title: Microbial bioavailability of 2,2',4,4'-Tetrabromodiphenyl ether (BDE-47) in natural sediments from major rivers of China.
abstract: Microbial degradation plays a crucial role in eliminating polybrominated diphenyl ethers (PBDEs) in environments. However, the microbial bioavailability of PBDEs in aquatic sediments is not well understood. In this work, the bioavailability of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), a typical PBDE congener, to PBDE-degrading microorganisms in natural sediments from six Chinese rivers under anaerobic conditions was investigated. The contents of black carbon (BC) and total organic carbon (TOC) in the six sediment samples were in the range of 0.025%-0.30% and 0.03%-3.38%, respectively. BDE-47 desorption from various sediments was fitted well with the first-order three-compartment desorption model. The desorbing fraction of sediment-associated BDE-47 at each desorption time interval exhibited a significant negative correlation with the BC content (p < 0.01). In the sediments, the anaerobic debromination of BDE-47 by microorganisms underwent a stepwise debromination pathway generating mainly three lower brominated congeners (BDE-28, -17 and -4). The microbial debromination ratio of BDE-47 ranged from 4.21% to 7.89% in various sediments after 120 d incubation anaerobically, and it negatively correlated with the content of sediment BC significantly (p < 0.01). However, the desorbing fraction and microbial debromination ratio of BDE-47 only showed weak correlations with the TOC content in sediments (p > 0.05). Furthermore, there was a significant positive correlation of desorbing fraction of BDE-47 from sediments with its microbial debromination ratio (p < 0.01) as well as with the level of its three lower brominated products (p < 0.05) after the first 20 d incubation. This study suggests that the BDE-47 bioavailability to microorganisms in anaerobic river sediments is mainly influenced by the content of sediment BC which controls the desorbing fraction of sediment-associated BDE-47.
authors.affiliation: State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
authors.forename: Baotong
authors.initials: B
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China. Electronic address: xiaxh@bnu.edu.cn.
authors.forename: Xinghui
authors.initials: X
authors.lastname: Xia
authors.affiliation: Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650, China. Electronic address: wushan@soil.gd.cn.
authors.forename: Shan
authors.initials: S
authors.lastname: Wu
authors.affiliation: College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Lu
authors.affiliation: State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
authors.forename: Xin'an
authors.initials: X
authors.lastname: Yin
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D001682:Biological Availability; D002681:China; D019015:Geologic Sediments / Q000737:chemistry*; D055768:Halogenated Diphenyl Ethers / Q000378:metabolism*; D045483:Rivers / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D055768:Halogenated Diphenyl Ethers; D014874:Water Pollutants, Chemical; C511295:2,2',4,4'-tetrabromodiphenyl ether
keywords: Bioavailability; Black carbon; Desorption; Microbial debromination; Polybrominated diphenyl ethers; Riverine sediments