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 28 th , 2015
Nitrogen oxides: Key trace gases in the troposphere NO x = NO + NO 2 NO y = NO + NO 2 + NO z NO z = HNO 3 + S PN + S AN AN = + aerosol nitrate alkyl + .... nitrates O 2 O 3 PN = peroxy nitrates NO x catalyzes O 3 formation requires VOCs and sunlight. -2-
Peroxycarboxylic nitric anhydrides (PANs, PN) - Mixed acid anhydrides (of nitric acid and a peroxycarboxylic acid). - Molecular Formula: R-C(O)O 2 NO 2 , R ≠ H - Examples: PAN: CH 3 -C(O)O 2 NO 2 PPN: C 2 H 5 -C(O)O 2 NO 2 PiBN: i-C 3 H 7 -C(O)O 2 NO 2 MPAN: CH 2 =C(CH 3 )-C(O)O 2 NO 2 APAN: CH 2 =CH-C(O)O 2 NO 2 - Decompose readily when heated. - NO x reservoir species in troposphere. - Lachrymators & eye irritants & phytotoxic. - Byproducts of O 3 production and components of photochemical smog. => Relative abundances give insights into types of VOCs involved in O 3 formation. -3- J. M. Roberts, Atmos. Environm . A 24 , 2, 243 (1990).
Measurement of NO z species by TD-CRDS Selective measurement of S PN and S AN by thermal dissociation (TD) inlet temperature quantify D NO 2 250 ° C : by cavity ring-down 450 ° C : spectroscopy (CRDS) 600 ° C : Charles Odame-Ankrah Dipayan Paul 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). -4-
Complications in the measurement of S PN by TD-CRDS O 2 CH 3 C(O)O 2 + NO CH 3 C(O)O + NO 2 CH 3 O 2 + CO 2 + NO 2 O 2 CH 3 O 2 + NO CH 3 O + NO 2 HO 2 + CH 2 O + NO 2 HO 2 + NO OH + NO 2 PAN ⇌ PA + NO 2 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). • To interpret measurements of S PN in ambient air, need measurements of PAN+PPN+PiBN+MPAN+APAN+... -5-
PAN-GC ECD Varian 3380CP - custom A/D - automated - low pptv LOD - selective J. Love Curtis - ≤10 min run time Berlinguette - 15 m RTX-1701 -1 mL Travis sample loop Tokarek 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). -6- T. W . Tokarek et al. Atmos. Meas. Techn. 7 , 3263-3283 (2014).
TD-CRDS vs. GC-ECD: complimentary techniques TD-CRDS GC-ECD Pretty Picture 120 pptv (3 s ) LOD < 10 pptv Time resolution 1 s 6 or 10 min S PN specific yes requires calibration no yes 48' × 24' size rack (sort of) NO, NO 2 , N 2 O 5 , chlorofluorocarbons interferences ClONO 2 , ... and alkyl nitrates -7-
FOSSILS August – September, 2013 Fort McMurray Oil Sands Strategic Investigation of Local Sources (part of JOSM) Convair Environment Canada – Meteorological Research Division – Climate Research Division – Air Quality Research Division AMS 13 • 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) Partners – Meteorological Service of Canada PNR – National Research Council of • Prediction (Edmonton) Canada (NRC) • Sciences (Edmonton) – Fort McKay First Nation Universities – Alberta Environment and – University of Toronto (measurements) Sustainable Resource – York University (measurements) Development (AESRD) University of Calgary (measurements: NO, NO 2 , N 2 O 5 , S PN, – Wood Buffalo – ClNO 2 , PANs, NO y , O 3 , j constants, met data, VOCs, ...) Environmental Association (WBEA) – University of Alberta (measurements) – Dalhousie University (modelling and satellite) – Carleton University (modelling) -8- photograph and text shamelessly lifted from a ppt presentation by Stewart Cober
FOSSILS August – September, 2013 -9-
Why quantify PANs in the AB oil sands? PANs • are NO x reservoir species. NO x has a lifetime of 1 – 2 days; PANs up to months in cold seasons; PANs export pollution. • can hide NO 2 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 NO y component in biomass burning plumes. - potentially import pollution from BC • allow insight into classes of VOCs involved in O 3 formation. -10-
Calibration of PAN-GC against TD-CRDS -11- T. W . Tokarek et al. Atmos. Meas. Techn. 7 , 3263-3283 (2014).
A typical PAN-GC chromatogram J. Huo -12- T. W . Tokarek et al. Atmos. Meas. Techn. 7 , 3263-3283 (2014).
PAN time series PANs • were produced during the day. • up to 25% of NO y • were short-lived (due to warm temperatures and high [NO]). • did not observe biomass burning plumes. -13- T. W . Tokarek et al. Atmos. Meas. Techn. 7 , 3263-3283 (2014).
Ozone production: linear combination model • PPN is made from propanal, an oxidation 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. (3.8 ± 0.1) [MPAN] (5.1 ± 0.1) [PPN] BHC [O 3 ] = [O 3 ] AHC [O 3 ] = [O 3 ] (5.1 ± 0.1) [PPN]+ (3.8 ± 0.1) [MPAN] (5.1 ± 0.1) [PPN] + (3.8 ± 0.1) [MPAN] 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). -14- T.W . Tokarek et al. manuscript in preparation (2014).
Ozone production: linear combination model 100% 75% • Aug 24: ~75% of O 3 from AHC • Aug 25: ~55% of O 3 from AHC 50% 25% 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). -15- T.W . Tokarek et al. manuscript in preparation (2014).
APAN and PiBN APAN is an acrolein PiBN is an i-butane oxidation product oxidation product (primary and cycloalkanes) • [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-
Travis GC-MS for quantification of VOCs 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 “ every instrument is only as Matthew good as its inlet. ” Saowopan • unsaturated compounds are prone to oxidation during preconcentration • heated stainless steel tube (to remove O 3 ) H. Hellén, P. Kuronen, and H. Hakola, Atmos. Environm . 57 , 35 (2012). -17-
Typical GC-MS chromatograms (clean air) “ Clean ” air chromatogram (Sept 02, 05:18) β -pinene Temperature α -pinene Total Ion Camphene Count (TIC) Carene Relative Ion Count (RIC) m/z 91-94 Limonene a -terpinene (?) -18- T.W . Tokarek et al. another manuscript in preparation (2014).
Typical GC-MS chromatogram (not-so-clean air) “ Not so clean ” chromatogram (Aug 27,18:04) α -pinene β -pinene Temperature Total Ion Camphene Count (TIC) Carene Relative Ion Count (RIC) o-xylene m/z 91-94 Limonene a -terpinene (?) -19- T.W . Tokarek et al. another manuscript in preparation (2014).
GC-MS time series -20- T.W . Tokarek et al. another manuscript in preparation (2014).
Time of day dependencies -21- T.W . Tokarek et al. another manuscript in preparation (2014).
Conclusions quantified PAN, PPN, MPAN, APAN, and PiBN in AB oil sands - up to 25% of NO y (during the day) - short-lived (in August) - O 3 maxima in region linked to oxidation of anthropogenic VOCs quantified selected medium volatility VOCs in AB oil sands - data analysis ongoing - monoterpenes anticorrelated with O 3 http://homepages.ucalgary.ca/~hosthoff -22-
PAN vs. NO y -23- T.W . Tokarek et al. manuscript in preparation (2014).
PiBN production 24
MPAN production 25
PAN production 26
PPN production 27
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