Isoprene Epoxydiols Derived Secondary Organic Aerosol (IEPOX-SOA): Insights from Aerosol Mass Spectrometer

Field Measurements

Weiwei Hu, Pedro Campuzano-Jost, Brett Palm, Douglas Day, Amber Ortega, Patrick Hayes, Qi Chen, Mikinori Kuwata, Yingjun Liu, Suzane Simoes de Sa, Scot T. Martin,

Min Hu, Sri Hapsari Budisulistiorini, Jason D. Surratt, Kenneth Docherty, Gabriel Isaacman, Allen H. Goldstein, Jason M. St. Clair, John D. Crounse, Paul O. Wennberg,

Abby Koss, Joost de Gouw, Fabien Paulot, Jordan Krechmer, Jose-Luis Jimenez*

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1 University of Colorado, Boulder, CO, USA; 2 University of Colorado, Boulder, CO, USA; 3 Harvard University,

Cambridge, MA, USA; 4 Nanyang Technological University, Singapore; 5 Peking University, Beijing, China; 6 The

University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; 7 Research Triangle Park, North Carolina, USA; 8

University of California, Berkeley, CA, USA; 10 California Institute of Technology, Pasadena, CA, USA

AMS user’s meeting @ Nanjing

IEPOX-SOA formation

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Surratt et al

2010

Measured IEPOX-SOA from AMS3

GEOS-Chem gas phase IEPOX for July 2013 by Fabien Paulot

Hayes et al., 2013; Pandolfi et al., 2014;

Hu et al., 2013;Hu et al., 2016;

Robinson et al., 2011;Chen et al.,2015;

Xu et al. 2014, 2015; Budisulistiorini et

al., 2013, 2015; Slowik et al., 2011

Hu et al., ACP 2015

Measured IEPOX-SOA from AMS4

GEOS-Chem gas phase IEPOX for July 2013 by Fabien Paulot

Hayes et al., 2013; Pandolfi et al., 2014;

Hu et al., 2013;Hu et al., 2016;

Robinson et al., 2011;Chen et al.,2015;

Xu et al. 2014, 2015; Budisulistiorini et

al., 2013, 2015; Slowik et al., 2011

Hu et al., ACP 2015

Outline:

1) Characterization of a Real-Time Tracer of IEPOX-SOA from AMS

2) Heterogeneous reaction of IEPOX-SOA

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IEPOX-SOA in SOAS6

Tetrols are 26% of IEPOX-SOA

IEPOX-SOA mass spectra

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m/z 82m/z 53

Fie

ld s

tudie

sL

ab s

tudie

s

Mass spectra come from Budisulistiorini et

al., 2013; Chen et al., 2014; Liu et al., 2014

We looked at other tracer ions in

IEPOX-SOA spectra, C5H6O+ is the best

one.

m/z

𝑓𝐶5𝐻6𝑂=C5H6O+/IEPOX-SOA= 12-40 ‰

Robinson et al., 2011; Lin et al., 2011;Budisulistiorini et al., 2013

IEPOX-SOA from AMS

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C5H6O+ recognition

Methylfuran structure

C5H6O+3-MeTHF-3,4-diols (C5H10O3)

Heat

decomposition

One of IEPOX-SOA species

Reviewer in recent ACP paper:

“m/z 82 is also found in SOA from biogenic monoterpene emissions… An unambiguous identification of isoprene SOA is thus not provided by the presence of m/z 82 alone…”

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Is C5H6O+ a good tracer for IEPOX-SOA?

To start: What’s the values of f82 or fC5H6O in different OA sources?

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GEOS-Chem gas phase IEPOX for July 2013 by Fabien Paulot

Datasets used in this study

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Signal-to-background contrast

Urban

Los Angeles area, US;

Beijing, China

Changdao island, Downwind China;

Barcelona area, Spain

Continental plumes

biomass burning

SEAC4RS aircraft: NW US

DC3 Aircraft: western US

BB lab emission and OH aged

SEAC4RS&DC3 aircraft: BB plumesPure primary OA

Coal combustion

Cooking

Vehicle exhaust

Std chemical species

Average fC5H6O in pollution & biomass-

burning ~1.7‰

𝑓𝐶5𝐻6𝑂 in pollution and biomass-burning emissions

OH aging effect on 𝑓𝐶5𝐻6𝑂

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Los Angeles area, US

ambient

OH-agedLos Angeles area, US

ambient

OH-aged

Oxidation tends to decrease fC5H6O in aerosols

OH aged

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𝑓𝐶5𝐻6𝑂 in isoprene influenced areas

Pollution &biomass burning

(Robinson et al., 2011)

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Pollution &biomass burning

(Robinson et al., 2011)

𝑓𝐶5𝐻6𝑂 in other isoprene SOA

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Pollution &biomass burning

(Robinson et al., 2011)Chen et al., 2014; Kroll et al., 2006; Ng et al., 2008

fC5H6O

enhanced in IEPOX-SOA

NOT enhanced in other isoprene SOA

𝑓𝐶5𝐻6𝑂 in other isoprene SOA

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Pollution &biomass burning

(Robinson et al., 2011)

𝑓𝐶5𝐻6𝑂 in monoterpene emissions

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Pollution &biomass burning

(Robinson et al., 2011)

𝑓𝐶5𝐻6𝑂 in monoterpene emissions

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Pollution &biomass burning

(Robinson et al., 2011)

Signal-to-background contrast

Monoterpene-SOA can enhance fC5H6O,

but much less than IEPOX-SOA

𝑓𝐶5𝐻6𝑂 in monoterpene emissions

Is C5H6O+ a good tracer for IEPOX-SOA ?

Can C5H6O+ be used to estimate IEPOX-SOA?

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Scientific questions:

Yes

IEPOX-SOA=𝐶5𝐻6𝑂𝑡𝑜𝑡𝑎𝑙 − 𝐶5𝐻6𝑂𝑏𝑎𝑐𝑘𝑔𝑟𝑜𝑢𝑛𝑑

𝑓𝐶5𝐻6𝑂𝐼𝐸𝑃𝑂𝑋−𝑆𝑂𝐴−𝑓𝐶5𝐻6𝑂𝑏𝑎𝑐𝑘𝑔𝑟𝑜𝑢𝑛𝑑

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Estimate IEPOX-SOA

pollution & biomass-

burning emissions

strongly influenced areas

Background from MT-

influenced regions

Measured by AMS

fC5H6O in fresh

IEPOX-SOA= 21‰

Background from pollution

and biomass burning emissions

Background from monoterpene emissions

Estimated IEPOX-SOA in SOAS

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Outline:

1) Characterization of a Real-Time Tracer of IEPOX-SOA from AMS

2) Heterogeneous reaction of IEPOX-SOA

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Scientific question: IEPOX-SOA fate

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IEPOX-SOA

Hu et al., ACP, 2016

More oxidized OA

and other OAs 1) Volatility of IEPOX-SOA?

2) Aging quickly to form

more oxidized OA ?

IEPOX-SOA account for 6-36% of OA in forest areas

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VOCs

HR-ToF-AMS

SMPS

PTR-TOFMS

ToF-CIMS

CO, O3

Ambient

aerosolPAM Reactor

Setup of Thermodenuder

Thermodenuder

Time resolution: 4 min

Temperature range: 35-260 ℃

Residence time: 21 s

Hu et al., ACP 2016;

Huffman et al., 2008 , 2009a, b

Volatility of IEPOX-SOA-partially exist as oligomers

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Faulhaber et al., 2009; Huffman et al., 2009; Hu et al., ACP, 2016

Monomers

Oligomers

Consistent with multiple

other studies: Lopez-

Hilfiker et al., 2016;

Isaacman-VanWertz et al.,

2016; Lin et al., 2014

Scientific question: IEPOX-SOA fate

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IEPOX-SOA

Hu et al., ACP, 2016

More Oxidized OA

and other OAs

oligomer

Gas-phase

monomer

1) Volatility of IEPOX-SOA?

2) Aging quickly to form

more oxidized OA ?

Low volatility

monomer

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PAM reactor: Designed by Prof. Bill Brune at Penn State

Kang et al., ACP 2007; Lambe et al., 2011, 2012; Ortega et al., ACP 2013; Li et al., 2014; Zhe et al., 2015; 2016

OH Production:

O2 + hv(185nm) O3

O3 + hv(254nm) + H2O 2 OH

H2O+hv(185nm)OH

Estimated OH conc. in reactor: 0-7×1010 (molec. cm-3)

Photochemical aging: several hours to a few months

OH

HR-ToF-AMS

SMPS

PTR-TOFMS

ToF-CIMS

CO, O3

Ambient

aerosol PAM Reactor

Setup of Oxidation flow reactor

Thermodenuder

VOCs

OFR

Simulated gas-phase IEPOX fate

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Hu et al., ACP, 2016

Negligible IEPOX-SOA formation in OFR

Ambient

OH Heterogeneous lifetime of IEPOX-SOA

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Lifetime is > 2 weeks

Assuming the ambient OH conc. is

~1.5×106 molec. cm-3

kOH=4.0±2.0×10-13 cm3 molec.-1 s-1

(19±9 days)

Hu et al., ACP, 2016

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-RH dependent

OH Heterogeneous lifetime of IEPOX-SOA

Hu et al., ACP, 2016

Conclusions• Heterogeneous oxidation of IEPOX-SOA Low volatility

Lifetime ~ >two weeks

• fC5H6O is a good tracer for IEPOX-SOA

• Low background levels in OA:

pollution and biomass-burning emissions:

0.02 - 3.5‰ with an average of 1.7 ‰

monoterpene emissions.

2.5 - 6‰

• Simplified method to estimate IEPOX-SOA from tracer

Performs well compared to PMF

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