短链脂肪酸对太湖底泥多氯联苯微生物厌氧脱氯的影响

选取二氯联苯PCB5和PCB12、四氯联苯PCB64和PCB71、类二噁英五氯联苯PCB105和PCB114、六氯联苯PCB149和PCB153、七氯联苯PCB170，考察了添加7.5mmol/L乙酸和7.5mmol/L混合酸（乙酸：丙酸：丁酸=1：1：1）条件下，9种典型商业多氯联苯单体在太湖底泥厌氧微环境中24周内的脱氯降解情况.结果表明：乙酸和混合酸的添加均在一定程度上强化了多氯联苯的降解，多氯联苯总浓度降低速率由（0.276±0.023） mg/（kg·week）分别加快至（0.383±0.033）和（0.410±0.036） mg/（kg·week）；提高了部分脱氯路径的相对反应速率，特别是单侧氯取代的对位脱氯，但未改变脱氯微生物对多氯联苯降解底物的选择性及主要脱氯路径；进一步降低了体系类二噁英多氯联苯总毒性当量（TEQ），24周降幅均在95%以上；乙酸和混合酸所起到的促进效果并无显著性差异.

Effects of short-chain fatty acids on microbial-catalyzed reductive dechlorination of polychlorinated biphenyls in Taihu Lake sediment microcosms

The dechlorination of 9 typical commercial polychlorinated biphenyl (PCB) congeners including PCB5, 12, 64, 71, 105, 114, 149, 153 and 170 was investigated in Taihu Lake sediment microcosms for 24 weeks with the supplementation of 7.5mmol/L acetate and 7.5mmol/L fatty acid mixture (acetate:propionate:butyrate=1:1:1), respectively. The addition of acetate and fatty acid mixture slightly enhanced the degradation of PCBs, with the dechlorination rate of total PCBs concentration increased from (0.276±0.023) mg/(kg·week) to (0.383±0.033) and (0.410±0.036) mg/(kg·week), respectively. The relative dechlorination rates of certain dechlorination pathways increased, especially for the single-flanked para dechlorination pathway, while, the target parent PCB congeners or the dechlorination pathways did not shift. The supplementation of carbon sources apparently favored the reduction of total toxic equivalent (TEQ) in the microcosms. The TEQ declined by greater than 95% within 24 weeks. No significant difference of enhanced degradation was observed in acetate and fatty acids mixture amended microcosms.