On the nature and sources of microplastics (MPs) and microrubbers (MRs) in urban snow

This work reports a characterization of microplastics (MPs) and microrubbers (MRs) such as color, size, shape, and the chemical composition in snowfall in central Iran (Qom) at five sites. Identification of MPs and MRs involved using a stereo microscope to evaluate physical characteristics such as thickness, shininess, hardness, and reaction to a hot needle. HYSPLIT trajectory and end-member microplastic (PM) mixing models are used to determine the contribution of local and remote sources to MPs. The mean (±SD) abundance of MPs and MRs is 23.8 ± 15.87 (MP/L) and 1.26 ± 1.16 (MR/L), respectively, whereas the mean (±SD) abundance of MPs and MRs is 30.7 ± 19.36 (MP/m²) and 1.58 ± 1.39 (MR/m²), respectively. The frequency of MP colors in order are: black (63.8%) > red (12.8%) > blue (11 %) > white (9.1%) > green (2.1%) > yellow (1.3%). About 71.6% and 3.6% of the identified MPs are 250–500 μm and >1000 μm, respectively. Snow samples contain different identified polymers such as polyethylene terephthalate (PET), nylon, viscose, polypropylene (PP), polyethylene (PE), polystyrene (PS), and polyvinyl chloride (PVC). Analysis reveals that 90% of Qom city's snowy day winds come from local sources. The high MP levels in are due to human activities from local origins according to end-member MP mixing model. Further study is needed to understand the potential impacts of MPs and MRs on ecosystems and human health.