Formaldehyde (HCHO) in air, snow, and interstitial air at Concordia (East Antarctic Plateau) in summer

Abstract. During the 2011/12 and 2012/13 austral summers, HCHO was investigated for the first time in ambient air, snow, and interstitial air at the Concordia site, located near Dome C on the East Antarctic Plateau, by deploying an Aerolaser AL-4021 analyzer. Snow emission fluxes were estimated from vertical gradients of mixing ratios observed at 1 cm and 1 m above the snow surface as well as in interstitial air a few centimeters below the surface and in air just above the snowpack. Typical flux values range between 1 and 2 × 1012 molecules m−2 s−1 at night and 3 and 5 × 1012 molecules m−2 s−1 at noon. Shading experiments suggest that the photochemical HCHO production in the snowpack at Concordia remains negligible compared to temperature-driven air–snow exchanges. At 1 m above the snow surface, the observed mean mixing ratio of 130 pptv and its diurnal cycle characterized by a slight decrease around noon are quite well reproduced by 1-D simulations that include snow emissions and gas-phase methane oxidation chemistry. Simulations indicate that the gas-phase production from CH4 oxidation largely contributes (66%) to the observed HCHO mixing ratios. In addition, HCHO snow emissions account for ~ 30% at night and ~ 10% at noon to the observed HCHO levels.

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Formaldehyde (HCHO) in air, snow and interstitial air at Concordia (East Antarctic plateau) in summer

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-14-32027-2014 ◽

2014 ◽

Vol 14 (23) ◽

pp. 32027-32070 ◽

Cited By ~ 4

Author(s):

S. Preunkert ◽

M. Legrand ◽

M. Frey ◽

A. Kukui ◽

J. Savarino ◽

...

Keyword(s):

Gas Phase ◽

Ambient Air ◽

Snow Surface ◽

Snow Pack ◽

Antarctic Plateau ◽

Mixing Ratios ◽

Emission Fluxes ◽

Oxidation Chemistry ◽

First Time ◽

Interstitial Air

Abstract. During the 2011/12 and 2012/13 austral summers HCHO was investigated for the first time in ambient air, snow, and interstitial air at the Concordia site located near Dome C on the East Antarctic plateau by deploying an Aerolaser AL-4021 analyser. Snow emission fluxes were estimated from vertical gradients of mixing ratios observed between 1 cm and 1 m above the snow surface as well as between interstitial air a few cm below the surface and in air just above the snow-pack. Typical flux values range between 1 to 2 × 1012 molecules m−2 s−1 at night and 3 to 5 × 1012 molecules m−2 s−1 at noon. Shading experiments suggest that the photochemical HCHO production in the snowpack at Concordia remains negligible compared to temperature-driven air–snow exchanges. At 1 m above the snow surface, the observed mean mixing ratio of 130 pptv and its diurnal cycle characterized by a slight decrease around noon are quite well reproduced by 1-D simulations that include snow emissions and gas phase methane oxidation chemistry.

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Kinetic and mechanistic study of the reaction between methane sulphonamide (CH3S(O)2NH2) and OH

10.5194/acp-2019-1030 ◽

2019 ◽

Author(s):

Matias Berasategui ◽

Damien Amedro ◽

Achim Edtbauer ◽

Jonathan Williams ◽

Jos Lelieveld ◽

...

Keyword(s):

Rate Coefficient ◽

Relative Rate ◽

Hydrogen Abstraction ◽

Initial Step ◽

Ambient Air ◽

Mechanistic Study ◽

Photo Oxidation ◽

Mixing Ratios ◽

In Situ Detection ◽

First Time

Abstract. Methane sulphonamide (MSAM), CH3S(O)2NH2, has recently been detected for the first time in ambient air over the Red Sea and the Gulf of Aden where peak mixing ratios of ~ 60 pptv were recorded. Prior to this study the rate constant for its reaction with the OH radical and the products thereby formed were unknown, precluding assessment of its role in the atmosphere. We studied the OH-initiated photo-oxidation of MSAM in air (298 K, 700 Torr total pressure) in a photochemical reactor using in situ detection of MSAM and its products by FTIR absorption spectroscopy. The relative rate technique, using three different reference compounds, was used to derive a rate coefficient of (1.4 ± 0.3) ×10−13 cm3 molecule−1 s−1. The main end products of the photo-oxidation observed by FTIR were CO2, CO, SO2 and HNO3 with molar yields of (0.73 ± 0.11), (0.28 ± 0.04), (0.96 ± 0.15) and (0.62 ± 0.09), respectively. N2O and HC(O)OH were also observed in smaller yields (0.09 ± 0.02), (0.03 ± 0.01). Both the low rate coefficient and the products formed are consistent with hydrogen abstraction from the -CH3 group as the dominant initial step. Based on our results MSAM has an atmospheric lifetime with respect to loss by reaction with OH of about 80 days.

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Measurements of HONO during BAQS-Met

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-12285-2010 ◽

2010 ◽

Vol 10 (24) ◽

pp. 12285-12293 ◽

Cited By ~ 16

Author(s):

J. J. B. Wentzell ◽

C. L. Schiller ◽

G. W. Harris

Keyword(s):

Gas Phase ◽

Water Vapour ◽

Nitrous Acid ◽

Meteorological Parameters ◽

Border Region ◽

Night Time ◽

Mixing Ratios ◽

Oxidation Chemistry ◽

Absorption Photometer ◽

Shed Light

Abstract. Measurements of nitrous acid (HONO) were performed as part of the 2007 Border Air Quality and Meteorology Study (BAQS-Met) at the Harrow, Ontario, Canada supersite between 20 June and 10 July 2007. Nitrous acid is an important precursor of the hydroxyl radical and understanding its chemistry is important to understanding daytime oxidation chemistry. The HONO measurements were made using a custom built Long Path Absorption Photometer (LOPAP). The goal of this work was to shed light on sources of daytime HONO in the border region. During the course of the campaign HONO mixing ratios consistently exceeded expected daytime values by more than a factor of 6. Mean daytime mixing ratios of 61 pptv were observed. While HONO decay began at sunrise, minimum HONO values were measured during the late afternoon. There was little difference between the daytime (mean = 1.5%) and night-time (mean = 1.7%) ratios of HONO/NO2, thus there was a very strong daytime source of HONO which is consistent with other recent studies. Correlations of daytime HONO production with a variety of chemical and meteorological parameters indicate that production is dependent on UV radiation, NO2 and water vapour but is not consistent with a simple gas phase process. Apparent rate constants for the production of HONO from photolyticaly excited NO2 and water vapour vary from 2.8–7.8×10−13 cm3 molec−1 s−1, during the campaign. These results appear to be consistent with the heterogeneous conversion of NO2 enhanced by photo-excitation.

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Kinetic and mechanistic study of the reaction between methane sulfonamide (CH3S(O)2NH2) and OH

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-2695-2020 ◽

2020 ◽

Vol 20 (5) ◽

pp. 2695-2707 ◽

Cited By ~ 2

Author(s):

Matias Berasategui ◽

Damien Amedro ◽

Achim Edtbauer ◽

Jonathan Williams ◽

Jos Lelieveld ◽

...

Keyword(s):

Rate Coefficient ◽

Relative Rate ◽

Hydrogen Abstraction ◽

Initial Step ◽

Ambient Air ◽

Mechanistic Study ◽

Photo Oxidation ◽

Mixing Ratios ◽

In Situ Detection ◽

First Time

Abstract. Methane sulfonamide (MSAM), CH3S(O)2NH2, was recently detected for the first time in ambient air over the Red Sea and the Gulf of Aden where peak mixing ratios of ≈60 pptv were recorded. Prior to this study the rate constant for its reaction with the OH radical and the products thereby formed were unknown, precluding assessment of its role in the atmosphere. We have studied the OH-initiated photo-oxidation of MSAM in air (298 K, 700 Torr total pressure) in a photochemical reactor using in situ detection of MSAM and its products by Fourier transform infrared (FTIR) absorption spectroscopy. The relative rate technique, using three different reference compounds, was used to derive a rate coefficient of (1.4±0.3)×10-13cm3molec.-1s-1. The main end products of the photo-oxidation observed by FTIR were CO2, CO, SO2, and HNO3 with molar yields of (0.73±0.11), (0.28±0.04), (0.96±0.15), and (0.62±0.09), respectively. N2O and HC(O)OH were also observed in smaller yields of (0.09±0.02) and (0.03±0.01). Both the low rate coefficient and the products formed are consistent with hydrogen abstraction from the −CH3 group as the dominant initial step. Based on our results MSAM has an atmospheric lifetime with respect to loss by reaction with OH of about 80 d.

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Measurements of HONO during BAQS-Met

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-15295-2010 ◽

2010 ◽

Vol 10 (6) ◽

pp. 15295-15323 ◽

Cited By ~ 2

Author(s):

J. J. B. Wentzell ◽

C. L. Schiller ◽

G. W. Harris

Keyword(s):

Gas Phase ◽

Water Vapour ◽

Nitrous Acid ◽

Meteorological Parameters ◽

Border Region ◽

Night Time ◽

Mixing Ratios ◽

Oxidation Chemistry ◽

Absorption Photometer ◽

Shed Light

Abstract. Measurements of nitrous acid (HONO) were performed as part of the 2007 Border Air Quality and Meteorology Study (BAQS-Met) at the Harrow Ontario supersite between 20 June and 10 July 2007. Nitrous acid is an important precursor of the hydroxy radical and understanding its chemistry is important to understanding daytime oxidation chemistry. The HONO measurements were made using a custom built Long Path Absorption Photometer (LOPAP). The goal of this work was to shed light on sources of daytime HONO in the border region. During the course of the campaign HONO mixing ratios consistently exceeded expected daytime values by as much as a factor of 6. Mean daytime concentrations of 61 pptv were observed. While HONO decay began at sunrise, minimum HONO values were not measured until the late afternoon. There was little difference between the daytime (mean=1.5%) and night-time (mean=1.7%) ratios of HONO/NO2. Thus there was a very strong daytime source of HONO which is consistent with other recent studies. Correlations of daytime HONO production with a variety of chemical and meteorological parameters indicate that production is dependent on UV radiation, NO2 and water vapour but is not consistent with a simple gas phase process. Apparent rate constants for the production of HONO from photolyticly excited NO2 and water vapour vary from 2.8–7.8×10−3 molec−1 s−1, during the campaign.

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Oxidation product characterization from ozonolysis of the diterpene ent-kaurene

10.5194/acp-2021-881 ◽

2021 ◽

Author(s):

Yuanyuan Luo ◽

Olga Garmash ◽

Haiyan Li ◽

Frans Graeffe ◽

Arnaud P. Praplan ◽

...

Keyword(s):

Gas Phase ◽

Mass Spectrometer ◽

Atmospheric Chemistry ◽

Ambient Air ◽

Proton Transfer Reaction ◽

Oxidation Products ◽

Ionization Mass ◽

Product Characterization ◽

First Time ◽

Clustering Patterns

Abstract. Diterpenes (C20H32) are biogenically emitted volatile compounds that only recently have been observed in ambient air. They are expected to be highly reactive, and their oxidation is likely to form condensable vapors. However, until now, no studies have investigated gas-phase diterpene oxidation. In this paper, we explored the ozonolysis of a diterpene, ent-kaurene, in a simulation chamber. Using state-of-the-art mass spectrometry, we characterized diterpene oxidation products for the first time, and we identified several products with varying oxidation levels, including highly oxygenated organic molecules (HOM) monomers and dimers. The most abundant monomers measured using a nitrate chemical ionization mass spectrometer were C19H28O8 and C20H30O5, and dimers were C38H60O6 and C39H62O6. The exact molar yield of HOM from kaurene ozonolysis was hard to quantify due to uncertainties in both the kaurene and HOM concentrations, but our best estimate was a few percent, which is similar to values reported earlier for many monoterpenes. We also monitored the decrease of the gas-phase oxidation products in response to an increased condensation sink in the chamber to deduce their affinity to condense. The oxygen content was a critical parameter affecting the volatility of products, with 4–5 O-atoms needed for the main monomeric species to condense. Finally, we report on the observed fragmentation and clustering patterns of kaurene in a Vocus proton transfer reaction time-of-flight mass spectrometer. Our findings highlight similarities and differences between diterpenes and smaller terpenes during their atmospheric oxidation, but more studies on different diterpenes are needed for a broader view of their role in atmospheric chemistry.

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The Impact of Ambient Atmospheric Mineral-Dust Particles on the Calcification of Lungs

Minerals ◽

10.3390/min11020125 ◽

2021 ◽

Vol 11 (2) ◽

pp. 125

Author(s):

Mariola Jabłońska ◽

Janusz Janeczek ◽

Beata Smieja-Król

Keyword(s):

Mineral Dust ◽

Smoking Habit ◽

Lower Lobe ◽

Ambient Air ◽

Dust Particles ◽

Masking Effect ◽

Amorphous Calcium Carbonate ◽

Calcium Salts ◽

The Impact ◽

First Time

For the first time, it is shown that inhaled ambient air-dust particles settled in the human lower respiratory tract induce lung calcification. Chemical and mineral compositions of pulmonary calcium precipitates in the lung right lower-lobe (RLL) tissues of 12 individuals who lived in the Upper Silesia conurbation in Poland and who had died from causes not related to a lung disorder were determined by transmission and scanning electron microscopy. Whereas calcium salts in lungs are usually reported as phosphates, calcium salts precipitated in the studied RLL tissue were almost exclusively carbonates, specifically Mg-calcite and calcite. These constituted 37% of the 1652 mineral particles examined. Mg-calcite predominated in the submicrometer size range, with a MgCO3 content up to 50 mol %. Magnesium plays a significant role in lung mineralization, a fact so far overlooked. The calcium phosphate (hydroxyapatite) content in the studied RLL tissue was negligible. The predominance of carbonates is explained by the increased CO2 fugacity in the RLL. Carbonates enveloped inhaled mineral-dust particles, including uranium-bearing oxides, quartz, aluminosilicates, and metal sulfides. Three possible pathways for the carbonates precipitation on the dust particles are postulated: (1) precipitation of amorphous calcium carbonate (ACC), followed by its transformation to calcite; (2) precipitation of Mg-ACC, followed by its transformation to Mg-calcite; (3) precipitation of Mg-free ACC, causing a localized relative enrichment in Mg ions and subsequent heterogeneous nucleation and crystal growth of Mg-calcite. The actual number of inhaled dust particles may be significantly greater than was observed because of the masking effect of the carbonate coatings. There is no simple correlation between smoking habit and lung calcification.

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CsOH and its Lighter Homologues – a Comparison

Zeitschrift für Naturforschung B ◽

10.5560/znb.2014-4163 ◽

2014 ◽

Vol 69 (11-12) ◽

pp. 1229-1236

Author(s):

Matthias Wörsching ◽

Constantin Hoch

Keyword(s):

Gas Phase ◽

Room Temperature ◽

Structure Type ◽

Alkali Metal Hydroxide ◽

X Ray ◽

Raman Spectroscopic ◽

Cesium Hydroxide ◽

Free Ion ◽

The One ◽

First Time

Abstract Cesium hydroxide, CsOH, was for the first time characterised on the basis of single-crystal data. The structure is isotypic to the one of the room-temperature modification of NaOH and can be derived from the NaCl structure type thus allowing the comparison of all alkali metal hydroxide structures. Raman spectroscopic investigations show the hydroxide anion to behave almost as a free ion as in the gas phase. The X-ray investigations indicate possible H atom positions.

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