Improved sampling efficiency of volatile halomethoxybenzenes and persistent organic pollutants reveals increasing concentrations in Canadian air.

Two long-term air monitoring programs for persistent organic pollutants (POPs) have been established in the Great Lakes Basin (GLB), Ontario, and Alert, Nunavut, Canada since the 1980s for evaluating regional and long-range transport (LRT) dynamics. With growing attention towards Chemicals of Emerging Arctic Concern (CEACs), including volatile halomethoxybenzenes (HMBs) and POPs, these programs have been expanded to monitor CEACs, which can experience significant sampling breakthrough due to their high volatility. To improve collection efficiency, a high-volume air sampler utilizing a polyurethane foam-XAD2 resin sandwich was implemented for concentration characterization at the Alert and GLB sites. At Alert, the air concentrations of hexachlorobutadiene (HCBD), hexachlorobenzene (HCB), pentachlorobenzene (PeCB), 2,4-dibromoanisole (DBA), 2,4,6-tribromoanisole (TBA), and drosophilin A methyl ether (DAME) have increased from 2009 to 2020, with the rising levels of HCBD, HCB, and PeCB potentially linked to unintentional byproducts from industrial processes. Atmospheric concentrations of HMBs and POPs at Alert are primarily governed by LRT, whereas local surface-air exchange exerts a secondary influence on DBA and TBA. In contrast, at GLB sites, local surface-air exchange is the predominant driver of HMB and POP concentrations, regardless of emission origins, with the exception of TBA at Evansville, where additional influencing factors may be involved ( LRT).