Insight into the size-resolved markers and eco-health significance of microplastics from typical sources in northwest China

Abstract. Research on atmospheric microplastics (MPs) from typical sources is limited, constraining the targeted management of pollution. Here, the source profiles of eight types of common MPs and three classes of plasticizers (i.e., phthalates, benzothiazole and its derivatives, and bisphenol A) emitted from five living sources, including Plastic Burning (PB), Fruit-bag Burning, Road Traffic (RT), Agricultural Film, and Livestock Breeding (LB), were determined in PM2.5 (particulate matter with aerodynamic diameters ≤ 2.5 µm) and PM10 (≤ 10 µm) in the Guanzhong Plain, northern China. PB exhibits high proportions of poly(methyl methacrylate) (PMMA) and 2-hydroxy benzothiazole (HOBT), with PMMA being more abundant in PM2.5–10 (aerodynamic diameters between 2.5 and 10 µm). FB exhibits a higher proportion of di-n-octyl phthalate (DnOP) in PM2.5–10 than in PM2.5. RT shows a distinguishable profile with high abundances of rubber. The abundance of 2-benzothiazolyl-N-morpholinosulfide (OBS) in PM2.5–10 was twice that in PM2.5 for RT. Polystyrene (PS) is the most abundant MP in AF. LB shows the distinguishing feature of benzothiazoles, especially OBS and N-cyclohexyl-2-benzothiazolesulfenamide (CBS). The eco-health risk assessments reveal that combustion-derived MPs (Plastic Burning and Fruit-bag Burning) indicate the highest ecological risk (Level III). Elevated hazard indices to human health were observed in LB and PB, primarily attributed to bis(2-ethylhexyl) phthalate (DEHP). Notably, PMMA, polyethylene terephthalate (PET), polyethylene (PE), bisphenol A (BPA), and phthalates (PAEs) emerged as key drivers of oxidative stress of PMs. This study advances the understanding of atmospheric MPs, offering critical insights for source tracking and risk assessment to mitigate their eco-health effects.