The fate of microplastics/nanoplastics (MPs/NPs) in constructed wetlands: Addressing methodological gaps and experimental challenges from lab-scale to full-scale

Microplastics and nanoplastics (MPs/NPs) are ubiquitous pollutants resulting from the widespread use of plastic products and the fragmentation of plastic litter upon release into the environment. Their unique physicochemical properties, such as heterogeneous nature, small size, and durability, pose threats to ecosystems and human health. Constructed wetlands (CWs) have demonstrated effective removal ability for MPs/NPs. However, different from conventional water-soluble pollutions, MPs/NPs tend to retain their physical and chemical status in CWs. Furthermore, the removal and behavior of MPs/NPs in CWs are closely influenced by both the properties of the particles and the surrounding environmental conditions. Thus, laboratory-scale removal efficiencies may differ significantly from those observed in field-scale systems, making them less representative of actual performance under real environmental conditions. This review systematically compares findings from laboratory-scale and field-scale CW studies, highlighting differences in MPs/NPs removal efficiencies and research priorities. The removal mechanisms and the impact of MPs/NPs on various CW components, including plants, substrates, microorganisms, and macroinvertebrates, are comprehensively analyzed. Additionally, a detailed analysis was conducted on the effects of MPs/NPs accumulation on conventional elemental cycling and interaction with other emerging contaminants within the systems. Finally, current challenges and future perspectives are presented. This review provides a theoretical basis for improving MPs/NPs removal and offers new insights into the difference between field and lab-scale studies, thereby deepening the understanding of MPs/NPs behavior and fate in CWs.