NO3 oxidation of methyl, ethyl, propyl, and butyl vinyl ethers has been studied under tropospheric conditions (atmospheric pressure and T = 293 ± 3 K) in the LISA indoor simulation chamber. NO3 was ...produced inside the reactor by thermal decomposition of N2O5 previously added to the air−VOC mixture, and concentrations were monitored using FTIR spectrometry. All the kinetic experiments were carried out by relative rate technique using isoprene as reference compound, leading to the rate constants k 1 = (7.2 ± 1.5) × 10-13, k 2 = (13.1 ± 2.7) × 10-13, k 3 = (13.3 ± 3.0) × 10-13, and k 4 = (17.0 ± 3.7) × 10-13 cm3 molecule-1 s-1 for methyl, ethyl, propyl, and butyl vinyl ethers, respectively. Main oxidation products have been identified like being formaldehyde and respectively methyl, ethyl, propyl, and butyl formates. Production yields of oxidation products were close to 50%. Oxygenated nitrates and peroxynitrates were also detected.
The temperature and concentration dependence of secondary organic aerosol (SOA) yields has been investigated for the first time for the photooxidation of n-dodecane (C12H26) in the presence of NO x ...in the CESAM chamber (French acronym for “Chamber for Atmospheric Multiphase Experimental Simulation”). Experiments were performed with and without seed aerosol between 283 and 304.5 K. In order to quantify the SOA yields, a new parametrization is proposed to account for organic vapor loss to the chamber walls. Deposition processes were found to impact the aerosol yields by a factor from 1.3 to 1.8 between the lowest and the highest value. As with other photooxidation systems, experiments performed without seed and at low concentration of oxidant showed a lower SOA yield than other seeded experiments. Temperature did not significantly influence SOA formation in this study. This unforeseen behavior indicates that the SOA is dominated by sufficiently low volatility products for which a change in their partitioning due to temperature would not significantly affect the condensed quantities.
This article presents the first study of the chemical reactivity of a photo-oxidation product of the 2-methyl-3-buten-2-ol (MBO) in the troposphere, the 2-hydroxy-2-methylpropanal (HMPr). Experiments ...were performed under controlled conditions for pressure (atmospheric pressure) and temperature (296±2
K) in the LISA indoor simulation chamber and in the EUPHORE outdoor simulation chamber to understand the transformations of HMPr in the atmosphere, using FTIR spectrometry. Reaction with OH radicals was studied in the presence and in the absence of NO
x
. All the kinetic studies were carried out by relative rate study using isoprene and/or
n-butylether as the reference compound. The rate constants found for these reactions were
J=(1.01±0.39)×10
−5
s
−1 and
k
HMPr+OH=(1.52±0.36)×10
−11
molecule
−1
cm
3
s
−1. For the reaction with OH radicals, an important production of acetone was observed, with a yield of
R
acetone=1.06±0.06.
The temperature and concentration dependence of secondary organic aerosol (SOA) yields has been investigated for the first time for the photooxidation of n-dodecane (C sub( 12)H sub( 26)) in the ...presence of NO sub( x) in the CESAM chamber (French acronym for "Chamber for Atmospheric Multiphase Experimental Simulation"). Experiments were performed with and without seed aerosol between 283 and 304.5 K. In order to quantify the SOA yields, a new parametrization is proposed to account for organic vapor loss to the chamber walls. Deposition processes were found to impact the aerosol yields by a factor from 1.3 to 1.8 between the lowest and the highest value. As with other photooxidation systems, experiments performed without seed and at low concentration of oxidant showed a lower SOA yield than other seeded experiments. Temperature did not significantly influence SOA formation in this study. This unforeseen behavior indicates that the SOA is dominated by sufficiently low volatility products for which a change in their partitioning due to temperature would not significantly affect the condensed quantities.
The role of relative humidity (RH) in secondary organic aerosol (SOA) formation from high-NO x photooxidation of long-chain alkanes was investigated by performing simulation chamber experiments on ...n-dodecane (C12H26). This molecule was chosen as a model compound for the class of long-chain alkanes. The experiments span a wide range of RH conditions from <1 to 70%. The humidity was found to reduce the SOA production yield by a factor of 2, from extremely dry (<1%) to humid (RH ≥ 5%) conditions. Measurements of major oxidation products in the gaseous and aerosol phases revealed the effect of water on a series of multiphasic reaction mechanisms and SOA production. Under very low RH, an acid-catalyzed “dehydration” reaction of polyfunctional molecules leads to lower volatility products. This pathway was found to be inhibited from dry to ambient RH conditions, explaining the SOA yield reduction. In addition to the previously established carbonyls and hydroxycarbonyls, novel tracers, that is, lactone and carboxylic acid, were identified using authentic standards, providing evidence for water-sensitive multiphasic pathways. Among the species formed via the dehydration channel, we find not only volatile species but also very reactive intermediates (e.g., dihydrofurans) which partition back to the gas phase. Owing to its double bond, it can be further oxidized to lower volatility secondary products, which forms a complex multiphasic scheme involving many condensation reaction–evaporation steps.
•Community-based review of different absorption cross-sections of ozone.•Different platforms (ground-based instruments, satellite sensors) and networks (Dobson, Brewer, LIDAR …).•Quantitative studies ...of the impact of different reference data on the retrieved atmospheric ozone amounts.•Recommendation of selected reference data.
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The activity “Absorption Cross-Sections of Ozone” (ACSO) started in 2008 as a joint initiative of the International Ozone Commission (IO3C), the World Meteorological Organization (WMO) and the IGACO (“Integrated Global Atmospheric Chemistry Observations”) O3/UV subgroup to study, evaluate, and recommend the most suitable ozone absorption cross-section laboratory data to be used in atmospheric ozone measurements. The evaluation was basically restricted to ozone absorption cross-sections in the UV range with particular focus on the Huggins band. Up until now, the data of Bass and Paur published in 1985 (BP, 1985) are still officially recommended for such measurements. During the last decade it became obvious that BP (1985) cross-section data have deficits for use in advanced space-borne ozone measurements. At the same time, it was recognized that the origin of systematic differences in ground-based measurements of ozone required further investigation, in particular whether the BP (1985) cross-section data might contribute to these differences.
In ACSO, different sets of laboratory ozone absorption cross-section data (including their dependence on temperature) of the group of Reims (France) (Brion et al., 1993, 1998, 1992, 1995, abbreviated as BDM, 1995) and those of Serdyuchenko et al. (2014), and Gorshelev et al. (2014), (abbreviated as SER, 2014) were examined for use in atmospheric ozone measurements in the Huggins band.
In conclusion, ACSO recommends:(a)The spectroscopic data of BP (1985) should no longer be used for retrieval of atmospheric ozone measurements.(b)For retrieval of ground-based instruments of total ozone and ozone profile measurements by the Umkehr method performed by Brewer and Dobson instruments data of SER (2014) are recommended to be used. When SER (2014) is used, the difference between total ozone measurements of Brewer and Dobson instruments are very small and the difference between Dobson measurements at AD and CD wavelength pairs are diminished.(c)For ground-based Light Detection and Ranging (LIDAR) measurements the use of BDM (1995) or SER (2014) is recommended.(d)For satellite retrieval the presently widely used data of BDM (1995) should be used because SER (2014) seems less suitable for retrievals that use wavelengths close to 300nm due to a deficiency in the signal-to-noise ratio in the SER (2014) dataset.
The work of ACSO also showed:•The need to continue laboratory cross-section measurements of ozone of highest quality. The importance of careful characterization of the uncertainties of the laboratory measurements.•The need to extend the scope of such studies to other wavelength ranges (particularly to cover not only the Huggins band but also the comparison with the mid-infrared region).•The need for regular cooperation of experts in spectral laboratory measurements and specialists in atmospheric (ozone) measurements.
Oxidation of biogenic volatile organic compounds (BVOC) by the nitrate radical (NO
) represents one of the important interactions between anthropogenic emissions related to combustion and natural ...emissions from the biosphere. This interaction has been recognized for more than 3 decades, during which time a large body of research has emerged from laboratory, field, and modeling studies. NO
-BVOC reactions influence air quality, climate and visibility through regional and global budgets for reactive nitrogen (particularly organic nitrates), ozone, and organic aerosol. Despite its long history of research and the significance of this topic in atmospheric chemistry, a number of important uncertainties remain. These include an incomplete understanding of the rates, mechanisms, and organic aerosol yields for NO
-BVOC reactions, lack of constraints on the role of heterogeneous oxidative processes associated with the NO
radical, the difficulty of characterizing the spatial distributions of BVOC and NO
within the poorly mixed nocturnal atmosphere, and the challenge of constructing appropriate boundary layer schemes and non-photochemical mechanisms for use in state-of-the-art chemical transport and chemistry-climate models. This review is the result of a workshop of the same title held at the Georgia Institute of Technology in June 2015. The first half of the review summarizes the current literature on NO
-BVOC chemistry, with a particular focus on recent advances in instrumentation and models, and in organic nitrate and secondary organic aerosol (SOA) formation chemistry. Building on this current understanding, the second half of the review outlines impacts of NO
-BVOC chemistry on air quality and climate, and suggests critical research needs to better constrain this interaction to improve the predictive capabilities of atmospheric models.
The density functional theory with the BH&HLYP functional has been used in this work to clarify discrepancies found in the literature about the effect of the increasing carbon chain on the reactivity ...of trans-2-alkenals from acrolein (C sub(3)) to trans-2-octenal (C sub(8)) with nitrate radical. In this work, it was found that (i) the alkyl chain length of the unsaturated aldehydes has little or no influence on the NO sub(3) reaction rate coefficients (ii) the abstraction of the aldehydic hydrogen from the alkenal is always dominant (83% for trans-2-butanal to trans-2-octenal). The addition channel, which mainly concerns the beta addition, has a small influence (17% of the total reaction for the whole series). These results are in good agreement with the experimental studies performed by Zhao et al. in 2011 and by Kerdouci et al. in 2012. All these findings will be useful to complete or improve structure-activity relationships developed to predict the reactivity of NO sub(3) radicals with organic compounds.
The Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS) officially became the 33rd European Research Infrastructure Consortium (ERIC) on 25 April 2023 with the support of 17 founding ...member and observer countries. As a pan-European legal organization, ACTRIS ERIC will coordinate the provision of data and data products on short-lived atmospheric constituents and clouds relevant to climate and air pollution over the next 15-20 years. ACTRIS was designed more than a decade ago, and its development was funded at national and European levels. It was included in the European Strategy Forum on Research Infrastructures (ESFRI) roadmap in 2016 and, subsequently, in the national infrastructure roadmaps of European countries. It became a landmark of the ESFRI roadmap in 2021. The purpose of this paper is to describe the mission of ACTRIS, its added value to the community of atmospheric scientists, providing services to academia as well as the public and private sectors, and to summarize its main achievements. The present publication serves as a reference document for ACTRIS, its users, and the scientific community as a whole. It provides the reader with relevant information and an overview on ACTRIS governance and services, as well as a summary of the main scientific achievements of the last 20 years. The paper concludes with an outlook on the upcoming challenges for ACTRIS and the strategy for its future evolution.
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