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，塑料污染的日益增长和普遍存在引起了人们的极大兴趣，特别是被称为“微塑料”(MP) 的小塑料颗粒 (< 5 mm)。它们的广泛存在可能对全球海洋生物构成威胁。海洋环境中的大多数纳米和微塑料 (N&MP) 污染被认为源自陆地来源，但其来源、传输路线和转化尚不确定。关于淡水和陆地系统的信息缺乏，关于纳米塑料污染的数据尤其稀疏。对淡水和陆地系统的系统研究的缺乏是一个关键的研究空白，因为对这些系统的塑料释放量的估计远高于海洋的塑料释放量。由于大多数塑料污染起源于城市环境，因此对城市流域的研究，特别是那些人口密度和工业活动较高的流域，对于源解析尤其重要。释放的塑料碎片在水、土壤和空气中传播。它可以在环境隔室之间交换，吸附有毒化合物，并最终被长距离携带，有可能对多种物种造成物理和化学伤害。测量挑战和缺乏标准化方法减缓了确定 N&MP 的环境流行率和影响的进展。本次综述的总体目标是报告城市流域中 N&MP 的来源和丰度。我们重点关注城市流域，并总结监测方法及其局限性，因为我们知道识别 N&MP 及其城市/工业来源对于减少它们在所有环境中的存在是必要的。