河流和海洋沉积物中有机紫外吸收剂的厌氧微生物降解机制研究

Exposure to Organic ultraviolet (UV) filters can induce various endocrine disrupting effects. Organic UV filters can be bio enriched and food chain transfer. Organic UV filters has be identified as a potential new threat to wild life. Organic UV filters are used widely in sunscreen, because of their hydrophobicity capability, UV filters are mainly adsorbed on anoxic and anaerobically sediment phases. Considering the weakness of riverine and coastal waters area sediment column environmental research on organic UV filters pollution characteristics of deposition, anaerobic degradation mechanism and controlled mechanisms for organic UV filters anaerobic degradation, on the basis of our previous work, this project aims to investigate the contamination characteristics and spatial variability of common organic UV filters in sediment columns of representative rivers of Pearl River Delta Region with different type of pollution, Pearl River estuary and bathing beach. Through laboratory experiments, this project will study the anaerobic degradation process, degrading bacteria and key degradation function genes of typical organic UV filters in river and marine sediment systems. By using microcosm experiments and metagenomic sequencing technology, we will study to screen the control factors for anaerobic degradation of organic UV filters in rivers and marine sedimentary environments, analysis the composition and structural changes of degrading bacteria groups under the combination of single factor and multi factor in the anaerobic degradation process of organic UV filters, to discuss its restrictive factors and controlled mechanisms. The results from this project research can provide scientific basis on evaluate the environmental persistence and study on enhanced pollution control, especially in situ remediation technology.

有机紫外吸收剂具有内分泌干扰效应，能生物富集和食物链传递，可对生态环境产生潜在危害。有机紫外吸收剂是防晒霜等护理品中主要添加成分，属憎水性化合物，主要吸附于缺氧和厌氧沉积相。鉴于国内外河流和近海海洋沉积柱中有机紫外吸收剂污染沉积特征、厌氧降解机理及其受控机制研究的薄弱，在前期工作基础上，本项目拟选择不同污染程度的珠江流域典型河流、珠江入海口和海洋浴场沉积柱研究沉积物中常见有机紫外吸收剂的污染特征和时空演变规律；实验室模拟研究典型有机紫外吸收剂在河流和海洋沉积体系中的厌氧降解过程、降解菌和关键降解功能基因；利用微宇宙实验结合高通量测序技术筛查河流和海洋沉积环境中有机紫外吸收剂厌氧降解过程控制因子，分析厌氧降解过程中单一因子和组合因子联合作用下降解菌群组成和结构变化趋势，探讨其制约因子和受控机制，为评价有机紫外吸收剂的环境持久性、强化污染原位修复技术研究提供科学依据。

有机紫外吸收剂是防晒霜等护理品中主要添加成分，属憎水性化合物，厌氧微生物降解是其重要的自然消减方式。本项目选择珠江典型河流和近海海洋浴场地表水、沉积物/沉积柱研究常见有机紫外吸收剂的污染特征和时空演变规律；实验室模拟研究典型有机紫外吸收剂在污泥和水-沉积物体系中的厌氧降解转化机理，分析了厌氧降解主要影响因素和筛选获得高效降解单菌。通过以上研究，项目取得的主要成果有：（1）珠三角市政污水处理厂五种常用生化处理工艺对有机紫外吸收剂的去除效率具有明显差异，A/O工艺去除效果最优，90.0%是通过生物单元去除，其中厌氧/缺氧单元占比更大，污水厂排水是受纳水环境中有机紫外吸收剂的重要污染来源；（2）西江和北江沉积物中主要有机紫外吸收剂是OMC，最高浓度68.3ng/g。西江排入珠江的紫外吸收剂年污染负荷通量（28332kg/year）远大于北江（1128kg/year），主要断面污染负荷通量有明显季节性差异。沉积柱（56-78cm）中有机紫外吸收剂检出浓度为ND-80.5ng/g，其中UV327检出浓度相对最高为1.77-321ng/g，表层浓度更高，这与近年来紫外吸收剂的生产和使用量增加有关；（3）典型有机紫外吸收剂BP-3的厌氧降解半衰期为3.73d，硝酸盐还原和硫酸盐还原条件对BP-3的厌氧降解有抑制作用，分离获得了一株拟杆菌属厌氧降解单菌，命名为Bacterodies.BP-3（专性厌氧菌）。厌氧降解单菌在丁酸钠共代谢条件下对BP-3的降解半衰期仅为0.944d。采用UPLC-TOF-MS鉴定出BP-3厌氧降解产物有5种，主要中间产物为2,4-2OH-二苯甲酮（BP-1），涉及的主要厌氧降解反应包括去甲基化、去羟基化和氨基化等；（4）水-沉积物体系中OMC和UV-326主要分配于沉积物相，占比达90.0%以上。BP-3在河流水-沉积物（高有机质）体系中的降解半衰期最短（4.18d），而UV-326在海水-沉积物体系中的降解半衰期最长（141d），沉积物有机质含量高更有利于目标紫外吸收剂在沉积相吸附和厌氧降解转化。项目研究成果标注发表论文12篇，第一标注10篇；培养硕士研究生3名。