Tyre road wear particles (TRWP) have been suggested as one of the primary, yet understudied, sources of microplastic to the environment. Further concern arises from chemical additives incorporated into the tyre material, as they can leach into the surrounding environment and have demonstrated links to aquatic toxicity. These chemicals include the vulcaniser hexa(methoxymethyl) melamine (HMMM)1,2 and 6PPD-quinone, a derivative of the antioxidant 6PPD3. The current study investigated inputs and co-occurrence of TRWP and tyre additive chemicals in an Australian urban water cycle during severe storm events in 2020. Grab samples were taken from a creek in Brisbane, QLD, which has direct traffic inputs from two major artery roads through the city. Samples were filtered to remove particles > 0.7 µm and the residue analysed with Pyrolysis GC-MS for markers of TRWP including synthetic and natural rubber. The filtrate was then extracted with solid phase extraction and analysed with LC-MSMS for a range of tyre related chemicals (n=16), including the new chemical of concern 6PPD-Quinone (standard obtained from the University of California4). Further, complementary non-target analysis was conducted with LC-QToF.
The urban hydrograph of storm water inputs to this urban water cycle were determined, with similar chemical profiles throughout each storm event, enabling a fingerprint of Brisbane traffic related chemical inputs to be established. Further, HMMM and 6PPD-Quinone were detected in all samples showing clear links to traffic related inputs, all be it at concentrations lower than those previously reported to have links with aquatic toxicity.