Effects of Tire Wear Particles on Soil Fertility and Physicochemical Properties: The Role of Typical Aging Patterns in the Environment

ObjectiveTire wear particles (TWPs) are key sources of microplastic pollution, and their long-term impact on human health and the environment is receiving increasing attention.MethodThis study investigated the release of heavy metals and sulfur from TWPs in soil, as well as their effects on soil physicochemical properties and fertility. It was also explored the role of different aging processes (photo-aging, lake water aging, and snowmelt water aging) on the properties of TWPs and their effects on soil fertility. Through laboratory simulations, fresh and aged TWPs were prepared and incubated in soil for various periods.ResultThe results indicated that aging significantly altered the physicochemical properties of TWPs, including surface morphology, functional groups, and specific surface area, which in turn affected their heavy metal and sulfur release behavior in soil. After the addition of TWPs to the soil, a decrease in soil organic matter (OM) content was observed, although the impacts on cation exchange capacity (CEC) and pH were minimal. At the same time, TWPs significantly increased the content of available phosphorus and alkali-hydrolyzable nitrogen in the soil, with a slight impact on available potassium. The effects of TWPs on soil physicochemical properties and fertility varied under different aging processes, with photo-aging and snowmelt aging showing the most pronounced effects. Pearson correlation analysis revealed a significant internal relationship between the physicochemical properties of TWPs and the soil response. As TWPs were incubated in soil for longer periods, their adverse effects on soil fertility indicators, especially OM, gradually intensified. Furthermore, TWPs may interfere with soil nutrient cycling, particularly nitrogen cycling, by affecting CEC.ConclusionThis study provides important insights for understanding the long-term ecological impact of TWPs on soil and offers a basis for accurate risk assessment.