Light Induced Mobilization of Heavy Metals from Tire Wear Particles in Aquatic Environments

Tire wear particles (TWPs) are produced in large amounts on roadways and end up in nearby waters. These particles contain metals that can leach out and affect water quality. The role of sunlight in driving this process is not well defined. In this study, TWPs were exposed to simulated sunlight in nanopure water to measure heavy metals' release and examine changes in particle characteristics.
Trace metals were quantified using inductively coupled plasma triple quadrupole mass spectrometry (ICP-QQQ), while scanning electron microscopy (SEM) was used to observe particle size and surface features. In addition, dissolved organic carbon (DOC) was measured to track organic leachate concentrations. The experiment was also conducted in estuarine and seawater matrices to understand how salinity influences leaching.
Initial results show that zinc and copper are the primary metals mobilized under light exposure in nanopure water. Cadmium, chromium, and lead were detected in bulk TWPs but were at or below detection limits in solution (<0.007 ppb). These findings suggest that environmental factors such as salinity and organic matter may strongly control the release of trace metals from TWPs.
This project demonstrates the sensitivity of ICP-QQQ for ultra-trace metal detection and the usefulness of combining spectroscopy, microscopy, and carbon analysis for complex environmental materials. Together, these approaches give a clearer view of how TWPs behave in aquatic systems and the risks they may pose..