Intensive Spatiotemporal Characterization of the Tire Wear Toxin 6PPD Quinone in Urban Waters.

6PPDQ is a tire-derived contaminant toxic to coho salmon (LC = 41-95 ng/L) found widely distributed in urban environments. Most monitoring efforts have relied on relatively few discrete samples collected at select locations across rain events. Early work has revealed that 6PPDQ concentrations vary widely over time and space, raising questions about when and where to collect samples. Here, we employ condensed phase membrane introduction mass spectrometry, a high-throughput analysis approach to characterize spatiotemporal variability of 6PPDQ in urban streams. Analytical method detection limits of 0.3-8 ng/L and a duty cycle of 2.5 min/sample enabled high-throughput adaptive sampling. Temporal sampling revealed dynamic 6PPDQ concentrations, with significant changes occurring over minutes during peak rainfall. Spatial variability was characterized at multiple sites along three watercourses during the first significant precipitation of autumn 2023 on central Vancouver Island, B.C., Canada. Site-specific concentrations suggest attenuation of 6PPDQ after point source inputs by some combination of physical (dilution, sorption) or chemical (degradation) processes. This is the first report of an intensive sampling campaign describing the spatiotemporal distribution of 6PPDQ, highlighting the need for careful consideration of sampling strategies to evaluate the risk and impact of 6PPDQ in urban waterways.