Impact of microplastics exposure to macrophytes of constructed wetlands

Abstract:

Microplastics, defined as <5 mm in plastic particle dimension, are ubiquitously distributed in the environment. However, stormwater and wastewater can carry microplastics, particularly from urban settings. However, the impact of microplastics in polluted water treating engineered bioreactors like constructed wetlands is not well known. This study aims to assess the impact of acute microplastics (i.e., polyethylene, polystyrene, and polyamide) exposure on photosynthetic attributes, modulate dynamics of antioxidative defence expression, and secondary metabolites to mitigate toxicity in macrophytes of constructed wetlands. Microplastics significantly reduce chlorophyll content and photosynthesis rate in leaves compared to that in control. Microplastics also cause oxidative damage of macrophyte leaves and roots, indicated by reactive oxygen species (ROS) generation. However, macrophytes in the constructed wetlands generate enzymatic and non-enzymatic antioxidative defense systems such as superoxide dismutase, peroxidase, and catalase, as well as ROS-scavenging compounds such as phenolic compounds and anthocyanin to alleviate oxidative stress. Future research is needed to assess how microplastics can influence overall effectiveness of constructed wetlands during treating stormwater and wastewater.