Tad Kleindienst - MARAMA

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Tad Kleindienst - MARAMA

Contribution of SOA to Ambient PM 2.5 Organic

Carbon in Eastern United States Locations

Tadeusz E. Kleindienst 1 , Edward O. Edney 1 , Michael Lewandowski 1 ,

John H. Offenberg 1 , and Mohammed Jaoui 2

1

National Exposure Research Laboratory, U.S. Environmental Protection Agency, Research

Triangle Park, North Carolina USA

2

Alion Science and Technology, Research Triangle Park, North Carolina USA

MANE-VU/Midwest RPO Regional Haze Science Meeting

Baltimore, Maryland

July 10, 2007


Background

• Condensable material formed from gas-phase reactions of

hydrocarbons produce secondary organic aerosol (SOA)

that comprises part of the organic carbon (OC) in PM2.5.

• SOA typically contains organic compounds more highly

polar than those from primary emissions and can be

semivolatile or nonvolatile.

• Recent data indicates SOA can be a significant summer

component of PM2.5 in the eastern U.S.

• Laboratory experiments indicate that organic products in

field samples can be associated with specific hydrocarbon

precursors (Edney et al. Atmos. Environ., 2003).

• Organic tracer technique for SOA has recently been

described (Kleindienst et al., Atmos. Environ., in press)


Other Approaches for Evaluating Ambient SOA

(SOA/OC)

● Deficit in chemical mass balance between measured OC

and primary organic aerosol (POA) from CMB analysis

(Schauer et al., 2002; Zheng et al., 2002)

● Contribution of SOA to PM 2.5 from OC/EC ratio

(Turpin and Huntzicker 1995)

● Relative contributions of anthropogenic and biogenic HCs

to SOA based on a combined 14 C and source-receptor

method

(e.g. Lewis et al., 2004)


Simplified View of Ambient Primary and Secondary Carbon

Organic Aerosol Component of PM

Secondary

Sources

Primary

Sources

Distribution of Source Contributions Changes with Season


General Description of SOA from Individual Source

SOA component from α-pinene

reactions with OH, O 3 , NO 3 followed

by secondary and higher order

aerosol-forming processes

Tracer

compounds

α-P SOA

Polar multifunctional oxygenates that

may include oligomers and other high

molecular-weight compounds


Objectives for the Study

• Find tracer compounds representative of the major SOA

precursors from laboratory studies.

• Identify tracer compounds found both in the laboratory and field.

• Estimate the mass fraction of tracers to the formed SOA

• Focus on isoprene, α-pinene, β-caryophyllene, toluene

• Determine major sources of SOA in PM 2.5 in RTP, NC,

Detroit, MI, and other locations using the tracer compounds.

• What fraction of the OC represented by SOC.

• Compare biogenic vs. anthropogenic contribution.

• Examine seasonal dependencies.

• Compare differences in location using the same analysis.


Experimental System for Laboratory Studies

Ozone, SO 2 and

NO/NO x

Analyzers

Gas Chromatography -

Flame Ionization

Detector (GC-FID)

Other Sampling

Hygrometer

SOC

Msmt

Inlet Manifold

Semicontinuous

Organic Carbon

Measurement

NERL Dynamic Photochemical

Reaction Simulator

Volume = 14.5 m 3

40 L min -1 (τ = 6 h)

Scanning Mobility

Particle Sizer

(SMPS)

Filter Sampling

Devices for

Chamber Aerosol

Gas Phase Carbonyl Product

Measurements

Chemical Composition

Mass Measurement

Inorganic

IC

GC-MS

Gravimetric Mass

Organic

SOA

Msmt

MALDI LC-ESI ESI

• Experiments conducted in a dynamic mode to operate at relatively low reactant concentrations

and to collect sufficient aerosol for analysis.

• Analyze tracer compounds by GC/ITMS and OA and OC by standard methods.


Reactive Systems Contributing to SOA Studied Here

• Isoprene Photooxidation

• Role of acid catalysis (H 2

SO 4

acidic seed; in presence of SO 2

)

• α-Pinene Oxidation

• Photooxidation

• Ozone reaction

• Role of acid catalysis

• Toluene Photooxidation

• β-Caryophyllene Oxidation

• Photooxidation

• Ozone reaction


Tracer Compounds from Laboratory Irradiations


Tracer Compounds for the Source Categories

α-Pinene SOA Tracers

• Pinic acid

• Pinonic acid

• 3-Acetyl pentanedioic acid

• 3-Acetyl hexanedioic acid

• 3-(2-Hydroxyethyl)-2,2-dimethylcyclobutane

carboxylic acid

• 3-Hydroxyglutaric acid

• 2-Hydroxy-4-isopropyladipic acid

• 3-Hydroxy-4,4-dimethylglutaric acid

Isoprene SOA Tracers

• 2-Methylglyceric acid

• 2-Methylerythritol

• 2-Methylthreitol

Toluene SOA Tracer

• 2,3-Dihydroxy-4-oxopentanoic acid

β-Caryophyllene SOA Tracer

• β-Caryophyllinic acid (C 14 H 22 O 4 )


Structures for Selected Tracer Compounds

α-Pinene tracers

Pinonic

acid

Pinic

acid

HO

O

OH

O

A–5

A–6

Isoprene tracers

T–3

Toluene tracer

A–2

O

HO

O O

OH

I–1

β-Caryophyllene tracer

A–3

I–2

C–1

A–4

HO

O

O

O

OH

I–3


Laboratory Data for Mass Fractions

(e.g., α-pinene photooxidation; OM/OC α-p = 1.37 ± 0.15)

Experiment ID

[hc o

]

(ppmC)

[NO X,o

]

(ppm)

[SOA]

(μg m -3 )

Σ [tr i

]

(μg m -3 )

α-p – 1 2.18 0.186 111.6 10.3 0.092

α-p – 2 4.18 0.450 74.2 11.9 0.160

α-p – 3 4.18 0.450 86.7 12.9 0.148

α-p – 4 2.19 0.272 72.0 5.8 0.081

α-p – 5 2.19 0.250 101.3 31 0.306

α-p – 6 3.13 0.317 128.0 16.7 0.130

α-p – 7 4.95 0.494 333.8 79.3 0.237

α-p – 8 5.27 0.490 298.3 39.4 0.132

α-p – 9 5.27 0.490 271.0 49.1 0.181

α-p – 10 2.43 0.307 80.9 29.8 0.368

α-p – 11 2.28 0.307 269.0 30.6 0.114

α-p – 12 2.32 0.279 65.4 10.3 0.157

α-p – 13 3.97 0.279 165.0 18.9 0.115

α-p – 14 1.04 0.409 9.7 0.99 0.102

α-p – 15 2.20 0.420 102 19.7 0.193

f soa

average f soa, α-p

0.168 ± 0.081

average f soc, α-p

0.231 ± 0.111


PM 2.5 Field Measurements

Research Triangle Park, NC* Summer 2000, 2001

Baltimore, MD* Summer 2001

Philadelphia, PA (NEOPS)* Summer 2001

New York, NY* Summer 2001

Tampa, FL (BRACE) Summer 2002

Research Triangle Park, NC Entire Year 2003

Detroit, MI (DEARS) Summer 2004, 2005

Detroit, MI (DEARS)

Winter

* Qualitative measurements with double derivative, PFBHA/BSTFA


Example of Tracer Compounds from TIC

(Detroit, MI, 24 Aug 2004; OC = 3.72 μg m -3 )

Sum of Tracer Concentrations as KPA

I : Isoprene: 168 ng m -3

A: α-Pinene: 153 ng m -3

B: β-Caryophyllene: 6.8 ng m -3

T : Toluene: 4.4 ng m -3


Relative Abundance of Tracer Compounds in RTP, NC 2003


Method for Estimating SOC Source Contributions

• Laboratory measurements

• Irradiated single component hydrocarbon/NO X mixtures; repeat for other conditions

• Identify tracer compounds and determine concentrations as ketopinic acid

• Calculate the mass fraction of the tracer compounds to the measured SOC

• Apply to field measurements

• Measure SOC tracers in ambient PM 2.5

• Apply the mass fraction factor to get the SOC for each precursor type

• Compare SOC contributions to the measured OC

• Assumptions and uncertainties

• Assume mass fraction of the tracers is the same in the field as in the laboratory.

• Other possible of sources of the tracer compounds currently not known

• Standard deviation of the mass fraction measurements were on average 35%

• Extrapolations from single hydrocarbon contributions to compound classes.

• Measurement of ambient OC and the precursor contribution to OC are

independent quantities.


Contribution of Isoprene SOC to Ambient OC

(Using 2-methylglyceric acid and two 2-methyl tetrols; 2003 - RTP, NC USA)

8

7

Winter Spring Summer Fall

OC

isoprene

6

5

4

3

2

1

0

12

20

27

27

31

41

45

48

55

69

83

90

105

118

132

153

160

174

176

209

216

230

237

239

245

253

262

265

279

293

304

321

324

342

363

ugC m -3

Julian Date - 2003


363

342

8

7

6

5

4

3

2

1

0

Contribution of Monoterpene SOC to Ambient OC

(Nine tracers for α-pinene; 2003 - RTP, NC USA)

Winter Spring Summer Fall

OC

a-pinene

12

20

27

27

31

41

45

48

55

69

83

90

105

118

132

153

160

174

176

209

216

230

237

239

245

253

262

265

279

293

304

321

324

Julian Date - 2003

ugC m -3


363

8

7

6

5

4

3

2

1

0

Contribution of Sesquiterpene SOC to Ambient OC

(Tracer using β-caryophyllinic acid; 2003 - RTP, NC USA)

Winter Spring Summer Fall

OC

b-caryophyllene

12

20

27

27

31

41

45

48

55

69

83

90

105

118

132

153

160

174

176

209

216

230

237

239

245

253

262

265

279

293

304

321

324

342

Julian Date - 2003

ugC m -3


Contribution of Aromatic SOC to Ambient OC

(Tracer using 2,3-dihydroxy-4-oxopentanoic acid; 2003 - RTP, NC USA)

8

7

Winter Spring Summer Fall

OC

toluene

6

5

4

3

2

1

0

12

20

27

27

31

41

45

48

55

69

83

90

105

118

132

153

160

174

176

209

216

230

237

239

245

253

262

265

279

293

304

321

324

342

363

ugC m -3

Julian Date - 2003


0

363

342

324

12

321

20

27

27

31

41

45

48

55

69

83

90

105

118

132

153

160

174

176

209

216

230

237

239

245

253

262

265

279

293

304

8

7

6

5

4

3

2

1

SOC Contributions to Ambient OC

(2003 – Research Triangle Park, NC)

Winter Spring Summer Fall

other

toluene

b-caryophyllene

isoprene

a-pinene

Julian Date 2003

ug C m -3


Bimonthly Contribution of SOC to Ambient OC

(2003 Research Triangle Park, NC)

OC Contributions (ug/m3)

6.0

5.0

4.0

3.0

2.0

1.0

0.21

0.36

0.44

estimated fraction SOC

0.68

0.41

0.28

0.0

Jan-Feb March-April May-June July-August Sept-Oct Nov-Dec

Isoprene a-Pinene b-Caryophyllene Toluene Other OC

Other OC = OC - Isoprene SOA - Aromatic SOA - Monoterpene SOA - Sesquiterpene SOA

Other OC includes biomass comb, gasoline exhaust, diesel emissions and meat cooking operations


SOC Contributions to Ambient OC

(DEARS Ambassador Bridge Site, Detroit, MI, 11 Aug – 1 Sep 2004)

6.0

5.0

Avg SOC mass: 1.55 μgC m -3

Avg fraction SOC: 0.474

Anthrop SOC/Total SOC: 0.13

Organic Carbon (ugC/m3)

4.0

3.0

2.0

1.0

0.0

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

Sample

Isoprene a-pinene b-Caryophyllene Toluene Other


Summary of Key Points

• Secondary organic aerosol from isoprene, monoterpenes, sesquiterpenes,

and aromatics contributes substantially to organic carbon in PM 2.5 in the

eastern U.S. mainly during the summer. Other U.S. areas under study.

• Aromatic contribution higher than typically predicated in air quality models.

• Organic carbon in PM 2.5 was found to range from 2 – 5 μgC m -3 throughout

the year with primary sources dominating in the winter and SOC

dominating during the summer. Primary and secondary contributions can

be offsetting leading to minor seasonal trends.

• Estimates of SOC contribution from biogenic HC precursors found to be

substantially greater than anthropogenic HC precursors in the eastern U.S.

• Results consistent with SOC contributions to the organic carbon measured

in laboratory mixtures and with 14 C data measured in laboratory

experiments and from 14 C in field studies.


Next Steps

• Conduct studies combining both CMB analysis for primary compounds

and mass fractions for secondary compounds to see the degree of

consistency between SOA and “other OC” from the CMB analysis.

• Look at alternative double derivative technique to improve sensitivity of

tracers from aromatic hydrocarbons.

• Use information from laboratory and field studies to provide basis for an

improved SOA module for CMAQ.

• Determine tracers compounds from other classes of possible SOA

producing hydrocarbons, such as, high MW alkanes, etc.

• Determine tracer compounds from additional high volume aromatic

hydrocarbons (e.g., m-xylene, 1,2,4-TMB) and sesquiterpenes (e.g., α-

humulene, α-farnesene).

• Examine SOA production from complex mixtures.

• Further study role of acid-catalysis on SOA formation and possible tracer

compounds produced.


Bibliography

• Edney et al., 2003, Polar organic oxygenates in PM 2.5

at a southeastern site in the United States, Atmos. Environ. 37,

3947-3965.

Kleindienst et al., 2004, Determination of secondary organic aerosol products from the photooxidation of toluene and

their implications in PM 2.5

. J. Atmos. Chem. 47, 79-100.

• Jaoui et al, 2004, Identification and quantification of aerosol polar oxygenated compounds bearing carboxylic or

hydroxyl groups. 1. Method development. Analyt. Chem. 76, 4765-4778.

• Jaoui et al., 2005, Identification and quantification of aerosol polar oxygenated compounds bearing carboxylic or

hydroxyl groups. 2. Organic tracer compounds from monoterpenes, Environ. Sci. Tech. 39, 5661-5673.

• Edney et al., 2005, Formation of 2-methyl tetrols and 2-methylglyceric acid in secondary organic aerosol from

laboratory irradiated isoprene/NO X

/SO 2

/air mixtures and their detection in ambient PM 2.5

samples collected in the

eastern United States, Atmos. Environ. 39, 5281-5289.

• Offenberg et al. 2006, Thermal properties of secondary organic aerosols. Geophys. Res. Lett. 33, L03816

• Claeys et al. 2007, Hydroxydicarboxylic acids: Markers for secondary organic aerosol from the photooxidation of α-

pinene. Environ. Sci. Technol. 41, 1628-1634.

• Jaoui et al., 2007, β-caryophyllinic acid: An atmospheric tracer for β-caryophyllene secondary organic aerosol.

Geophys. Res. Lett. 34, L05816.

• Surratt et al. 2007, Evidence for organosulfates in secondary organic aerosol. Environ. Sci. Technol. 41, 517-527.

• Lewandowski et al., 2007, Composition of PM 2.5

during the summer of 2003 in Research Triangle Park, North

Carolina. Atmos. Environ. 47, 4073-4083.

• Offenberg et al. 2007, Contributions of toluene and α-pinene to SOA formed in an irradiated toluene/α-pinene/NO X

/air

mixture: Comparison of results using 14 C content and SOA organic tracer methods. Env. Sci. Technol. 41, 3972-3976.

Kleindienst et al., 2007, Estimates of the contribution of biogenic and anthropogenic hydrocarbons to secondary

organic aerosol at a Southeastern U.S. Location, Atmos. Environ. (in press).


Disclaimer

Although this work was reviewed by U.S. EPA and

approved for publication, it may not necessarily reflect

official Agency policy.

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