Article
Analytical determination of the aerosol organic mass-to-organic carbon ratio
Journal of the Air & Waste Management Association
(2012)
Abstract
Particulate matter (PM) with an aerodynamic diameter
2.5 m (PM2.5) was collected daily (mid-July 1998 to the
end of December 1999) over a 24-hr sampling period in a
mixed light industrial-residential area in Atlanta, GA, to
provide a subset of data for the Aerosol Research and
Inhalation Epidemiology Study (ARIES). This study included
the measurement of organic carbon (OC), elemental
carbon (EC), and individual organic compounds. OC
and EC average mean concentrations were 4.50 0.33
and 2.08 0.19 g/m3, respectively. The ratio of organic
matter mass (OM) to OC in PM2.5 aerosols in Atlanta was
measured using three different approaches: (1) solvent
extract residue gravimetric masses to individual OC concentrations
of sequential apolar to polar solvent extracts
(dichloromethane, acetone, and water); (2) mass balance
of the PM2.5 measured gravimetric mass minus the mass
concentrations of the inorganic/elemental constituents to
the total OC concentration; and (3) polar organic compound
speciation with the concentration weighted ratio
to the total OC concentration. We found very good agreement
between approach 1 and 2. The average OM/OC
ratio calculated from the extract residue mass was 2.14
0.17. The average OM/OC ratio determined by mass balance
was 2.16 0.43 for the whole period. The concentration
weighted ratio calculated from the concentrations
of polar organic compounds ranged between 1.55 and
1.72, which was likely a lower limit for the ratio because
of the limited number of the polar organic compounds
that can be quantified using gas chromatographic methods.
We found seasonal differences with an OM/OC range
of 1.77 in December 1999 to 2.39 in July 1999. These
results suggest that the previously accepted value of 1.4
for the OM/OC ratio was too low even for urban locations
during the winter months. Molecular-level speciation of
the PM2.5-associated organic compounds showed that the
concentrations of the molecular markers for wood smoke
represented approximately 12–15% of the total polar organic
compound concentrations during the winter
months.
Disciplines
Publication Date
January 24, 2012
DOI
10.3155/1047-3289.59.1.58
Publisher Statement
Copyright 2009 Air & Waste Management Association. Publisher's version of record: http://dx.doi.org/10.3155/1047-3289.59.1.58
Citation Information
L. Mazzoleni, Hazem S El-Zanan, Barbara Zielinska, Lynn R. Mazzoleni, et al.. "Analytical determination of the aerosol organic mass-to-organic carbon ratio" Journal of the Air & Waste Management Association Vol. 59 Iss. 1 (2012) p. 58 - 69 ISSN: 1047-3289 Available at: http://works.bepress.com/l-mazzoleni/1/