潮间带微表层沉积物抗生素类光降解行为研究

As one of the most vigorous ecosystems, the intertidal zone is the important natural habitat for various organisms including shellfish, crabs, fish, and birds etc. For the past few years the intertidal zones have been severely polluted and become the important reservoir of pseudo-persistent antibiotics. As the key process to evaluate the fate and risk of antibiotics in the intertidal zones, the photochemical transformation of antibiotics in the micro-surface sediments of the intertidal zones seems to be thoroughly ignored. The physicochemical properties, elemental components, organic and mineral composition, as well as spectrum characterization of the intertidal micro-surface sediments would be investigated in this proposal. The adsorption models and mechanisms of antibiotics to the humus-removed sediments and natural sediments would be developed and illuminated. The kinetic processes of antibiotics photoreaction in the humus-removed sediments would be developed under the certain conditions of pH, temperature and water content, etc. With the single and many photosensitive substances, the kinetic processes of antibiotics photoreaction in the humus-removed sediments would be developed respectively. The environmental factor effect and the joint effect of photosensitive substances of the intertidal micro-surface sediments on the photochemical reaction of antibiotics would be elucidated as well. Subsequently the photodegradation mechanisms of antibiotics in the intertidal micro-surface sediments would be illuminated, and the quantitatively predictive models would be constituted to assess the antibiotics photoreaction the intertidal micro-surface sediments based on the descriptors including sediment physicochemical properties and adsorption capacity of antibiotics to sediments. This project would enrich the methods and theories of environmental photochemistry.

潮间带是底栖生物、鱼类和鸟类等多种生物的重要栖息地，而抗生素类污染物对潮间带生态系统的风险几为人们所忽视，潮间带微表层沉积物抗生素类的光转化过程是抗生素类风险评估的重要环节。课题以潮间带微表层沉积物为对象，以不同源潮间带微表层沉积物的理化性质、元素组成、光谱特征、有机组成、矿物特征等分析为前提，以脱腐殖质沉积物和天然沉积物对抗生素类吸附热力学模拟研究为基础，开展pH、温度、盐度、含水量等环境条件下脱腐殖质沉积物表面抗生素类光解反应动力学模拟，以脱腐殖质沉积物为基质开展光敏物质单独作用和多种光敏物质共存下抗生素类药物光解反应动力学模拟研究，阐释不同源潮间带沉积物表面抗生素类药物光解反应的环境因素作用以及多光敏物质联合效应，揭示不同源潮间带沉积物表面抗生素类药物光解反应机理，构建以沉积物理化性质和结构特征以及沉积物抗生素吸附能力等为描述符的潮间带微表层沉积物抗生素类光解行为的定量评价模型。

本项目从2017年到2020年这四年的时间里，项目组成员按照计划有条不紊的推进本项目实施，并结合研究过程中发现的问题对研究方法和内容进行调整、改进、扩展和深化。课题以典型潮间带微表层沉积物为研究对象，以潮间带微表层沉积物抗生素类药物光解反应动力学模拟为基础，揭示了潮间带微表层沉积物抗生素类药物光解行为的反应机理，构建了潮间带微表层沉积物抗生素类药物光解行为的定量化预测模型，并开发了纺锤状纳米级Fe2O3/g-C3N4高效光解材料。其主要的研究进展如下：（1）解析了潮间带微表层沉积物中抗生素赋存规律：表水和微表层沉积物中奎诺酮类、四环素类、大环内脂类赋存浓度分别为：66.04-228.82ng·L-1 和61.26-84.60ng·g-1，表水中抗生素在养殖场附近浓度较高，沉积物中抗生素浓度在不同采样点没有表现出空间差异性；另外，表水中抗生素表现出显著性季节性差异。环境风险评价表明3类抗生素在此区域处于中等偏低的含量水平。（2）探究了潮间带微表层沉积物中抗生素光化学行为机制：微表层沉积物中四环素的光解速率常数为7.04×10-3h-1-9.19×10-3h-1；随着卤离子浓度由1%-5%增加，四环素的光降解速率缓慢增加；随着pH由6-10增加，四环素的光解反应速率加快；微表层沉积物中四环素可以发生间接光解反应，间接光解反应过程中产生的3DOM*比1O2和·OH对四环素光化学反应的作用更强烈。（3） 模拟了微表层沉积物中抗生素光解动力学：四环素光解模型为t1/2=122.45-1.5clay+4.47×10-2silt-3.36×10-2sand-9.42×10-1OM-31.55×DCB-Al-3.66DCB-Fe游离氧化铁含量（DCB-Fe）、游离氧化铝含量（DCB-Al）、土壤粒径和有机质含量（OM）是影响四环素光解速率重要因子。（4）开发了高效高分散性光催化剂一步合成法：以尿素为前驱体和九水合硝酸铁经溶剂热法复合形成配合物后煅烧，制备了高效高分散性纳米级Fe2O3/g-C3N4光催化材料。