城镇化影响下人畜共用药环境残留的流域生态过程及机制研究

This project aims to explore mechanism of representative pollutants residues on ecological responses to urbanization at watershed scale. The project will analyze the spatial properties of human and veterinary pharmaceuticals residues in sediment and their pollutant sources in a typical urbanizing watershed. It aims to figure out the mechanism of residual processes of representative pollutants (pharmaceuticals) during human activities process (urbanization), integrating with analysis of urbanization gradient from minimum watershed classification. Ecological responses and their controlling factors will be explored with microbial community structure, combined responses of nitrogen cycle and antibiotic resistance gene, integrating with spatial properties of urbanization at regional scale. Coupling relationship and its mechanisms also will be characterize between pollutants residues and environmental factors on ecological effects in response to urbanization, based on their relationships between spatial properties, which are considered as internal drive mechanism (pollutants) and the external drive mechanism (environmental factors), respectively. The project will explore the driving mechanism by human activates on water environment quality evolution (pharmaceuticals and its ecological responses) and evolution process and controlling factors at watershed scale. The findings from the project will contribute to the screening of pharmaceuticals residues and ecological risks management at regional scale, and also provide a valuable methodology for studying water environment quality evolution impacted by emerging contaminants at regional scale.

本项目以污染物环境残留的生态响应过程及机制为研究主题，通过典型城镇化流域沉积物中人畜药物环境残留及其污染源类型的空间属性关系分析，结合最小流域单元分类的城镇化梯度解译，研究人类活动过程（城镇化）特征污染物环境残留过程机制；以沉积物氮循环联合响应、微生物群落特征和抗生素抗性基因作为人畜药物环境残留的生态响应指标，结合区域空间城镇化属性特征，研究人类活动过程特征污染物环境残留的生态响应行为及其调控因子；以污染物为内在驱动因素，城镇化属性的环境条件为外在关联因子，通过抗性基因-微生物群落结构-氮循环响应的生态响应链机理解析，研究污染物与环境关联因子对生态响应行为的耦合关系和作用机制，揭示人畜药物环境残留过程的生态响行为的人类活动驱动机制（城镇化）。本项目的完成为区域空间人畜药物环境残留的甄别与风险管理提供理论基础和科学依据，并为新兴污染物的区域环境质量演变机制研究提供方法论。

人畜药物及其生态风险的甄别、防治及管理具有重要的理论和现实意义。项目以晋江流域为研究对象，研究城镇化过程流域抗生素环境残留特征及影响因素，以此为污染物内在驱动因素，其他环境条件为外在关联因子，研究抗生素残留的生态响应行为及其调控因子，解析抗生素环境残留过程的生态响应行为过程的驱动机制。结果表明，晋江流域抗生素存在兽用药和人用药共同污染的特征，人为活动的持续排放是其在流域环境累积残留的主要驱动因素。抗生素残留对沉积物酶活性有显著的影响，但影响效应易被其他环境因子所覆盖。抗生素对微生物优势菌属的存在具有很高的影响效应，但重金属存在显著降低抗生素对优势菌属筛选效应。抗生素对抗生素抗性基因的丰度具有很高的解释度，但反过来抗性基因丰度被抗生素的解释度却显著下降，存在其他环境因素的抗性协同诱导效应。长期处于高浓度抗生素残留的环境微生物群落表现出选择-适应过程现象，低浓度磺胺类重新选择效应大于四环素类。长期处于低浓度的环境微生物群落呈现选择-适应-丢失现象，抗生素浓度升高可表现出重新选择的过程。抗生素重新暴露对抗性基因表达丰度的影响效应，与沉积物的总氮、总碳、砷、锌、微生物多样性及优势菌属等内在因素有关。整合子基因intI1可能介导了土霉素对tetC和tetG基因的表达丰度，在流域上游表现出较高的抗性基因转化迁移潜力，而人口活动较为强烈的区段，已然形成一定程度稳定的抗性格局，与抗生素的流域残留的驱动因素较为一致。Cu/Zn存在显著影响抗生素对土壤及其所处环境的线蚓肠道微生物群落物种均一性，但对抗生素对蚯蚓肠道微生物群落的碳源代谢能力影响效应随浓度、时间和抗生素种类表现出明显差异。蚯蚓肠道微生物群落随暴露时间延长表现出抗生素与重金属协同抗性的适应行为。上述研究结果为区域空间人畜药物环境残留的甄别与风险管理提供理论基础和科学依据，并为流域尺度污染物生态响应行为机制研究提供指标体系和方法论。