The Steubenville Comprehensive Air Monitoring Program (SCAMP): Concentrations and Solubilities of PM_2.5 Trace Elements and Their Implications for Source Apportionment and Health Research

Abstract

The elemental compositions of the water-soluble and acid-digestible fractions of 24-hr integrated fine particulate matter (PM 2.5 ) samples collected in Steubenville, OH, from 2000 to 2002 were determined using dynamic reaction cell inductively coupled plasma-mass spectrometry. The water-soluble elemental compositions of PM 2.5 samples collected at four satellite monitoring sites in the surrounding region were also determined. Fe was the most abundant but least water soluble of the elements determined at the Steubenville site, having a mean ambient concentration of 272 ng/m 3 and a median fractional solubility of 6%. Fe solubility and its correlations with SO 4 2Ϫ and temperature varied significantly by season, consistent with the hypothesis that secondary sulfates may help to mobilize soluble Fe under suitable summertime photochemical conditions. Significantly higher ambient concentrations were observed at Steubenville than at each of the four satellite sites for 10 of the 18 elements (Al, As, Ca, Cd, Fe, Mg, Mn, Na, Pb, and Zn) determined in the water-soluble PM 2.5 fraction. Concentrations of Fe, Mn, and Zn at Steubenville were substantially higher than concentrations reported recently for larger U.S. cities. Receptor modeling identified seven sources affecting the Steubenville site. An (NH 4 ) 2 SO 4 -dominated source, likely representing secondary PM 2.5 from coal-fired plants to the west and southwest of Steubenville, accounted for 42% of the PM 2.5 mass, and two sources likely dominated by emissions from motor vehicles and from iron and steel facilities in the immediate Steubenville vicinity accounted for 20% and 10%, respectively. Other sources included an NH 4 NO 3 source (15%), a crustal source (6%), a mixed nonferrous metals and industrial source (3%), and a primary coal combustion source (3%). Results suggest the importance of very different regional and local source mechanisms in contributing to PM 2.5 mass at Steubenville and reinforce the need for further research to elucidate whether metals such as Fe, Mn, and Zn play a role in the PM 2.5 health effects observed previously there. INTRODUCTIONAlthough trace elements generally account for only a few percent of the total mass of ambient fine particulate matter (PM 2.5 ) in the United States, their characterization is an essential part of PM 2.5 source apportionment and health effects research. Numerous recent receptor modeling studies 1-4 have used fine particulate trace element concentration data to help identify sources that emit PM 2.5 or its precursors. These studies increasingly are using techniques such as backward trajectory analysis and potential source contribution function (PSCF) modeling 5,6 to geographically corroborate the compositional source profiles derived from multivariate models like Positive Matrix Factorization (PMF) or Unmix. The results are particularly relevant given the need to develop State Implementation Plans (SIPs) to reduce ambient PM 2.5 concentrations in nonattainment areas under the National Ambient Air Quali...

On dithiothreitol (DTT) as a measure of oxidative potential for ambient particles: evidence for the importance of soluble transition metals

“…To identify species that might contribute to DTT loss in PM samples we measured the rate of DTT consumption in the presence of 18 individual quinones, PAHs, and dissolved transition metals, all of which are commonly present in ambient PM (Connell et al, 2006; Shinyashiki et al, 2009; Vidrio et al, 2009; Walgraeve et al, 2010). As shown in Fig.…”

“…As described in Sect. S2 of the Supplement, we use median concentrations of individual quinones in urban PM 2.5 reported in the review by Walgraeve et al (2010), and median soluble PM 2.5 metal concentrations from several studies (Connell et al, 2006; Verma et al, 2009a; Vidrio et al, 2009). Because the oxidation state of soluble Fe was not provided in these articles, we assume soluble Fe is 80 % Fe(II) and 20 % Fe(III), based on measurements of urban particles from Majestic et al (2007).…”

On dithiothreitol (DTT) as a measure of oxidative potential for ambient particles: evidence for the importance of soluble transition metals

“…Co is the third most reactive metal (Fig. 3), but since atmospheric PM 2.5 concentrations of Co are very low (Connell et al, 2006;Verma et al, 2009a) and would not cause significant DTT loss, we did not measure responses over a range of Co concentrations. V and Ni(II), the next most reactive metals, have very similar concentration responses.…”

“…Chem. Phys., 12, 9321-9333, 2012 www.atmos-chem-phys.net/12/9321/2012/ in urban PM 2.5 reported in the review by Walgraeve et al (2010), and median soluble PM 2.5 metal concentrations from several studies (Connell et al, 2006;Verma et al, 2009a;Vidrio et al, 2009). Because the oxidation state of soluble Fe was not provided in these articles, we assume soluble Fe is 80 % Fe(II) and 20 % Fe(III), based on measurements of urban particles from Majestic et al (2007).…”

Source Apportionment of Urban Background Particulate Matter in Birmingham, United Kingdom Using a Mass Closure Model

“…Particulate matter varies in sizes, components, and composition depending on the primary emission sources, age, atmospheric processing and gaseous emissions (Vallius, 2005). The vehicular emissions, secondary aerosol, marine, resuspension of soil, industry, biomass burning, waste incineration and road dust constitute the major emission sources in the urban environment (Harrison et al, 2003a;Charron et al, 2005;Connell et al, 2006). The † Now at Federal University of Agriculture, Abeokuta different chemical substances such as metals, water-soluble ions, elemental carbon, aromatic hydrocarbons, organic acids, alcohols, levoglucosans, sterols, polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds are considered as the particulate matter (PM) components (Harrison et al, 2003a, b;Harrison et al, 2004;Dall'Osto et al, 2008;Harrison and Yin, 2010;Yin et al, 2010;Taiwo et al, 2014b).…”