Atmospheric chemistry
Observation-based assessment of atmospheric sulphur surrounding a major aluminum smelter in British Columbia, Canada
Recent developments at an aluminum (Al) smelter in Kitimat, BC resulted in a permitted increase of 27 to 42 tonnes of sulphur dioxide (SO2) emissions per day. Gaseous SO2 is a pollutant known to contribute to acidic deposition through processes of wet and dry deposition and can additionally react in-atmosphere to form particulate sulphate (pSO42-). Between June 2017 to October 2018, an extensive network consisting of ion exchange resin (IER) column, passive-diffusive, and active filter-pack samplers was established to provide an estimate of total annual S deposition and pSO42- variation throughout the Kitimat Valley. Filter-pack sampling determined the relative concentration of pSO42- increased downwind of the smelter. Comparison of observation-based and modelled total annual deposition suggested CALPUFF was accurate in representing the spatial viability of S deposition (R2 = > 0.85). However, the model appeared to overpredict near-field deposition suggesting the potential of underestimation further downwind of the smelter.
Author Keywords: aluminum smelter, atmospheric deposition, filter-pack sampler, ion-exchange column sampler, pSO42-, SO2
Passive sampling of indoor and outdoor atmospheric nitrogen dioxide in the greater Toronto area
The reliability and performance of four passive sampler membrane coatings specific to nitrogen dioxide (NO2) were evaluated through co-exposure at multiple Ontario Ministry of Environment and Climate Change (OMOECC) active monitoring stations. All four coatings performed relatively similar under a wide range of meteorological conditions, notably showing exposure-specific atmospheric uptake rates. Further, indoor and outdoor atmospheric concentrations of NO2 (a marker of traffic-related air pollution) were evaluated at multiple elementary schools in a high-density traffic region of Toronto, Ontario, using a Triethanolamine based passive sampler membrane coating. Samplers were also co-exposed at OMOECC active monitoring stations to facilitate calibration of exposure-specific atmospheric uptake rates. Indoor NO2 atmospheric concentrations were 40 to 50% lower than outdoor concentrations during the spring−summer and autumn−winter periods, respectively. In large cities such as Toronto (Population 2,700,000), the influence of a single major road on outdoor and indoor NO2 concentrations is predominantly masked by spatially-extensive high-density traffic.
Author Keywords: active sampler, membrane coating type, nitrogen dioxide, passive sampler, Toronto, traffic density