Characteristics of microplastics in soil and throughfall and their relationships with meteorological factors in a temperate forest ecosystem of the Changbai Mountains.

Microplastics (MPs) can undergo long-range atmospheric transport and deposit in remote forests. However, the presence and behavior of MPs within forest ecosystems remain inadequately characterized. This study examined the abundance, characteristics and meteorological correlations of MPs in a temperate forest of the Changbai Mountains. MPs occurred in soils (209.8 ± 9.6 items kg-1) and throughfall (11.9 ± 0.7 items 100 mL-1), with an annual throughfall deposition flux of 9.22 × 104 items m-2 year-1. Soil MPs were predominantly composed of polyethylene terephthalate (PET), fragments (31.1%) and films (29.2%) morphologies, whereas throughfall MPs were mainly polyvinyl chloride (PVC), fibers (35.7%) and films (28.2%). Small-sized MPs (1-100 μm) constituted 42% of MPs in throughfall but only 19.7% in soils. Summer demonstrated the highest deposition flux. The abundance of MPs in both soil and throughfall exhibited polymer- and shape-specific correlations with meteorological variables such as wind speed and humidity. These results emphasize that the deposition and accumulation of MPs may be associated with complex interactions among properties of MPs and meteorological conditions. Consequently, our findings underscore the importance of integrating canopy-mediated atmospheric inputs and soil dynamics into regional ecological risk assessments pertaining to temperate forest ecosystems.