Abstract

The urban aquatic environment is a repository of anthropogenic organic chemicals. Some of these are classified as contaminants of emerging concerns (CEC) due to their newly discovered environmental and health risks. These chemicals enter the aquatic environment through various routes, including urban runoff, wastewater discharge and snow melting. While some efforts have been invested in monitoring these substances along these routes, the coverage is limited to a small set of chemicals. This thesis aims to address environmental exposures of CEC and identifying lesser-known chemicals of environmental concerns, e.g., transformation products (TPs). Targeted and non-targeted analyses were conducted on 42 surface water and 30 snow samples in Montreal. The analyses focused on automobile-derived compounds used as industrial antioxidants and vulcanization accelerators. Samples were processed using solid-phase extraction (SPE). Liquid chromatography-mass spectrometry (Orbitrap LC-MS) was used for the sample analyses. Fifteen target compounds were quantified using internal standard calibration. Non-targeted screening of lesser-known contaminants and their TPs generated over 30,000 features in snow and 17,000 in surface water. Feature prioritization was based on peak intensity (>10000) and detection frequency (≥ 50%) while identification relied on retention time and substructural information. To further facilitate the identification of TPs, an additional oxidation experiment was conducted by exposing the parent compounds to ultra-violet (UV) radiation in a multi-lamp photochemical reactor. From the non-targeted analysis and transformation experiments, 37 analytes were identified. Our findings highlight the presence of lesser-known CEC including chemicals used as tire additives and their transformation products in the urban aquatic environment. This study also underscores the importance of using targeted and non-targeted screening approaches to identify and assess these compounds and their TPs.