A first look at atmospheric concentrations and temporal trends of phthalates in distinct urban sectors of the Greater Toronto Area

Abstract

Measurements of the outdoor air concentrations of phthalates (PHTs) using passive sampling media (polyurethane foam (PUF) disks) were conducted at 8 different sites across the Greater Toronto Area (GTA) during 2016–2017. Highest PHT levels were obtained at sites characterized by high levels of urban and traffic activity. The PHT profile was mainly dominated by bis(2-ethylhexyl) phthalate (DEHP), whose median air concentration across the examined sites was MDEHP = 1200 pg/m3. It was discovered that PHT levels had a strong correlation with the ambient temperature. Warmer months appeared to contribute to greater emission of PHTs at most sites. Clausius Clapeyron (CC) plots were used to investigate the presence of temperature dependent processes governing PHT emissions, such as secondary volatilization from environmental surfaces. Enthalpies of surface-air exchange calculated from CC plots were compared to respective enthalpies of vaporization for each PHT. Those values were used to examine importance of localized water-air and land-air exchanges on atmospheric levels of PHTs. The data suggested that secondary volatilizations are relevant PHT contributors and appear to depend on sampling site and PHT type. Enthalpies associated with Henry's law constant were also evaluated, providing evidence of secondary volatilization from water bodies. This work is part of an on-going study which already evaluated levels of organophosphate esters (OPEs), polybrominated diphenyl ethers (PBDEs) and polycyclic aromatic compounds (PACs) at the same sites. Ultimately, the variability in ambient concentrations of PHTs in the GTA are believed to be due to a combination of both primary and secondary sources.