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peroxycarboxylic nitric anhydrides by GC-ECD and of medium - - PowerPoint PPT Presentation

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Measurements of peroxycarboxylic nitric anhydrides by GC-ECD and of medium volatility biogenic and anthropogenic VOCs by GC-ion-trap-MS in ambient air at a ground site near Ft. McKay, AB T.W. Tokarek, J.A. Huo, C.A. Odame-Ankrah, M. Saowapon,

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SLIDE 1

Measurements of peroxycarboxylic nitric anhydrides by GC-ECD and of medium volatility biogenic and anthropogenic VOCs by GC-ion-trap-MS in ambient air at a ground site near Ft. McKay, AB

T.W. Tokarek, J.A. Huo, C.A. Odame-Ankrah,

  • M. Saowapon, and

H.D. Osthoff* Western Canada Trace Organics Workshop, Calgary, AB, April 28th, 2015

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SLIDE 2

Nitrogen oxides: Key trace gases in the troposphere

PN = peroxy nitrates AN = alkyl nitrates

O3

NOx catalyzes O3 formation requires VOCs and sunlight.

O2

NOx = NO + NO2 NOy = NO + NO2 + NOz NOz = HNO3 +SPN +SAN + aerosol nitrate + ....

  • 2-
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SLIDE 3

Peroxycarboxylic nitric anhydrides (PANs, PN)

  • J. M. Roberts, Atmos. Environm. A 24, 2, 243 (1990).
  • Mixed acid anhydrides (of nitric acid and a peroxycarboxylic acid).
  • Molecular Formula: R-C(O)O2NO2, R ≠ H
  • Examples:

PAN: CH3-C(O)O2NO2 PPN: C2H5-C(O)O2NO2 PiBN: i-C3H7-C(O)O2NO2 MPAN: CH2=C(CH3)-C(O)O2NO2 APAN: CH2=CH-C(O)O2NO2

  • Decompose readily when heated.
  • NOx reservoir species in troposphere.
  • Lachrymators & eye irritants & phytotoxic.
  • Byproducts of O3 production and components of photochemical smog.

=> Relative abundances give insights into types of VOCs involved in O3 formation.

  • 3-
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SLIDE 4

Selective measurement of SPN and SAN by thermal dissociation (TD) inlet temperature 250 °C : 450 °C : 600 °C :

Measurement of NOz species by TD-CRDS

D.A. Day, P.J. Wooldridge, M.B. Dillon, J.A. Thornton, and R.C. Cohen J. Geophys. Res.-Atmos 107(D6), 4046 (2002).

  • D. Paul, A. Furgeson, and H.D. Osthoff Rev. Sci. Instrum. 80(11), 114101 (2009).
  • D. Paul and H.D. Osthoff Anal. Chem. 82(15), 6695 (2010).

quantify DNO2 by cavity ring-down spectroscopy (CRDS)

  • 4-

Dipayan Paul Charles Odame-Ankrah

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SLIDE 5
  • D. Paul, A. Furgeson, and H.D. Osthoff Rev. Sci. Instrum. 80(11), 114101 (2009).
  • D. Paul and H.D. Osthoff Anal. Chem. 82(15), 6695 (2010).

Complications in the measurement of SPN by TD-CRDS

  • 5-

PAN ⇌ PA + NO2

CH3C(O)O2 + NO  CH3C(O)O + NO2  CH3O2 + CO2 + NO2 CH3O2 + NO  CH3O + NO2 HO2 + CH2O + NO2 HO2 + NO  OH + NO2

O2 O2

  • To interpret measurements of SPN in ambient air, need measurements of

PAN+PPN+PiBN+MPAN+APAN+...

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SLIDE 6

PAN-GC

based on F. M. Flocke, A. J. Weinheimer, A. L. Swanson, J. M. Roberts, R. Schmitt, and S. Shertz, J. Atmos. Chem. 52, 1, 19 (2005).

  • T. W

. Tokarek et al. Atmos. Meas. Techn. 7, 3263-3283 (2014).

  • 6-

Travis Tokarek

  • custom A/D
  • automated
  • low pptv LOD
  • selective
  • ≤10 min run time

ECD Varian 3380CP

  • J. Love Curtis

Berlinguette

  • 15 m RTX-1701
  • 1 mL

sample loop

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SLIDE 7

TD-CRDS vs. GC-ECD: complimentary techniques

TD-CRDS GC-ECD Pretty Picture LOD 120 pptv (3s) < 10 pptv Time resolution 1 s 6 or 10 min specific SPN yes requires calibration no yes size 48'×24' rack (sort of) interferences NO, NO2, N2O5, ClONO2, ... chlorofluorocarbons and alkyl nitrates

  • 7-
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SLIDE 8

FOSSILS August – September, 2013

Environment Canada

– Meteorological Research Division – Climate Research Division – Air Quality Research Division

  • Processes Research Section (Toronto)
  • Modelling and Integration Research Section (Toronto)
  • Measurements and Analysis Research Section (Toronto)
  • Analysis and Air Quality Section (Ottawa)
  • Emissions Research and Measurements Section (Ottawa)

– Meteorological Service of Canada PNR

  • Prediction (Edmonton)
  • Sciences (Edmonton)

Universities

– University of Toronto (measurements) – York University (measurements) – University of Calgary (measurements: NO, NO2, N2O5, SPN, ClNO2, PANs, NOy, O3, j constants, met data, VOCs, ...) – University of Alberta (measurements) – Dalhousie University (modelling and satellite) – Carleton University (modelling)

  • 8-

Partners

– National Research Council of Canada (NRC) – Fort McKay First Nation – Alberta Environment and Sustainable Resource Development (AESRD) – Wood Buffalo Environmental Association (WBEA)

Fort McMurray Oil Sands Strategic Investigation of Local Sources (part of JOSM)

photograph and text shamelessly lifted from a ppt presentation by Stewart Cober

AMS 13 Convair

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SLIDE 9

FOSSILS August – September, 2013

  • 9-
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SLIDE 10

Why quantify PANs in the AB oil sands?

  • 10-

PANs

  • are NOx reservoir species.

NOx has a lifetime of 1 – 2 days; PANs up to months in cold seasons; PANs export pollution.

  • can hide NO2 from satellites.
  • are lachrymators & phytotoxic.
  • have not been quantified in northern AB since the 1980s.

E Peake, M A Maclean, P F Lester, H S Sandhu, Atmos. Environm. 22 973-81 (1988).

  • are the major NOy component in biomass burning plumes.
  • potentially import pollution from BC
  • allow insight into classes of VOCs involved in O3 formation.
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SLIDE 11
  • 11-

Calibration of PAN-GC against TD-CRDS

  • T. W

. Tokarek et al. Atmos. Meas. Techn. 7, 3263-3283 (2014).

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SLIDE 12
  • 12-

A typical PAN-GC chromatogram

  • J. Huo
  • T. W

. Tokarek et al. Atmos. Meas. Techn. 7, 3263-3283 (2014).

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SLIDE 13
  • 13-

PAN time series

  • T. W

. Tokarek et al. Atmos. Meas. Techn. 7, 3263-3283 (2014).

PANs

  • were produced

during the day.

  • up to 25% of NOy
  • were short-lived

(due to warm temperatures and high [NO]).

  • did not observe

biomass burning plumes.

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SLIDE 14
  • 14-

Ozone production: linear combination model

LCM based on J. M. Roberts et al., J. Geophys. Res. 107, D214554 (2002) and J. M. Roberts et al. J. Geophys. Res. 112, D20306 (2007).

  • PPN is made from propanal, an
  • xidation product of n-alkanes ( C3)

=> anthropogenic marker.

  • MPAN is made from methacrolein, an

isoprene oxidation product => biogenic marker.

  • PAN is made from acetaldehyde

=> both biogenic and anthropogenic sources. => express PAN as a linear combination of biogenic (MPAN) and anthropogenic (PPN) components.

T.W . Tokarek et al. manuscript in preparation (2014).

BHC [O3] = [O3 ]  (3.8±0.1) [MPAN] (5.1±0.1)[PPN]+ (3.8±0.1)[MPAN] AHC [O3] = [O3 ]  (5.1±0.1)[PPN] (5.1±0.1)[PPN] + (3.8±0.1)[MPAN]

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SLIDE 15
  • 15-

Ozone production: linear combination model

LCM based on J. M. Roberts et al., J. Geophys. Res. 107, D214554 (2002) and J. M. Roberts et al. J. Geophys. Res. 112, D20306 (2007). T.W . Tokarek et al. manuscript in preparation (2014).

100% 75% 50% 25%

  • Aug 24: ~75% of O3 from AHC
  • Aug 25: ~55% of O3 from AHC
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SLIDE 16
  • [APAN] and [PiBN] correlate with [PPN] with near-zero intercept

=> consistent with co-location of sources.

  • [APAN]/[PPN] ratios are greater than for the other data sets, possibly because of higher

automobile traffic and associated tailpipe emissions.

  • 16-

APAN and PiBN

PiBN is an i-butane

  • xidation product

APAN is an acrolein

  • xidation product

(primary and cycloalkanes)

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SLIDE 17

GC-MS for quantification of VOCs

  • 17-

Travis Tokarek

  • Griffin 450
  • Tenax preconcentration (10 min)
  • DB-5 column (30 m)
  • N. C. Bouvier-Brown et al. Atmos. Chem. Phys. 9, 5505 (2009).
  • Electron impact ionization
  • ion trap MS (used m/z 50 – 450)
  • post-data acquisition SIM

Matthew Saowopan

“every instrument is only as good as its inlet.”

  • unsaturated compounds are

prone to oxidation during preconcentration

  • heated stainless steel tube

(to remove O3)

  • H. Hellén, P. Kuronen, and H. Hakola,
  • Atmos. Environm. 57, 35 (2012).
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SLIDE 18

Typical GC-MS chromatograms (clean air)

  • 18-

“Clean” air chromatogram (Sept 02, 05:18)

α-pinene β-pinene Limonene Camphene Carene

Temperature Total Ion Count (TIC) Relative Ion Count (RIC) m/z 91-94

T.W . Tokarek et al. another manuscript in preparation (2014).

a-terpinene (?)

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SLIDE 19
  • 19-

Typical GC-MS chromatogram (not-so-clean air)

“Not so clean” chromatogram (Aug 27,18:04)

α-pinene β-pinene Limonene Camphene Carene

Temperature Total Ion Count (TIC) Relative Ion Count (RIC) m/z 91-94

a-terpinene (?)

  • -xylene

T.W . Tokarek et al. another manuscript in preparation (2014).

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SLIDE 20
  • 20-

GC-MS time series

T.W . Tokarek et al. another manuscript in preparation (2014).

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SLIDE 21
  • 21-

Time of day dependencies

T.W . Tokarek et al. another manuscript in preparation (2014).

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SLIDE 22

Conclusions

  • 22-

 quantified PAN, PPN, MPAN, APAN, and PiBN in AB oil sands

  • up to 25% of NOy (during the day)
  • short-lived (in August)
  • O3 maxima in region linked to oxidation of anthropogenic VOCs

 quantified selected medium volatility VOCs in AB oil sands

  • data analysis ongoing
  • monoterpenes anticorrelated with O3

http://homepages.ucalgary.ca/~hosthoff

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SLIDE 23
  • 23-

PAN vs. NOy

T.W . Tokarek et al. manuscript in preparation (2014).

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SLIDE 24

24

PiBN production

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SLIDE 25

25

MPAN production

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SLIDE 26

26

PAN production

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SLIDE 27

27

PPN production

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SLIDE 28

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