中的 LMW-PAHs，导致野生和渔业生物体内高分子量 PAHs（HMW-PAHs）的生物积累。基于这种变化，PAHs 在丰水期造成的生态风险降低，并且在这个河口观察到 PAHs 的时空分布不平衡。这些结果表明，温度的季节性变化通过细菌介导的 LMW-PAH 生物降解影响渔业生物体内 HMW-PAH 的积累。
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