How Does the Sample How Does the Sample Affect the Measurement of Affect the Measurement of Different Carbon Fractions?Different Carbon Fractions?

Judith C. Chow Desert Research InstituteReno, NV

presented at the

International Workshop for the Development of Research Strategies for the Sampling and Analysis of Organic and Elemental Carbon Fractions in Atmospheric Aerosols

Durango, Colorado

March 4, 2003

Types of Sample EffectsTypes of Sample Effects

• Filter samples

• Carbon particle composition

• Chemical and physical interactions between carbon and other constituents

Filter Sample BiasesFilter Sample Biases

• Non-uniform filter deposit biases scaling from punch to whole filter

• Non-uniform filter punch deposit biases optical monitoring and charring

• Too light or too dark particle deposits make pyrolysis correction uncertain

• More heavily loaded samples require longer combustion time at each temperature step

• Organic vapor adsorption and volatilization in filter biases OC and pyrolysis correction

Non-Uniform Sample DepositsNon-Uniform Sample Deposits(Chow, 1995)(Chow, 1995)

Carbon Particle CompositionCarbon Particle Composition• Ambient mixtures, source mixtures, and pure

carbon substances do not respond to heating in the same way

• Thermal evolution protocols are poorly documented and characterized

• Thermal evolution temperatures are not optimized to bracket compositions

• Carbonates are not present in most ambient PM2.5 samples, and CaCO3 evolves at >800 °C if they are present

• Samples do not respond the same as calibration standards

At Least 15 International Thermal At Least 15 International Thermal Combustion Carbon MethodsCombustion Carbon Methods

• Oregon Graduate Institute thermal optical reflectance (TOR) (Huntzicker et al., 1982)

• IMPROVE TOR and thermal optical transmittance (TOT)

(Chow et al., 1993, 2001)

• NIOSH TOT (NIOSH, 1999)

• ACE-Asia TOT (Mader et al., 2001)

• Hong Kong University of Science and Technology UST-3 TOT (Yang and Yu, 2002)

At Least 15 International Thermal At Least 15 International Thermal Combustion Carbon Methods Combustion Carbon Methods (continued)(continued)

• Meteorological Service of Canada MSC1 TOT (Sharma et al., 2002)

• U.S. Speciation Trends Network (STN) TOT

• General Motors Research Laboratory two temperature (Cadle et al., 1980)

• Brookhaven National Laboratory two temperature (Tanner et al., 1982)

• Japanese two temperature (Mizohata and Ito, 1985)

At Least 15 International Thermal At Least 15 International Thermal Combustion Carbon Methods Combustion Carbon Methods (continued)(continued)

• Two-temperature thermal manganese oxidation (Fung, 1990)

• R&P two temperature (Rupprecht et al., 1995)

• French two-temperature pure oxygen combustion (Cachier, 1989a, 1989b)

• Lawrence Berkeley Laboratory continuous temperature ramp (Novakov, 1982)

• German VDI extraction/combustion(Verein Deutcher Ingenieure, 1999)

Differences among Operating Differences among Operating ParametersParameters

• Combustion atmospheres

• Temperature ramping rates

• Temperature plateaus

• Residence time at each plateau

• Optical monitoring configuration and wavelength

• Standardization

• Sample aliquot and size

• Oxidation (C to CO2) catalyst

• Evolved carbon detection method

• Carrier gas flow through or across the sample

• Location of the temperature monitor relative to the sample

Laboratory Laboratory intercomparisointercomparisons are not ns are not consistent consistent (Schmid et al., (Schmid et al., 2001)2001)

11

TO

T

10

TO

T

11

bT

OT

12

TO

T

12

TO

T

11

TO

T

10

TO

T

11

bT

OT

13

TO

R

13

TO

R

Same method intercomparisons Same method intercomparisons show differences show differences (Schauer et al., 2003)(Schauer et al., 2003)

0

0.5

1

1.5

2

TOTE TOTB TOTH TOTC TOTD TOTF TOTG TOTA

Analysis Method

EC

(µ

g c

m-2

)

Denv1 AVG

STD+ STD-

0

4

8

12

16

TOTF TOTG TOTC TOTD TOTA TOTB TOTH TOTE

Analysis Method

EC

(µ

g c

m-2

)

ACE Kosa1 AVG

STD+ STD-

Comparison of EC Concentrations Comparison of EC Concentrations between TMO and TOR Methodsbetween TMO and TOR Methods

(Fung et al., 2002)(Fung et al., 2002)

0

10

20

30

40

50

0 10 20 30 40 50

IMPROVE TOR Elemental Carbon (EC) (µg/cm2)

TM

O E

lem

enta

l C

arb

on

(E

C)

(µg

/cm

2 )

Non-Urban IMPROVE

Korean Urban

Carbon Black

Hong Kong Urban

y=0.73x, R2=0.79

y=0.78x, R2=0.91

y=1.07x, R2=0.98

y=1.22x, R2=0.97

IMPROVEIMPROVEcarbon carbon

thermogramthermogram

STNSTNcarbon carbon

thermograthermogramm

200

220

240

260

280

300

320

340

360

380

400

0 200 400 600 800 1000 1200 1400

Process Time (sec)

FID

res

pons

e (c

ount

s)

0

500

1000

1500

2000

2500

3000

Lase

r R

efle

ctan

ce,

Lase

r T

rans

mitt

ance

, T

empe

ratu

re (

ºC)

FID

Laser Reflectance

Laser Transmittance

Filter Temperature

OC/EC split

Sample ID: Q20204

0

100

200

300

400

500

600

700

800

900

1000

0 200 400 600 800 1000 1200 1400

Process Time (sec)

Tem

per

atu

re (

ºC)

FID_8

SOTmp

LaserT

LaserR

He

ECT

ECR

Sample from Sample from Hong Kong urban Hong Kong urban site on 04/17/01 site on 04/17/01 with with 9.9 ± 0.8 ug/m9.9 ± 0.8 ug/m33 OCOCand and 7.8 ± 0.8 ug/m7.8 ± 0.8 ug/m33 ECEC

Carbon Source ProfilesCarbon Source Profiles(Watson et al., 1994)(Watson et al., 1994)

Diesel-fueled vehiclesGasoline-fueled

vehicles

Hong Hong Kong Kong Vehicle Vehicle Exhaust Exhaust Profiles Profiles (Cao et al., (Cao et al., 2003)2003)

OC1OC2OC3OC4EC1EC2EC3OP

0

3

6

9

12

15

Diesel LPG Gasoline

Figure 11.5 Distribution of the concentration and percentage of 8 carbon fractions in diesel,gasoline and LPG vehicle exhaust

Con

cent

rati

on

g m

-3P

erce

ntag

e (%

)

0

10

20

30

Source Differences in Carbon Fractions

BRAVO BRAVO Source Source Profiles Profiles (Chow et al., (Chow et al., 2003)2003)

Motor Vehicle Composite (BVRDMV)

0

5

10

15

20

25

30

35

40

OC1120 °C

OC2250 °C

OC3450 °C

OC4550 °C

OP EC1550 °C

EC2675 °C

EC3750 °C

Carbon Fraction and Thermal Evolution Temperature

Pe

rce

nt

of

PM

2.5

Ma

ss

Vegetative Burning Composite (BURN)

0

5

10

15

20

25

30

35

40

OC1120 °C

OC2250 °C

OC3450 °C

OC4550 °C

OP EC1550 °C

EC2675 °C

EC3750 °C

Carbon Fraction and Thermal Evolution Temperature

Pe

rce

nt

of

PM

2.5

Ma

ss

Coal-Fired Boiler Composite (CFPP)

0

5

10

15

20

25

30

35

40

OC1120 °C

OC2250 °C

OC3450 °C

OC4550 °C

OP EC1550 °C

EC2675 °C

EC3750 °C

Carbon Fraction and Thermal Evolution Temperature

Pe

rce

nt

of

PM

2.5

Ma

ss

Cement Kiln Composite (CEM)

0

5

10

15

20

25

30

35

40

OC1120 °C

OC2250 °C

OC3450 °C

OC4550 °C

OP EC1550 °C

EC2675 °C

EC3750 °C

Carbon Fraction and Thermal Evolution Temperature

Pe

rce

nt

of

PM

2.5

Ma

ss

Cooking Composite (COOK)

0

5

10

15

20

25

30

35

40

OC1120 °C

OC2250 °C

OC3450 °C

OC4550 °C

OP EC1550 °C

EC2675 °C

EC3750 °C

Carbon Fraction and Thermal Evolution Temperature

Pe

rce

nt

of

PM

2.5

Ma

ss

Catalytic Cracker Composite (CAT1)

0

5

10

15

20

25

30

35

40

OC1120 °C

OC2250 °C

OC3450 °C

OC4550 °C

OP EC1550 °C

EC2675 °C

EC3750 °C

Carbon Fraction and Thermal Evolution Temperature

Pe

rce

nt

of

PM

2.5

Ma

ss

Source Differences in Carbon Fractions

No relationship between No relationship between EC and carbonate by acidificationEC and carbonate by acidification

(Chow and Watson, 2002)(Chow and Watson, 2002)

-10

-5

0

5

10

15

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Measured Carbonate Carbon (µg/sample)

Dif

fere

nc

e B

etw

een

No

n-A

cid

ifie

d a

nd

Ac

idif

ied

E

C a

nd

EC

3 (µ

g/s

am

ple

)

EC EC3

IMPROVE samples and IMPROVE protocol

Carbon Standards Should be Carbon Standards Should be Similar to SamplesSimilar to Samples• Water-soluble organics

(e.g., sucrose, KHP, organic acids)

• Carbon dioxide and methane

• Nebulized charcoal resuspension

• Carbon blacks

• Graphite powders

• Organic dyes (e.g., nigrosin, C48N9H51)

• Carbon arc emissions

• Simulated source emissions

• Neutral density filters

Some Organic Compounds Absorb LightSome Organic Compounds Absorb Light(Justus et al., 1993)(Justus et al., 1993)

Transmission through nigrosin (C48N9H51) dye

Chemical Composition of Chemical Composition of Carbon Black and Fresh SootCarbon Black and Fresh Soot

(Watson and Valberg, 2001)(Watson and Valberg, 2001)

Soot - Woodburning Fireplace Chimney

Other20%

Soluble Organics

14%

Ash19%

Elemental Carbon

47%

Soot - Diesel EngineSulfate

and Other8%

Elemental Carbon

61%

Metals1%

Soluble Organics

30%

Carbon Black

Elemental Carbon

98%

Ash1%

Soluble Organics

1%

Chemical and Physical Chemical and Physical Interactions of Carbon with Interactions of Carbon with Other ConstituentsOther Constituents

• Oxidation interactions

• Catalytic reactions

• Optical interactions

Increasing rate Increasing rate of graphite of graphite oxidation by oxidation by MnOMnO22 (Fung, 1990)(Fung, 1990)

1000°K

900°K

833°K

800°K

Catalytic reactions with glass-fiber filter Catalytic reactions with glass-fiber filter (525 °C)(525 °C)

(Lin and Friedlander, 1988a, 1988b, 1988c)(Lin and Friedlander, 1988a, 1988b, 1988c)

Na, K, Pb, Mn, Fe, Ca, V, Cu, Ni, Co, and Cr compounds are known catalysts

Carbon Fractions are Probably Carbon Fractions are Probably Different for Different ApplicationsDifferent for Different Applications

• Visibility and radiation balance

– Visible light absorption and scattering by particles in the atmosphere

• Source attribution

– Consistently define fractions in source and receptor samples

• Health effects

– Absorption of toxic substances on EC

• Chemical and physical models

– Reaction surfaces, catalytic properties

Research NeedsResearch Needs• Critically summarize and review non-

atmospheric carbon literature• Document methods (combustion

temperatures, ramping rates, residence times, optical pyrolysis corrections)

• Prepare different standards representing different black carbon sources

• Perform optical modeling to verify changes in absorption and scattering properties

Research NeedsResearch Needs (continued)(continued)

• Optimize carbon fractions for source identification

• Quantify effects of pyrolysis on and within a filter to resolve reflectance/transmittance differences

• Quantify effects of non-absorbing particles, optical monitoring wavelengths, initial darkness, carbonate deposits, and oxygen-supplying minerals

• Calibrate reflectance and transmittance measurements and report with carbon fractions at beginning, minimum, oxygen introduction, and end of analysis

ReferencesReferences

Cachier, H.; Bremond, M.P.; and Buat-Ménard, P. (1989a). Thermal separation of soot carbon. Aerosol Sci. Technol., 10(2):358-364.

Cachier, H.; Bremond, M.P.; and Buat-Ménard, P. (1989b). Determination of atmospheric soot carbon with a simple thermal method. Tellus, 41B(3):379-390.

Cadle, S.H.; Groblicki, P.J.; and Stroup, D.P. (1980). An automated carbon analyzer for particulate samples. Anal. Chem., 52(13):2201-2206.

Cao, J.J.; Ho, K.F.; Lee, S.C.; Fung, K.; Zhang, X.Y.; Chow, J.C.; and Watson, J.G. (2003). Characterization of roadside fine particulate carbon and its 8 fractions in Hong Kong. Sci. Total Environ., submitted.

Chow, J.C.; Watson, J.G.; Pritchett, L.C.; Pierson, W.R.; Frazier, C.A.; and Purcell, R.G. (1993). The DRI Thermal/Optical Reflectance carbon analysis system: Description, evaluation and applications in U.S. air quality studies. Atmos. Environ., 27A(8):1185-1201.

ReferencesReferences (continued)(continued)

Chow,J.C. (1995). Summary of the 1995 A&WMA critical review: Measurement methods to determine compliance with ambient air quality standards for suspended particles. EM 1, 12-15.

Chow, J.C.; Watson, J.G.; Crow, D.; Lowenthal, D.H.; and Merrifield, T. (2001). Comparison of IMPROVE and NIOSH carbon measurements. Aerosol Sci. Technol., 34(1):23-34.

Chow, J.C.; and Watson, J.G. (2002). PM2.5 carbonate concentrations at regionally representative Interagency Monitoring of Protected Visual Environment sites. J. Geophys. Res., 107(D21):ICC 6-1-ICC 6-9. doi: 10.1029/2001JD000574.

Chow, J.C.; Watson, J.G.; Kuhns, H.D.; Etyemezian, V.; Lowenthal, D.H.; Crow, D.J.; Kohl, S.D.; Engelbrecht, J.P.; and Green, M.C. (2003). Source profiles for industrial, mobile, and area sources in the Big Bend Regional Aerosol Visibility and Observational (BRAVO) Study. Chemosphere, submitted.

Fung, K.K. (1990). Particulate carbon speciation by MnO2 oxidation. Aerosol Sci. Technol., 12(1):122-127.

Fung, K.K.; Chow, J.C.; and Watson, J.G. (2002). Evaluation of OC/EC speciation by thermal manganese dioxide oxidation and the IMPROVE method. J. Air & Waste Manage. Assoc., 52(11):1333-1341.

ReferencesReferences (continued)(continued)

Huntzicker, J.J.; Johnson, R.L.; Shah, J.J.; and Cary, R.A. (1982). Analysis of organic and elemental carbon in ambient aerosols by a thermal-optical method. In Particulate Carbon: Atmospheric Life Cycle, G.T. Wolff and R.L. Klimisch, Eds. Plenum Press, New York, NY, pp. 79-88.

Justus, B.L.; Huston, A.L.; and Campillo, A.J. (1993). Broadband thermal optical limiter. Appl. Phys. Lett., 63(11):1483-1485.

Lin, C.; and Friedlander, S.K. (1988a). Soot oxidation in fibrous filters. 1. Deposit structure and reaction mechanisms. Langmuir, 4(4):891-898.

Lin, C.; and Friedlander, S.K. (1988b). Soot oxidation in fibrous filters. 2. Effects of temperature, oxygen partial pressure, and sodium additives. Langmuir, 4(4):898-903.

Lin, C.I.; and Friedlander, S.K. (1988c). A note on the use of glass fiber filters in the thermal analysis of carbon containing aerosols. Atmos. Environ., 22(3):605-607.

ReferencesReferences (continued)(continued)

Mader, B.T.; Flagan, R.C.; and Seinfield, J.H. (2001). Sampling atmospheric carbonaceous aerosols using a particle trap impactor/denuder sampler. Environ. Sci. Technol., 35(24), 4857-4867.

Mizohata, A.; and Ito, N. (1985). Analysis of organic and elemental carbon in atmospheric aerosols by thermal method. Annual Report of the Radiation Center of Osaka Prefecture, 26(0):51-55.

NIOSH (1999). Method 5040 Issue 3 (Interim): Elemental carbon (diesel exhaust). In NIOSH Manual of Analytical Methods, 4th ed. National Institute of Occupational Safety and Health, Cincinnati, OH.

Novakov, T. (1982). Soot in the atmosphere. In Particulate Carbon: Atmospheric Life Cycle, G.T. Wolff and R.L. Klimisch, Eds. Plenum Press, New York, NY, pp. 19-41.

ReferencesReferences (continued)(continued)

Rupprecht, E.G.; Patashnick, H.; Beeson, D.E.; Green, R.E.; and Meyer, M.B. (1995). A new automated monitor for the measurement of particulate carbon in the atmosphere. In Proceedings, Particulate Matter: Health and Regulatory Issues, J.A. Cooper and L.D. Grant, Eds. Air and Waste Management Association, Pittsburgh, PA, pp. 262-267.

Schmid, H.P.; Laskus, L.; Abraham, H.J.; Baltensperger, U.; Lavanchy, V.M.H.; Bizjak, M.; Burba, P.; Cachier, H.; Crow, D.J.; Chow, J.C.; Gnauk, T.; Even, A.; ten Brink, H.M.; Giesen, K.P.; Hitzenberger, R.; Hueglin, C.; Maenhaut, W.; Pio, C.A.; Puttock, J.; Putaud, J.P.; Toom-Sauntry, D.; and Puxbaum, H. (2001). Results of the "Carbon Conference" international aerosol carbon round robin test: Stage 1. Atmos. Environ., 35(12):2111-2121.

Sharma, S.; Brook, J.; Cachier, H.; Chow, J.C.; Gaudenzi, A.; and Lu, G. (2002). Light absorption and thermal measurements of black carbon in different regions of Canada. J. Geophys. Res., 107(D24):AAC 11-1-AAC 11-11. doi:10.1029/2002JD002496.

ReferencesReferences (continued)(continued)

Tanner, R.L.; Gaffney, J.S.; and Phillips, M.F. (1982). Determination of organic and elemental carbon in atmospheric aerosol samples by thermal evolution. Anal. Chem., 54(9):1627-1630.

Verein Deutcher Ingenieure (1999). Method 2465 Part 2: Measurement of soot (ambient air)-Thermographic determination of elemental carbon after thermal desorption of organic carbon. Prepared by Verein Deutcher Ingenieure, Beuth, Berlin, FRG.

Watson, A.Y.; and Valberg, P.A. (2001). Carbon black and soot: Two different substances. Am. Industrial Hygiene Assoc. J., 62(Mar/Apr):218-228.

Watson, J.G.; Chow, J.C.; Lowenthal, D.H.; Pritchett, L.C.; Frazier, C.A.; Neuroth, G.R.; and Robbins, R. (1994). Differences in the carbon composition of source profiles for diesel- and gasoline-powered vehicles. Atmos. Environ., 28(15):2493-2505.

Yang, H.; and Yu, J.Z. (2002). Uncertainties in charring correction in the analysis of elemental and organic carbon in atmospheric particles by thermal/optical methods. Environ. Sci. Technol., 36(23):5199-5204.