Elucidating determinants of aerosol composition through particle-type-based receptor modeling
Date
2011
Authors
McGuire, M. L.
Jeong, C. -H
Slowik, J. G.
Chang, R. Y. -W
Corbin, J. C.
Lu, G.
Mihele, C.
Rehbein, P. J. G.
Sills, D. M. L.
Abbatt, J. P. D.
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Journal ISSN
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Abstract
An aerosol time-of-flight mass spectrometer (ATOFMS) was deployed at a semi-rural site
in southern Ontario to characterize the size and chemical composition of individual
particles. Particle-type-based receptor modelling of these data was used to investigate
the determinants of aerosol chemical composition in this region. Individual particles
were classified into particle-types and positive matrix factorization (PMF) was applied
to their temporal trends to separate and cross-apportion particle-types to factors. The
extent of chemical processing for each factor was assessed by evaluating the internal
and external mixing state of the characteristic particle-types. The nine factors
identified helped to elucidate the coupled interactions of these determinants.
Nitrate-laden dust was found to be the dominant type of locally emitted particles
measured by ATOFMS. Several factors associated with aerosol transported to the site from
intermediate local-to-regional distances were identified: the Organic factor was
associated with a combustion source to the north-west; the ECOC Day factor was
characterized by nearby local-to-regional carbonaceous emissions transported from the
south-west during the daytime; and the Fireworks factor consisted of pyrotechnic
particles from the Detroit region following holiday fireworks displays. Regional aerosol
from farther emissions sources was reflected through three factors: two Biomass Burning
factors and a highly chemically processed Long Range Transport factor. The Biomass
Burning factors were separated by PMF due to differences in chemical processing which
were in part elucidated by the passage of two thunderstorm gust fronts with different
air mass histories. The remaining two factors, ECOC Night and Nitrate Background,
represented the night-time partitioning of nitrate to pre-existing particles of
different origins. The distinct meteorological conditions observed during this
month-long study in the summer of 2007 provided a unique range of temporal variability,
enabling the elucidation of the determinants of aerosol chemical composition, including
source emissions, chemical processing, and transport, at the Canada-US border. This
paper presents the first study to elucidate the coupled influences of these determinants
on temporal variability in aerosol chemical composition using single particle-type-based
receptor modelling.
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Citation
McGuire, M. L., C. -H Jeong, J. G. Slowik, R. Y. -W Chang, et al. 2011. "Elucidating determinants of aerosol composition through particle-type-based receptor
modeling." Atmospheric Chemistry and Physics 11(15): 8133-8155.