Academic literature on the topic 'Nitrate radicals; Troposphere'
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Journal articles on the topic "Nitrate radicals; Troposphere"
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Vrekoussis, M., M. Kanakidou, N. Mihalopoulos, P. J. Crutzen, J. Lelieveld, D. Perner, H. Berresheim, and E. Baboukas. "Role of the NO<sub>3</sub> radicals in oxidation processes in the eastern Mediterranean troposphere during the MINOS campaign." Atmospheric Chemistry and Physics 4, no. 1 (February 3, 2004): 169–82. http://dx.doi.org/10.5194/acp-4-169-2004.
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Abstract. During the MINOS campaign (28 July-18 August 2001) the nitrate (NO3) radical was measured at Finokalia station, on the north coast of Crete in South-East Europe using a long path (10.4 km) Differential Optical Absorption Spectroscopy instrument (DOAS). Hydroxyl (OH) radical was also measured by a Chemical Ionization Mass-Spectrometer (Berresheim et al., 2003). These datasets represent the first simultaneous measurements of OH and NO3 radicals in the area. NO3 radical concentrations ranged from less than 3x107 up to 9x108 radicals· cm-3 with an average nighttime value of 1.1x108 radicals· cm-3. The observed NO3 mixing ratios are analyzed on the basis of the corresponding meteorological data and the volatile organic compound (VOC) observations which were measured simultaneously at Finokalia station. The importance of the NO3 radical chemistry relatively to that of OH in the dimethylsulfide (DMS) and nitrate cycles is also investigated. The observed NO3 levels regulate the nighttime variation of DMS. The loss of DMS by NO3 during night is about 75% of that by OH radical during day. NO3 and nitrogen pentoxide (N2O5) reactions account for about 21% of the total nitrate (HNO3(g)+NO-3(g)) production.
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Murphy, J. G., J. A. Thornton, P. J. Wooldridge, D. A. Day, R. S. Rosen, C. Cantrell, R. E. Shetter, B. Lefer, and R. C. Cohen. "Measurements of the sum of HO<sub>2</sub>NO<sub>2</sub> and CH<sub>3</sub>O<sub>2</sub>NO<sub>2</sub> in the remote troposphere." Atmospheric Chemistry and Physics Discussions 3, no. 6 (November 12, 2003): 5689–710. http://dx.doi.org/10.5194/acpd-3-5689-2003.
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Abstract. The chemistry of peroxynitric acid (HO2NO2) and methyl peroxynitrate (CH3O2NO2) is predicted to be particularly important in the upper troposphere where temperatures are frequently low enough that these compounds do not rapidly decompose. At temperatures below 240 K, we calculate that about 20% of NOy in the mid and polar latitude upper troposphere is HO2NO2. Under these conditions, the reaction of OH with HO2NO2 is estimated to account for as much as one third of the permanent loss of hydrogen radicals. During the Tropospheric Ozone Production about the Spring Equinox (TOPSE) campaign, we used thermal dissociation laser-induced fluorescence (TD-LIF) to measure the sum of peroxynitrates (SPNs equivanlent HO2NO2 + CH3O2NO2 + PAN + PPN + ...), aboard the NCAR C-130 research aircraft. We infer the sum of HO2NO2 and CH3O2NO2 as the difference between SPN measurements and gas chromatographic measurements of the two major peroxy acyl nitrates, peroxy acetyl nitrate (PAN) and peroxy propionyl nitrate (PPN). Comparison with NOy and other nitrogen oxide measurements confirms the importance of HO2NO2 and CH3O2NO2 to the reactive nitrogen budget and shows that current thinking about the chemistry of these species is approximately correct. The temperature dependence of the inferred concentrations corroborates the contribution of overtone photolysis to the photochemistry of peroxynitric acid.
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Fischer, E. V., D. J. Jacob, R. M. Yantosca, M. P. Sulprizio, D. B. Millet, J. Mao, F. Paulot, et al. "Atmospheric peroxyacetyl nitrate (PAN): a global budget and source attribution." Atmospheric Chemistry and Physics Discussions 13, no. 10 (October 15, 2013): 26841–91. http://dx.doi.org/10.5194/acpd-13-26841-2013.
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Abstract. Peroxyacetyl nitrate (PAN) formed in the atmospheric oxidation of non-methane volatile organic compounds (NMVOCs), is the principal tropospheric reservoir for nitrogen oxide radicals (NOx = NO + NO2). PAN enables the transport and release of NOx to the remote troposphere with major implications for the global distributions of ozone and OH, the main tropospheric oxidants. Simulation of PAN is a challenge for global models because of the dependence of PAN on vertical transport as well as complex and uncertain NMVOC sources and chemistry. Here we use an improved representation of NMVOCs in a global 3-D chemical transport model (GEOS-Chem) and show that it can simulate PAN observations from aircraft campaigns worldwide. The immediate carbonyl precursors for PAN formation include acetaldehyde (44% of the global source), methylglyoxal (30%), acetone (7%), and a suite of other isoprene and terpene oxidation products (19%). A diversity of NMVOC emissions is responsible for PAN formation globally including isoprene (37%) and alkanes (14%). Anthropogenic sources are dominant in the extratropical Northern Hemisphere outside the growing season. Open fires appear to play little role except at high northern latitudes in spring, although results are very sensitive to plume chemistry and plume rise. Lightning NOx is the dominant contributor to the observed PAN maximum in the free troposphere over the South Atlantic.
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Fischer, E. V., D. J. Jacob, R. M. Yantosca, M. P. Sulprizio, D. B. Millet, J. Mao, F. Paulot, et al. "Atmospheric peroxyacetyl nitrate (PAN): a global budget and source attribution." Atmospheric Chemistry and Physics 14, no. 5 (March 14, 2014): 2679–98. http://dx.doi.org/10.5194/acp-14-2679-2014.
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Abstract. Peroxyacetyl nitrate (PAN) formed in the atmospheric oxidation of non-methane volatile organic compounds (NMVOCs) is the principal tropospheric reservoir for nitrogen oxide radicals (NOx = NO + NO2). PAN enables the transport and release of NOx to the remote troposphere with major implications for the global distributions of ozone and OH, the main tropospheric oxidants. Simulation of PAN is a challenge for global models because of the dependence of PAN on vertical transport as well as complex and uncertain NMVOC sources and chemistry. Here we use an improved representation of NMVOCs in a global 3-D chemical transport model (GEOS-Chem) and show that it can simulate PAN observations from aircraft campaigns worldwide. The immediate carbonyl precursors for PAN formation include acetaldehyde (44% of the global source), methylglyoxal (30%), acetone (7%), and a suite of other isoprene and terpene oxidation products (19%). A diversity of NMVOC emissions is responsible for PAN formation globally including isoprene (37%) and alkanes (14%). Anthropogenic sources are dominant in the extratropical Northern Hemisphere outside the growing season. Open fires appear to play little role except at high northern latitudes in spring, although results are very sensitive to plume chemistry and plume rise. Lightning NOx is the dominant contributor to the observed PAN maximum in the free troposphere over the South Atlantic.
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Vrekoussis, M., M. Kanakidou, N. Mihalopoulos, P. J. Crutzen, J. Lelieveld, D. Perner, H. Berresheim, and E. Baboukas. "Role of NO<sub>3</sub> radical in oxidation processes in the eastern Mediterranean troposphere during the MINOS campaign." Atmospheric Chemistry and Physics Discussions 3, no. 3 (June 19, 2003): 3135–69. http://dx.doi.org/10.5194/acpd-3-3135-2003.
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Abstract. During the MINOS campaign (28 July–18 August 2001) nitrate (NO3) radical was measured at Finokalia, on the north coast of Crete in South-East Europe using a long path (10.4 km) Differential Optical Absorption Spectroscopy instrument (DOAS). Hydroxyl (OH) radical was also measured by a Chemical Ionization Mass-Spectrometer (Berresheim et al., this issue). These datasets represent the first simultaneous measurements of OH and NO3 radicals in the area. NO3 radical concentrations ranged from less than 3·107 up to 9·108 radical·cm-3 with an average value of 1.1·108 radical·cm−3. The observed NO3 mixing ratios are analyzed on the basis of the corresponding meteorological data and the volatile organic compound (VOC) observations simultaneously obtained at Finokalia station. The importance of the NO3 radical relatively to that of OH in the dimethylsulfide (DMS) and nitrate cycles is also investigated. The observed NO3 levels clearly regulate the diurnal variation of DMS. NO3 and N2O5 reactions account for about 21% of the total nitrate (HNO3(g) + NO−3(part)) production.
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Murphy, J. G., J. A. Thornton, P. J. Wooldridge, D. A. Day, R. S. Rosen, C. Cantrell, R. E. Shetter, B. Lefer, and R. C. Cohen. "Measurements of the sum of HO<sub>2</sub>NO<sub>2</sub> and CH<sub>3</sub>O<sub>2</sub>NO<sub>2</sub> in the remote troposphere." Atmospheric Chemistry and Physics 4, no. 2 (February 27, 2004): 377–84. http://dx.doi.org/10.5194/acp-4-377-2004.
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Abstract. The chemistry of peroxynitric acid (HO2NO2) and methyl peroxynitrate (CH3O2NO2)is predicted to be particularly important in the upper troposphere where temperatures are frequently low enough that these compounds do not rapidly decompose. At temperatures below 240K, we calculate that about 20% of NOy in the mid- and high-latitude upper troposphere is HO2NO2. Under these conditions, the reaction of OH with HO2NO2 is estimated to account for as much as one third of the permanent loss of hydrogen radicals. During the Tropospheric Ozone Production about the Spring Equinox (TOPSE) campaign, we used thermal dissociation laser-induced fluorescence (TD-LIF) to measure the sum of peroxynitrates (PNs HO2NO2+CH3O2NO2+PAN+PPN+...) aboard the NCAR C-130 research aircraft. We infer the sum of HO2NO2 and CH3O2NO2 as the difference between PN measurements and gas chromatographic measurements of the two major peroxy acyl nitrates, peroxy acetyl nitrate (PAN) and peroxy propionyl nitrate (PPN). Comparison with NOy and other nitrogen oxide measurements confirms the importance of HO2NO2 and CH3O2NO2 to the reactive nitrogen budget and shows that current thinking about the chemistry of these species is approximately correct. During the spring high latitude conditions sampled during the TOPSE experiment, the model predictions of the contribution of (HO2NO2+CH3O2NO2) to NOy are highly temperature dependent: on average 30% of NOy at 230K, 15% of NOy at 240K, and 5% of NOy above 250K. The temperature dependence of the inferred concentrations corroborates the contribution of overtone photolysis to the photochemistry of peroxynitric acid. A model that includes IR photolysis (J=1x10-5s-1) agreed with the observed sum of HO2NO2+CH3O2NO2 to better than 35% below 240K where the concentration of these species is largest.
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Clemitshaw, Kevin C. "Coupling between the Tropospheric Photochemistry of Nitrous Acid (HONO) and Nitric Acid (HNO3)." Environmental Chemistry 3, no. 1 (2006): 31. http://dx.doi.org/10.1071/en05073.
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Environmental Context.Nitrous acid (HONO) is formed in the troposphere in urban, rural and remote environments via several uncertain heterogeneous and photochemical processes that involve nitric acid (HNO3). A recently recognised process is initiated by the deposition and migration of HNO3 within snow-pack surfaces to form nitrate anions (NO3−). Photo-reduction of NO3− followed by acidification of the nitrite (NO2−) photo-product leads to emissions of gas-phase HONO. Seasonal observations at Halley, Antarctica are consistent with the formation of HONO via this process, which is potentially of global significance because much of the Earth’s land (and sea) surface is covered with snow and is sunlit for much of the year. Both HONO and HNO3 significantly influence the production of ozone (O3), which acts as a greenhouse gas in the troposphere, via their respective roles as a source of hydroxyl radicals (OH•) and as a sink for OH• and nitrogen dioxide (NO2). Abstract.The tropospheric photochemistry of nitrous acid (HONO) and its coupling with that of nitric acid (HNO3) in urban, rural and remote atmospheres are highlighted in terms of established and uncertain homogeneous and heterogeneous sources and sinks, together with known and potential effects and impacts. Observations made at Halley, Antarctica, via optical detection of an azo dye derivative of HONO are consistent with snow-pack photochemical production of HONO, which has potential significance for the production of hydroxyl radicals (OH•) and ozone (O3) on regional and global scales. Recent developments in measurement methods for HONO and HNO3 are also highlighted. It is now timely to conduct a formal intercomparison of the methods in order to evaluate and enhance their capabilities, and to validate the growing body of HONO and HNO3 data obtained in urban, rural and remote locations.
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Ng, N. L., A. J. Kwan, J. D. Surratt, A. W. H. Chan, P. S. Chhabra, A. Sorooshian, H. O. T. Pye, et al. "Secondary organic aerosol (SOA) formation from reaction of isoprene with nitrate radicals (NO<sub>3</sub>)." Atmospheric Chemistry and Physics 8, no. 14 (August 1, 2008): 4117–40. http://dx.doi.org/10.5194/acp-8-4117-2008.
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Abstract. Secondary organic aerosol (SOA) formation from the reaction of isoprene with nitrate radicals (NO3) is investigated in the Caltech indoor chambers. Experiments are performed in the dark and under dry conditions (RH&lt10%) using N2O5 as a source of NO3 radicals. For an initial isoprene concentration of 18.4 to 101.6 ppb, the SOA yield (defined as the ratio of the mass of organic aerosol formed to the mass of parent hydrocarbon reacted) ranges from 4.3% to 23.8%. By examining the time evolutions of gas-phase intermediate products and aerosol volume in real time, we are able to constrain the chemistry that leads to the formation of low-volatility products. Although the formation of ROOR from the reaction of two peroxy radicals (RO2) has generally been considered as a minor channel, based on the gas-phase and aerosol-phase data it appears that RO2+RO2 reaction (self reaction or cross-reaction) in the gas phase yielding ROOR products is a dominant SOA formation pathway. A wide array of organic nitrates and peroxides are identified in the aerosol formed and mechanisms for SOA formation are proposed. Using a uniform SOA yield of 10% (corresponding to Mo≅10 μg m−3), it is estimated that ~2 to 3 Tg yr−1 of SOA results from isoprene+NO3. The extent to which the results from this study can be applied to conditions in the atmosphere depends on the fate of peroxy radicals in the nighttime troposphere.
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Apel, E. C., J. R. Olson, J. H. Crawford, R. S. Hornbrook, A. J. Hills, C. A. Cantrell, L. K. Emmons, et al. "Impact of the deep convection of isoprene and other reactive trace species on radicals and ozone in the upper troposphere." Atmospheric Chemistry and Physics Discussions 11, no. 10 (October 5, 2011): 27243–84. http://dx.doi.org/10.5194/acpd-11-27243-2011.
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Abstract. Observations of a comprehensive suite of inorganic and organic trace gases, including non-methane hydrocarbons (NMHCs), halogenated organics and oxygenated volatile organic compounds (OVOC), obtained from the NASA DC-8 over Canada during the ARCTAS aircraft campaign in July 2008 illustrate that convection is important for redistributing both long and short-lived species throughout the troposphere. Convective outflow events were identified by the elevated mixing ratios of organic species in the upper troposphere relative to background conditions. Several dramatic events were observed in which isoprene and its oxidation products were detected at hundreds of pptv at altitudes higher than 8 km. Two events are studied in detail using detailed experimental data and the NASA Langley Research Center (LaRC) box model. One event had no lightning NOx (NO + NO2) associated with it and the other had substantial lightning NOx (LNOx). When convective storms transport isoprene from the boundary layer to the upper troposphere and LNOx is present, there is a large effect on the expected ensuing chemistry. The model predicts a dominant impact on HOx and nitrogen-containing species; the relative contribution from other species such as peroxides is insignificant. The isoprene reacts quickly, resulting in primary and secondary products, including formaldehyde and methyl glyoxal. The model predicts enhanced production of alkyl nitrates (ANs) and peroxyacyl nitrate compounds (PANs). PANs persist because of the cold temperatures of the upper troposphere resulting in a large change in the NOx mixing ratios, compared to the case in which no isoprene is convected, a scenario which is also explored by the model. This, in turn, has a large impact on the HOx chemistry. Ozone production is substantial during the first few hours following the event, resulting in a net gain of approximately 10 ppbv compared to the scenario in which no isoprene is present aloft. In the case of isoprene being present aloft but no LNOx, OH is reduced due to scavenging by isoprene, which serves to slow the chemistry resulting in longer lifetimes for species that react with OH.
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Apel, E. C., J. R. Olson, J. H. Crawford, R. S. Hornbrook, A. J. Hills, C. A. Cantrell, L. K. Emmons, et al. "Impact of the deep convection of isoprene and other reactive trace species on radicals and ozone in the upper troposphere." Atmospheric Chemistry and Physics 12, no. 2 (January 27, 2012): 1135–50. http://dx.doi.org/10.5194/acp-12-1135-2012.
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Abstract. Observations of a comprehensive suite of inorganic and organic trace gases, including non-methane hydrocarbons (NMHCs), halogenated organics and oxygenated volatile organic compounds (OVOCs), obtained from the NASA DC-8 over Canada during the ARCTAS aircraft campaign in July 2008 illustrate that convection is important for redistributing both long- and short-lived species throughout the troposphere. Convective outflow events were identified by the elevated mixing ratios of organic species in the upper troposphere relative to background conditions. Several dramatic events were observed in which isoprene and its oxidation products were detected at hundreds of pptv at altitudes higher than 8 km. Two events are studied in detail using detailed experimental data and the NASA Langley Research Center (LaRC) box model. One event had no lightning NOx (NO + NO2) associated with it and the other had substantial lightning NOx (LNOx > 1 ppbv). When convective storms transport isoprene from the boundary layer to the upper troposphere and no LNOx is present, OH is reduced due to scavenging by isoprene, which serves to slow the chemistry, resulting in longer lifetimes for species that react with OH. Ozone and PAN production is minimal in this case. In the case where isoprene is convected and LNOx is present, there is a large effect on the expected ensuing chemistry: isoprene exerts a dominant impact on HOx and nitrogen-containing species; the relative contribution from other species to HOx, such as peroxides, is insignificant. The isoprene reacts quickly, resulting in primary and secondary products, including formaldehyde and methyl glyoxal. The model predicts enhanced production of alkyl nitrates (ANs) and peroxyacyl nitrate compounds (PANs). PANs persist because of the cold temperatures of the upper troposphere resulting in a large change in the NOx mixing ratios which, in turn, has a large impact on the HOx chemistry. Ozone production is substantial during the first few hours following the convection to the UT, resulting in a net gain of approximately 10 ppbv compared to the modeled scenario in which LNOx is present but no isoprene is present aloft.
Dissertations / Theses on the topic "Nitrate radicals; Troposphere"
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King, Martin D. "Kinetics and mechanisms of reactions of NOâ†3 with some biogenic species." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299017.
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Allan, Beverley. "A spectroscopic study of radical chemistry in the troposphere." Thesis, University of East Anglia, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266729.
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Smith, Nicola. "A spectroscopic study of the role of the nitrate radical in the troposphere." Thesis, University of East Anglia, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297008.
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Kerdouci, Jamila. "Réactivité des composés organiques volatils avec le radical nitrate : développement d’une relation de type structure réactivité." Thesis, Paris Est, 2011. http://www.theses.fr/2011PEST1090.
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Durant la nuit, le radical nitrate (NO3) est le principal oxydant troposphérique des composés organiques. La compréhension de l'implication des composés organiques dans les processus de chimie troposphérique exige donc une connaissance des constantes cinétiques de leurs réactions avec le radical NO3. Toutefois, au regard du nombre considérable de composés organiques émis ou formés dans la troposphère, il est difficilement envisageable d'appréhender la réactivité de chaque composé en nous reposant exclusivement sur des études de laboratoire. Celles-ci se doivent d'être complétées par l'usage de méthodes prédictives. Nous avons donc, au cours de ce travail, développé une relation de type structure-réactivité (SAR) qui permet le calcul des constantes de vitesse des réactions des composés organiques avec le radical nitrate. Cette méthode prédictive empirique permet d'estimer la réactivité d'un composé à partir de sa structure moléculaire et a été élaborée à partir de constantes cinétiques expérimentales publiées dans la littérature. De plus, conjointement au développement de cette SAR, les constantes cinétiques des réactions d'aldéhydes et d'éthers insaturés avec le radical nitrate ont été mesurées au laboratoire. Ces études expérimentales ont ainsi contribué à étoffer la base de données cinétiques sur laquelle repose cette SAR afin de permettre son parachèvement. Cette SAR reproduit, à un facteur deux près, plus de 90% des constantes cinétiques des alcènes et des composés aliphatiques oxygénés saturés et insaturésThe nitrate radical (NO3) is the main oxidant of organic compounds in the night-time troposphere. Thus, comprehension of organic compounds involvement in tropospheric chemical processes requires the knowledge of the rate coefficients for their reactions with the nitrate radical. Nevertheless, considering the wide range of organic compounds emitted or formed in the atmosphere, it is difficult to determine the reactivity of each compound only with laboratory studies. Thereby, these experimental studies have to be completed by predictive methods. In this study, a group-additivity method is therefore used to develop a new Structure-Activity Relationship (SAR) which allows prediction of the rate constants for reactions of organic compounds with the NO3 radical. This empirical method is based on the prediction of a rate constant leaning only on the molecular structure of the organic compound. It relies on experimental rate constants available in the literature. Moreover, the rate constants of unsaturated aldehydes and ethers with the nitrate radical have been measured. Thereby, these experimental studies contribute to expend the kinetic database used for the SAR development and allow its improvement. For saturated and unsaturated oxygenated compounds, more than 90% of the rate constants are reproduced within a factor of two
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Scarfogliero, Michaël. "Étude en atmosphère simulée de la chimie troposphérique nocturne de composés organiques volatils oxygénés." Thesis, Paris Est, 2008. http://www.theses.fr/2008PEST0010.
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L’oxydation troposphérique des composés organiques volatils (COV) constitue une contribution importante à la formation de photooxydants. L’évaluation de l’impact environnemental des COV rend indispensable d’acquérir une bonne compréhension des processus en jeu. Ce travail porte donc sur l’étude en atmosphère simulée de la réactivité troposphérique avec le radical nitrate (NO3) de COV oxygénés appartenant à une série homogène d’éthers vinyliques aliphatiques (méthyl, éthyl, propyl et butyl vinyl éthers), et à une série de trois esters (acétates d’isopropényle, de vinyle, et d’allyle), auxquelles s’ajoute le 2,3,2 méthylbutènol (MBO). Pour tous ces composés, des études cinétiques (destinées à mesurer la constante d’oxydation par NO3 des produits étudiés) ont été menées selon la méthode relative, et pour certains composés selon la méthode absolue. Des études mécanistiques (destinées à identifier et quantifier les produits de la réaction, et à élucider le mécanisme réactionnel) ont également été menées. Une réévaluation de la constante cinétique d’oxydation du propène par NO3, qui a été mesurée selon la méthode absolue, a également été faite. Les expériences ont été menées dans la chambre de simulation atmosphérique du LISA, à température ambiante et à pression atmosphérique. Les durées de vie des composés étudiés vis-à-vis de NO3 ont été calculées, et comparées à celles vis-à-vis du radical OH et de l’ozone. Les résultats montrent que NO3 peut constituer un puits majeur pour les COV les plus réactifs, comme les éthers vinyliques. Par ailleurs, les apports de nos résultats aux règles de réactivité des COV ont été discutésThe tropospheric oxidation of the volatile organic compounds (VOC) constitutes an important contribution to the formation of photooxydants. It is necessary to acquire a good comprehension of the concerned chemical processes in order to correctly evaluate the environmental impact of the VOC. This work thus concerns the study under simulated conditions of the tropospheric reactivity with the nitrate radical (NO3) of oxygenated VOC pertaining to a homologous series of aliphatic vinyl ethers (methyl, éthyl, propyl and butyl vinyl ethers), and to a series of three esters (allyl and vinyl, isopropenyl acetates). In addition, the 2,3,2 méthylbutènol (MBO) has been studied too. For all these compounds, kinetic studies (in order to measure the rate constant of NO3 oxidation of the studied products) were performed according to the relative rate method, and for some compounds according to the absolute method. Mechanistic studies (in order to identify and quantify the reaction products, and to elucidate the chemical mechanism) were also performed. A revaluation of the rate constant of NO3 oxidation of propene, which was measured according to the absolute method, was also performed. The experiments were carried out in the LISA atmospheric simulation chamber, at room temperature and atmospheric pressure. The lifetimes of the studied compounds with respect to NO3 were calculated, and were compared to those with respect to OH radical and to ozone. The results show that NO3 can be a major sink for the most reactive VOC, like the vinyl ethers. In addition, the contributions of our results to the rules of reactivity of the VOC were discussed
Book chapters on the topic "Nitrate radicals; Troposphere"
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Burrows, J. P., T. Behmann, J. N. Crowley, D. Maric, A. Lastätter-Weißenmayer, G. K. Moortgat, D. Perner, and M. Weißenmayer. "Laboratory and Field Measurement Studies of the Tropospheric Chemistry of Nitrate and Peroxy Radicals." In Chemical Processes in Atmospheric Oxidation, 91–99. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-642-59216-4_5.
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Wayne, Richard P., Pete Biggs, and Carlos E. Canosa-Mas. "Studies of the Kinetics and Mechanisms of Interactions of Nitrate and Peroxy Radicals of Tropospheric Interest." In Chemical Processes in Atmospheric Oxidation, 232–40. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-642-59216-4_25.
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Calvert, Jack, Abdelwahid Mellouki, John Orlando, Michael Pilling, and Timothy Wallington. "Rate Coefficients and Mechanisms for the Atmospheric Oxidation of the N-Atom-Containing Oxygenates." In Mechanisms of Atmospheric Oxidation of the Oxygenates. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199767076.003.0011.
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The many different nitrogen-containing oxygenated volatile organic compounds that are present in the troposphere play important roles in the chemistry of our atmosphere. They can be emitted directly into the atmosphere, such as in the case of amides that are widely used as organic solvents, starting materials, or intermediates in different industries (e.g., synthetic polymers, manufacture of dyes, and synthesis of pesticides). Amides are formed in situ as intermediate products in the degradation of amines (e.g., see Tuazon et al., 1994; Finlayson-Pitts and Pitts, 2000). Nitrogen-containing oxygenated organic compounds are formed in the atmosphere also via reactions of alkoxy (RO) and alkyl peroxy radicals (RO2) with NO or NO2 leading to alkyl nitrates, alkyl nitrites, and peroxy acetyl nitrates. However, primary sources of these organic species have also been suggested such as diesel and other engines and biomass burning (e.g., see Simpson et al., 2002). Alkyl nitrates (RONO2) have been detected in both the urban and the remote troposphere (e.g., see Roberts, 1990; Walega et al., 1992; Atlas et al., 1992; Ridley et al., 1997; and Stroud et al., 2001; see also section I-D). Nitrates are formed as minor products in the reaction of peroxy radicals with NO. The nitrate yield increases with the size of peroxy radicals and can be as high as 20–30% for large (>C6) radicals (Calvert et al., 2008). Peroxyacyl nitrates (RC(O)O2NO2) are important constituents of urban air pollution. They have been identified in ambient air (e.g., see Bertman and Roberts, 1991; Williams et al., 1997, 2000; Nouaime et al., 1998; Hansel and Wisthaler, 2000; also see section I-D). They are formed from photochemical reactions via RC(O)O2 + NO2. A major role of these compounds is their capacity to act as a reservoir for NOx that can be transported from polluted urban to remote regions that are poor NOx regions and where their presence can increase NOx levels (Roberts, 1990). As with other volatile organic compounds (VOCs), once released to the atmosphere, nitrogen-containing organic compounds are expected to undergo degradation primarily via reaction with hydroxyl and nitrate radicals, reaction with ozone, and photolysis. Thermal decomposition is an important loss process for the peroxyacyl nitrates.
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Calvert, Jack, Abdelwahid Mellouki, John Orlando, Michael Pilling, and Timothy Wallington. "Rate Coefficients and Mechanisms for the Atmospheric Oxidation of the Aldehydes." In Mechanisms of Atmospheric Oxidation of the Oxygenates. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199767076.003.0007.
Full textAbstract:
Aldehydes are emitted from a variety of anthropogenic sources associated with natural gas and petroleum combustion (for examples, see tables I-C-2 and I-C-3). Winer et al. (1992) have discussed direct emissions of aldehydes from biogenic sources. They are also important intermediates in the oxidation of directly emitted organic compounds. For example, formaldehyde, CH2O formed in the reaction of CH3O with O2 . . . CH3O + O2 → CH2O + HO2 . . . CH3O is formed in the oxidation of methane, and a number of other compounds. There are also many other sources of CH2O; for example, the Leeds University’s Master Chemical Mechanism (MCM) lists a total of ∼ 140 CH2O precursors: http://mcm.leeds.ac.uk/MCM/. Aldehydes with saturated hydrocarbon chains (termed alkanals or acyclic aldehydes) react mainly with OH during the day and with NO3 at night. The aldehydic C—H bond is weaker than those in the hydrocarbon chain; and, certainly for the shorter carbon chain species, abstraction by both OH and NO3 occurs primarily at the aldehydic center to form an acyl radical which reacts rapidly with O2 to form an acylperoxy radical, e.g., . . . CH3CHO + OH → CH3CO + H2O . . . . . . CH3CO + O2 → CH3C(O)O2 . . . An important reaction of the acylperoxy radical is with NO2 to form an acylperoxy nitrate. In the example shown, the oxidation of acetaldehyde gives acetyl peroxy radicals which can react with NO2 to form peroxyacetyl nitrate, CH3C(O)O2NO2, generally known as PAN: . . . CH3C(O)O2 + NO2 → CH3C(O)O2NO2 . . . Peroxyacyl nitrates dissociate quite quickly at 298 K, to regenerate peroxyacyl radicals. For example, PAN has a lifetime of about 50 min. The lifetime increases rapidly at the lower temperatures experienced at higher altitudes and is several months at the temperatures (∼ 250 K) of the upper troposphere. This long lifetime provides a mechanism for the transport of NOx from polluted areas to less polluted areas, by transfer of peroxyacyl nitrates from the boundary layer to the free troposphere; subsequent subsidence can return them to the boundary layer where they dissociate at the higher temperatures encountered there. The atmospheric reactions of the nitrates are discussed in detail in chapters VIII and IX.