Tracking traffic-derived benzothiazoles and benzotriazoles in urban air and water near roadways: A multi-phase passive sampling approach for risk assessment

Traffic-derived heterocyclic compounds, particularly benzothiazoles (BTs) and benzotriazoles (BTRs), are increasingly recognized as persistent, mobile, and toxic (PMT) contaminants in urban environments. While their occurrence in various environmental matrices has been documented, simultaneous monitoring in air and water environments remains limited. The present study employed an integrated passive sampling approach to simultaneously monitor BTs, BTRs, and their transformation products near high-traffic roadways. Water monitoring was conducted using Polar Organic Chemical Integrative Sampler, Chemcatcher, and polydimethylsiloxane (PDMS) sampler, whereas air monitoring utilized PDMS of varying thicknesses to estimate ambient concentrations based on compound-specific uptake kinetics. The use of a variable-thickness PDMS enables calibration-free quantification using the contaminant mass ratio approach, offering a practical alternative to conventional methods. BTs were detected widely in both environmental compartments, whereas BTRs were absent in the air, likely because of their high polarity and low volatility. Spatiotemporal trends revealed consistent contamination linked to traffic emissions and runoff, with lower concentrations observed during the second sampling period. A preliminary environmental risk assessment suggested that the observed concentrations posed low ecological risk; however, the persistence and ubiquity of the compounds necessitate continued monitoring. The present study demonstrates the effectiveness of a dual-matrix passive monitoring strategy and supports its application for comprehensive exposure assessment of traffic-derived emerging contaminants.