Source Apportionment of Fine (PM1.8) and Ultrafine (PM0.1) Airborne Particulate Matter during a Severe Winter Pollution Episode
ABSTRACT Size-resolved samples of airborne particulate matter (PM) collected during a severe winter pollution episode at three sites in the San Joaquin Valley of California were extracted with organic solvents and analyzed for detailed organic compounds using GC-MS. Six particle size fractions were characterized with diameter (Dp) < 1.8 microm; the smallest size fraction was 0.056 < Dp < 0.1 microm which accounts for the majority of the mass in the ultrafine (PM0.1) size range. Source profiles for ultrafine particles developed during previous studies were applied to the measurements at each sampling site to calculate source contributions to organic carbon (OC) and elemental carbon (EC) concentrations. Ultrafine EC concentrations ranged from 0.03 microg m(-3) during the daytime to 0.18 microg m(-3) during the nighttime. Gasoline fuel, diesel fuel, and lubricating oil combustion products accounted for the majority of the ultrafine EC concentrations, with relatively minor contributions from biomass combustion and meat cooking. Ultrafine OC concentrations ranged from 0.2 microg m(-3) during the daytime to 0.8 microg m(-3) during the nighttime. Wood combustion was found to be the largest source of ultrafine OC. Meat cooking was also identified as a significant potential source of PM0.1 mass but further study is required to verify the contributions from this source. Gasoline fuel, diesel fuel, and lubricating oil combustion products made minor contributions to PM0.1 OC mass. Total ultrafine particulate matter concentrations were dominated by contributions from wood combustion and meat cooking during the current study. Future inhalation exposure studies may wish to target these sources as potential causes of adverse health effects.
- SourceAvailable from: Andrius Garbaras
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- "Cascade impactors were used to study fine particulate matter in numerous studies (Cabada et al., 2004; Chow et al., 2008; Fang et al., 2006; Huang et al., 2004; Yao et al., 2001; Keywood et al., 1999; Kleeman et al., 2008; Liu et al., 2008; Lü et al., 2012; Plaza et al., 2011; Singh et al., 2003), however only a few of them attempted to study stable carbon isotope ratio values (Cachier et al., 1985; Garbaras et al., 2009; Sang et al., 2012; Wang et al., 2012) that are a useful tool to identify the sources of particulate matter. Furthermore, δ 13 C TC values can provide a useful starting point in detecting and distinguishing carbonaceous aerosol particles. "
ABSTRACT: Abstract Carbonaceous aerosol sources were investigated by measuring the stable carbon isotope ratio (δ13CTC) in size segregated aerosol particles. The samples were collected with a micro-orifice uniform deposit impactor (MOUDI) in 11 size intervals ranging from 0.056 μm to 18 μm. The aerosol particle size distribution obtained from combined measurements with a scanning mobility particle sizer (SMPS; TSI 3936) and an aerosol particle sizer (APS; TSI 3321) is presented for comparison with MOUDI data. The analysis of δ13CTC values revealed that the total carbonaceous matter in size segregated aerosol particles significantly varied from -23.4 ± 0.1 ‰ in a coarse mode to -30.1 ± 0.5 ‰ in a fine mode. A wide range of the δ13CTC values of size segregated aerosol particles suggested various sources of aerosol particles contributing to carbonaceous particulate matter. Therefore, the source mixing equation was applied to verify the idea of mixing of two sources: continental non-fossil and fossil fuel combustion. The obtained δ13CTC value of aerosol particles originating from fossil fuel combustion was -28.0 — -28.1 ‰, while the non-fossil source δ13CTC value was in the range of -25.0 — -25.5 ‰. The two source mixing model applied to the size segregated samples revealed that the fossil fuel combustion source contributed from 100 % to 60 % to the carbonaceous particulate matter in the fine mode range (Dp < 1 μm). Meanwhile the second, continental non-fossil, source was the main contributor in the coarse fraction (Dp > 2 μm). The particle range from 0.5 to 2.0 μm was identified as a transition region where two sources almost equally contributed to carbonaceous particulate matter. The proposed mixing model offers an alternative method for determining major carbonaceous matter sources where radiocarbon analysis may lack the sensitivity (as in size segregated samples).Atmospheric Research 05/2015; DOI:10.1016/j.atmosres.2015.01.014 · 2.42 Impact Factor
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- "also been included in some analyses, but comparatively few researchers have simultaneously factored chemical composition data from particles in different size ranges (Yakovleva et al., 1999; Dillner et al., 2005; Han et al., 2006; Pere-Trepat et al., 2007; Yatkin and Bayram, 2008; Amato et al., 2009; Gietl and Klemm, 2009; Karanasiou et al., 2009; Kleeman et al., 2009; Srivastava et al., 2009). All of these studies used data with limited size or temporal resolution, typically 2–6 size ranges and 12–24-h average composition data; the study with the highest size and time resolution had 8 size ranges and 3-hour time resolution (Han et al., 2006). "
ABSTRACT: A size-resolved submicron organic aerosol composition dataset from a high-resolution time-of-flight mass spectrometer (HR-ToF-AMS) collected in Mexico City during the MILAGRO campaign in March 2006 is analyzed using 3-dimensional (3-D) factorization models. A method for estimating the precision of the size-resolved composition data for use with the factorization models is presented here for the first time. Two 3-D models are applied to the dataset. One model is a 3-vector decomposition (PARAFAC model), which assumes that each chemical component has a constant size distribution over all time steps. The second model is a vector-matrix decomposition (Tucker 1 model) that allows a chemical component to have a size distribution that varies in time. To our knowledge, this is the first report of an application of 3-D factorization models to data from fast aerosol instrumentation; it is also the first application of this vector-matrix model to any ambient aerosol dataset. A larger number of degrees of freedom in the vector-matrix model enable fitting real variations in factor size distributions, but also make the model susceptible to fitting noise in the dataset, giving some unphysical results. For this dataset and model, more physical results were obtained by partially constraining the factor mass spectra using a priori information and a new regularization method. We find four factors with each model: hydrocarbon-like organic aerosol (HOA), biomass-burning organic aerosol (BBOA), oxidized organic aerosol (OOA), and a locally occurring organic aerosol (LOA). These four factors have previously been reported from 2-dimensional factor analysis of the high-resolution mass spectral dataset from this study. The size distributions of these four factors are consistent with previous reports for these particle types. Both 3-D models produce useful results, but the vector-matrix model captures real variability in the size distributions that cannot be captured by the 3-vector model. A tracer m/z-based method provides a useful approximation for the component size distributions in this study. Variation in the size distributions is demonstrated in a case study day with a large secondary aerosol formation event, in which there is evidence for the coating of HOA-containing particles with secondary species, shifting the HOA size distribution to larger particle sizes. These 3-D factorizations could be used to extract size-resolved aerosol composition data for correlation with aerosol hygroscopicity, cloud condensation nuclei (CCN), and other aerosol impacts. Furthermore, application of these 3-D factorization models to other fast and chemically complex 3-D datasets, including those from thermal desorption or chromatographic separation, has the potential to provide further insights into organic aerosol sources and processing.Atmospheric Measurement Techniques 01/2011; 5(1). DOI:10.5194/amtd-4-4561-2011 · 3.21 Impact Factor
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- "some of the highest airborne PM concentrations in the United States, especially in the winter when elevated temperature inversions create stagnation events lasting more than a week. Numerous source ap- 5 portionment studies have been carried out in the SJV over the past decades (Chow et al., 1992, 2007; Magliano et al., 1999; Schauer and Cass, 2000; Rinehart et al., 2006; Chen et al., 2007; Kleeman et al., 2009). Earlier efforts apportioned the sources of PM 10 (Chow et al., 1992), while more recent studies have focused on finer particles . "
ABSTRACT: Molecular markers are organic compounds used to represent known sources of particulate matter (PM) in statistical source apportionment studies. The utility of molecular markers depends on, among other things, their ability to represent PM volatility under realistic atmospheric conditions. We measured the particle-phase concentrations and temperature-induced volatility of commonly-used molecular markers in California's heavily polluted San Joaqin Valley. Concentrations of elemental carbon, organic carbon, levoglucosan, and polycyclic aromatic hydrocarbons were not reduced by mild (~10 K) heating. In contrast, both hopane/sterane and n-alkane concentrations were reduced, especially during the summer sampling events at the urban site. These results suggest that hopanes and steranes have effective saturation concentrations ~1 μg m−3, and therefore can be considered semi-volatile in realistic ambient conditions. The volatility behavior of n-alkanes during the urban summer is consistent with that predicted for absorption by suberic acid (a C8 diacid) using a group contribution modelling method. Observations can also be matched by an absorbent whose composition is based on recently-obtained high-resolution aerosol mass spectrometer factors (approximately 33% "hydrocarbon-like" and 67% oxygenated organic aerosol). The diminished volatility of the n-alkanes, hopanes, and steranes during rural and/or winter experiments could be explained by a more oxygenated absorbing phase along with a non-absorptive partitioning mechanism, such as adsorption to soot. This suggests that the temperature-induced volatility of large hydrocarbons in PM is most important if a relatively non-polar absorbing organic phase exists. While the activity coefficients of most organic aerosol compounds may be close to unity, the assumption of ideality for large hydrocarbons (e.g., hopanes) may result in large errors in partitioning calculations.Atmospheric Chemistry and Physics 01/2010; 11(1). DOI:10.5194/acpd-10-20329-2010 · 4.88 Impact Factor