Burning Issues

1: Environ Sci Technol 2001 Dec 1;35(23):4604-21

Atmospheric aerosol over Vermont: chemical composition and sources.

Polissar AV, Hopke PK, Poirot RL.

Department of Chemical Engineering, Clarkson University, Potsdam, New York
13699-5810, USA.

Aerosol chemical composition data for PM2.5 samples collected during the period
from 1988 to 1995 at Underhill, VT, were analyzed. Sulfur and black carbon mass
concentrations ranged from 0.01 to 6.5 microg m(-3) and from 0.05 to 2.2 microg
m(-3), respectively, while the total fine aerosol mass concentration ranged from
0.2 to 51.1 microg m(-3). Seasonal variations with maxima during the summer and
minima in winter/spring were observed for sulfur and the fine mass
concentrations. No annual pattern was observed for black carbon. Seasonal
variations for most of the other anthropogenic species had maxima in winter and
spring and minima in the summer. A factor analysis method, positive matrix
factorization (PMF), utilizing error estimates of the data to provide optimum
data point scaling was used to obtain information about possible sources of the
aerosol. An 11-factor solution was obtained. The six sources representing wood
burning, coal and oil combustion, coal combustion emissions plus photochemical
sulfate production, metal production plus municipal waste incineration, and
emissions from motor vehicles were identified. Emissions from smelting of
nonferrous metal ores, arsenic smelting, and soil particles and particles with
high concentrations of Na were also identified by PMF.
Potential source
contribution function (PSCF) analysis combines the aerosol data with the air
parcel backward trajectories. PSCF was applied to identify possible source areas
and pathways that give rise to the observed high particulate mass concentrations
from these 11 sources. The CAPITA Monte Carlo trajectory model was used to
obtain 10 sets of 5-day air parcel back trajectories arriving every 2 h for the
7-yr period from 1988 to 1995. The PSCF plot for the black carbon factor shows
high probabilities in the area surrounding the sampling site, indicating a
strong local influence from residential wood combustion in northern New England and southwestern Quebec.
Similar large potential source areas in the midwestern
United States were identified for the two coal combustion factors. The
midwestern United States was also identified as the source region for the Zn-Pb
factor. The oil combustion factor was associated with the east coast of the
United States. The results for the Pb-Mn factor suggests high probability over
the nearby Montreal urban area and the areas in the midwestern United States.
The windblown dust emissions from the areas to the north are significant
contributors for the soil factor. Canadian Ni smelters are the main sources for
the As factor, although there is some contribution from coal-fired power plants
to the south and west of Underhill, VT. It is concluded that the combination of
the two receptor modeling methods, PMF and PSCF, provides an effective way in
identifying atmospheric aerosol sources and their likely locations. Emissions
from different anthropogenic activities as well as secondary aerosol production
are the main sources of aerosol measured in Vermont. Fuel combustion, local wood
smoke, municipal waste incineration, and the secondary sulfate production
collectively accounted for about 87% of the fine mass concentrations measured in

PMID: 11770762 [PubMed - in process]

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