The threats of micro- and nanoplastics to aquatic ecosystems and water health

Micro(nano)plastics (MNPs) are pervasive in global water sources, posing indirect threats to water quality by disrupting biogeochemical cycles, facilitating pathogen dispersion and interacting with emerging contaminants. Here we delve into the intricate ways in which MNPs affect nutrient sequestration, essential element adsorption and microbial functions, consequently impacting the carbon, nitrogen, phosphorus and sulfur cycles in aquatic environments. MNPs act as carriers for pathogens, potentially exacerbating transmission risks and endangering both aquatic ecosystems and human health. Moreover, their synergy with emerging contaminants amplifies contaminant persistence and bioavailability, warranting a deeper understanding of these implications for water security. We outline strategies for assessing the contributions of MNPs and implementing regulatory frameworks to mitigate their indirect effects. To manage these interactions under fluctuating environmental variables, advanced water treatment, modular control strategies, and early warning are essential. A holistic approach involving research, innovation and policy is imperative to protect water quality from MNPs-related impacts. Micro- and nanoplastics indirectly threaten water quality by disrupting biogeochemical cycles, transporting pathogens and interacting with emerging contaminants. This Review highlights their complex environmental roles and outlines regulatory and technological strategies to mitigate their impacts on aquatic ecosystems and water health.