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Barbara J. TurpinRutgers University
With Contributions from:Annmarie
Carlton, Katye Altieri, Sybil Seitzinger, Barbara
Ervens, Ho‐Jin Lim, Yi Tan, Mark Perri
Secondary and Regional Contributions to Organic PM
Unit Name
Optional Presentation Title Dept of Environmental Sciences
ObjectiveConduct controlled laboratory experiments investigating
secondary organic aerosol (SOA) formation through cloud processing
In the Process• Consider whether experiments suggest “source tracers” or
“process indicators” to aid field investigations of SOA
• Examine Pittsburgh Supersite data for evidence of SOA formation through cloud processing
• Provide kinetic/mechanistic data needed to refine SOA models
Unit Name
Optional Presentation Title Secondary Organic Aerosol
In‐Cloud SOA Formation
Organic gases are oxidized (e.g., in interstitial spaces of clouds) to water-soluble compounds.
Water-soluble gases partition into cloud droplets and oxidize further (e.g., by ·OH formed photochemically).
Low volatility products remain in the particle phase upon cloud evaporation, contributing secondary organic aerosol (SOA), especially in FT
(Blando and Turpin, 2000; Gelencser and Varga, 2005)
organic gases, NOx…
Cloud evaporation SOA
In-cloud chemistry
Unit Name
Optional Presentation Title Secondary Organic Aerosol
Evidence for In‐Cloud SOA
Heald et al., 2005 (ICART): Organic PM concentrations in FT exceed current model predictions (i.e., without in-cloud SOA). Polidori et al., 2006 (Pittsburgh); Lim and Turpin, 2002 (Atlanta): Elevated ground level SOA with down-mixing of air from aloft.
Heald et al., 2006; Chebbi and Carlier, 1996; Yu et al., 2005; Kawamura et al., 1993: Concentration dynamics link oxalic acid with potential aqueous precursor aldehydes or with sulfate (formed through cloud processing).Sorooshian et al. 2006 (ICART); 2007(MACE); Crahan et al., 2004: In-cloud organic acid measurements/simulations suggest oxalic acid is formed through cloud processing.
Warneck, 2003; Ervens et al., 2004; Lim et al., 2005: predict in-cloud organic acids and SOA from emissions
Organic PM Concentrations Aloft
Oxalic Acid Concentration Dynamics
Cloud Chemistry Modeling
Unit Name
Optional Presentation Title
Lim Cloud Chemistry Model (to guide experiments):
Secondary Organic Aerosol
Phase transfersRxs with •OH
Aqueous phase
ISOPRENE + oxidants (·OH, O3 , NO3 )
HOCH2CHO CHOCHO CH3COCHO(glycolaldehyde) (glyoxal) (methylglyoxal)
HOCH2CH(OH)2 (OH)2CHCH(OH)2 CH3COCH(OH)2
HOCH2COOH CH3COCOOH(glycolic acid) (pyruvic acid)
(OH)2CHCOOH CH3COOH(glyoxylic acid - hydrated) (acetic acid)
HOOCCOOH CH2(OH)2(oxalic acid) (formaldehyde - hydrated)
CO2 HCOOH(formic acid)
Gas phase
67%
33% 92%8%
85%
15%
Lim et al., 2005
Unit Name
Optional Presentation Title
CH3COCHO(methylglyoxal)
CH3COCH(OH)2
CH3COCOOH(pyruvic acid)
CH3 COCOOH
CH3 COH
(acetaldehyde)
CH3 COH
Ervens
Model:
aqueous methylglyoxal
and pyruvic
acid photo‐oxidation does not form low volatility organic acids
Secondary Organic Aerosol
Unit Name
Optional Presentation Title
Predicted In‐Cloud SOA Concentrations: (Ervens
et al., 2004; Lim et al., 2005)
Secondary Organic Aerosol
10 – 25% of measured oxalic acid formed from aqueous reactions with methylglyoxal, glyoxal and glycolaldehyde(clean – polluted continental)
Oxalic acid remains mostly in the particle phase upon droplet evaporation, forming SOA.
Additional precursors
Additional low volatility organics
Aqueous photooxidation pathways/products largely assumed
Predicted products had not been verified experimentally
Unit Name
Optional Presentation Title
Objective:Validate and refine aqueous-phase reaction pathways and improve kinetics
Approach:Conduct aqueous-phase photooxidation experiments, measure products, model product formation
Organic + H2 O2 + UV (plus controls)
To provide supply of ·OH
Secondary Organic Aerosol
Unit Name
Optional Presentation Title Secondary Organic Aerosol
Results:
Oxalic acid is formed from GLY, MG, PA
*Typical cloud/fog pH 2-5; Catalase to stop reactions; Samples frozenCarlton et al., 2006; Altieri et al., 2006; Carlton et al (2007)
Organic
Conc.(N)H2 O2pH*
Glyoxal
2 mM(3)10 mM4.1 - 4.8
Methylglyoxal
2 mM(3)10 mM4.2 – 4.5
Pyruvic Acid
10 mM(3)20 mM2.7
Experiment ORG+UV+H2 O2
UV Control ORG+ H2 O2
H2 O2 Control ORG+UV
Organic Control
UV+H2 O2
Unit Name
Optional Presentation Title
Pyruvic
Acid Results:
Secondary Organic Aerosol
Phase transfersRxs with •OH
Aqueous phase
ISOPRENE + oxidants (·OH, O3 , NO3 )
HOCH2CHO CHOCHO CH3COCHO(glycolaldehyde) (glyoxal) (methylglyoxal)
HOCH2CH(OH)2 (OH)2CHCH(OH)2 CH3COCH(OH)2
HOCH2COOH CH3COCOOH(glycolic acid) (pyruvic acid)
(OH)2CHCOOH CH3COOH(glyoxylic acid - hydrated) (acetic acid)
HOOCCOOH CH2(OH)2(oxalic acid) (formaldehyde - hydrated)
CO2 HCOOH(formic acid)
Gas phase
67%
33% 92%8%
85%
15%
Carlton et al., 2006
Unit Name
Optional Presentation Title
m/z0 100 200 300 400 500 600
Ion
Abun
danc
e (a
rbitr
ary
units
)
0
100000
200000
300000
400000
500000
600000
89
87
73
175
Electrospray
Ionization Mass Spectrum (ESI‐MS): Mixed Standard of Pyruvic
Acid and Predicted Products
Pyruvic
Glyoxylic
Oxalic
Pyruvic
Secondary Organic Aerosol
ESI: soft ionization, does not
fragment
positive mode protonates
cmpds
with basic functional
groups MW+1
negative deprotonates
cmpds
with acidic functional groups
MW‐1
Unit Name
Optional Presentation Title
m /z
0 100 200 300 400 500 600
Ion
Abu
ndan
ce (a
rbitr
ary
units
)
0
50000
150000
200000
250000
300000
89
103
133
147
177
217
m /z
200 210 220 230 240 250
Ion
Abu
ndan
ce
0
10000
20000
30000
40000
50000
60000
Δ12 Δ14 Δ16
ESI‐MS Spectrum of Pyruvic
Acid Experiment(t=202 min): Regular Distribution of Oligomer
System
Secondary Organic Aerosol
Δ12 Δ14 Δ16
Lim mechanism is incomplete; oxalic acid and larger MWt
(oligomers) formAltieri et al., 2006
Unit Name
Optional Presentation Title
CH3COCOOH(pyruvic acid)
(OH)2CHCOOH CH3COOH
(glyoxylic acid - hydrated) (acetic acid)
HOOCCOOH CH2(OH)2(oxalic acid) (formaldehyde - hydrated)
CO2 HCOOH(formic acid)
Oligomers
Secondary Organic Aerosol
Oxalic acid and oligomers
form. Both are likely to contribute to SOA after droplet evaporation.
Unit Name
Optional Presentation Title
Glyoxal:
Lim model reproduces H2
O2
in reaction vessel but poor prediction of oxalic acid (r2
= 0.001) meas. glyoxylic
acid cannot explain oxalic acid formation
0123456789
10
0 50 100 150
Time (min)
Con
cent
ratio
n (m
M)
[H2O2] (3/15/05)[H2O2] (5/7/05)[H2O2] (model)
Hydrogen Peroxide Hydroxyl Radical
[H2 O2 ]
Secondary Organic Aerosol
LIM MODEL: Glyoxal Glyoxylic Acid Oxalic Acid
Unit Name
Optional Presentation Title
0 200 400 600 8000
10000
20000
30000
40000
50000
m/z0 200 400 600 800
Ion
abun
danc
e
0
20000
40000
60000
80000
100000
120000
117
131
89
73
positive mode
negative mode
Glyoxal
Results ‐
ESI‐MS:
Mixture standard
containing the precursor
and products that are
predicted by initial model
The spectrum we would
expect if the initial
mechanism were complete
m/z
Positive mode
Negative mode
Glyoxal
Oxalic Acid
Ion
Abun
danc
e
Secondary Organic Aerosol
Unit Name
Optional Presentation Title Positive mode
0 200 400 600 8000
10000
50000
55000
60000
Negative mode
0 200 400 600 8000
10000
20000
30000
40000
9 min.
149
0 200 400 600 800
Ion
abun
danc
e0
1000030000400005000060000
0 200 400 600 8000
10000
20000
30000
40000
32 min.
173
89
m/z0 200 400 600 800
0100002000030000400005000060000
m/z0 200 400 600 800
0
10000
20000
30000
40000
151 min
89
201313
0 200 400 600 8000
20000
40000
60000
80000
100000
0 200 400 600 8000
10000
20000
30000
40000
0 min.
117
131
Glyoxal rapidly destroyed
Spectral “complexity”develops that cannot be explained by initial mechanism
(large compounds with alcohol/aldehyde (pos) and acid (neg) functionalities)
“Complexity” in positive and negative modes dissipates ∼30-40 min
oxalic acid formed (dominates 150 min spectrum)
Glyoxal
Oxalic Acid
Glyoxal
Results: ESI‐MS
Unit Name
Optional Presentation Title
-1000
49000
99000
149000
199000
249000
299000
349000
399000
0 2 4 6 8 10 12
Retention Time (min)
Absorbance (mAU)
t = 0 mins. t = 2 mins. t = 32 mins.t = 61 mins.t = 146 mins. Oxalic acid
Unresolved carbon (large, multifunctional, alcohol or acid functionalities)
Formic acid
Glyoxylic acid
Glyoxal Glyoxylic Acid Oxalic Acid
Secondary Organic Aerosol
Glyoxal
Results: ESI‐MS
Unit Name
Optional Presentation Title
Expanded Glyoxal
Photooxidation
Mechanism
Secondary Organic Aerosol
(glyoxal-hydrated) (OH)2CHCH(OH)2
(OH)2CHCOOH (glyoxylic acid-hydrated)
HOOCCOOH (oxalic acid)
CO2
HCOOH(formic acid)
large multifunctional
compounds
·OH
·OH
·OH
·OH·OH
·OH
H2O2
·OH
(glyoxal-hydrated) (OH)2CHCH(OH)2
(OH)2CHCOOH (glyoxylic acid-hydrated)
HOOCCOOH (oxalic acid)
CO2
HCOOH(formic acid)
large multifunctional
compounds
·OH
·OH
·OH
·OH·OH
·OH
H2O2
·OH
a
bc
k = 3E10k = 1.1E8
k = 5E3
.OH
(glyoxal-hydrated) (OH)2CHCH(OH)2
(OH)2CHCOOH (glyoxylic acid-hydrated)
HOOCCOOH (oxalic acid)
CO2
HCOOH(formic acid)
large multifunctional
compounds
·OH
·OH
·OH
·OH·OH
·OH
H2O2
·OH
(glyoxal-hydrated) (OH)2CHCH(OH)2
(OH)2CHCOOH (glyoxylic acid-hydrated)
HOOCCOOH (oxalic acid)
CO2
HCOOH(formic acid)
large multifunctional
compounds
·OH
·OH
·OH
·OH·OH
·OH
H2O2
·OH
a
bc
k = 3E10k = 1.1E8
k = 5E3
.OH
H2 O2
Unit Name
Optional Presentation Title Secondary Organic Aerosol
-1000
49000
99000
149000
199000
249000
299000
349000
399000
0 2 4 6 8 10 12
Retention Time (min)
Absorbance (mAU)
t = 0 mins. t = 2 mins. t = 32 mins.t = 61 mins.t = 146 mins. Oxalic acid
Unresolved carbon (large, multifunctional, alcohol or acid functionalities)
Formic acid
Glyoxylic acid
Glyoxal Glyoxylic Acid Oxalic AcidGlyoxal Formic Acid
• Not identified as an aqueous- phase glyoxal oxidation product in the atmospheric chemistry literature
• Food/Dye Lit: Close proximity of the two carbonyl double bonds enhances reactivity toward nucleophilic attack (Rao and Rao J.Anal.Chem., 2005)
HO COH
COH
OHH H
glyoxal hydrated
OH HO COH
COH
OHH H
2 H CO
OH
formic acid
Unit Name
Optional Presentation Title
Expanded Glyoxal
Photooxidation
Mechanism
Secondary Organic Aerosol
(glyoxal-hydrated) (OH)2CHCH(OH)2
(OH)2CHCOOH (glyoxylic acid-hydrated)
HOOCCOOH (oxalic acid)
CO2
HCOOH(formic acid)
large multifunctional
compounds
·OH
·OH
·OH
·OH·OH
·OH
H2O2
·OH
(glyoxal-hydrated) (OH)2CHCH(OH)2
(OH)2CHCOOH (glyoxylic acid-hydrated)
HOOCCOOH (oxalic acid)
CO2
HCOOH(formic acid)
large multifunctional
compounds
·OH
·OH
·OH
·OH·OH
·OH
H2O2
·OH
a
bc
k = 3E10k = 1.1E8
k = 5E3
.OH
(glyoxal-hydrated) (OH)2CHCH(OH)2
(OH)2CHCOOH (glyoxylic acid-hydrated)
HOOCCOOH (oxalic acid)
CO2
HCOOH(formic acid)
large multifunctional
compounds
·OH
·OH
·OH
·OH·OH
·OH
H2O2
·OH
(glyoxal-hydrated) (OH)2CHCH(OH)2
(OH)2CHCOOH (glyoxylic acid-hydrated)
HOOCCOOH (oxalic acid)
CO2
HCOOH(formic acid)
large multifunctional
compounds
·OH
·OH
·OH
·OH·OH
·OH
H2O2
·OH
a
bc
k = 3E10k = 1.1E8
k = 5E3
.OH
H2 O2
Unit Name
Optional Presentation Title Secondary Organic Aerosol
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0 100 200 300 400 500
Time (min)
Con
cent
ratio
n (m
M)
0.00
0.05
0.10
0.15
0.20
0.25Predicted formicFormic Acid, Exp. 1, 2Predicted oxalicOxalic Acid, Exp. 1, 2
Measurements and Predictions Using Expanded Mechanism
Formic Acid (r2 = 0.6)
Oxalic Acid (r2 = 0.8)
Meas/Modeled glyoxylic acid <MDL. Only 1% of oxalic acid from glyoxal →
glyoxylic acid → oxalic acid pathway. Large multifunctional products important to oxalic acid formation and contribute to SOA themselves.
Reaction Vessel Max:0.02 g Oxalic / g Glyoxal (90 min)0.3 g MF cmpd / g Glyoxal (30 min)
Carlton et al., 2007
Unit Name
Optional Presentation Title Secondary Organic Aerosol
(a) ESI-MS 69 min. neg mode
(b) ESI FT-ICR MS69 min. neg mode
Peak Location300 350 400 450 500
Peak
Hei
ght
0
20
40
m/z50 100 150 200 250 300 350 400 450 500 550 6001000
Ion
abun
danc
e
0
2000
4000
6000
8000
10000
C14H17O12377.070380
C17H13O11393.044360
C16H19O14435.075940
C13H15O12363.054800
C23H13O20465.177920
C12H13O20476.99925
m/z0 100 200 300
Ion
abun
danc
e
0100000200000300000400000500000
73
87
89
MethylglyoxalResults:
PA
GA•“haystacks” with regular pattern of mass differences; oligomer system
•Like pyruvic acid experiments (MG itself not involved)
•Structure not seen in mixed stds (not artifact)
•No oligomers in controls (·OH involved)
OA
Unit Name
Optional Presentation Title Secondary Organic Aerosol
Methylglyoxal:
H3C CO
COH
OHH OH H3C C
OCOH
OHH H3C C
OOH H C
OOH+
methylglyoxal hydratedacetic acid formic acid
-1000
49000
99000
149000
199000
249000
299000
0 2 4 6 8 10 12
Retention Time (min)
Absorbance (mAU)
t = 2 mins.
t = 69 mins.
t = 129 mins.
t = 204 mins.
t = 249 mins.
t = 369 mins.Oxalic
Large multifunctional compounds
Formic
Glyoxylic
Pyruvic
Acetic
Abs
orba
nce
Retention Time (min)
t=2 min
Formic and acetic acid form directlyInsufficient glyoxylic to explain oxalicOligomers involved in oxalicOligomers and oxalic → SOA
Unit Name
Optional Presentation Title Secondary Organic Aerosol
Expanded Methylglyoxal
Mechanism
CO2
(Methylglyoxal-hydrated)CH3COCH(OH)2
(OH)2CHCOOH (glyoxylic acid-hydrated)
HOOCCOOH (oxalic acid)
HCOOH(formic acid)
CH3COCOOH(pyruvic acid)
CH3COOH(acetic acid)
CH2(OH)(formaldehyde-hydrated)
.OH
.OH.OH
.OH
.OH
.OH.OH
.OH
.OH
hυ/∙ΟΗ
large oligomericcompounds
hυ/∙ΟΗ
CO2
(Methylglyoxal-hydrated)CH3COCH(OH)2
(OH)2CHCOOH (glyoxylic acid-hydrated)
(OH)2CHCOOH (glyoxylic acid-hydrated)
HOOCCOOH (oxalic acid) HOOCCOOH (oxalic acid)
HCOOH(formic acid)
HCOOH(formic acid)
CH3COCOOH(pyruvic acid)CH3COCOOH(pyruvic acid)
CH3COOH(acetic acid)CH3COOH(acetic acid)
CH2(OH)(formaldehyde-hydrated)
CH2(OH)(formaldehyde-hydrated)
.OH
.OH.OH
.OH
.OH
.OH.OH
.OH
.OH
hυ/∙ΟΗ
large oligomericcompounds
hυ/∙ΟΗ
Initial ‐
Lim
Expanded ‐
experiments
Oligomers
Unit Name
Optional Presentation Title
MG UV/H2O2 t=69 min. neg mode fticrms
OM:OC ratio1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
Freq
uenc
y
0
200
400
600
800
1000
methylglyoxalpyruvic acidacetic acid
glyoxylic acid
oxalic acidformic acid
300 – 500 amu500 – 700 amu
Secondary Organic Aerosol
Methylglyoxal
Results: OM/OC = 1.0‐2.5 (avg
1.9) for m/z>300
FT-ICR provides exact elemental comp. >300 m/z
OM/OC comparable to cloud water, regional aerosol. Lower than organic acids
Unit Name
Optional Presentation Title
0
1
2
3
0 1 2 3 4 5 6 7 80
1
2
3
0
5
10
0
1
2
3
0 1 2 3 4 5 6 7 80
1
2
3
02468
0 1 2 3 4 5 6 7 802468
% y
ield
%
yie
ld
cloud cycles0 1 2 3 4 5 6 7 8
0
5
10
cloud cycles cloud cycles cloud cycles
Cloud parcel model: Isoprene with/without cloud chemistry. Barbara Ervens
Collaboration (see poster)
10NOVOC
x
=10NOVOC
x=125
NOVOC
x=
•
Cloud chemistry yields
~ 0.5 -
5% •
Approximately doubles SOA
Gas phase chemistry + uptake only
With cloud chemistry
50NOVOC
x=
Secondary Organic Aerosol
Unit Name
Optional Presentation Title
CMAQ runs: Annmarie
Carlton Collaboration (see poster)
With and without in‐cloud SOA formation (using Yields of 4 to 30%)
Secondary Organic Aerosol
Surface conc. ofSOA from cloud pr
Non-convective Cloud fraction
Free troposphere:SOA from cloud pr
Cloud-free areas
SOA from cloud processing – Eastern United States
Unit Name
Optional Presentation Title
Experimental Findings:
Oxalic acid forms from glyoxal/methylglyoxal in aqueous-phase
Oligomers and other large multifunctional compounds also form
Thus, SOA will form through cloud processing
Large multifunctional compounds (including oligomers) appear to play a role in oxalic acid formation
Experiments used to validate and refine reaction pathways/kinetics
This work demonstrates a linkage between marine, biogenic and anthropogenic precursors of glyoxal, methylglyoxal and pyruvic acid (including isoprene) and in-cloud SOA formation
Secondary Organic Aerosol
Unit Name
Optional Presentation Title
Future DirectionsUse mass spectroscopic tools to better understand:
The structure and properties of oligomers
Oligomer formation and degradation
Pursue continued methylglyoxal
model improvements:Through improved understanding of oligomers
Through experiments with intermediates
Incorporate this process into atmospheric models:Chemical and Cloud parcel models: kinetics to atmospheric yields and parameterizations
Air quality and climate models: Magnitude and implications
Secondary Organic Aerosol
Unit Name
Optional Presentation Title Secondary Organic Aerosol
AcknowledgementsPast/present Students, Postdocs CollaboratorsAnnmarie Carlton Sybil SeitzingerKatie Altieri Barbara ErvensYi Tan Jeehuin LeeMark Perri John ReinfelderHo-Jin LimAdam Reff
Support Related Modeling StudiesU.S. EPA – STAR CMAQ poster - CarltonNSF Cloud parcel poster - Ervens