Microplastic Pollution in Seasonal Snow Cover of Major Agricultural Regions and Its Source Analysis, China

Microplastics have become a ubiquitous environmental pollutant, widely distributed across various media within natural ecosystems and human living environments. Currently, scholars have primarily focused on the characteristics of microplastics in natural environments, while research into microplastics within snow cover in agricultural areas remains scarce. This study focuses on the Songnen Plain in Northeast China, where 25 sampling points were selected in February 2023. Through laboratory analysis and modelling techniques, it examines the spatial distribution characteristics and potential sources of microplastics within snow cover on agricultural fields. Results indicate the following: (1) The average abundance of microplastics in snow cover on the Songnen Plain was 1451.07 N·L−1. Fragment-type microplastics predominated, with over 86.38 ± 6.62% of particles concentrated within the 20–50 μm size range. A total of 27 types of microplastic polymers were detected, with polyamide (PA) being the predominant polymer type, while polyethylene (PE), polytetrafluoroethylene (PTFE), and polylactic acid (PLA) were the secondary predominant polymer types. Potential sources of microplastics in snow cover on the Songnen Plain encompass agricultural production activities, emissions from industrial buildings, domestic waste inputs, road traffic sources, and textiles and wastewater. (2) Microplastic abundance in agricultural areas is 1–4 orders of magnitude higher than in natural areas, and comparable to or 1 order of magnitude higher than in urban snow. The particle size of microplastics in farmland snow cover is comparable to that in natural areas, being slightly smaller than that in urban snow. The morphology of microplastics in snow cover farmland is essentially identical between natural and urban areas. The composition of microplastics in snow cover farmland differs from that in natural areas, with polyamide (PA) being the most prevalent component, whereas polyethylene terephthalate (PET) dominates in natural areas. Compared to urban areas, the proportion of polytetrafluoroethylene (PTFE) and polylactic acid (PLA) in snow microplastics is higher in agricultural regions.