Characterization and comparison of microplastic occurrence in point and non-point pollution sources

Small plastic fragments, referred to as microplastics (MP), have recently been studied due to their potentially more harmful effects as compared with larger plastic wastes. Despite the growing number of studies regarding MPs, an in-depth assessment of the types and amount of MP from different point sources (PS) and non-point sources (NPS) are relatively scarce. Therefore, this study mainly focused on the identifying and classifying different types of MP from point and non-point sources. Wastewater, stormwater runoff, and surface water samples were collected to compare the types, sizes, and distribution of MPs from different sources. Polyethylene terephthalate (PET) was found to be the most common type of polymer found in NPS and PS catchment areas amounting to greater than 5% to 30% of the total MP, whereas the dominant polymer found in the highway catchment area is rubber. Since particles less than 0.5 mm were not adequately removed by wastewater and stormwater treatment processes, relatively smaller MP sizes may persist in the natural environment. Ultimately, the amount and type of polymers in the environment are highly dependent on the anthropogenic activities in the catchment areas, type of treatment employed, and the transport pathways of MPs.