Microbial dechlorination of three PCB congeners in river sediment

• Published in: Chemosphere (Oxford) 2001-11, Vol.45 (6), p.849-856
• Main Authors: Chang, B.V, Liu, W.G, Yuan, S.Y
• Format: Article
• Language: English
• Subjects: Applied sciences; Bacteria; Bacteria, Anaerobic - physiology; Biodegradation of pollutants; Biological and medical sciences; Biological and physicochemical properties of pollutants. Interaction in the soil; Biotechnology; Chlorine Compounds - metabolism; Dechlorination; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environment and pollution; Environmental Monitoring; Environmental Pollutants - metabolism; Exact sciences and technology; Freshwater; Fundamental and applied biological sciences. Psychology; Geologic Sediments - chemistry; Geologic Sediments - microbiology; Industrial applications and implications. Economical aspects; PCBs; Pollution; Pollution, environment geology; Polychlorinated Biphenyls - metabolism; River sediment; Soil and sediments pollution; Taiwan, Keelung R
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/S0045-6535(01)00106-0

We investigated the potential for the anaerobic degradation of three PCB congeners (2,3,5,6-CB, 2,3,4,5-CB, and 2,3,4,5,6-CB) in sediments collected from five monitoring sites along the Keelung River in northern Taiwan. Optimal conditions for congener dechlorination were 30°C and pH 7.0. Intermediate 2,3,4,5-CB products were identified as 2,3,5-CB, 2,4,5-CB, and 2,5-CB. Intermediate 2,3,4,5,6-CB products were identified as 2,3,5,6-CB, 2,3,6-CB, and 2,5-CB. For 2,3,5,6-CB, intermediate products were identified as 2,3,6-CB and 2,5-CB. Dechlorination rates for PCB congeners were observed as (fastest to slowest): 2,3,4-CB>2,3,4,5-CB>2,3,4,5,6-CB>2,3,5,6-CB>2,2 ′,3,3 ′,4,4 ′-CB>2,2 ′,4,4 ′,6,6 ′-CB>2,2 ′,3,4,4 ′,5,5 ′-CB>2,2 ′,3,3 ′,4,4 ′,5,5 ′-CB. Rates decreased for mixtures of the eight congeners. Dechlorination rates for the three primary congeners under different reducing conditions occurred in the order of (fastest to slowest): methanogenic condition > sulfate-reducing condition > nitrate-reducing condition. Under methanogenic and sulfate-reducing conditions, dechlorination rates were enhanced by the addition of lactate, pyruvate, or acetate, but delayed by the addition of manganese oxide, or ferric chloride. Under nitrate-reducing condition, dechlorination rates were delayed by the addition of lactate, pyruvate, acetate, manganese oxide or ferric chloride. Treatment with such microbial inhibitors as bromoethanesulfonic acid (BESA) or molybdate revealed that methanogen and sulfate-reducing bacteria were involved in the dechlorination of these three PCB congeners.