Feasibility of using Pleurozium schreberi as a biomonitor to study antiozonant dispersion: A case study in Southern Quebec

Abstract

p-Phenylenediamine antioxidants (PPDs), widely used as additives in tires and rubber, are released into the environment through tire and road wear particles. These compounds undergo oxidative processes, forming quinone derivatives that pose significant environmental and health risks, particularly to aquatic organisms (EPA, 2024). While runoff has been identified as the primary transport mechanism, the atmospheric dispersion of PPDs has received less attention. Bryophytes have been widely used as biomonitors of airborne contaminants and atmospheric deposition. Using a biomonitoring approach, this study investigated the atmospheric deposition of PPD antiozonants, including 6PPD, 6PPDQ, and DPPD, across Southern Quebec (Canada), a region characterized by the highest population density and pollution levels in the province. Samples of Pleurozium schreberi, a common species used for biomonitoring of atmospheric deposition, were collected on three site types with varying degrees of traffic exposure: roadsides, parks/playgrounds, and non-urban areas. Our findings demonstrated atmospheric dispersion of PPDs throughout Southern Quebec with a decreasing trend in total concentrations of PPDs with increasing distance from traffic. 6PPDQ was the most frequently detected compound, ranging from <LOQ to 3.71 ng g⁻¹. DPPD, the least detected, ranged from <LOQ to 4.92 ng g⁻¹. 6PPD showed intermediate detection frequencies but the highest concentrations, up to 59.01 ng g⁻¹. This study validates that P. schreberi is a valuable tool for low-cost monitoring of PPD dispersal. Results underscore the spatial variability of PPDs and their derivatives, influenced by proximity to pollution sources, environmental conditions, and site characteristics. This study provides one of the few pieces of evidence supporting the atmospheric dispersion of PPDs, highlighting the need for further investigation.