SOCAAR is pleased to announce our next seminar in our 2013-2014 seminar
series.
Aerosol Acidity: Observations and Impacts
Jennifer Murphy,
Associate Professor, Department of Chemistry, University of Toronto
Aerosol acidity is important because it influences gas-particle partitioning and
particle chemistry, as well as the impact of particles in terms of human and
ecosystem health. Two different metrics may be applicable in different
situations: 1) strong acidity, which represents the sum of H+ and HSO4-
concentrations in particles per unit volume of air, and 2) aerosol pH, which
represents the activity of the H+ ion in aerosol liquid water. While strong
acidity can be calculated directly based on the difference between measured
anions and cations, estimates of aerosol pH require thermodynamic modelling
calculations. Furthermore, as aerosol strong acidity approaches zero, estimates
of pH become highly uncertain. In this seminar, I will present estimates of
aerosol acidity made using online Ambient Ion Monitor Ion Chromatograph and
Aerosol Mass Spectrometer instruments, and demonstrate why simultaneous
measurements of gas phase ammonia and/or nitric acid are crucial for
constraining pH estimates. I will also present an analysis of spatial and temporal
trends in aerosol acidity using 20 years of particulate data from eight
geographically diverse sites in the Canadian Air and Precipitation Monitoring
Network (CAPMoN). Finally, I will show some examples of how aerosol acidity
can affect gas-particle partitioning of ionisable compounds such as amines and
perfluorinated acids.
December 4, 2013, 3 - 4 pm
Wallberg Building, 200 College Street, Room 407
The seminar will be recorded and posted on the SOCAAR website:
www.socaar.utoronto.ca
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