Reply on RC5

Abstract. Research on atmospheric microplastics (MPs) from typical sources is limited, constraining the targeted management of pollution. Here, the characteristics and source profiles of eight types of common MPs and three classes of plasticizers (phthalates, benzothiazole and its derivatives, bisphenol A) emitted from plastic burning (PB), fruit bag burning (FB), road traffic (RT), agricultural film (AF) and livestock breeding (LB) sources were determined in PM2.5 and PM10 in the Guanzhong Plain, northern China. PB features high proportions of poly(methyl methacrylate) and 2-hydroxy benzothiazole, with poly(methyl methacrylate) being more abundant in coarse particles (PMcoarse). FB exhibits the higher proportion of di-n-octyl phthalate in PMcoarse than PM2.5. RT shows a distinguishable profile with high abundances of rubber. The abundance of 2-benzothiazolyl-N-morpholinosulfide in PMcoarse was twice that in PM2.5 for RT. Polystyrene is the most abundant MP in AF. LB shows the distinguishing feature of benzothiazoles, especially 2-benzothiazolyl-N-morpholinosulfide and N-cyclohexyl-2-benzothiazolesulfenamide. The eco-health risk assessments reveal combustion-derived MPs (PB and FB) pose 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. Notably, poly(methyl methacrylate, polyethylene terephthalate, polyethylene, bisphenol A and phthalates emerged as key drivers of oxidative stress. This study advances the understanding of atmospheric MPs, offering critical insights for source tracking and risk assessment to mitigate their eco-health effects.