Source Apportionment of PM2.5 Mass and Carbon in Seattle using

Chemical Mass Balance and Positive Matrix Factorization

Naydene Maykut, Puget Sound Clean Air AgencyNaydene Maykut, Puget Sound Clean Air AgencyJoellen Lewtas, U.S. EPAJoellen Lewtas, U.S. EPA

Tim Larson, University of WashingtonTim Larson, University of Washington

Introduction• Extensive PM2.5 speciation data available from an

urban IMPROVE site in Seattle (284 days over three years)

• Source Apportionment comparison between traditional CMB approach with newer PMF method

• For PMF method: include temperature resolved carbon fractions rather than traditional OC/EC split

Beacon Hill Site

Seattle

• >45 species measured on Wednesdays and Saturdays 4/96 to 1/99 (289 samples)

• XRF (Fe to Zr, Pb) , PIXE (Na to Mn, Mo) , IC

• Carbon measurements: OC & EC temperature dependent volatilization (TOR)

Measured Species in Seattle(IMPROVE protocol)

PMF MethodUsed 7 carbon fractions from TOR

(O1, O2, 03, O4, E1, E2, E3)

as well as usual elements and ions

Input species and uncertainties

Robust Mode : FPEAK = +0.2

TOR Analysis

200 400 600 800 1000 1200 14001600 1800 20002200Time (sec)

OC1 OC2 OC3 OC4 EC1 EC2 EC3

100

200

300

400

500

600

700

800

Tem

per

atu

re (C

)

Temperature Profile

Laser Signal

CH4 Calibration

FID Baseline

Organic Carbon

Elemental Carbon

Pyrolized carbonHe He + O2

Seattle PMF Results(288 Samples: all seasons)

Source Percent Range

Vegetative Burning 33.8 (1.0)* 0.0 – 80.5

Fuel Oil 1.8 (0.3) 0.0 – 36.5

Diesel Vehicles 14.5 (0.6) 0.0 - 61.1

Gasoline Vehicles 5.4 (0.3) 0.0 – 71.4

Secondary (Sulfate) 19.1 (0.7) 0.0 – 57.1

Marine/ Secondary/ Pulp Mill

8.9 (0.4) 0.0 – 33.5

Paved Road Dust 8.7 (0.4) 0.0 – 59.8

Marine 7.7 (0.8) 0.0 – 61.1*Standard Error

0

10

20

30

40

0

2

4

6

8

0

0.1

0.2

0.3

0.4

E3 Zn Mn Ti As Cu Cr Br

0

10

20

30

40

0

2

4

6

8

E2 H Si Al Fe Ca V Ni K Pb0

0.1

0.2

0.3

0.4

E3 Zn Mn Ti As Cu Cr Br

0

10

20

30

40

0

2

4

6

8

E2 H Si Al Fe Ca V Ni K Pb0

0.1

0.2

0.3

0.4

E3 Zn Mn Ti As Cu Cr Br

0

10

20

30

40

0

2

4

6

8

E2 H Si Al Fe Ca V Ni K Pb0

0.1

0.2

0.3

0.4

E3 Zn Mn Ti As Cu Cr Br

SO4 NO3 Na Cl O1 O2 O3 O4 E1

SO4 NO3 Na Cl O1 O2 O3 O4 E1

SO4 NO3 Na Cl O1 O2 O3 O4 E1

SO4 NO3 Na Cl O1 O2 O3 O4 E1

E2 H Si Al Fe Ca V Ni K Pb

Road Dust

Marine

Marine/Secondary/Pulp Mill

Secondary

Source Profiles from PMF (Mass %)

0

10

20

30

40

SO4 NO3 Na Cl O1 O2 O3 O4 E1

0

10

20

30

40

0

2

4

6

8

E2 H Si Al Fe Ca V Ni K Pb

0

2

4

6

8

0

0.1

0.2

0.3

0.4

E3 Zn Mn Ti As Cu Cr Br

0

0.1

0.2

0.3

0.4

E3 Zn Mn Ti As Cu Cr Br

0

10

20

30

40

0

2

4

6

8

0

0.1

0.2

0.3

0.4

E3 Zn Mn Ti As Cu Cr Br

0

10

20

30

40

0

2

4

6

8

0

0.1

0.2

0.3

0.4

E3 Zn Mn Ti As Cu Cr Br

SO4 NO3 Na Cl O1 O2 O3 O4 E1

SO4 NO3 Na Cl O1 O2 O3 O4 E1

SO4 NO3 Na Cl O1 O2 O3 O4 E1

E2 H Si Al Fe Ca V Ni K Pb

E2 H Si Al Fe Ca V Ni K Pb

E2 H Si Al Fe Ca V Ni K Pb

Diesel

Gasoline

Vegetative

Fuel Oil

Source Profiles from PMF (Mass %)

Carbon Apportionment

Source Apportionment of Organic and Elemental Carbon

using PMFSource OC(%) EC(%)

Vegetative Burning 57 47Diesel Vehicles 19 36Gasoline Vehicles 5 1Secondary 12 9Fuel Oil 3 4Road Dust 2 2Marine (Sea Salt) 2 0

CMB Source Apportionment - Beacon Hill

Mobile43%

Sulfate18%

Vegetative Burning

15%

Road Dust4% Marine

9%

Industry7%

Nitrate4%

PMF SOURCE APPORTIONMENT - SEATTLE BEACON HILL 1996-99 USING CARBON FRACTIONS

Sulfate19%

Secondary 9%

Vegetative Burning

34%

Gas Vehicles5%

Diesel15%

Fuel Oil2%

Marine8%

Road Dust9%

King County 1996 Emission Inventory (corrected for secondary pollutants; sulfate, nitrate

and sea salt)

Diesel18%

Gasoline5%

Secondary34%

Vegetative Burning

28%

Industry3%

Dust3%

Other7%Fuel

2%

Seattle PMF vs. CMB

• CMB Source Apportionment - Beacon Hill

Mobile43%

Sulfate18%

Vegetative Burning

15%

Road Dust4% Marine

9%

Industry7%

Nitrate4%

PMF SOURCE APPORTIONMENT - SEATTLE BEACON HILL 1996-99 USING CARBON FRACTIONS

Sulfate19%

Secondary 9%

Vegetative Burning

34%

Gas Vehicles5%

Diesel15%

Fuel Oil2%

Marine8%

Road Dust9%

Conclusions

• CMB source profiles invaluable in identifying PMF “factors”

• PMF “factors” may approximate local source profiles– Next step - use PMF factors as combustion-derived profiles in

CMB analysis

• Using both models adds insight into the understanding of the composition of the aerosol in the urban airshed– PMF – urban-specific, combustion-derived profiles– CMB – minor impacts from known point sources

Why This Study was Important

• Use of Carbon Fractions in PMF– contributed to a defensible split between burning,

diesel and gasoline

– identified that carbon fractions may prove useful in identifying sources

– raised the question whether PMF factors could be improved by de-coupling carbon

Diesel/Gasoline PM Ratios

• Diesel tailpipe/gasoline tailpipe emission-factor ratio (PM10)– 3.0 (EPA, 1995)

• Diesel/gasoline PM2.5 source-contribution derived ratio– 3.2 Pasadena and 3.0 West Los Angeles (Schauer et al.,

1996– 2.7 (Seattle 8 Factor) and 3.1 (Seattle 9 Factor)– 2.1 Spokane (Kim et al., 2001)

Source OC (%) EC (%)

PMF Vegetative 48 15

Denver RWC* 51 +12 12 +4

PMF Gasoline 24 2

Phoenix Gasoline**

30 +12 14 +8

PMF Diesel 37 26

Phoenix Diesel** 40 +7 30 - 60

Source Composition of OC and EC (PMF vs Source Tests)

* Watson, Chow and Houck, 1996 **Watson et al., 1994