Influence of polymer age and soil aggregation on microplastic transport in soil erosion events

The transport of microplastics within and across terrestrial ecosystems is a critical factor controlling plastic pollution in the environment. However, our understanding of these transport processes remains extremely limited. Particular uncertainty surrounds how the changes driven by aging of plastics, for example in surface roughness or hydrophobicity, affect polymer transport.  In this study we compare the rate of transportation of pristine and aged polystyrene microplastics in a simulated rainfall event providing the first empirical data describing these processes. Additionally, we quantified the proportion of both aged and pristine microplastics incorporated into soil aggregates after several wet-dry cycles and the influence wet-dry cycles had on microplastic mobilization. The results from this study will provide critical insights into the influence of polymer age on microplastic mobility and retention in terrestrial environments.