Zhu Baotong, Xia Xinghui, Wu Shan, Lu Xiaoxia, Yin Xin'an
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
Chemosphere. 2016 Jun;153:386-93. doi: 10.1016/j.chemosphere.2016.03.050. Epub 2016 Mar 28.
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.
微生物降解在环境中消除多溴二苯醚（PBDEs）的过程中起着关键作用。然而，人们对多溴二苯醚在水生沉积物中的微生物生物可利用性了解并不充分。在本研究中，我们考察了典型的多溴二苯醚同系物2,2',4,4'-四溴二苯醚（BDE-47）在厌氧条件下对来自中国六条河流的天然沉积物中多溴二苯醚降解微生物的生物可利用性。六个沉积物样品中黑碳（BC）和总有机碳（TOC）的含量分别在0.025% - 0.30%和0.03% - 3.38%范围内。BDE-47从各种沉积物中的解吸情况与一级三室解吸模型拟合良好。在每个解吸时间间隔内，沉积物结合态BDE-47的解吸分数与BC含量呈显著负相关（p < 0.01）。在沉积物中，微生物对BDE-47的厌氧脱溴遵循逐步脱溴途径，主要生成三种低溴代同系物（BDE-28、-17和-4）。厌氧培养120天后，不同沉积物中BDE-47的微生物脱溴率在4.21%至7.89%之间，且与沉积物BC含量呈显著负相关（p < 0.01）。然而，BDE-47的解吸分数和微生物脱溴率与沉积物中TOC含量仅呈现弱相关性（p > 0.05）。此外，在培养的前20天，沉积物中BDE-47的解吸分数与其微生物脱溴率（p < 0.01）以及三种低溴代产物的水平（p < 0.05）之间存在显著正相关。本研究表明，厌氧河流沉积物中微生物对BDE-47的生物可利用性主要受沉积物BC含量的影响，BC含量控制着沉积物结合态BDE-47的解吸分数。
