Academic interests
- Analytical Mass Spectrometry (proton-transfer-reaction mass spectrometry)
- Volatile organic compounds
- Transport and Photochemistry of Atmospheric Trace Gases (in-situ measurements and modeling)
Publications
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Bunkan, Arne Joakim C.; Gorzkowska-Sobas, Agnieszka A; Brinchmann, Erika Zardin; Languille, Baptiste; Mikoviny, Tomas & Nielsen, Claus Jørgen
[Show all 8 contributors for this article]
(2026).
Characterization of a Pilot-Scale Corona Radical Shower Non-Thermal Plasma Discharge Using Propene.
Plasma chemistry and plasma processing.
ISSN 0272-4324.
46(3).
doi:
10.1007/s11090-026-10646-8.
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A pilot-scale non-thermal plasma unit (NTP) and a UV-C photolysis unit for industrial emission control were integrated in the wind tunnel facility at the Norwegian Defence Research Establishment and characterized employing propene as model VOC. The experiments were monitored by high-resolution Proton-Transfer-Reaction Time-of-Flight mass spectrometry (PTR-ToF-MS), and the results show that gas phase chemistry in the NTP discharge strongly resembles the naturally occurring OH radical-induced oxidation in the Earth’s atmosphere – the main products being formaldehyde, acetaldehyde, acetone, and hydroxy acetone. A chemical box model, based on a well-established atmospheric oxidation mechanism, reproduces the experimental results and allows identification of chemical ‘hot-spots’ in the system.
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Steimer, Sarah S.; Elmgren, Max; Håland, Alexander; Johansson, Christer; Mikoviny, Tomas & Norman, Michael
[Show all 12 contributors for this article]
(2025).
Emission rates and composition of particulate matter from a large waste fire in Stockholm, Sweden.
Atmospheric Environment.
ISSN 1352-2310.
362.
doi:
10.1016/j.atmosenv.2025.121529.
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Uncontrolled waste burning and accidental waste fires are an important source of emissions into the air. However, there are currently only few field studies providing data on these emissions. In this study, we investigated the emission rates, pollutant dispersion and particle composition for a large waste fire in Stockholm county, Sweden. Our results show that the waste fire, while burning, may have contributed as much as 5 times the mean PM10 emissions from road traffic of the municipality it was located in (ca 95 000 inhabitants), which highlights the potential impact of temporary events such as waste fires on air quality. Gaussian dispersion calculations were used to model the spatial distribution of measured PM10 data, demonstrating its use for assessment of exposure and deposition. Particles impacted by the waste fire were enriched in several potentially toxic metals and metalloids including arsenic, copper, cadmium and, in particular, lead when compared to particles collected after the fire. In addition, they may also pose an increased cancer risk on a per-mass basis compared to the post-fire period due to the larger mass fraction of relevant PAHs.
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Drewry, Benjamin J.; Mikoviny, Tomas; Wisthaler, Armin; Rochelle, Gary T.; Stevens, Carl & Erickson, Kahiso
(2025).
Emissions with Various Water Wash Configurations during Pilot Plant Testing of Aqueous Piperazine for CO2 Capture.
Industrial & Engineering Chemistry Research.
ISSN 0888-5885.
64(10),
p. 5522–5535.
doi:
10.1021/acs.iecr.4c03763.
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Five wash configurations were tested for 800 hours at a pilot plant campaign at the National Carbon Capture Center (NCCC): (1) a single-stage water wash (WWC), (2) a trickle bed alone, (3) the WWC + trickle bed, (4) the WWC + a third bed with structured packing (Bed 3 + WW), and (5) the WWC converted to an acid wash + the third bed (AW + Bed 3). Gas-phase analysis by PTR-ToF-MS (proton transfer reaction–time-of-flight–mass spectrometry) quantified outlet emissions of more than 38 species including ammonia, piperazine (PZ), 1-methylpiperazine (MPZ), acetaldehyde, and formaldehyde. The acid wash reduced ammonia to less than 10 ppb. Two-stage wash configurations reduced PZ and other amines to less than 0.1 ppb. The total listed hazardous air pollutants (HAPs) including aldehydes were not effectively removed by any of the wash configurations but were less than 10 tons/year when scaled to a 460 MW facility. All non-PZ emissions, including HAPs, were significantly reduced by thermal reclaiming of the solvent.
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Gkatzelis, Georgios I.; Coggon, Matthew M.; Stockwell, Chelsea E.; Hornbrook, Rebecca S.; Allen, Hannah & Apel, Eric C.
[Show all 65 contributors for this article]
(2024).
Parameterizations of US wildfire and prescribed fire emission ratios and emission factors based on FIREX-AQ aircraft measurements.
Atmospheric Chemistry and Physics (ACP).
ISSN 1680-7316.
24(2),
p. 929–956.
doi:
10.5194/acp-24-929-2024.
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Extensive airborne measurements of non-methane organic gases (NMOGs), methane, nitrogen oxides, reduced nitrogen species, and aerosol emissions from US wild and prescribed fires were conducted during the 2019 NOAA/NASA Fire Influence on Regional to Global Environments and Air Quality campaign (FIREX-AQ). Here, we report the atmospheric enhancement ratios (ERs) and inferred emission factors (EFs) for compounds measured on board the NASA DC-8 research aircraft for nine wildfires and one prescribed fire, which encompass a range of vegetation types. We use photochemical proxies to identify young smoke and reduce the effects of chemical degradation on our emissions calculations. ERs and EFs calculated from FIREX-AQ observations agree within a factor of 2, with values reported from previous laboratory and field studies for more than 80 % of the carbon- and nitrogen-containing species. Wildfire emissions are parameterized based on correlations of the sum of NMOGs with reactive nitrogen oxides (NOy) to modified combustion efficiency (MCE) as well as other chemical signatures indicative of flaming/smoldering combustion, including carbon monoxide (CO), nitrogen dioxide (NO2), and black carbon aerosol. The sum of primary NMOG EFs correlates to MCE with an R2 of 0.68 and a slope of −296 ± 51 g kg−1, consistent with previous studies. The sum of the NMOG mixing ratios correlates well with CO with an R2 of 0.98 and a slope of 137 ± 4 ppbv of NMOGs per parts per million by volume (ppmv) of CO, demonstrating that primary NMOG emissions can be estimated from CO. Individual nitrogen-containing species correlate better with NO2, NOy, and black carbon than with CO. More than half of the NOy in fresh plumes is NO2 with an R2 of 0.95 and a ratio of NO2 to NOy of 0.55 ± 0.05 ppbv ppbv−1, highlighting that fast photochemistry had already occurred in the sampled fire plumes. The ratio of NOy to the sum of NMOGs follows trends observed in laboratory experiments and increases exponentially with MCE, due to increased emission of key nitrogen species and reduced emission of NMOGs at higher MCE during flaming combustion. These parameterizations will provide more accurate boundary conditions for modeling and satellite studies of fire plume chemistry an
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Wojnowski, Wojciech Karol; Yang, Aileen; Mikoviny, Tomas; Wisthaler, Armin & Thunshelle, Kari
(2024).
Exposure to cooking emitted volatile organic compounds with recirculating and extracting ventilation solutions.
Building and Environment.
ISSN 0360-1323.
261.
doi:
10.1016/j.buildenv.2024.111743.
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Energy-efficient urban development leads to the compact design of apartments. Recirculating ventilation solutions are an attempt to minimize the space required for ventilation ducting, but more data on their performance are needed. Cooking is a major source of volatile organic compounds (VOCs) emissions. It is necessary to assess how well recirculating kitchen hoods perform in reducing the residents' exposure to cooking fumes compared to extracting hoods, and what airflow rates assure good removal efficiency. We have monitored the occupant exposure to several VOCs generated during the cooking of a model meal under different ventilation scenarios in a purpose-built test kitchen resembling the layout of a modern, open-space apartment. Time-resolved VOC emission profiles were measured using a proton transfer reaction time-of-flight mass spectrometer. The performance of activated carbon sorption-based filters for recirculating kitchen hoods in the removal of selected VOCs was also assessed. Alcohols, particularly ethanol, dominated emissions from cooking a typical Norwegian meal, but they also included acetaldehyde, acetone, carboxylic acids, and trimethylamine, among others. The use of recirculating kitchen hoods led to, on average, higher occupant exposure to VOCs compared to extracting kitchen hoods during and after cooking. This was in part due to the poor ethanol removal efficiency of the recirculating ventilation's air filters.
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Mikoviny, Tomas; Nielsen, Claus Jørgen; Wisthaler, Armin & Zhu, Liang
(2024).
Experimental and Theoretical Study of the OH-Initiated Degradation of Ethylenediamine (NH<inf>2</inf>CH<inf>2</inf>CH<inf>2</inf>NH<inf>2</inf>) under Simulated Atmospheric Conditions. Part 1: Kinetics of the Ethylenediamine + OH Gas Phase Reaction.
ACS Earth and Space Chemistry.
doi:
10.1021/acsearthspacechem.4c00271.
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The ethylenediamine (NH2CH2CH2NH2) reaction with OH radicals was studied under natural sunlight conditions in a large outdoor atmospheric simulation chamber and in theoretical calculations based on CCSD(T*)-F12a/aug-cc-pVTZ//M06-2X/aug-cc-pVTZ quantum chemistry results. The OH rate coefficient was determined in relative rate experiments employing online PTR-ToF-MS detection to be kOH = (2.8 ± 0.8) × 10–10 cm3 molecule–1 s–1 at 308 ± 3 K and 1013 ± 3 hPa. The theoretical study includes a conformational mapping of ethylenediamine showing nine conformers to be considered in reaction kinetics modeling, CCSD(T*)-F12a/aug-cc-pVTZ optimized geometries, and results from vibrational anharmonicity calculations for all conformers. The rate coefficients for the OH radical reaction with each of the nine ethylenediamine conformers were obtained in master equation calculations showing the kinetics being governed by both the formation of prereaction adducts and by tight transition states giving a Boltzmann conformer weighted rate coefficient kOH = 2.9 × 10–10 cm3 molecule–1 s–1, and a 1:1 branching between H-abstraction from the NH2 and CH2 groups at 298 K and 1013 hPa. The calculated rate coefficient shows a negative temperature dependence and a negligible variation with pressure under atmospheric conditions. The theoretical kinetics data were aligned to the experimental result, and the rate coefficient in the 200–400 K region can be approximated by a modified Arrhenius expression k(T) = 1.23 × 10–10 × (T/298)0.6 × exp(249 K/T) cm3 molecule–1 s–1.
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Tan, Wen; Zhu, Liang; Mikoviny, Tomas; Nielsen, Claus Jørgen; Wisthaler, Armin & D'Anna, Barbara
[Show all 13 contributors for this article]
(2024).
Experimental and Theoretical Study of the OH-Initiated Degradation of Piperidine under Simulated Atmospheric Conditions.
Journal of Physical Chemistry A.
ISSN 1089-5639.
128(14),
p. 2789–2814.
doi:
10.1021/acs.jpca.3c08415.
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The OH-initiated photo-oxidation of piperidine and the photolysis of 1-nitrosopiperidine were investigated in a large atmospheric simulation chamber and in theoretical calculations based on CCSD(T*)-F12a/aug-cc-pVTZ//M062X/aug-cc-pVTZ quantum chemistry results and master equation modeling of the pivotal reaction steps. The rate coefficient for the reaction of piperidine with OH radicals was determined by the relative rate method to be kOH-piperidine = (1.19 ± 0.27) × 10–10 cm3 molecule–1 s–1 at 304 ± 2 K and 1014 ± 2 hPa. Product studies show the piperidine + OH reaction to proceed via H-abstraction from both CH2 and NH groups, resulting in the formation of the corresponding imine (2,3,4,5-tetrahydropyridine) as the major product and in the nitramine (1-nitropiperidine) and nitrosamine (1-nitrosopiperidine) as minor products. Analysis of 1-nitrosopiperidine photolysis experiments under natural sunlight conditions gave the relative rates jrel = j1-nitrosoperidine/jNO2 = 0.342 ± 0.007, k3/k4a = 0.53 ± 0.05 and k2/k4a = (7.66 ± 0.18) × 10–8 that were subsequently employed in modeling the piperidine photo-oxidation experiments, from which the initial branchings between H-abstraction from the NH and CH2 groups, kN–H/ktot = 0.38 ± 0.08 and kC2–H/ktot = 0.49 ± 0.19, were derived. All photo-oxidation experiments were accompanied by particle formation that was initiated by the acid–base reaction of piperidine with nitric acid. Primary photo-oxidation products including both 1-nitrosopiperidine and 1-nitropiperidine were detected in the particles formed. Quantum chemistry calculations on the OH initiated atmospheric photo-oxidation of piperidine suggest the branching in the initial H-abstraction routes to be ∼35% N1, ∼50% C2, ∼13% C3, and ∼2% C4. The theoretical study produced an atmospheric photo-oxidation mechanism, according to which H-abstraction from the C2 position predominantly leads to 2,3,4,5-tetrahydropyridine and H-abstraction from the C3 position results in ring opening followed by a complex autoxidation, of which the first few steps are mapped in detail. H-abstraction from the C4 position is shown to result mainly in the formation of piperidin-4-one and 2,3,4,5-tetrahydropyridin-4-ol, whereas H-abstraction from N1 under atmospheric conditions primarily leads to 2,3,4,5-tetrahydropyridine and in minor amounts of 1-nitrosopiperidine and 1-nitropiperidine. The calculated rate coefficient for the piperidine + OH reaction agrees with the experimental value within 35%, and aligning the theoretical numbers to the experimental value results in k(T) = 2.46 × 10–12 × exp(486 K/T) cm3 molecule–1 s–1 (200–400 K).
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Yang, Aileen; Andersen, Kamilla Heimar; Hak, Claudia; Mikoviny, Tomas; Wisthaler, Armin & Holøs, Sverre Bjørn
(2023).
Effect of demand-controlled ventilation strategies on indoor air pollutants in a classroom: A Norwegian case study.
Journal of Physics: Conference Series (JPCS).
ISSN 1742-6588.
2654.
doi:
10.1088/1742-6596/2654/1/012087.
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The choice of the minimum ventilation rate (Vmin) in a demand-controlled ventilation strategy can influence energy demand but also introduce outdoor air pollutants. The latter may have direct health effects, as well as affect indoor chemical reactions. In this paper, we evaluate the effect of ventilation rates and operation hours on the level of CO2, nitrogen dioxide (NO2), and ozone (O3) in a classroom during normal use. We compared the baseline ventilation scenario (S0) with a Vmin of 430 m3/h with S1; Vmin of 150 m3/h for normal ventilation operation time (6:30-17:00) and continuous ventilation for 24h (S2). We found that S1 with reduced Vmin would lower the ozone concentration by 35% during the hours before occupancy compared to S0. Moreover, continuous ventilation during night time with a low Vmin resulted in almost as high O3 concentrations as the baseline ventilation scenario. As O3 reacts easily with certain VOCs to produce secondary organic aerosols, the level of Vmin and the ventilation duration would impact the indoor air quality upon entering the classroom.
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Elihn, Karine; Dalmijn, Joost; Froment, Jean Francois; Håland, Alexander; Johansson, Jana H. & Karlsson, Hanna L.
[Show all 16 contributors for this article]
(2023).
Air quality impacts of a large waste fire in Stockholm, Sweden.
Atmospheric Environment.
ISSN 1352-2310.
315.
doi:
10.1016/j.atmosenv.2023.120124.
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Fires in waste facilities are a common occurrence. Since many waste facilities are located adjacent to densely populated areas, these fires could potentially expose large populations to the emitted pollutants. However, at the moment there are only few field studies investigating the impact of waste fire emissions on air quality since the unpredictable nature of these events makes them challenging to capture. This study investigated the impact of a large and persistent un-prescribed fire in a waste storage facility in Stockholm county, Sweden, on the local air quality of two residential areas in close proximity to the fire. In-situ measurements of particulate matter, black carbon and nitrogen oxide concentrations were conducted both during open burning and after the fire was fully covered. In addition, filter samples were collected for offline analysis of organic composition, metal content and toxicity. Strongly increased concentrations of PM10, PM2.5 and black carbon were found during the open burning period, especially when the wind was coming from the direction of the fire. In addition, elevated concentrations of particulate heavy metals and polycyclic aromatic hydrocarbons were observed in the air during the open burning period. These results show that waste fires can have a strong impact on the air quality of nearby residential areas.
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Geetha, Anjitha Sarachandra Kumar; Mikoviny, Tomas; Piel, Felix Maximilian & Wisthaler, Armin
(2023).
Room temperature rate coefficients for the reaction of chlorine atoms with a series of volatile methylsiloxanes (L<inf>2</inf>-L<inf>5</inf>, D<inf>3</inf>-D<inf>6</inf>).
International Journal of Chemical Kinetics.
ISSN 0538-8066.
55(9),
p. 570–576.
doi:
10.1002/kin.21657.
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Abstract The kinetics of chlorine (Cl) atom reactions with a series of volatile methylsiloxanes (VMS) including hexamethyldisiloxane (L2), octamethyltrisiloxane (L3), decamethyltetrasiloxane (L4), dodecamethylpentasiloxane (L5), hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) were investigated in relative rate experiments at room temperature and atmospheric pressure. The experiments were carried out in a 0.2 m 3 PFA Teflon chamber, employing proton‐transfer‐reaction time‐of‐flight mass spectrometry (PTR‐ToF‐MS) as the chemical‐analytical tool. The following relative and absolute reaction rate coefficients were obtained using isoprene as reference compound ( k VMS /k isoprene ; k VMS × 10 10 cm 3 molec −1 s −1 ): L2 (0.32 ± 0.02; 1.31 ± 0.21), L3 (0.38 ± 0.00; 1.56 ± 0.23), L4 (0.48 ± 0.01; 1.98 ± 0.29), L5 (0.54 ± 0.03; 2.22 ± 0.34), D3 (0.14 ± 0.02; 0.56 ± 0.13), D4 (0.26 ± 0.01; 1.05 ± 0.16), D5 (0.36 ± 0.02; 1.46 ± 0.22), D6 (0.39 ± 0.02; 1.61 ± 0.25). The following relative and absolute reaction rate coefficients were obtained using toluene as reference compound ( k VMS /k toluene ; k VMS × 10 10 cm 3 molec −1 s −1 ): L2 (1.59 ± 0.18; 0.95 ± 0.14), L3 (2.25 ± 0.14; 1.35 ± 0.16), L4 (2.38 ± 0.01; 1.43 ± 0.14), L5 (3.57 ± 0.11; 2.14 ± 0.22), D3 (0.87 ± 0.01; 0.52 ± 0.05), D4 (1.48 ± 0.12; 0.89 ± 0.11), D5 (2.02 ± 0.15; 1.21 ± 0.15), D6 (2.54 ± 0.11; 1.52 ± 0.17). Our data confirm that reactions with Cl atoms need to be taken into account when assessing the decomposition of VMS in Cl‐rich tropospheric environments.
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Tomsche, Laura; Piel, Felix Maximilian; Mikoviny, Tomas; Nielsen, Claus Jørgen; Guo, Hongyu & Campuzano-Jost, Pedro
[Show all 17 contributors for this article]
(2023).
Measurement report: Emission factors of NH3 and NHx for wildfires and agricultural fires in the United States.
Atmospheric Chemistry and Physics (ACP).
ISSN 1680-7316.
23(4),
p. 2331–2343.
doi:
10.5194/acp-23-2331-2023.
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Abstract. During the 2019 Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) study, the NASA DC-8 carried out in situ chemical measurements in smoke plumes emitted from wildfires and agricultural fires in the contiguous United States. The DC-8 payload included a modified proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) for the fast measurement of gaseous ammonia (NH3) and a high-resolution time-of-flight aerosol mass spectrometer (AMS) for the fast measurement of submicron particulate ammonium (NH4+). We herein report data collected in smoke plumes emitted from 6 wildfires in the Western United States, 2 prescribed grassland fires in the Central United States, 1 prescribed forest fire in the Southern United States, and 66 small agricultural fires in the Southeastern United States. Smoke plumes contained double to triple digit ppb levels of NH3. In the wildfire plumes, a significant fraction of NH3 had already been converted to NH4+ at the time of sampling (≥2 h after emission). Substantial amounts of NH4+ were also detected in freshly emitted smoke from corn and rice field fires. We herein present a comprehensive set of emission factors of NH3 and NHx, with NHx=NH3+NH4+. Average NH3 and NHx emission factors for wildfires in the Western United States were 1.86±0.75 g kg−1 and 2.47±0.80 g kg−1 of fuel burned, respectively. Average NH3 and NHx emission factors for agricultural fires in the Southeastern United States were 0.89±0.58 and 1.74±0.92 g kg−1, respectively. Our data show no clear inverse correlation between modified combustion efficiency (MCE) and NH3 emissions. The observed NH3 emissions were significantly higher than measured in previous laboratory experiments in the FIREX FireLab 2016 study.
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Håland, Alexander; Mikoviny, Tomas; Syse, Elisabeth Emilie & Wisthaler, Armin
(2022).
On the development of a new prototype PTR-ToF-MS instrument and its application to the detection of atmospheric amines.
Atmospheric Measurement Techniques.
ISSN 1867-1381.
15(21),
p. 6297–6307.
doi:
10.5194/amt-15-6297-2022.
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We herein report on the development of a new prototype PTR-ToF-MS (proton-transfer-reaction time-of-flight mass spectrometry) instrument that combines a hollow cathode glow discharge (HCGD) ion source with a focusing ion–molecule reactor (FIMR), which consists of a resistive glass drift tube surrounded by quadrupole rods. The new instrument configuration hybridizes the two main current commercial PTR-ToF-MS instrument designs. We provide a detailed technical description of the new analyzer and its optimized operational settings for detecting volatile amines via proton transfer reactions from hydronium (H3O+) or ammonium (NH4+) ions. We show that the new prototype PTR-ToF-MS instrument is capable of monitoring rapid changes of sticky amines on the timescale of a few seconds and detects atmospheric variations of amines down to single-digit parts per trillion by volume (pptv) levels. Application examples given include the real-time monitoring of (i) methylamine emitted from a Chenopodium vulvaria L. plant, (ii) small alkylamines in ambient air on site of an agricultural research center (Senter for husdyrforsøk, Ås, Norway), and (iii) an industrial amine (2-amino-2-methylpropan-1-ol, AMP) on site and downwind of a carbon dioxide (CO2) capture test center (Technology Centre Mongstad – TCM, Mongstad, Norway).
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Lee, Young Ro; Huey, L. Gregory; Tanner, David J.; Takeuchi, Masayuki; Qu, Hang & Liu, Xiaoxi
[Show all 34 contributors for this article]
(2022).
An investigation of petrochemical emissions during KORUS-AQ: Ozone production, reactive nitrogen evolution, and aerosol production.
Elementa: Science of the Anthropocene.
10(1).
doi:
10.1525/elementa.2022.00079.
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Emissions and secondary photochemical products from the Daesan petrochemical complex (DPCC), on the west coast of South Korea, were measured from the NASA DC-8 research aircraft during the Korea-United States Air Quality campaign in 2016. The chemical evolution of petrochemical emissions was examined utilizing near-source and downwind plume transects. Small alkenes, such as ethene (C2H4), propene (C3H6), and 1,3-butadiene (C4H6), dominated the hydroxyl (OH) radical reactivity near the source region. The oxidation of these alkenes in the petrochemical plumes led to efficient conversion of nitrogen oxides (NOx) to nitric acid (HNO3), peroxycarboxylic nitric anhydrides (PANs), and alkyl nitrates (ANs), where the sum of the speciated reactive nitrogen contributes more than 80% of NOy within a few hours. Large enhancements of short-lived NOx oxidation products, such as hydroxy nitrates (HNs) and peroxyacrylic nitric anhydride, were observed, in conjunction with high ozone levels of up to 250 ppb, which are attributed to oxidation of alkenes such as 1,3-butadiene. Instantaneous ozone production rates, P(O3), near and downwind of the DPCC ranged from 9 to 24 ppb h−1, which were higher than those over Seoul. Ozone production efficiencies ranged from 6 to 10 downwind of the DPCC and were lower than 10 over Seoul. The contributions of alkenes to the instantaneous secondary organic aerosol (SOA) production rate, P(SOA), were estimated to be comparable to those of more common SOA precursors such as aromatics at intermediate distances from the DPCC. A model case study constrained to an extensive set of observations provided a diagnostic of petrochemical plume chemistry. The simulated plume chemistry reproduced the observed evolution of ozone and short-lived reactive nitrogen compounds, such as PANs and HNs as well as the rate and efficiency of ozone production. The simulated peroxy nitrates (PNs) budget included large contributions (approximately 30%) from unmeasured PNs including peroxyhydroxyacetic nitric anhydride and peroxybenzoic nitric anhydride. The large, predicted levels of these PAN compounds suggest their potential importance in chemical evolution of petrochemical plumes. One unique feature of the DPCC plumes is the substantial contribution of 1,3-butadiene to ozone and potentially SOA production. This work suggests that reductions in small alkene, especially 1,3-butadiene, emissions from the DPCC should be a priority for reducing downwind ozone.
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Bunkan, Arne Joakim Coldevin; Reijrink, Nina Gwendolyn; Mikoviny, Tomas; Müller, Markus; Nielsen, Claus Jørgen & Zhu, Liang
[Show all 7 contributors for this article]
(2022).
Atmospheric Chemistry of N-Methylmethanimine (CH<inf>3</inf>N=CH<inf>2</inf>): A Theoretical and Experimental Study.
Journal of Physical Chemistry A.
ISSN 1089-5639.
126(20),
p. 3247–3264.
doi:
10.1021/acs.jpca.2c01925.
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The OH-initiated photo-oxidation of N-methylmethanimine, CH3N═CH2, was investigated in the 200 m3 EUPHORE atmospheric simulation chamber and in a 240 L stainless steel photochemical reactor employing time-resolved online FTIR and high-resolution PTR-ToF-MS instrumentation and in theoretical calculations based on quantum chemistry results and master equation modeling of the pivotal reaction steps. The quantum chemistry calculations forecast the OH reaction to primarily proceed via H-abstraction from the ═CH2 group and π-system C-addition, whereas H-abstraction from the −CH3 group is a minor route and forecast that N-addition can be disregarded under atmospheric conditions. Theoretical studies of CH3N═CH2 photolysis and the CH3N═CH2 + O3 reaction show that these removal processes are too slow to be important in the troposphere. A detailed mechanism for OH-initiated atmospheric degradation of CH3N═CH2 was obtained as part of the theoretical study. The photo-oxidation experiments, obstructed in part by the CH3N═CH2 monomer–trimer equilibrium, surface reactions, and particle formation, find CH2═NCHO and CH3N═CHOH/CH2═NCH2OH as the major primary products in a ratio 18:82 ± 3 (3σ-limit). Alignment of the theoretical results to the experimental product distribution results in a rate coefficient, showing a minor pressure dependency under tropospheric conditions and that can be parametrized k(T) = 5.70 × 10–14 × (T/298 K)3.18 × exp(1245 K/T) cm3 molecule–1 s–1 with k298 = 3.7 × 10–12 cm3 molecule–1 s–1. The atmospheric fate of CH3N═CH2 is discussed, and it is concluded that, on a global scale, hydrolysis in the atmospheric aqueous phase to give CH3NH2 + CH2O will constitute a dominant loss process. N2O will not be formed in the atmospheric gas phase degradation, and there are no indications of nitrosamines and nitramines formed as primary products.
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Wolfe, Glenn M.; Hanisco, Thomas F.; Arkinson, Heather L.; Blake, Donald R.; Wisthaler, Armin & Mikoviny, Tomas
[Show all 28 contributors for this article]
(2022).
Photochemical evolution of the 2013 California Rim Fire: Synergistic impacts of reactive hydrocarbons and enhanced oxidants.
Atmospheric Chemistry and Physics (ACP).
ISSN 1680-7316.
22(6),
p. 4253–4275.
doi:
10.5194/acp-22-4253-2022.
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Large wildfires influence regional atmospheric composition, but chemical complexity challenges model predictions of downwind impacts. Here, we elucidate key connections within gas-phase photochemistry and assess novel chemical processes via a case study of the 2013 California Rim Fire plume. Airborne in situ observations, acquired during the NASA Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) mission, illustrate the evolution of volatile organic compounds (VOCs), oxidants, and reactive nitrogen over 12 h of atmospheric aging. Measurements show rapid formation of ozone and peroxyacyl nitrates (PNs), sustained peroxide production, and prolonged enhancements in oxygenated VOCs and nitrogen oxides (NOx). Observations and Lagrangian trajectories constrain a 0-D puff model that approximates plume photochemical history and provides a framework for evaluating process interactions. Simulations examine the effects of (1) previously unmeasured reactive VOCs identified in recent laboratory studies and (2) emissions and secondary production of nitrous acid (HONO). Inclusion of estimated unmeasured VOCs leads to a 250 % increase in OH reactivity and a 70 % increase in radical production via oxygenated VOC photolysis. HONO amplifies radical cycling and serves as a downwind NOx source, although impacts depend on how HONO is introduced. The addition of initial HONO (representing primary emissions) or particulate nitrate photolysis amplifies ozone production, while heterogeneous conversion of NO2 suppresses ozone formation. Analysis of radical initiation rates suggests that oxygenated VOC photolysis is a major radical source, exceeding HONO photolysis when averaged over the first 2 h of aging. Ozone production chemistry transitions from VOC sensitive to NOx sensitive within the first hour of plume aging, with both peroxide and organic nitrate formation contributing significantly to radical termination. To simulate smoke plume chemistry accurately, models should simultaneously account for the full reactive VOC pool and all relevant oxidant sources.
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Tan, Wen; Zhu, Liang; Mikoviny, Tomas; Nielsen, Claus Jørgen; Tang, Yizhen & Wisthaler, Armin
[Show all 15 contributors for this article]
(2021).
Atmospheric Chemistry of 2-Amino-2-methyl-1-propanol: A Theoretical and Experimental Study of the OH-Initiated Degradation under Simulated Atmospheric Conditions.
Journal of Physical Chemistry A.
ISSN 1089-5639.
125(34),
p. 7502–7519.
doi:
10.1021/acs.jpca.1c04898.
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The OH-initiated degradation of 2-amino-2-methyl-1-propanol [CH3C(NH2)(CH3)CH2OH, AMP] was investigated in a large atmospheric simulation chamber, employing time-resolved online high-resolution proton-transfer reaction-time-of-flight mass spectrometry (PTR-ToF-MS) and chemical analysis of aerosol online PTR-ToF-MS (CHARON-PTR-ToF-MS) instrumentation, and by theoretical calculations based on M06-2X/aug-cc-pVTZ quantum chemistry results and master equation modeling of the pivotal reaction steps. The quantum chemistry calculations reproduce the experimental rate coefficient of the AMP + OH reaction, aligning k(T) = 5.2 × 10–12 × exp (505/T) cm3 molecule–1 s–1 to the experimental value kexp,300K = 2.8 × 10–11 cm3 molecule–1 s–1. The theoretical calculations predict that the AMP + OH reaction proceeds via hydrogen abstraction from the −CH3 groups (5–10%), −CH2– group, (>70%) and −NH2 group (5–20%), whereas hydrogen abstraction from the −OH group can be disregarded under atmospheric conditions. A detailed mechanism for atmospheric AMP degradation was obtained as part of the theoretical study. The photo-oxidation experiments show 2-amino-2-methylpropanal [CH3C(NH2)(CH3)CHO] as the major gas-phase product and propan-2-imine [(CH3)2C═NH], 2-iminopropanol [(CH3)(CH2OH)C═NH], acetamide [CH3C(O)NH2], formaldehyde (CH2O), and nitramine 2-methyl-2-(nitroamino)-1-propanol [AMPNO2, CH3C(CH3)(NHNO2)CH2OH] as minor primary products; there is no experimental evidence of nitrosamine formation. The branching in the initial H abstraction by OH radicals was derived in analyses of the temporal gas-phase product profiles to be BCH3/BCH2/BNH2 = 6:70:24. Secondary photo-oxidation products and products resulting from particle and surface processing of the primary gas-phase products were also observed and quantified. All the photo-oxidation experiments were accompanied by extensive particle formation that was initiated by the reaction of AMP with nitric acid and that mainly consisted of this salt. Minor amounts of the gas-phase photo-oxidation products, including AMPNO2, were detected in the particles by CHARON-PTR-ToF-MS and GC×GC-NCD. Volatility measurements of laboratory-generated AMP nitrate nanoparticles gave ΔvapH = 80 ± 16 kJ mol–1 and an estimated vapor pressure of (1.3 ± 0.3) × 10–5 Pa at 298 K. The atmospheric chemistry of AMP is evaluated and a validated chemistry model for implementation in dispersion models is presented.
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Pan, Da; Benedict, Katherine B.; Golston, Levi M.; Wang, Rui; Collett, Jeffrey L. & Tao, Lei
[Show all 15 contributors for this article]
(2021).
Ammonia Dry Deposition in an Alpine Ecosystem Traced to Agricultural Emission Hotpots.
Environmental Science and Technology.
ISSN 0013-936X.
55(12),
p. 7776–7785.
doi:
10.1021/acs.est.0c05749.
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Elevated reactive nitrogen (Nr) deposition is a concern for alpine ecosystems, and dry NH3 deposition is a key contributor. Understanding how emission hotspots impact downwind ecosystems through dry NH3 deposition provides opportunities for effective mitigation. However, direct NH3 flux measurements with sufficient temporal resolution to quantify such events are rare. Here, we measured NH3 fluxes at Rocky Mountain National Park (RMNP) during two summers and analyzed transport events from upwind agricultural and urban sources in northeastern Colorado. We deployed open-path NH3 sensors on a mobile laboratory and an eddy covariance tower to measure NH3 concentrations and fluxes. Our spatial sampling illustrated an upslope event that transported NH3 emissions from the hotspot to RMNP. Observed NH3 deposition was significantly higher when backtrajectories passed through only the agricultural region (7.9 ng m–2 s–1) versus only the urban area (1.0 ng m–2 s–1) and both urban and agricultural areas (2.7 ng m–2 s–1). Cumulative NH3 fluxes were calculated using observed, bidirectional modeled, and gap-filled fluxes. More than 40% of the total dry NH3 deposition occurred when air masses were traced back to agricultural source regions. More generally, we identified that 10 (25) more national parks in the U.S. are within 100 (200) km of an NH3 hotspot, and more observations are needed to quantify the impacts of these hotspots on dry NH3 deposition in these regions.
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Fagerlund, Johan; Zevenhoven, Ron; Thomassen, Jørgen; Tednes, Marius; Abdollahi, Farhang & Thomas, Laurent
[Show all 12 contributors for this article]
(2021).
Performance of an amine-based CO2 capture pilot plant at the Fortum Oslo Varme Waste to Energy plant in Oslo, Norway.
International Journal of Greenhouse Gas Control.
ISSN 1750-5836.
106,
p. 1–14.
doi:
10.1016/j.ijggc.2020.103242.
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Fortum Oslo Varme AS (FOV) decided (in July 2018) to build a 1:350 scale pilot plant to demonstrate that the selected Shell’s CANSOLV capture technology using solvent DC-103 is suitable for cleaning CO₂ from the exhaust gases of their waste to energy (WtE) plant at Klemetsrud in Oslo, Norway. This paper presents the most important measurement data and results from a pilot plant testing campaign from March to December 2019. The project stated requirements for the successful completion of the first pilot plant campaign were at least 2000 operational hours and total amine emissions lower than 0.4 ppmv on average over the last 500 h of testing. Emphasis is on the online emission measurement results both with and without an aerosol emissions mitigation system located downstream of the capture unit. The impact of perturbations in the plant operating conditions and inlet gas quality is discussed, in particular the particulates content. The pilot plant campaign achieved its primary purpose of demonstrating low amine emissions. It also produced important data on absorbent degradation in actual operation on WtE flue gas while confirming other performance parameters such as CO2 capture efficiency, steam consumption and CO2 product purity. Thus, it can be concluded that the all requirements according to objectives of the pilot campaign were successfully met.
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Antonsen, Simen Gjelseth; Bunkan, Arne Joakim Coldevin; Mikoviny, Tomas; Nielsen, Claus Jørgen; Stenstrøm, Yngve H. & Wisthaler, Armin
[Show all 7 contributors for this article]
(2020).
Atmospheric Chemistry of Methyl Isocyanide – an Experimental and Theoretical Study.
Journal of Physical Chemistry A.
ISSN 1089-5639.
124(32),
p. 6562–6571.
doi:
10.1021/acs.jpca.0c05127.
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The reaction of CH3NC with OH radicals was studied in smog chamber experiments employing PTR-ToF-MS and long-path FTIR detection. The rate coefficient was determined to be kCH3NC+OH = (7.9 ± 0.6) × 10–11 cm3 molecule–1 s–1 at 298 ± 3 K and 1013 ± 10 hPa; methyl isocyanate was the sole observed product of the reaction. The experimental results are supported by CCSD(T*)-F12a/aug-cc-pVTZ//M06-2X/aug-cc-pVTZ quantum chemistry calculations showing the reaction to proceed primarily via electrophilic addition to the isocyanide carbon atom. On the basis of the quantum chemical data, the kinetics of the OH reaction was simulated using a master equation model revealing the rate coefficient to be nearly independent of pressure at tropospheric conditions and having a negative temperature dependence with kOH = 4.2 × 10–11 cm3 molecule–1 s–1 at 298 K. Additional quantum chemistry calculations on the CH3NC reactions with O3 and NO3 show that these reactions are of little importance under atmospheric conditions. The atmospheric fate of methyl isocyanide is discussed.
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Antonsen, Simen Gjelseth; Bunkan, Arne Joakim Coldevin; Mikoviny, Tomas; Nielsen, Claus Jørgen; Stenstrøm, Yngve H. & Wisthaler, Armin
[Show all 7 contributors for this article]
(2020).
Atmospheric chemistry of diazomethane – an experimental and theoretical study.
Molecular Physics.
ISSN 0026-8976.
p. 1–8.
doi:
10.1080/00268976.2020.1718227.
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The kinetics of the O3, OH and NO3 radical reactions with diazomethane were studied in smog chamber experiments employing long-path FTIR and PTR-ToF-MS detection. The rate coefficients were determined to be k CH2NN+O3 = (3.2 ± 0.4) × 10−17 and k CH2NN+OH = (1.68 ± 0.12) × 10−10 cm3 molecule−1 s−1 at 295 ± 3 K and 1013 ± 30 hPa, whereas the CH2NN + NO3 reaction was too fast to be determined in the static smog chamber experiments. Formaldehyde was the sole product observed in all the reactions. The experimental results are supported by CCSD(T*)-F12a/aug-cc-pVTZ//M062X/aug-cc-pVTZ calculations showing the reactions to proceed exclusively via addition to the carbon atom. The atmospheric fate of diazomethane is discussed.
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Tan, Wen; Zhu, Liang; Mikoviny, Tomas; Nielsen, Claus Jørgen; Wisthaler, Armin & D´Anna, Barbara
[Show all 14 contributors for this article]
(2020).
Experimental and Theoretical Study of the OH-Initiated Degradation of Piperazine under Simulated Atmospheric Conditions.
Journal of Physical Chemistry A.
ISSN 1089-5639.
doi:
10.1021/acs.jpca.0c10223.
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The OH-initiated photo-oxidation of piperazine and 1-nitropiperazine as well as the photolysis of 1-nitrosopiperazine were investigated in a large atmospheric simulation chamber. The rate coefficient for the reaction of piperazine with OH radicals was determined by the relative rate method to be kOH-piperazine = (2.8 ± 0.6) × 10–10 cm3 molecule–1 s–1 at 307 ± 2 K and 1014 ± 2 hPa. Product studies showed the piperazine + OH reaction to proceed both via C–H and N–H abstraction, resulting in the formation of 1,2,3,6-tetrahydropyrazine as the major product and in 1-nitropiperazine and 1-nitrosopiperazine as minor products. The branching in the piperazinyl radical reactions with NO, NO2, and O2 was obtained from 1-nitrosopiperazine photolysis experiments and employed analyses of the 1-nitropiperazine and 1-nitrosopiperazine temporal profiles observed during piperazine photo-oxidation. The derived initial branching between N–H and C–H abstraction by OH radicals, kN–H/(kN–H + kC–H), was 0.18 ± 0.04. All experiments were accompanied by substantial aerosol formation that was initiated by the reaction of piperazine with nitric acid. Both primary and secondary photo-oxidation products including 1-nitropiperazine and 1,4-dinitropiperazine were detected in the aerosol particles formed. Corroborating atmospheric photo-oxidation schemes for piperazine and 1-nitropiperazine were derived from M06-2X/aug-cc-pVTZ quantum chemistry calculations and master equation modeling of the pivotal reaction steps. The atmospheric chemistry of piperazine is evaluated, and a validated chemical mechanism for implementation in dispersion models is presented.
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Schroeder, Jason R.; Crawford, James H.; Ahn, Joon-Young; Chang, Limseok; Fried, Alan & Walega, James
[Show all 25 contributors for this article]
(2020).
Observation-based modeling of ozone chemistry in the Seoul metropolitan area during the Korea-United States Air Quality Study (KORUS-AQ).
Elementa: Science of the Anthropocene.
8(1).
doi:
10.1525/elementa.400.
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The Seoul Metropolitan Area (SMA) has a population of 24 million and frequently experiences unhealthy levels of ozone (O3). In this work, measurements taken during the Korea-United States Air Quality Study (KORUS-AQ, 2016) are used to explore regional gradients in O3 and its chemical precursors, and an observationally-constrained 0-D photochemical box model is used to quantify key aspects of O3 production including its sensitivity to precursor gases. Box model performance was evaluated by comparing modeled concentrations of select secondary species to airborne measurements. These comparisons indicate that the steady state assumption used in 0-D box models cannot describe select intermediate species, highlighting the importance of having a broad suite of trace gases as model constraints. When fully constrained, aggregated statistics of modeled O3 production rates agreed with observed changes in O3, indicating that the box model was able to represent the majority of O3 chemistry. Comparison of airborne observations between urban Seoul and a downwind receptor site reveal a positive gradient in O3 coinciding with a negative gradient in NOx, no gradient in CH2O, and a slight positive gradient in modeled rates of O3 production. Together, these observations indicate a radical-limited (VOC-limited) O3 production environment in the SMA. Zero-out simulations identified C7+ aromatics as the dominant VOC contributors to O3 production, with isoprene and anthropogenic alkenes making smaller but appreciable contributions. Simulations of model sensitivity to decreases in NOx produced results that were not spatially uniform, with large increases in O3 production predicted for urban Seoul and decreases in O3 production predicted for far-outlying areas. The policy implications of this work are clear: Effective O3 mitigation strategies in the SMA must focus on reducing local emissions of C7+ aromatics, while reductions in NOx emissions may increase O3 in some areas but generally decrease the regional extent of O3 exposure.
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Fried, Alan; Walega, James; Weibring, Petter; Richter, Dirk; Simpson, Isobel J. & Blake, Donald R.
[Show all 35 contributors for this article]
(2020).
Airborne formaldehyde and volatile organic compound measurements over the Daesan petrochemical complex on Korea’s northwest coast during the Korea-United States Air Quality study: Estimation of emission fluxes and effects on air quality.
Elementa: Science of the Anthropocene.
8:121(1),
p. 1–28.
doi:
10.1525/elementa.2020.121.
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Chen, Xin; Millet, Dylan B.; Singh, Hanwant B.; Wisthaler, Armin; Apel, Eric C. & Atlas, Elliot L.
[Show all 34 contributors for this article]
(2019).
On the sources and sinks of atmospheric VOCs: an integratedanalysis of recent aircraft campaigns over North America.
Atmospheric Chemistry and Physics (ACP).
ISSN 1680-7316.
19(14),
p. 9097–9123.
doi:
10.5194/acp-19-9097-2019.
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We apply a high-resolution chemical transport model (GEOS-Chem CTM) with updated treatment of volatile organic compounds (VOCs) and a comprehensive suite of airborne datasets over North America to (i) characterize the VOC budget and (ii) test the ability of current models to capture the distribution and reactivity of atmospheric VOCs over this region. Biogenic emissions dominate the North American VOC budget in the model, accounting for 70 % and 95 % of annually emitted VOC carbon and reactivity, respectively. Based on current inventories anthropogenic emissions have declined to the point where biogenic emissions are the dominant summertime source of VOC reactivity even in most major North American cities. Methane oxidation is a 2× larger source of nonmethane VOCs (via production of formaldehyde and methyl hydroperoxide) over North America in the model than are anthropogenic emissions. However, anthropogenic VOCs account for over half of the ambient VOC loading over the majority of the region owing to their longer aggregate lifetime. Fires can be a significant VOC source episodically but are small on average. In the planetary boundary layer (PBL), the model exhibits skill in capturing observed variability in total VOC abundance (R2=0.36) and reactivity (R2=0.54). The same is not true in the free troposphere (FT), where skill is low and there is a persistent low model bias (∼ 60 %), with most (27 of 34) model VOCs underestimated by more than a factor of 2. A comparison of PBL : FT concentration ratios over the southeastern US points to a misrepresentation of PBL ventilation as a contributor to these model FT biases. We also find that a relatively small number of VOCs (acetone, methanol, ethane, acetaldehyde, formaldehyde, isoprene + oxidation products, methyl hydroperoxide) drive a large fraction of total ambient VOC reactivity and associated model biases; research to improve understanding of their budgets is thus warranted. A source tracer analysis suggests a current overestimate of biogenic sources for hydroxyacetone, methyl ethyl ketone and glyoxal, an underestimate of biogenic formic acid sources, and an underestimate of peroxyacetic acid production across biogenic and anthropogenic precursors. Future work to improve model representations of vertical transport and to address the VOC biases discussed are needed to advance predictions of ozone and SOA formation.
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Piel, Felix; Muller, Markus; Mikoviny, Tomas; Pusede, Sally E. & Wisthaler, Armin
(2019).
Airborne measurements of particulate organic matter by proton-transfer-reaction mass spectrometry (PTR-MS): a pilot study.
Atmospheric Measurement Techniques.
ISSN 1867-1381.
12(11),
p. 5947–5958.
doi:
10.5194/amt-12-5947-2019.
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Herein we report on the first successful airborne deployment of the CHemical Analysis of AeRosol ONline (CHARON) particle inlet which allowed us to measure the chemical composition of atmospheric submicrometer particles in real time using a state-of-the-art proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS) analyzer. The data were collected aboard the NASA DC-8 Airborne Science Laboratory on 26 June 2018 over California in the frame of NASA's Student Airborne Research Program (SARP). We show exemplary data collected when the airplane (i) shortly encountered a fresh (<1 h old) smoke plume that had emanated from the Lions Fire in the Sierra Nevada, (ii) intercepted a particle plume emitted from an amine gas treating unit of a petroleum refinery close to Bakersfield, (iii) carried out a spatial survey in the boundary layer over the San Joaquin Valley and (iv) performed a vertical profile measurement over the greater Bakersfield area. The most important finding from this pilot study is that the CHARON PTR-ToF-MS system measures fast enough to be deployed on a jet research aircraft. The data collected during 3 to 15 s long plume encounters demonstrate the feasibility of airborne point or small area emission measurements. Further improvements are, however, warranted to eliminate or reduce the observed signal tailing (1/e decay time between 6 and 20 s). The fast time response of the analyzer allowed us to generate highly spatially resolved maps (1–2 km in the horizontal, 100 m in the vertical) of atmospheric particle chemical constituents. The chemical information that was extracted from the recorded particle mass spectra includes (i) mass concentrations of ammonium, nitrate and total organics; (ii) mass concentrations of different classes of organic compounds (CH vs. CHO vs. CHN vs. CHNO compounds; monoaromatic vs. polyaromatic compounds); (iii) aerosol bulk average O:C¯¯¯¯¯¯¯¯ and H:C¯¯¯¯¯¯¯¯ ratios; (iv) mass concentrations of selected marker molecules (e.g., levoglucosan in particles emitted from a wildfire, an alkanolamine in particles emitted from a petroleum refinery) and (v) wildfire emission ratios (Δtotal organics/ΔCO = 0.054; Δlevoglucosan/ΔCO = 7.9×10−3; Δvanillic acid/ΔCO = 4.4×10−4 and Δretene/ΔCO = 1.9×10−4; all calculated as peak area ratios, in grams per gram). The capability of the CHARON PTR-ToF-MS instrument to chemically characterize submicrometer atmospheric particles in a quantitative manner, at the near-molecular level, and in real time brings a new and unprecedented measurement capability to the airborne atmospheric science community.
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Zhu, Liang; Mikoviny, Tomas; Morken, Anne Kolstad; Tan, Wen & Wisthaler, Armin
(2018).
A compact and easy-to-use mass spectrometer for online monitoring of amines in the flue gas of a post-combustion carbon capture plant.
International Journal of Greenhouse Gas Control.
ISSN 1750-5836.
78,
p. 349–353.
doi:
10.1016/j.ijggc.2018.09.003.
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Liu, Xiaoxi; Huey, L. Gregory; Yokelson, Robert J.; Selimovic, Vanessa; Simpson, Isobel J. & Müller, Markus
[Show all 38 contributors for this article]
(2017).
Airborne measurements of western U.S. wildfire emissions: Comparison with prescribed burning and air quality implications.
Journal of Geophysical Research (JGR): Atmospheres.
ISSN 2169-897X.
122(11),
p. 6108–6129.
doi:
10.1002/2016JD026315.
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Wildfires emit significant amounts of pollutants that degrade air quality. Plumes from three wildfires in the western U.S. were measured from aircraft during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) and the Biomass Burning Observation Project (BBOP), both in summer 2013. This study reports an extensive set of emission factors (EFs) for over 80 gases and 5 components of submicron particulate matter (PM1) from these temperate wildfires. These include rarely, or never before, measured oxygenated volatile organic compounds and multifunctional organic nitrates. The observed EFs are compared with previous measurements of temperate wildfires, boreal forest fires, and temperate prescribed fires. The wildfires emitted high amounts of PM1 (with organic aerosol (OA) dominating the mass) with an average EF that is more than 2 times the EFs for prescribed fires. The measured EFs were used to estimate the annual wildfire emissions of carbon monoxide, nitrogen oxides, total nonmethane organic compounds, and PM1 from 11 western U.S. states. The estimated gas emissions are generally comparable with the 2011 National Emissions Inventory (NEI). However, our PM1 emission estimate (1530 ± 570 Gg yr−1) is over 3 times that of the NEI PM2.5 estimate and is also higher than the PM2.5 emitted from all other sources in these states in the NEI. This study indicates that the source of OA from biomass burning in the western states is significantly underestimated. In addition, our results indicate that prescribed burning may be an effective method to reduce fine particle emissions. ©2017. American Geophysical Union. All Rights Reserved.
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Lakey, PSJ; Wisthaler, Armin; Berkemeier, T; Mikoviny, Tomas; Poschl, U & Shiraiwa, M.
(2017).
Chemical kinetics of multiphase reactions between ozone and human skin lipids: Implications for indoor air quality and health effects.
Indoor Air.
ISSN 0905-6947.
27(4),
p. 816–828.
doi:
10.1111/ina.12360.
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Perring, Anne E.; Schwarz, Joshua P.; Markovic, Milos Z.; Fahey, David W.; Jimenez, José L. & Campuzano-Jost, Pedro
[Show all 18 contributors for this article]
(2017).
In situ measurements of water uptake by black carbon-containing aerosol in wildfire plumes.
Journal of Geophysical Research (JGR): Atmospheres.
ISSN 2169-897X.
122(2),
p. 1086–1097.
doi:
10.1002/2016JD025688.
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Water uptake by black carbon (BC)-containing aerosol was quantified in North American wildfire plumes of varying age (1 to ~40 h old) sampled during the SEAC4RS mission (2013). A Humidified Dual SP2 (HD-SP2) is used to optically size BC-containing particles under dry and humid conditions from which we extract the hygroscopicity parameter, κ, of materials internally mixed with BC. Instrumental variability and the uncertainty of the technique are briefly discussed. An ensemble average κ of 0.04 is found for the set of plumes sampled, consistent with previous estimates of bulk aerosol hygroscopicity from biomass burning sources. The temporal evolution of κ in the Yosemite Rim Fire plume is explored to constrain the rate of conversion of BC-containing aerosol from hydrophobic to more hydrophilic modes in these emissions. A BC-specific κ increase of ~0.06 over 40 h is found, fit well with an exponential curve corresponding to a transition from a κ of 0 to a κ of ~0.09 with an e-folding time of 29 h. Although only a few percent of wildfire particles contain BC, a similar κ increase is estimated for bulk aerosol and the measured aerosol composition is used to infer that the observed κ change is driven by a combination of incorporation of ammonium sulfate and oxidation of existing organic materials. Finally, a substantial fraction of wildfire-generated BC-containing aerosol is calculated to be active as cloud condensation nuclei shortly after emission likely indicating efficient wet removal. These results can constrain model treatment of BC from wildfire sources. ©2016. American Geophysical Union. All Rights Reserved.
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Mikoviny, Tomas; Nielsen, Claus Jørgen; Tan, Wen; Wisthaler, Armin; Zhu, Liang & Morken, Anne Kolstad
[Show all 7 contributors for this article]
(2017).
Ambient Measurements of Amines by PTR-QiTOF: Instrument Performance Assessment and Results from Field Measurements in the Vicinity of TCM, Mongstad.
Energy Procedia.
114,
p. 1017–1021.
doi:
10.1016/j.egypro.2017.03.1246.
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A PTR-QiTOF instrument was deployed in the field in the vicinity of the CO2 Technology Center Mongstad (TCM) for measuring amines in ambient air. The observed single-to-double-digit pptv levels of dimethylamine (DMA) and trimethylamine (TMA) are comparable to natural background values reported in the literature for these species. No indication was found that these small alkylamines stem from industrial activities at Mongstad. Monoethanolamine (MEA) was observed at single-digit pptv levels, but further analytical work is needed to validate measurements at such low concentrations. No indication was found that small enhancements in ambient MEA levels were caused by emissions from TCM. No other industrial amines (2-amino-2-methylpropanol, diethylamine and piperazine) were detected in ambient air. According to the current state of knowledge, the observed levels of amines pose no harm to human health or the environment.
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Schroeder, Jason R.; Crawford, James H.; Fried, Alan; Walega, James; Weinheimer, Andrew & Wisthaler, Armin
[Show all 12 contributors for this article]
(2017).
New insights into the column CH2O/NO2 ratio as an indicator of near-surface ozone sensitivity.
Journal of Geophysical Research (JGR): Biogeosciences.
ISSN 2169-8953.
122(16),
p. 8885–8907.
doi:
10.1002/2017JD026781.
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Satellite-based measurements of the column CH2O/NO2 ratio have previously been used to estimate near-surface ozone (O3) sensitivity (i.e., NOx or VOC limited), and the forthcoming launch of air quality-focused geostationary satellites provides a catalyst for reevaluating the ability of satellite-measured CH2O/NO2 to be used in this manner. In this study, we use a 0-D photochemical box model to evaluate O3 sensitivity and find that the relative rate of radical termination from radical-radical interactions to radical-NOx interactions (referred to as LROx/LNOx) provides a good indicator of maximum O3 production along NOx ridgelines. Using airborne measurements from NASA's Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relative to Air Quality (DISCOVER-AQ) deployments in Colorado, Maryland, and Houston, we show that in situ measurements of CH2O/NO2 can be used to indicate O3 sensitivity, but there is an important “transition/ambiguous” range whereby CH2O/NO2 fails to categorize O3 sensitivity, and the range and span of this transition/ambiguous range varies regionally. Then, we apply these findings to aircraft-derived column density measurements from DISCOVER-AQ and find that inhomogeneities in vertical mixing in the lower troposphere further degrades the ability of column CH2O/NO2 to indicate near-surface O3 sensitivity (i.e., the transition/ambiguous range is much larger than indicated by in situ data alone), and we hypothesize that the global transition/ambiguous range is sufficiently large to make the column CH2O/NO2 ratio unuseful for classifying near-surface O3 sensitivity. Lastly, we present a case study from DISCOVER-AQ-Houston that suggests that O3 sensitivity on exceedance days may be substantially different than on nonexceedance days (which may be observable from space) and explore the diurnal evolution of O3 sensitivity, O3 production, and the column CH2O/NO2 ratio. The results of these studies suggest that although satellite measurements of CH2O/NO2 alone may not be sufficient for accurately classifying near-surface O3 sensitivity, new techniques offered by geostationary platforms may nonetheless provide methods for using space-based measurements to develop O3 mitigation strategies. ©2017. American Geophysical Union. All Rights Reserved.
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Zhu, Liang; Mikoviny, Tomas; Wisthaler, Armin & Nielsen, Claus Jørgen
(2017).
A Sampling Line Artifact in Stack Emission Measurement of Alkanolamine-enabled Carbon Capture Facility: Surface Reaction of Amines with Formaldehyde.
Energy Procedia.
114,
p. 1022–1025.
doi:
10.1016/j.egypro.2017.03.1247.
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Laboratory experiments were carried out to study Schiff-base condensation reactions between amines and formaldehyde that occur on inlet lines of emission monitoring instruments. Primary amines and formaldehyde were found to quickly react on inlet surfaces to form the respective Schiff-base condensation products. Secondary and tertiary amines did not react with formaldehyde. Schiff-base condensation reactions between primary amines and formaldehyde were also observed to occur on the ∼110 m long inlet line that connects the absorber stack of the amine-based PCCC facility at Mongstad to the FT-IR and PTR-ToF-MS emission monitors. Emissions of primary amines and formaldehyde may be underestimated if condensation reactions of these species in inlet lines are not taken into account. The PTR-ToF-MS monitor does, however, also quantitatively detect the Schiff-base condensation products, making it straightforward to derive the correct amine and formaldehyde concentrations in the amine wash gas.
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Antonsen, Simen Gjelseth; Bunkan, Arne Joakim Coldevin; D'Anna, Barbara; Eichler, Philipp; Farren, Naomi J. & Hallquist, Mattias
[Show all 15 contributors for this article]
(2017).
Atmospheric Chemistry of tert-butylamine and AMP.
Energy Procedia.
114,
p. 1026–1032.
doi:
10.1016/j.egypro.2017.03.1248.
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The atmospheric chemistry of (CH3)3CNH2 (tert-butylamine, tBA) and (CH3)2(CH2OH)CNH2 (2-amino-2-methyl-1-propanol, AMP) has been studied by quantum chemistry methods and in photo-oxidation experiments in the EUPHORE chamber in Valencia (Spain). Aerosol formation and composition has been quantified. Yields of nitramines and other products in the photo-oxidations have been determined and complete photo-oxidation schemes including branching between the major reaction routes have been obtained.
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Fisher, Jenny A.; Jacob, Daniel J.; Travis, Katherine R.; Kim, Patrick S.; Marais, Eloise A. & Miller, Christopher Chan
[Show all 34 contributors for this article]
(2016).
Organic nitrate chemistry and its implications for nitrogen budgets in an isoprene- and monoterpene-rich atmosphere: Constraints from aircraft (SEAC4RS) and ground-based (SOAS) observations in the Southeast US.
Atmospheric Chemistry and Physics (ACP).
ISSN 1680-7316.
16(9),
p. 5969–5991.
doi:
10.5194/acp-16-5969-2016.
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Bunkan, Arne Joakim Coldevin; Mikoviny, Tomas; Nielsen, Claus Jørgen; Wisthaler, Armin & Zhu, Liang
(2016).
Experimental and Theoretical Study of the OH-Initiated Photo-oxidation of Formamide.
Journal of Physical Chemistry A.
ISSN 1089-5639.
120(8),
p. 1222–1230.
doi:
10.1021/acs.jpca.6b00032.
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Liu, Xiaoxi; Zhang, Yangmei; Huey, Lewis Gregory; Yokelson, Robert J.; Wang, Yuesi & Jiménez, José Luis
[Show all 36 contributors for this article]
(2016).
Agricultural fires in the southeastern U.S. during SEAC4RS: Emissions of trace gases and particles and evolution of ozone, reactive nitrogen, and organic aerosol.
Journal of Geophysical Research (JGR): Atmospheres.
ISSN 2169-897X.
121(12),
p. 7383–7414.
doi:
10.1002/2016JD025040.
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Fried, Alan R.; Barth, Mary C.; Bela, Megan M.; Weibring, Petter K.A.; Richter, Dirk A. & Walega, James G.
[Show all 33 contributors for this article]
(2016).
Convective transport of formaldehyde to the upper troposphere and lower stratosphere and associated scavenging in thunderstorms over the central United States during the 2012 DC3 study.
Journal of Geophysical Research (JGR): Biogeosciences.
ISSN 2169-8953.
121(12),
p. 7430–7460.
doi:
10.1002/2015JD024477.
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Bunkan, Arne Joakim Coldevin; Hetzler, Jens; Mikoviny, Tomas; Wisthaler, Armin; Nielsen, Claus Jørgen & Olzmann, Matthias
(2015).
The reactions of N-methylformamide and N,N-dimethylformamide with OH and their photo-oxidation under atmospheric conditions: experimental and theoretical studies.
Physical Chemistry, Chemical Physics - PCCP.
ISSN 1463-9076.
17(10),
p. 7046–7059.
doi:
10.1039/C4CP05805D.
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The reactions of OH radicals with CH3NHCHO (N-methylformamide, MF) and (CH3)2NCHO (N,N-dimethylformamide, DMF) have been studied by experimental and computational methods. Rate coefficients were determined as a function of temperature (T = 260–295 K) and pressure (P = 30–600 mbar) by the flash photolysis/laser-induced fluorescence technique. OH radicals were produced by laser flash photolysis of 2,4-pentanedione or tert-butyl hydroperoxide under pseudo-first order conditions in an excess of the corresponding amide. The rate coefficients obtained show negative temperature dependences that can be parameterized as follows: kOH+MF = (1.3 ± 0.4) × 10−12 exp(3.7 kJ mol−1/(RT)) cm3 s−1 and kOH+DMF = (5.5 ± 1.7) × 10−13 exp(6.6 kJ mol−1/(RT)) cm3 s−1. The rate coefficient kOH+MF shows very weak positive pressure dependence whereas kOH+DMF was found to be independent of pressure. The Arrhenius equations given, within their uncertainty, are valid for the entire pressure range of our experiments. Furthermore, MF and DMF smog-chamber photo-oxidation experiments were monitored by proton-transfer-reaction time-of-flight mass spectrometry. Atmospheric MF photo-oxidation results in 65% CH3NCO (methylisocyanate), 16% (CHO)2NH, and NOx-dependent amounts of CH2[double bond, length as m-dash]NH and CH3NHNO2 as primary products, while DMF photo-oxidation results in around 35% CH3N(CHO)2 as primary product and 65% meta-stable (CH3)2NC(O)OONO2 degrading to NOx-dependent amounts of CH3N[double bond, length as m-dash]CH2 (N-methylmethanimine), (CH3)2NNO (N-nitroso dimethylamine) and (CH3)2NNO2 (N-nitro dimethylamine). The potential for nitramine formation in MF photo-oxidation is comparable to that of methylamine whereas the potential to form nitrosamine and nitramine in DMF photo-oxidation is larger than for dimethylamine. Quantum chemistry supported atmospheric degradation mechanisms for MF and DMF are presented. Rate coefficients and initial branching ratios calculated with statistical rate theory based on molecular data from quantum chemical calculations at the CCSD(T*)-F12a/aug-cc-pVTZ//MP2/aug-cc-pVTZ level of theory show satisfactory agreement with the experimental results. It turned out that adjustment of calculated threshold energies by 0.2 to 8.8 kJ mol−1 lead to agreement between experimental and predicted results.
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Müller, Markus; Mikoviny, Tomas & Wisthaler, Armin
(2014).
Detector aging induced mass discrimination and non-linearity effects in PTR-ToF-MS.
International Journal of Mass Spectrometry.
ISSN 1387-3806.
365-366,
p. 93–97.
doi:
10.1016/j.ijms.2013.12.008.
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Maguta, Mihayo Musabila; Aursnes, Marius; Bunkan, Arne Joakim Coldevin; Edelen, Katie; Mikoviny, Tomas & Nielsen, Claus Jørgen
[Show all 9 contributors for this article]
(2014).
Atmospheric fate of nitramines: An experimental and theoretical study of the OH reactions with CH<sub>3</sub>NHNO<sub>2</sub> and (CH<sub>3</sub>) <sub>2</sub>NNO<sub>2</sub>.
Journal of Physical Chemistry A.
ISSN 1089-5639.
118(19),
p. 3450–3462.
doi:
10.1021/jp500305w.
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Weber, Ulrich Wolfgang; Kampman, Niko; Mikoviny, Tomas; Thomassen, Jorgen & Sundal, Anja
(2021).
Noble Gases as Monitoring Tracers in CCS: A Case study with CO2 from the Waste-To-Energy Plant Klemetsrud, Norway.
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Published
Feb. 17, 2015 8:11 AM
- Last modified
Feb. 17, 2015 8:12 AM
