PM_2.5 source apportionment with organic markers in the Southeastern Aerosol Research and Characterization (SEARCH) study

Figures & data

Table 1. Descriptions of source profiles available for effective variance–chemical mass balance (EV-CMB) modeling

ID^a	Source Mnemonic	Source Profile Description	Number of Samples
1	BRVEH	BRAVO roadside sampling	2^b
2	TAVEH	Tahoe roadside sampling	2^c
3	MXTUN	Mexico City tunnel sampling	3^d
4	BRBURN	BRAVO biomass burning	4^e
5	BRCOOK	BRAVO cooking	4^f
6	CFPPOUT	Coal-fired power plant emissions	5^g
7	PVRD^h	Paved road dust	—
8	AMSUL	Pure ammonium sulfate	—
9	AMNIT	Pure ammonium nitrate	—
10	MAR	Pure sea salt	—

Notes: ^aProfiles 1–6 include organic speciation by thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS). Profiles 7–10, taken from Chow et al. (2007a), contain no TD-GC/MS species. See Table S-5 for the 10 source profiles included in the EV-CMB source apportionment.^bRoadside sampling (Chow et al., 2004).^cVehicle emissions (Kuhns et al., 2004).^dTunnel sampling (Chow et al., 2002b).^eOpen burning of Mesquite, Tamarisk, Huisache, and grass (Chow et al., 2004).^fSmoked, charcoal, and propane chicken, as well as charcoal hamburger.^gSampling after sulfur dioxide scrubbers (outlet) at four coal-fired power plant boiler stacks in Georgia and one in Alabama.^hChow et al. (2007a).

Table 2. Average source contributions (µg/m³) to PM_2.5 mass estimated with the PMF-CMB solution

Source	Marker Species^a	Average Source Contribution Estimate (SCE; µg/m^3)	SCE (%)^b
Atlanta (JST site)
Motor vehicle exhaust	Ba, Fe, Cu, and EC	2.45 ± 1.00	19.4
Biomass burning	K and OC	2.45 ± 0.86	19.4
Vegetative detritus	n-alkanes (n-C29 to n-C35)	0.19 ± 0.25	1.5
Coal combustion	Se and As	0.38 ± 0.74	3.0
Road dust	Al, Si, and Fe	0.52 ± 0.16	4.1
Secondary sulfate	SO4^2−	5.69 ± 0.81	45.1
Secondary nitrate	NO3^−	0.46 ± 0.22	3.6
Salt	Na^+	0.49 ± 0.20	3.9
Average measured PM2.5 mass		12.86 ± 0.62
Average estimated PM2.5 mass		12.63 ± 1.77
Birmingham (BHM site)
Motor vehicle exhaust	EC and OC	2.64 ± 0.54	21.0
Biomass burning 1 (open burning)	K^+ and K	1.42 ± 0.32	11.3
Biomass burning 2 (RWC^c)	Retene^d	0.81 ± 0.81	6.5
Vegetative detritus	n-alkanes (n-C31 to n-C35)	0.48 ± 0.34	3.8
Industrial emissions	Cu and Fe	0.51 ± 0.27	4.1
Unknown	Hopanes	0.19 ± 0.30	1.5
Road dust	Al and Si	0.78 ± 0.18	6.2
Secondary sulfate	SO4^2−	5.37 ± 0.41	42.7
Secondary nitrate	NO3^−	0.28 ± 0.11	2.2
Salt	Na^+	0.10 ± 0.04	0.8
Average measured PM2.5 mass		12.85 ± 0.62
Average estimated PM2.5 mass		12.57 ± 1.24

Notes: ^aDetermined from EV-CMB “MPIN” diagnostics using PMF-derived source factors and average concentrations at each site.^bAverage percent of estimated PM_2.5 mass accounted for by estimated source contributions.^cResidential wood combustion.^dRetene was first recognized as a biomass burning marker by Ramdahl (1983).

Figure 1. Monthly average PMF-CMB source contributions for Atlanta, Georgia (JST site). Values are normalized to the average contribution for each source for all samples. Motor vehicle exhaust contributions are dominated by engine exhaust. Complete data were available from January through April on only 26 days. Therefore, averages are presented only for May through December.

Figure 2. Monthly average PMF-CMB source contributions for Birmingham, Alabama (BHM site). Values are normalized to the average contribution for each source for all samples. Motor vehicle exhaust is dominated by engine exhaust.

Table 3. Sensitivity tests for EV-CMB source contribution estimates^a for average concentrations^b at Atlanta, Georgia (JST site)

	EV-CMB Source Contribution Estimates (SCEs; µg/m^3)
Case	BRVEH	TAVEH	MXTUN	BRBURN	BRCOOK	CFPPOUT	PVRD	AMSUL	AMNIT	MAR	PCT^c	R^2d	Chi^2e
1A^f	2.1 ± 0.9	—	—	0.89 ± 0.44	2.5 ± 0.6	0.56 ± 0.06	0.04 ± 0.10	4.3 ± 0.4	0.14 ± 0.11	0.15 ± 0.06	82%	0.98	1.55
1B^g	0.06 ± 0.05	—	—	1.11 ± 0.33	3.3 ± 0.3	0.58 ± 0.06	0.15 ± 0.10	4.4 ± 0.4	0.24 ± 0.03	0.15 ± 0.07	78%	0.96	0.94
2A^f	—	0	—	0.85 ± 0.44	3.7 ± 0.4	0.57 ± 0.06	0.13 ± 0.10	4.5 ± 0.4	0.24 ± 0.03	0.16 ± 0.06	79%	0.97	1.48
2B^g	—	0.33 ± 0.44	—	1.04 ± 0.34	3.2 ± 0.4	0.59 ± 0.06	0.16 ± 0.10	4.4 ± 0.4	0.24 ± 0.03	0.15 ± 0.06	79%	0.96	0.98
3A^f	—	—	1.85 ± 0.57	1.55 ± 0.68	2.3 ± 0.6	0.49 ± 0.07	0	4.2 ± 0.4	0	0.13 ± 0.09	82%	0.98	1.16
3B^g	—	—	1.03 ± 0.46	1.08 ± 0.33	2.7 ± 0.4	0.54 ± 0.06	0.06 ± 0.10	4.4 ± 0.4	0.08 ± 0.10	0.15 ± 0.06	78%	0.96	0.92

Notes: ^aSee Table 1 for source profile descriptions and Table S-5 for source profiles. ^bThe uncertainties of the average concentrations are estimated as the root-mean-square error (RMSE) of the individual samples. ^cPercent of measured mass accounted for, by estimated source contribution. ^dR², squared correlation coefficient. ^eChi-square. ^fEV-CMB with conventional species (i.e., elements, ions, and organic and elemental carbon) only. ^gEV-CMB with conventional and TD-GC/MS organic species.

Figure 3. Comparson of the BRVEH and MXTUN motor vehicle exhaust source profiles. (See Table 1 for profile descriptions and Tables S-2 and S-3 for species descriptions.)

Table 4. Average source contribution estimates (SCEs) from EV-CMB solutions for individual samples with and without organic compounds

		Source Contribution Estimates with Conventional Species		Source Contribution Estimates with TD-GC/MS Organic Species
Source Name	Source Mnemonic	(µg/m^3)	Percent Mass^a	(µg/m^3)	Percent Mass
Atlanta, GA (JST site)
Motor vehicle exhaust (Mexico City tunnel)	MXTUN	1.03 ± 0.49	9.4	0.81 ± 0.18	8.6
Biomass burning (BRAVO)	BRBURN	2.6 ± 0.9	24	1.44 ± 0.19	15.4
BRAVO cooking	BRCOOK	2.0 ± 0.5	18.6	1.60 ± 0.23	17.2
Coal-fired power plant emissions^b	CFPP	0.48 ± 0.07	4.4	0.54 ± 0.06	5.7
Paved road dust	PVRD	0.24 ± 0.10	2.1	0.33 ± 0.10	3.6
Pure ammonium sulfate	AMSUL	4.2 ± 0.4	38	4.3 ± 0.4	46
Pure ammonium nitrate	AMNIT	0.20 ± 0.10	1.79	0.19 ± 0.07	1.99
Pure sea salt	MAR	0.13 ± 0.11	1.19	0.15 ± 0.09	1.61
Average measured PM2.5 mass	Meas.^c	12.9 ± 0.6		12.9 ± 0.6
Average estimated PM2.5 mass	Est.	11.0 ± 1.2		9.4 ± 0.6
Average R-square	R^2d	0.93		0.78
Average chi-square	Chi-square^e	3.5		12.0
	PCT^f	88		75
Birmingham, AL (BHM site)
Motor vehicle exhaust (Mexico City tunnel)	MXTUN	2.8 ± 0.8	24	1.22 ± 0.11	13.3
Biomass burning (BRAVO)	BRBURN	2.5 ± 1.0	21	1.35 ± 0.16	14.7
BRAVO cooking	BRCOOK	1.97 ± 0.61	16.5	1.11 ± 0.20	12.0
Coal-fired power plant emissions^b	CFPP	0.38 ± 0.10	3.1	0.54 ± 0.06	5.9
Paved road dust	PVRD	0.66 ± 0.28	5.5	1.09 ± 0.33	11.9
Pure ammonium sulfate	AMSUL	3.3 ± 0.4	27	3.5 ± 0.3	38
Pure ammonium nitrate	AMNIT	0.12 ± 0.09	1.01	0.15 ± 0.07	1.66
Pure sea salt	MAR	0.23 ± 0.18	1.91	0.26 ± 0.13	2.9
Average measured PM2.5 mass	Meas.	12.8 ± 0.6		12.8 ± 0.6
Average estimated PM2.5 mass	Est.	12.0 ± 1.5		9.2 ± 0.6
Average R-square	R^2	0.94		0.70
Average chi-square	Chi-square	3.0		16.9
	PCT	96		73

Notes: ^aAverage percent of model calculated PM_2.5 mass accounted for by estimated source contributions. ^bCoal-fired power plant emissions from boiler stacks, referred to as coal combustion. ^cAverage measured PM_2.5. ^dAverage R-square (R²). ^eAverage chi-square. ^fAverage ratio of model calculated to measured PM_2.5 mass expressed as a percent.

Figure 4. Monthly average EV-CMB source contributions (µg/m³) for Atlanta, Georgia (JST site), using conventional plus organic species. (Complete data were available from January through April on only 26 days. Therefore, averages are presented only for May through December.)

Figure 5. Monthly average EV-CMB source contributions (µg/m³) for Birmingham, Alabama (BHM site), using conventional and organic species.

Table 5. Comparison of EV-CMB source contribution estimates for combustion sources in Atlanta, Georgia (JST site), during summer 2008–2010 with those of Zheng et al. (2007) during summer 2001

	Source Contribution Estimates (Percent of Calculated Mass)
Source	Zheng et al.	EV-CMB^a	EV-CMB^b
Motor vehicle exhaust	6.8%	6.5%	5.5%
Cooking	11.3%	21%	22%
Biomass burning	0.44%	17.8%	7.8%
Unidentified OM^c	23%	—	—
Sum	42%	45%	35%

Notes: ^aEV-CMB results based on conventional species from this study. ^bEV-CMB results based on conventional plus organic species by the TD-GC/MS method from this study. ^cBased on unaccounted-for OC in Zheng et al. (2007).

Chow, J.C., J.G. Watson, D.H. Lowenthal, L.-W.A. Chen, B. Zielinska, L.R. Mazzoleni, and K.L. Magliano. 2007a. Evaluation of organic markers for chemical mass balance source apportionment at the Fresno supersite. Atmos. Chem. Phys. 7:1741–1754. doi:10.5194/acp-7-1741-2007

 Google Scholar

Chow, J.C., J.G. Watson, H.D. Kuhns, V.R. Etyemezian, D.H. Lowenthal, D.J. Crow, S.D. Kohl, J.P. Engelbrecht, and M.C. Green. 2004. Source profiles for industrial, mobile, and area sources in the Big Bend Regional Aerosol Visibility and Observational (BRAVO) Study. Chemosphere 54:185–208. doi:10.1016/j.chemosphere.2003.07.004

 PubMed Web of Science ®Google Scholar

Kuhns, H.D., M.-C.O.Chang, J.C. Chow, V.R. Etyemezian, L.-W.A. Chen, N.J. Nussbaum, S.K. Nathagoundenpalayam, T.C. Trimble, S.D. Kohl, M. MacLaren, M. Abu-Allaban, J.A. Gillies, and A.W. Gertler. 2004. Lake Tahoe Source Characterization Study, Desert Research Institute, Reno, NV.

 Google Scholar

Chow, J.C., J.G. Watson, S.A. Edgerton, and E. Vega. 2002b. Chemical composition of PM10 and PM2.5 in Mexico City during winter 1997. Sci. Total Environ. 287:177–201. doi:10.1016/S0048-9697(01)00982-2

 PubMed Web of Science ®Google Scholar

Ramdahl, T. 1983. Retene-A molecular marker of wood combustion in ambient air. Nature 306:580–582. doi:10.1038/306580a0

 Web of Science ®Google Scholar

Zheng, M., G.R. Cass, L. Ke, F. Wang, J.J. Schauer, E.S. Edgerton, and A.G. Russell. 2007. Source apportionment of daily fine particulate matter at Jefferson street, Atlanta, GA, during summer and winter. J. Air Waste Manage. Assoc. 57:228–242. doi:10.1080/10473289.2007.10465322

 Web of Science ®Google Scholar