Source Apportionment of PM2.5
Mass and Carbon in Seattle using
Chemical Mass Balance and
Positive Matrix Factorization
Naydene Maykut, Puget Sound Clean Air Agency
Joellen Lewtas, U.S. EPA
Tim 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
Seattle
Beacon Hill Site
Measured Species in Seattle
(IMPROVE protocol)
• >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)
PMF Method
Used 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
Temperature (C)
800
700
Temperature Profile
600
Laser Signal
500
400
He
He + O2
Pyrolized carbon
300
200
Elemental
Carbon
Organic
Carbon
100
OC1 OC2 OC3
CH4 Calibration
FID Baseline
OC4
EC1
EC2 EC3
200 400 600 800 1000 1200 1400 1600 1800 2000 2200
Time (sec)
Seattle PMF Results
(288 Samples: all seasons)
Source
Vegetative Burning
Fuel Oil
Diesel Vehicles
Gasoline Vehicles
Secondary (Sulfate)
Marine/ Secondary/
Pulp Mill
Paved Road Dust
Marine
*Standard Error
Percent
33.8 (1.0)*
1.8 (0.3)
14.5 (0.6)
5.4 (0.3)
19.1 (0.7)
8.9 (0.4)
Range
0.0 – 80.5
0.0 – 36.5
0.0 - 61.1
0.0 – 71.4
0.0 – 57.1
0.0 – 33.5
8.7 (0.4)
7.7 (0.8)
0.0 – 59.8
0.0 – 61.1
Source Profiles from PMF (Mass %)
Road Dust
40
8
0.4
30
6
0.3
20
4
0.2
10
2
0.1
0
0
SO4 NO3 Na Cl O1 O2 O3 O4 E1
E2
H
Si Al Fe Ca V
Ni K Pb
0
E3 Zn Mn Ti As Cu Cr Br
Marine
40
8
0.4
30
6
0.3
20
4
0.2
10
2
0.1
0
SO4 NO3 Na Cl
O1 O2 O3 O4 E1
0
0
E2 H Si Al Fe Ca V
Ni K Pb
E3 Zn Mn Ti As Cu Cr Br
Marine/Secondary/Pulp Mill
40
8
0.4
30
6
0.3
20
4
0.2
10
2
0.1
0
0
E2 H Si Al Fe Ca V
SO4 NO3 Na Cl O1 O2 O3 O4 E1
Ni K Pb
0
E3 Zn Mn Ti As Cu Cr Br
Secondary
40
8
0.4
30
6
0.3
20
4
0.2
10
2
0.1
0
SO4 NO3 Na Cl O1 O2 O3 O4 E1
0
0
E2 H Si Al Fe Ca V
Ni K Pb
E3 Zn Mn Ti As Cu Cr Br
Source Profiles from PMF (Mass %)
Diesel
40
8
0.4
30
6
0.3
20
4
0.2
10
2
0.1
0
SO4 NO3 Na Cl O1 O2 O3 O4 E1
0
0
E2
H
Si Al Fe Ca V
Ni K Pb
E3 Zn Mn Ti As Cu Cr Br
Gasoline
40
8
0.4
30
6
0.3
20
4
0.2
10
2
0.1
0
SO4 NO3 Na Cl O1 O2 O3 O4 E1
0
0
E2
H
Si Al Fe Ca V
Ni K Pb
E3 Zn Mn Ti As Cu Cr Br
Vegetative
40
8
0.4
30
6
0.3
20
4
0.2
10
2
0.1
0
SO4 NO3 Na Cl O1 O2 O3 O4 E1
0
0
E2
H
Si Al Fe Ca V
Ni K Pb
E3 Zn Mn Ti As Cu Cr Br
Fuel Oil
40
8
0.4
30
6
0.3
20
4
0.2
10
2
0.1
0
SO4 NO3 Na Cl O1 O2 O3 O4 E1
0
E2
H
Si Al Fe Ca V
Ni K Pb
0
E3 Zn Mn Ti As Cu Cr Br
Carbon Apportionment
Source Apportionment of
Organic and Elemental Carbon
using PMF
Source
OC(%)
EC(%)
Vegetative Burning
Diesel Vehicles
Gasoline Vehicles
Secondary
Fuel Oil
Road Dust
Marine (Sea Salt)
57
19
5
12
3
2
2
47
36
1
9
4
2
0
CMB Source Apportionment - Beacon Hill
Road Dust
Industry
Marine 7%
4%
9%
Nitrate
4%
Vegetative
Burning
Sulfate
15%
18%
Mobile
43%
PMF SOURCE APPORTIONMENT - SEATTLE
BEACON HILL 1996-99 USING CARBON FRACTIONS
Road Dust
Marine
9%
8%
Secondary 9%
King County 1996 Emission Inventory
(corrected for secondary pollutants; sulfate, nitrate
and sea salt)
Other Industry
Fuel Dust 7%
3%
2% 3%
Secondary
34%
Gasoline
5%
Vegetative
Burning
28%
Diesel
18%
Sulfate
19%
Gas Vehicles
5%
Vegetative
Burning
34%
Fuel Oil
Diesel 2%
15%
Seattle PMF vs. CMB
CMB Source Apportionment - Beacon Hill
•
Road Dust
Industry
Marine 7%
4%
9%
Nitrate
4%
Vegetative
Burning
Sulfate
15%
18%
Mobile
43%
PMF SOURCE APPORTIONMENT - SEATTLE
BEACON HILL 1996-99 USING CARBON FRACTIONS
Road Dust
Marine
9%
8%
Secondary 9%
Sulfate
19%
Gas Vehicles
5%
Vegetative
Burning
34%
Fuel Oil
Diesel 2%
15%
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 Composition of OC and EC
(PMF vs Source Tests)
Source
OC (%)
EC (%)
PMF Vegetative
48
15
Denver RWC*
51 +12
12 +4
PMF Gasoline
24
2
Phoenix
Gasoline**
PMF Diesel
30 +12
37
26
Phoenix Diesel**
40 +7
30 - 60
* Watson, Chow and Houck, 1996
14 +8
**Watson et al., 1994