城市水体中微塑料的来源、赋存及其生态风险研究进展

A Critical Review on the Sources,Occurrences and Ecological Risk of Microplastics in Urban Waters

微塑料是一种高度多样化的污染物,形态各异、组成复杂且具有生物难降解性,导致的环境污染问题引起了广泛关注。已有的文献主要总结了海洋和淡水系统中微塑料的赋存特征和危害,城市水体是内陆淡水环境的重要组成部分,和人类生产和生活息息相关。目前缺乏对城市水体中微塑料来源、赋存特征和生态风险的系统归纳。该文概括了这几方面的研究,得出如下的若干结果。城市水体中的微塑料可通过污水处理厂排水、地表径流、合流制溢流、塑料设施老化释放、大气沉降等进入水环境。主要赋存类型为PP(聚丙烯)和PE(聚乙烯),其丰度、类型、尺寸和颜色的赋存受叠加的人为因素影响,包括降雨季节变化、土地利用类型和城市化工业化程度。微塑料可对水生生物造成危害,并与众多污染物发生协同效应,最终通过食物链危害人体健康,具有一定的生态风险。目前主要采用生态风险指数法对城市水体中微塑料进行评价,评价结果多为低风险。此外,国内外为减少城市水环境微塑料提出的许多管理措施,在一定程度上缓解了微塑料污染。最后,该文对城市水体中微塑料研究进行了展望,其内容包括建立源解析方法,阐明各污染源对水体微塑料污染的贡献;加强微塑料和其它污染物的协同赋存与污染特征以及纳米塑料检测方法的研究;建立科学系统的方法评价影响城市水体微塑料赋存的因素,如城市土地使用量、下水道网络的扩充、排水系统容量增加等;深入研究微塑料对水生态系统功能的影响,包括碳/氮循环等生物地球化学循环。此外,该文认为,全面评价城市水体中微塑料的生态风险应重视微塑料进入食物链后的放大和累积效应。

Microplastics are a highly diverse contaminants with various shapes,complex composition and biodegradability,leading to widespread concern about environmental pollution.The existing study mainly summarizes the occurrences,characteristics and hazards of microplastics in marine and freshwater systems,while urban waters are an important part of inland freshwater environment and closely related to human production and life.There is a lack of systematic generalization of microplastic sources,occurrences,characteristics and ecological risks in urban waters.This paper summarizes these aspects of the study and concludes that microplastics in urban waters can enter the water environment through wastewater treatment plant discharge,surface runoff,combined system overflow,plastic facilities aging release,and atmospheric deposition.The main occurrences types are PP and PE,and their abundance,type,size and color occurrences are influenced by superimposed anthropogenic factors,including seasonal changes in rainfall,land use type and degree of urbanization and industrialization.Microplastics can cause harm to aquatic organisms and have a synergistic effect with many pollutants,eventually endangering human health through food chain and posing a certain ecological risk.At present,the ecological risk index method is mainly used to evaluate microplastics in urban waters,and the evaluation results mostly indicated low risks.In addition,many management measures proposed at home and abroad to reduce microplastics in urban water environment are summarized,which alleviate microplastic pollution to some extent.Finally,this paper provides an outlook on the research of microplastics in urban waters:to establish a source analysis method to elucidate the contribution of various pollution sources to microplastic pollution in water bodies;to strengthen the research on the synergistic contribution and pollution characteristics of microplastics and other pollutants as well as the detection methods of nano-plastics;to establish a scientific and systematic method to evaluate factors affecting the contribution of microplastics in urban waters,such as the amount of urban land use,the expansion of sewerage network,and the increase of drainage system capacity;to thoroughly study the impact of microplastics on the function of water ecosystems,including the biogeochemical cycles such as carbon/nitrogen cycle.In addition,the amplification and accumulation effects of microplastics in the food chain are essential for a comprehensive evaluation of ecological risks of microplastics in urban waters.