Hutchinson, Tom

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

This study was designed to determine the geochemistry and potential toxicity of water draining a large slag pile in Sudbury, Ontario, which runs through a pond complex prior to entering Alice Lake. Slag leaching experiments confirmed slag is a source of sulphate, heavy metals (including Fe, Al, Ni, Co, Cu, Zn, Pb, Cr, Mn) and base cations (Ca, K, Mg, Na). Concentrations of most metals draining through slag in column experiments were similar to metal concentrations measured at the base of the slag pile, although base cations, S and pH were much higher, possibly because of water inputs interacting with the surrounding basic glaciolacustrine landscape. The increase in pH rapidly precipitates metals leading to high accumulation in the surface sediments. Away from the base of the pile, an increase in vegetation cover leads to an increase in DOC and nutrients and transport of metals with strong binding affinities (Cu). Total metal concentration in water and sediment exceed provincial water quality guidelines, particularly near the slag pile, however WHAM7 modeling indicated that the free metal ion concentration in water is very low. Nevertheless, toxicity experiments showed that water with greater concentrations of solutes collected close to the slag pile negatively impacts D. magna suggesting that water draining the slag pile can adversely impact biota in nearby drainage areas.

Author Keywords: geochemistry, heavy metals, leaching, non-ferrous slag, precipitation, toxicity