PM_2.5 Source Apportionment: Reconciling Receptor Models for U.S. Nonurban and Urban Long-Term Networks

Figures & data

Figure 1. STN and IMPROVE PM_2.5 chemical speciation sites in Minnesota. The STN sites are (1) Mille Lacs (ML), (2) Minneapolis—Phillips Neighborhood (MPN), (3) St. Paul—Harding High School (SPH), and (4) Rochester (ROC). The IMPROVE sites are (1) Voyageurs National Park (VOYA), (2) Boundary Waters Canoe Area (BOWA), (3) Blue Mounds State Park (BLMO), and (4) Great River Bluffs State Park (GRRI).

Table 1. Data Groupings for Unmix and PMF model inputs. *

Modeling Group^a	Location Code ^b (Network)	Period	Number of Samples Reported	Number of Valid Samples ^c	Fraction of Data Used for Receptor Modeling	PM2.5 Concentration Range (Mean) in μg/m^3
I	ML (STN)	July 14, 2003 ^d –July 30, 2005	234	209	89.3%	0.8–59 (7.4)
	MPN (STN)	July 17, 2003–December 13, 2006	367	334	91%	1.3–31.1 (9.9)
	SPH (STN)	July 20, 2003–March 29, 2005	100	98	98%	1.0–28.8 (9.9)
	ROC (STN)	July 20, 2003–December 20, 2006	189	179	94.7%	1.0–34.6 (10.1)
	Total		890	820	92.1%
II	ML (STN)	September 8, 2002–July 11, 2003	92	90	97.8%	1.2–28.3 (7.7)
	MPN (STN)	January 11, 2001–July 11, 2003	238	222	93.2%	1.3–36.8 (11.8)
	SPH (STN)	September 22, 2001–July 14, 2003	104	97	93.2%	1.5–30.2 (11.2)
	ROC (STN)	September 22, 2001–July 14, 2003	97	87	89.7%	1.9–29.7 (10.7)
	Total		531	496	93.4%
III	BLMO (IMPROVE)	July 25, 2002–December 30, 2005	399	229	57.4%	0.9–30.7 (7.7)
IV	GRRI (IMPROVE)	July 25, 2002–December 30, 2005	392	358	91.3%	1.0–58.2 (8.4)
V	BOWA (IMPROVE)	January 5, 2000–December 30, 2005	641	394	61.5%	0.2–22.2 (4.4)
	VOYA (IMPROVE)	January 5, 2000–December 30, 2005	673	478	71%	0.1–21.5 (4.1)
	Total		1314	872	66.4%
Notes: ^aTotals are provided for groups including more than one site. Modeling group I: STN sites after July 15, 2003; modeling group II: STN sites before July 15, 2003. ^bSee site locations in Figure 1. ^cValidation includes removing incomplete data and data with poor material balance.27 ^dAlthough overall the AQS database shows uncertainties only after July 15, 2003, in this one instance at ML uncertainties were reported on July 14, 2003. *Although the same data are used in this study and in Chen et al.,27 a mislabeling of sampling sites was discovered after final proofing of that paper. Chen et al.27 labeled GRRI data as BLMO and BLMO data as GRRI, and a corrigendum had been issued. This paper presents the correct information.

Figure 2. Comparison of PMF geological factors with measured geological source profiles: (a) soil dust, (b) Ca-rich dust, and (c) taconite dust. Error bars in part c (not shown in parts a and b) represent the boot-strapping uncertainties for the Group I taconite factor calculated by PMF. See Table 1 for modeling groups I–V. OCR and ECR indicate OC and EC measured by TOR, whereas OCT and ECT indicate OC and EC measured by TOT.

Figure 3. Comparison of PMF combustion factors with measured combustion source profiles: (a) gasoline vehicle, (b) diesel vehicle, and (c) biomass burning (BB). See Table 1 for modeling groups I–V.

Table 2. SCEs (in μg/m³) by source type, site, and receptor model for STN sites after July 15, 2003 (modeling group I)

Sources/Site, Model		ML			MPN			SPH			ROC
		PMF	Unmix	EV-CMB	PMF	Unmix	EV-CMB	PMF	Unmix	EV-CMB	PMF	Unmix	EV-CMB
Secondary	Sulfate	1.96	2.19	1.93	2.78	2.74	2.65	2.57	2.56	2.44	3.01	2.96	2.83
	Nitrate	1.70	2.32	2.00	2.29	3.03	2.43	2.67	3.42	2.91	2.70	3.41	3.03
	SOC			0.37			0.12			0.13			0.18
	Sum	3.66	4.51	4.30	5.07	5.77	5.20	5.24	5.98	5.48	5.71	6.37	6.04
Stationary	Taconite (dust)	0.05		0.05	0.08		0.09	0.07		0.09	0.04		0.04
	Sum	0.05	0.00	0.05	0.08	0.00	0.09	0.07	0.00	0.09	0.04	0.00	0.04
Area	Soil dust	0.94	0.46	0.48	0.58	0.31	0.33	0.51	0.28	0.29	0.55	0.25	0.25
	Ca-rich dust	0.16	0.52	0.07	0.29	0.59	0.15	0.23	0.48	0.07	0.48	0.92	0.34
	Salt			0.08			0.13			0.12			0.11
	Biomass burning	0.07	0.05	0.46	0.20	0.10	0.83	0.19	0.10	0.71	0.13	0.07	0.77
	Sum	1.17	1.03	1.09	1.07	1.00	1.44	0.93	0.86	1.19	1.16	1.24	1.47
Mobile	Gasoline	2.36	1.25	0.92	3.32	2.72	1.83	3.10	2.25	0.83	2.75	1.85	0.76
	Diesel	0.07	0.34	1.16	0.19	0.68	3.17	0.31	0.76	4.84	0.12	0.55	2.30
	Sum	2.43	1.59	2.08	3.51	3.40	5.00	3.41	3.00	5.67	2.87	2.39	3.06
Total		7.3	7.1	7.5	9.7	10.2	11.7	9.7	9.8	12.4	9.8	10.0	10.6
Measured PM2.5			7.4			9.9			9.9			10.1

Table 3. SCEs (in μg/m³) by source type, site, and receptor model for STN sites before July 15, 2003 (modeling group II)

Sources/Site, Model		ML			MPN			SPH			ROC
		PMF	Unmix	EV-CMB	PMF	Unmix	EV-CMB	PMF	Unmix	EV-CMB	PMF	Unmix	EV-CMB
Secondary	Sulfate	2.67	2.69	2.21	3.66	3.72	3.01	2.86	3.21	2.58	3.18	2.92	2.72
	Nitrate	2.04	2.92	2.33	2.76	4.07	3.35	2.82	4.00	3.43	2.97	4.13	3.55
	SOC			0.29			0.11			0.22			0.22
	Sum	4.71	5.61	4.83	6.42	7.79	6.47	5.68	7.21	6.23	6.15	7.05	6.49
Stationary	Taconite (dust)			0.02			0.06			0.08			0.02
	Sum	0.00	0.00	0.02	0.00	0.00	0.06	0.00	0.00	0.08	0.00	0.00	0.02
Area	Soil dust	0.31	0.33	0.37	0.50	0.64	0.63	0.42	0.59	0.45	0.44	0.44	0.49
	Ca-rich dust	0.16	0.28	0.03	0.41	0.63	0.13	0.32	0.54	0.06	0.76	1.09	0.38
	Salt	0.37		0.25	0.60		0.45	0.54		0.37	0.49		0.39
	Biomass burning	0.04	0.08	0.51	0.10	0.17	0.79	0.09	0.17	0.89	0.03	0.07	0.71
	Sum	0.88	0.69	1.16	1.61	1.44	2.00	1.37	1.30	1.77	1.72	1.60	1.97
Mobile	Gasoline	1.57	0.82	1.43	2.06	1.18	2.91	3.03	1.18	1.63	2.05	1.11	1.31
	Diesel	0.36	0.52	0.90	1.19	1.32	2.53	1.24	1.99	3.96	0.49	0.75	1.90
	Sum	1.93	1.34	2.33	3.25	2.50	5.44	4.27	3.17	5.59	2.54	1.86	3.21
Total		7.5	7.6	8.3	11.3	11.7	13.9	11.3	11.7	13.7	10.4	10.5	11.7
Measured PM2.5			7.7			11.8			11.2			10.7

Table 4. SCEs (in μg/m³) by source type, site, and receptor model for IMPROVE sites (modeling groups V, III, and IV)

Sources/Site, Model		BOWA			VOYA			BLMO			GRRI
		PMF	Unmix	EV-CMB	PMF	Unmix	EV-CMB	PMF	Unmix	EV-CMB	PMF	Unmix	EV-CMB
Secondary	Sulfate	2.23	1.99	1.91	1.97	1.88	1.68	2.68	2.22	2.49	3.31	4.07	3.32
	Nitrate	0.64	0.98	0.85	0.70	1.04	0.87	2.48	3.06	3.00	2.43	3.34	2.77
	SOC			0.03			0.02			0.01			0.04
	Sum	2.87	2.97	2.79	2.67	2.92	2.57	5.16	5.28	5.50	5.74	7.41	6.13
Stationary	Taconite (dust)	0.06	0.17	0.02	0.04	0.13	0.01			0.00			0.01
	Coal utility			0.22			0.20	0.68	0.53	0.36			0.43
	Sum	0.06	0.17	0.24	0.04	0.13	0.21	0.68	0.53	0.36	0.00	0.00	0.44
Area	Soil dust	0.46	0.01	0.22	0.34	0.01	0.15	0.47	0.81	0.38	0.15	0.22	0.16
	Ca-rich dust	0.05	0.50	0.02	0.04	0.38	0.00	0.64	0.92	0.04	0.62	0.35	0.06
	Salt	0.20	0.39	0.04	0.21	0.41	0.04			0.10			0.05
	Biomass burning	0.69	0.34	0.89	0.67	0.27	0.93	0.60		1.20	1.28	0.01	1.23
	Sum	1.40	1.24	1.17	1.26	1.07	1.12	1.71	1.73	1.72	2.05	0.58	1.50
Mobile	Gasoline	0.09	0.05	0.33	0.09	0.05	0.29	0.11	0.24	0.31	0.53	0.47	0.62
	Sum	0.09	0.05	0.33	0.09	0.05	0.29	0.11	0.24	0.31	0.53	0.47	0.62
Total		4.4	4.4	4.5	4.1	4.2	4.2	7.7	7.8	7.9	8.3	8.5	8.7
Measured PM2.5			4.4			4.1			7.7			8.4

Table 5. FSCs (% of PM_2.5) from this study compared with those from similar environments

		STN						IMPROVE
Source Category	Source	This Study Post-July 15, 2003	This Study Pre-July 15, 2003	Detroit I,^a Michigan (PMF)	Detroit II, ^b Michigan (PMF)	Chicago, ^c Illinois (PMF)	Chicago, ^c Illinois (CMB)	This Study	BOND. ^d Illinois (PMF)	MACA, ^e Kentucky (PMF)
PM2.5 (μg/m^3)		7.4–10.1	7.7–11.8	16.0	15.8	15.0	15.0	4.1–8.4	10.9	12.7
Secondary	Sulfate	27	29	31	27	37	31	41	27	49
	OP-rich Sulfate									16
	Nitrate	28	31	28	25	21	20	28	24	3
	SOC	2	2					0
Stationary	Taconite (dust)	1	3					1
	Iron/Steel/Mn			3		4	2
	Copper smelter					1			2
	Lead smelter								4
	Metal plating				3				5
	Industrial zinc				5
	Industrial					2
	Refinery						0
	CFPP						1	6		1
Area	Soil dust	5	4	8	4	6	2	5	6	5
	Ca-rich dust	4	4				1	5	3
	Salt	1	4	4		3		4		3
	BB	3	3	3	2	5	11	13	12	14
Mobile	Gasoline	21	16	15	21 ^f			4	17 ^f	7
	Diesel	13	13	4	14					3
	Mobile					23	31
	Sum	105	109	96	101	102	99	107	100	101
Notes: ^aDetroit Allen Park, November 1, 2000–May 1, 2005.62 ^bDetroit Allen Park, January 1, 2002–March 31, 2005.61 ^cChicago Lawndale, 2001–2003.63 ^dBondville, IL, 2002–2004.61 ^eMammoth Cave, KY, 2002–2004.64 ^fMixture of gasoline and SOC contribution.

Figure 4. Model-collective estimates (i.e., square and number: average; bar: median; box: 10th and 90th percentiles) of fractional source contributions (FSCs) for (a) STN sites after July 15, 2003; (b) STN sites prior to July 15, 2003; and (c) IMPROVE sites.

Figure 5. EBT probability maps for (a, b) secondary sulfate, (c, d) soil dust, (e, f) biomass burning, and (g, h) secondary nitrate factors resolved by PMF for the ROC and GRRI sites.

Chen , L.-W. A. , Watson , J.G. , Chow , J.C. , DuBois , D.W. and Herschberger , L. 2010 . Chemical Mass Balance Source Apportionment for Combined PM2.5 Measurements from U.S. Non-Urban and Urban Long-Term Networks . Atmos. Environ. , 44 : 4908 – 4918 .

 Web of Science ®Google Scholar

Gildemeister , A.E. , Hopke , P.K. and Kim , E. 2007 . Sources of Fine Urban Particulate Matter in Detroit, MI . Chemosphere , 69 : 1064 – 1074 .

 PubMed Web of Science ®Google Scholar

Buzcu-Guven , B. , Brown , S.G. , Frankel , A. , Hafner , H.R. and Roberts , P.T. 2007 . Analysis and Apportionment of Organic Carbon and Fine Particulate Matter Sources at Multiple Sites in the Midwestern United States . J. Air Waste Manage. Assoc. , 57 : 606 – 619 . doi: 10.3155/1047-3289.57.5.606

 Web of Science ®Google Scholar

Rizzo , M.J. and Scheff , P.A. 2007 . Fine Particulate Source Apportionment Using Data from the USEPA Speciation Trends Network in Chicago, Illinois: Comparison of Two Source Apportionment Models . Atmos. Environ. , 41 : 6276 – 6288 .

 Web of Science ®Google Scholar

Zhao , W.X. and Hopke , P.K. 2006 . Source Identification for Fine Aerosols in Mammoth Cave National Park . Atmos. Res. , 80 : 309 – 322 .

 Web of Science ®Google Scholar