Nanomaterial control in constructed wetlands: Linking environmental fate, ecological effects, and sustainable management

The widespread production and release of nanomaterials (NMs) have resulted in their continuous input into aquatic environments. Constructed wetlands (CWs), as important ecological interfaces between anthropogenic sources and receiving waters, continuously receive and retain NMs, whose long-term accumulation may further affect CW ecological functions. Based on this context, this review develops a unified “fate–effects–control” framework to systematically evaluate the environmental fate, ecological effects, and control strategies of metal-based NMs (m-NMs), carbon-based NMs (c-NMs), and nanoplastics (p-NMs) in CWs. Available distribution data indicate that the substrate–biofilm compartment serves as the primary sink for NMs, whereas plants mainly play an auxiliary role in their retention. Continuous retention and accumulation of NMs in CWs can result in long-term exposure. Current direct evidence from CW studies indicates that the reported ecological responses are predominantly inhibitory and may further affect water purification and greenhouse-gas emissions. Meanwhile, some studies have also reported material- and exposure-dependent stimulatory or adaptive responses. These effects may involve oxidative stress, membrane damage, metabolic disruption, and alterations in electron-transfer pathways. Based on these findings, we further evaluate the application potential and long-term operational limitations of CWs for NM control and propose a shift from solely pursuing removal efficiency toward the integrated optimization of NM retention, water-treatment performance, and long-term operational stability. Enhancement approaches involving substrates, biological processes, plants, and hydraulic structures are further summarized, together with future research priorities, to support the long-term risk control and sustainable management of NMs in CWs.