The growing and pervasive presence of plastic pollution has attracted considerable interest in recent years, especially small (< 5 mm) plastic particles known as ‘microplastics’ (MPs). Their widespread presence may pose a threat to marine organisms globally. Most of the nano and microplastic (N&MP) pollution in marine environments is assumed to originate from land-based sources, but their sources, transport routes, and transformations are uncertain. Information on freshwater and terrestrial systems is lacking, and data on nanoplastic pollution are particularly sparse. The shortage of systematic studies of freshwater and terrestrial systems is a critical research gap because estimates of plastic release into these systems are much higher than those for oceans. As most plastic pollution originates in urban environments, studies of urban watersheds, particularly those with high population densities and industrial activities, are especially relevant with respect to source apportionment. Released plastic debris is transported in water, soil, and air. It can be exchanged between environmental compartments, adsorb toxic compounds, and ultimately be carried long distances, with potential to cause both physical and chemical harm to a multitude of species. Measurement challenges and a lack of standardized methods has slowed progress in determining the environmental prevalence and impacts of N&MPs. An overall aim of this review is to report the sources and abundances of N&MPs in urban watersheds. We focus on urban watersheds, and summarize monitoring methods and their limitations, knowing that identifying N&MPs and their urban/industrial sources is necessary to reduce their presence in all environments.

近年来，塑料污染的日益普遍普及引起了人们的极大兴趣，尤其是被称为“微塑料”（MPs）的小（<5毫米）塑料颗粒。它们的广泛存在可能对全球海洋生物构成威胁。假定海洋环境中的大多数纳米和微塑料（N＆MP）污染源自陆源，但其来源，运输路线和转化方式尚不确定。缺乏有关淡水和陆地系统的信息，关于纳米塑料污染的数据特别稀少。缺乏对淡水和陆地系统的系统研究是一个关键的研究缺口，因为对这些系统中塑料释放的估计远高于海洋。由于大多数塑料污染源于城市环境，关于城市流域的研究，尤其是那些人口密度高和工业活动频繁的流域，在源头分配方面特别重要。释放的塑料碎片会在水，土壤和空气中运输。它可以在环境隔室之间交换，吸附有毒化合物，并最终被带走很长距离，有可能对多种物种造成物理和化学伤害。衡量方面的挑战和缺乏标准化的方法减慢了确定N＆MP的环境流行率和影响的进度。审查的总体目的是报告城市流域N＆MP的来源和丰富程度。我们着眼于城市流域，总结了监测方法及其局限性，因为他们知道