复合污染区域沉积物中多溴联苯醚微生物转化机理及其种群响应特征研究

With the shrinking of update cycles for electronic products, the environmental exposure of brominated flame retardants with heavy metals have driven the seriously combined pollution in sediments of river, estuary and offshore, during the production, use, discard and disassemble processes of the huge amount of electronic appliances in China. In this study, the distribution properties of polybrominated diphenyl ethers (PBDEs) and heavy metals in combined polluted sediment are going to be determined at first. Based on the practical sediment samples and lab scale experiments, the microbial transformation properties and effects on PBDEs in different types of sediments, including rivers, brackish water and marine area, are going to be investigated. To verify the dominant degradation and sensitive groups, the microbial population structures of representative samples would be analyzed with high throughput pyrosequencing technology. With metagenomics technology, the microbial degradation/resistance genes could be further investigated. In addition, the co-occurrence correlations among the pollutants distribution characteristics, microbial population and functional genes, and environmental factors could be constructed to further clarify the response mechanisms of microbial population in PBDEs and heavy metals combined polluted sediments. According to these results, the transformation properties PBDEs in different sediments, as well as the following induced environmental and ecological risks are gonging to be further investigated. Finally, the results of this study provide scientific basic data for the further researches on the environmental ecological effects and safety assessments in combined polluted areas of PBDEs and heavy metals.

随着电子电器产品更新换代周期的缩短，巨量电子电器生产、应用及废弃拆解造成的溴系阻燃剂环境暴露已联同重金属对我国相关城市河道、河口及近海区域沉积物造成严重的复合污染。本项目基于典型多溴联苯醚(PBDEs)与重金属复合污染区域沉积物中污染物组成及浓度分布特性分析，提出以实际污染沉积物和室内模拟试验为对象，探讨不同类型（河涌、淡咸水交汇区和海洋）沉积物中PBDEs的微生物迁移转化特性和作用机制；结合高通量测序技术对微生物种群结构的分析，明确优势代谢菌群及敏感菌群的组成，识别其相关代谢/抗性功能基因；在此基础上，构建污染物分布特征—微生物种群、基因信息—环境因素之间的关联性，阐明复合污染沉积物中微生物种群的响应机制；从而，探讨不同沉积物样品中PBDEs的迁移转化可能引发的环境生态效应，为PBDEs和重金属复合污染区域环境生态和安全性评估提供可靠的理论依据。

多溴联苯醚（PBDEs）作为典型卤代阻燃剂应用广泛，因具有持久性、生物蓄积性和潜在毒性等特征，其环境释放、累积和生态效应已成为世界性问题。得克隆（DP）作为PBDEs等阻燃剂的替代品，其环境效应也逐渐受到广泛关注。课题组前期研究发现，电子废弃物拆解（浙江台州）和PBDEs 生产（江苏省）对长江口和邻近的东海区域产生了广泛影响。鉴于电子电器产品在生产、使用、废弃、拆解过程中可能导致阻燃剂与重金属复合污染，本研究通过采集我国不同类型区域沉积物样品，重点考查了黄渤海、东海、长江口及南海等区域表层沉积物中PBDEs等典型卤代阻燃剂和重金属复合污染特性。结果表明，各区域沉积物存在一定的卤代阻燃剂与重金属复合污染，且PBDEs和DP的浓度水平基本呈近海到远海区域逐渐降低的趋势。黄渤海区域沉积物中PBDEs和DP的浓度水平高于东海、长江口和南海区域，且存在明显的环境迁移转化特性。通过分析各典型区域沉积物中微生物种群特性及组成，发现复合污染对微生物种群丰度、种群多样性组成及其优势菌群等存在一定的影响。同时，沉积物中微生物菌群组成受到温度、盐度、pH、溶解氧等环境因子的影响。为了进一步明确PBDEs等阻燃剂的微生物转化机制，课题组从复合污染沉积物中筛选得到多株可在重金属存在条件下对BDE209，DP等有一定降解效果的菌株（Ochrobactrum sp.，Gordonia sp .，Pseudoalteromonas sp.，Cobetia sp.等），并对其降解特性、代谢途径、转化机制及其功能基因等开展了系统研究，揭示了复合污染条件下污染物的迁移转化特性。据此，本项目相关研究结果可为我国入海口及近海海域沉积物中PBDEs、DP等卤代阻燃剂与重金属复合污染区域环境生态和安全性评估提供基础数据和有益参考。