Intensive Spatiotemporal\nCharacterization of the Tire\nWear Toxin 6PPD Quinone in Urban Waters

6PPDQ is a tire-derived contaminant toxic to coho salmon\n(LC<sub>50</sub> = 41–95 ng/L) found widely distributed in\nurban environments.\nMost monitoring efforts have relied on relatively few discrete samples\ncollected at select locations across rain events. Early work has revealed\nthat 6PPDQ concentrations vary widely over time and space, raising\nquestions about when and where to collect samples. Here, we employ\ncondensed phase membrane introduction mass spectrometry, a high-throughput\nanalysis approach to characterize spatiotemporal variability of 6PPDQ\nin urban streams. Analytical method detection limits of 0.3–8\nng/L and a duty cycle of 2.5 min/sample enabled high-throughput adaptive\nsampling. Temporal sampling revealed dynamic 6PPDQ concentrations,\nwith significant changes occurring over minutes during peak rainfall.\nSpatial variability was characterized at multiple sites along three\nwatercourses during the first significant precipitation of autumn\n2023 on central Vancouver Island, B.C., Canada. Site-specific concentrations\nsuggest attenuation of 6PPDQ after point source inputs by some combination\nof physical (dilution, sorption) or chemical (degradation) processes.\nThis is the first report of an intensive sampling campaign describing\nthe spatiotemporal distribution of 6PPDQ, highlighting the need for\ncareful consideration of sampling strategies to evaluate the risk\nand impact of 6PPDQ in urban waterways.