Photolytic Degradation Pathways of Tire Tread Particle Organics in Aquatic Systems

Tire tread particles (TTPs) are an important source of microplastic and organic pollution in aquatic systems. In contact with natural waters, TTPs release complex mixtures of trace organics that have been shown to pose emerging risks to ecosystems, human health, and water quality. While TTP leachates are known to contain elevated levels of dissolved organic carbon and toxic compounds such as 6PPD-quinone, their transformation mechanisms in natural waterways remain poorly understood.

This project examines the potential attenuation of TTP-derived contaminants in natural waters due to exposure to sunlight. Controlled irradiation experiments were conducted with TTP leachates in the presence of natural organic matter exposed to UVA and solar irradiation, using molecular probes to quantify photochemically produced reactive intermediates (PPRIs), which include singlet oxygen , hydroxyl radicals , and triplet-state dissolved organic matter, and are quantified using molecular probes (furfuryl alcohol, pCBA, and 2,4,6-trimethylphenol, respectively). high-performance liquid chromatography (HPLC) tracks the degradation of target compounds and probe loss.

Preliminary results demonstrate that direct photolytic pathways contribute to TTP transformation, with singlet oxygen and triplet-state dissolved organic matter being the most active PPRIs.

The results provide initial evidence that photolysis can attenuate a subset of TTP leachate constituents that could potentially decrease the toxicity of water matrices impacted by TTPs. This work contributes to a mechanistic understanding of TTP degradation in aquatic environments and supports the development of treatment strategies addressing microplastic-associated contaminants in stormwater and reuse systems.