Quantification of selected microplastics in Australian urban road dust

Microplastics (15000 mu m) are pervasive in every compartment of our environment. However, little is understood regarding the concentration and size distribution of microplastics in road dust, and how they change in relation to human activity. Within road dust, microplastics move through the environment via atmospheric transportation and stormwater run-off into waterways. Human exposure pathways to road dust include dermal contact, inhalation and ingestion. In this study, road dust along an urban to rural transect within South-East Queensland, Australia was analysed using Accelerated Solvent Extraction followed by pyrolysis Gas Chromatography-Mass Spectrometry (Pyr-GC/MS). Polypropylene, polystyrene, polyethylene terephthalate, polyvinyl chloride, poly (methyl methacrylate) and polyethylene were quantified. Microplastic concentrations ranged from similar to 0.5 mg/g (rural site) to 6 mg/g (Brisbane city), consisting primarily of polyvinyl chloride (29%) and polyethylene terephthalate (29%). Size fractionation (< 250 mu m, 250-500 mu m, 500-1000 mu m, 1000-2000 mu m and 2000-5000 mu m) established that the < 250 mu m size fraction contained the majority of microplastics by mass (mg/g). Microplastic concentrations in road dust demonstrated a significant relationship with the volume of vehicles (r(2) = 0.63), suggesting traffic, as a proxy for human movement, is associated with increased microplastic concentrations in the built environment.

Automated summary

Microplastics, mainly composed of PVC and PET, were found to be prevalent in road dust in urban and rural areas of South-East Queensland, Australia. The study revealed a significant relationship between microplastic concentrations in road dust and the volume of vehicles, indicating human activity as a factor influencing microplastic pollution in the environment.