|
Atmos. Chem. Phys. Discuss., 8, 13801-13845, 2008
www.atmos-chem-phys-discuss.net/8/13801/2008/ doi:10.5194/acpd-8-13801-2008 © Author(s) 2008. This work is distributed under the Creative Commons Attribution 3.0 License. |
Characterization of the size-segregated water-soluble inorganic ions at eight Canadian rural sites
Air Quality Research Division, Science and Technology Branch, Environment Canada 4905 Dufferin Street, Toronto, Ontario, M3H 5T4, Canada
Abstract. Size-segregated water-soluble inorganic ions, including particulate sulphate (SO42-), nitrate (NO3-), ammonium (NH4+), chloride (Cl-) and base cations (K+, Na+, Mg2+, Ca2+), were measured using a Micro-Orifice Uniform Deposit Impactor (MOUDI) during fourteen short-term field campaigns at eight locations in both polluted and remote regions of eastern and central Canada. The size distributions of SO42- and NH4+ were unimodal, peaking at 0.3–0.6 μm in diameter, during most of the campaigns, although a bimodal distribution was found during one campaign and a trimodal distribution during another campaign made at a coastal site. The size distributions of NO3- were unimodal, peaking at 4.0–7.0 μm, during the warm-season campaigns and bimodal, with one peak at 0.3–0.6 μm and another at 4–7 μm, during the cold-season campaigns. A unimodal size distribution, peaking at 4–6 μm, was found for Cl-, Na+, Mg2+ and Ca2+ during approximately half of the campaigns and a bimodal distribution, with one peak at 2 μm and the other at 6 μm, was found during the rest of the campaigns. For K+, a bimodal distribution, with one peak at 0.3 μm and the other at 4 μm, was observed during most of the campaigns. The measured ion concentrations varied by one order of magnitude across the various sites. The air-mass origins and meteorological conditions both played important roles in formulating the observed geographical and seasonal patterns of these ion species concentration levels, size distributions and fine particle acidity.
Citation: Zhang, L., Vet, R., Wiebe, A., Mihele, C., Sukloff, B., Chan, E., Moran, M. D., and Iqbal, S.: Characterization of the size-segregated water-soluble inorganic ions at eight Canadian rural sites, Atmos. Chem. Phys. Discuss., 8, 13801-13845, doi:10.5194/acpd-8-13801-2008, 2008.