scholarly journals Representing Organic Compound Oxidation in Chemical Mechanisms for Policy-Relevant Air Quality Models under Background Troposphere Conditions

Atmosphere ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 171 ◽  
Author(s):  
Richard G. Derwent
Keyword(s):  
Organic Compound ◽  
Hydroxyl Radical ◽  
Organic Compounds ◽  
Hydroxyl Radicals ◽  
Tropospheric Chemistry ◽  
Chemical Mechanism ◽  
Chemical Mechanisms ◽  
Photochemical Formation ◽  
Master Chemical Mechanism ◽  
Background Troposphere

This intercomparison has taken thirteen chemical mechanisms and compared how they treat VOC oxidation and degradation and its relationship to the photochemical formation of ozone and hydroxyl radicals. Here, we have looked in some detail at the incremental responses of hydroxyl radicals to incremental additions of a range of organic compounds under conditions appropriate to the background atmosphere. Most of the time, with most organic compounds and most chemical mechanisms, incremental additions of an organic compound led to depletion of hydroxyl radical concentrations. The chemical mechanisms studied demonstrated increasingly negative incremental hydroxyl radical reactivities with increasing carbon numbers for the alkanes ethane, propane and n-butane. Hydroxyl radical incremental reactivities for the simple alkenes, ethylene and propylene, were reasonably consistent across the chemical mechanisms studied. However, this consistent representation did not extend to trans but-2-ene, where reactivity estimates spanned a range of a factor of five. Incremental reactivities were reasonably well-defined for isoprene which was encouraging in view of its importance to background tropospheric chemistry. The most serious discrepancies emerging from this study were found with the aromatics toluene and o-xylene, and with the Master Chemical Mechanism and these are discussed in some detail.

scholarly journals The community atmospheric chemistry box model CAABA/MECCA-4.0

2019 ◽  
Vol 12 (4) ◽  
pp. 1365-1385 ◽  
Author(s):  
Rolf Sander ◽  
Andreas Baumgaertner ◽  
David Cabrera-Perez ◽  
Franziska Frank ◽  
Sergey Gromov ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Box Model ◽  
Chemical Mechanism ◽  
Chemical Mechanisms ◽  
Community Model ◽  
Volatile Organic ◽  
Master Chemical Mechanism ◽  
New Feature ◽  
User Friendly ◽  
Skeletal Mechanism

Abstract. We present version 4.0 of the atmospheric chemistry box model CAABA/MECCA that now includes a number of new features: (i) skeletal mechanism reduction, (ii) the Mainz Organic Mechanism (MOM) chemical mechanism for volatile organic compounds, (iii) an option to include reactions from the Master Chemical Mechanism (MCM) and other chemical mechanisms, (iv) updated isotope tagging, and (v) improved and new photolysis modules (JVAL, RADJIMT, DISSOC). Further, when MECCA is connected to a global model, the new feature of coexisting multiple chemistry mechanisms (PolyMECCA/CHEMGLUE) can be used. Additional changes have been implemented to make the code more user-friendly and to facilitate the analysis of the model results. Like earlier versions, CAABA/MECCA-4.0 is a community model published under the GNU General Public License.

scholarly journals Yields of oxidized volatile organic compounds during the OH radical initiated oxidation of isoprene, methyl vinyl ketone, and methacrolein under high-NO<sub>x</sub> conditions

2011 ◽  
Vol 11 (21) ◽  
pp. 10779-10790 ◽  
Author(s):  
M. M. Galloway ◽  
A. J. Huisman ◽  
L. D. Yee ◽  
A. W. H. Chan ◽  
C. L. Loza ◽  
...  
Keyword(s):  
Secondary Production ◽  
First Generation ◽  
Vinyl Ketone ◽  
Methyl Vinyl Ketone ◽  
Chemical Mechanism ◽  
Total Production ◽  
Production Term ◽  
Methyl Vinyl ◽  
Chemical Mechanisms ◽  
Master Chemical Mechanism

Abstract. We present first-generation and total production yields of glyoxal, methylglyoxal, glycolaldehyde, and hydroxyacetone from the oxidation of isoprene, methyl vinyl ketone (MVK), and methacrolein (MACR) with OH under high NOx conditions. Several of these first-generation yields are not included in commonly used chemical mechanisms, such as the Leeds Master Chemical Mechanism (MCM) v. 3.2. The first-generation yield of glyoxal from isoprene was determined to be 2.1 (±0.6)%. Inclusion of first-generation production of glyoxal, glycolaldehyde and hydroxyacetone from isoprene greatly improves performance of an MCM based model during the initial part of the experiments. In order to further improve performance of the MCM based model, higher generation glyoxal production was reduced by lowering the first-generation yield of glyoxal from C5 hydroxycarbonyls. The results suggest that glyoxal production from reaction of OH with isoprene under high NOx conditions can be approximated by inclusion of a first-generation production term together with secondary production only via glycolaldehyde. Analogously, methylglyoxal production can be approximated by a first-generation production term from isoprene, and secondary production via MVK, MACR and hydroxyacetone. The first-generation yields reported here correspond to less than 5% of the total oxidized yield from isoprene and thus only have a small effect on the fate of isoprene. However, due to the abundance of isoprene, the combination of first-generation yields and reduced higher generation production of glyoxal from C5 hydroxycarbonyls is important for models that include the production of the small organic molecules from isoprene.

Interactions and implications of halogens and VOCs on tropospheric oxidant cycles in the remote atmosphere

2020 ◽  
Author(s):  
Eric C. Apel
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Model Development ◽  
Tropospheric Chemistry ◽  
Chemical Mechanism ◽  
Chemical Production ◽  
Four Seasons ◽  
The Pacific ◽  
Volatile Organic ◽  
Remote Troposphere

&lt;p&gt;Reactive halogens have wide-ranging consequences on tropospheric chemistry including ozone destruction, HOx and NOx partitioning, oxidization of volatile organic compounds (VOCs) and initiation of new particle formation. Of particular note and importance, the tropospheric Ox loss due to halogens is estimated to be between 10-20% globally, and up to 50% in some local marine environments. In this work, we include a state-of-the-art coupled halogen and VOCs chemical mechanism into the CAM-Chem global model. Complementing the model development and providing the opportunity to test the model are recent results from the NASA Atmospheric Tomography (ATom) experiment. &amp;#160;ATom was conducted with a heavily instrumented NASA DC-8 aircraft over the course of two and a half years, transecting the lengths of the Pacific and Atlantic Oceans during four seasons, constantly profiling from the surface (200 m) to the upper troposphere/lower stratosphere (12000 m). The ATom payload included instruments that measured both inorganic halogens and organic halogen-containing very short-lived substances (VSLS), as well as those that measured additional volatile organic compounds (VOCs), including hydrocarbons and oxygenated VOCs (OVOCs), both of which react with halogens. Modeled BrO is sensitive to the inclusion of reactions between Br and OVOCs, particularly the aldehydes, which rapidly convert Br to HBr, a far less reactive form of Br&lt;sub&gt;y&lt;/sub&gt;. These reactions can have large implications in the remote troposphere where the ATom measurements have revealed significant emissions and chemical production of low molecular weight aldehydes over the remote marine environment. A version of CAM-chem, updated to include aldehyde emissions from the ocean to close the gap between models and measurements, is used in these analyses. Comparisons between measured and modeled halogen containing species, both organic and inorganic, is presented along with a summary of the implications of our findings on the overall budgets of tropospheric halogens and ozone.&lt;/p&gt;

scholarly journals Protocol for the development of the Master Chemical Mechanism, MCM v3 (Part A): tropospheric degradation of non-aromatic volatile organic compounds

2002 ◽  
Vol 2 (6) ◽  
pp. 1847-1903 ◽  
Author(s):  
S. M. Saunders ◽  
M. E. Jenkin ◽  
R. G. Derwent ◽  
M. J. Pilling
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Good Description ◽  
Field Studies ◽  
Companion Paper ◽  
Chemical Mechanism ◽  
North West ◽  
Radical Intermediates ◽  
Volatile Organic ◽  
Master Chemical Mechanism

Abstract. Kinetic and mechanistic data relevant to the tropospheric degradation of volatile organic compounds (VOC), and the production of secondary pollutants, have previously been used to define a protocol which underpinned the construction of a near-explicit Master Chemical Mechanism. In this paper, an update to the previous protocol is presented, which has been used to define degradation schemes for 107 non-aromatic VOC as part of version 3 of the Master Chemical Mechanism (MCM v3). The treatment of 18 aromatic VOC is described in a companion paper. The protocol is divided into a series of subsections describing initiation reactions, the reactions of the radical intermediates and the further degradation of first and subsequent generation products. Emphasis is placed on updating the previous information, and outlining the methodology which is specifically applicable to VOC not considered previously (e.g. a- and b-pinene). The present protocol aims to take into consideration work available in the open literature up to the beginning of 2001, and some other studies known by the authors which were under review at the time. Application of MCM v3 in appropriate box models indicates that the representation of isoprene degradation provides a good description of the speciated distribution of oxygenated organic products observed in reported field studies where isoprene was the dominant emitted hydrocarbon, and that the a-pinene degradation chemistry provides a good description of the time dependence of key gas phase species in a-pinene/NOX photo-oxidation experiments carried out in the European Photoreactor (EUPHORE). Photochemical Ozone Creation Potentials (POCP) have been calculated for the 106 non-aromatic non-methane VOC in MCM v3 for idealised conditions appropriate to north-west Europe, using a photochemical trajectory model. The POCP values provide a measure of the relative ozone forming abilities of the VOC. Where applicable, the values are compared with those calculated with previous versions of the MCM.

scholarly journals Yields of oxidized volatile organic compounds during the OH radical initiated oxidation of isoprene, methyl vinyl ketone, and methacrolein under high–NO<sub>x</sub> conditions

2011 ◽  
Vol 11 (4) ◽  
pp. 10693-10720 ◽  
Author(s):  
M. M. Galloway ◽  
A. J. Huisman ◽  
L. D. Yee ◽  
A. W. H. Chan ◽  
C. L. Loza ◽  
...  
Keyword(s):  
Secondary Production ◽  
First Generation ◽  
Vinyl Ketone ◽  
Methyl Vinyl Ketone ◽  
Chemical Mechanism ◽  
Total Production ◽  
Production Term ◽  
Methyl Vinyl ◽  
Chemical Mechanisms ◽  
Master Chemical Mechanism

Abstract. We present first-generation and total production yields of glyoxal, methylglyoxal, glycolaldehyde, and hydroxyacetone from the oxidation of isoprene, methyl vinyl ketone (MVK), and methacrolein (MACR) with OH under high NOx conditions. Several of these first-generation yields are not included in commonly used chemical mechanisms, such as the Leeds Master Chemical Mechanism (MCM) v. 3.1. Inclusion of first-generation production of glyoxal, glycolaldehyde and hydroxyacetone from isoprene and methylglyoxal from MACR greatly improves performance of an MCM based model during the initial part of the experiments. In order to further improve performance of the MCM based model, higher generation glyoxal production was reduced by lowering the first-generation yield of glyoxal from C5 carbonyls. The results suggest that glyoxal production from reaction of OH with isoprene under high NOx conditions can be approximated by inclusion of a first-generation production term together with secondary production only via glycolaldehyde. Analogously, methylglyoxal production can be approximated by a first-generation production term from isoprene, and secondary production via MVK, MACR and hydroxyacetone. The first-generation yields reported here correspond to less than 5% of the total oxidized yield from isoprene and thus only have a small effect on the fate of isoprene. However, due to the abundance of isoprene, the combination of first-generation yields and reduced higher generation production of glyoxal from C5 carbonyls is important for models which include the production of the small organic molecules from isoprene.

scholarly journals Protocol for the development of the Master Chemical Mechanism, MCM v3 (Part B): tropospheric degradation of aromatic volatile organic compounds

2002 ◽  
Vol 2 (6) ◽  
pp. 1905-1938 ◽  
Author(s):  
M. E. Jenkin ◽  
S. M. Saunders ◽  
V. Wagner ◽  
M. J. Pilling
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
First Generation ◽  
Companion Paper ◽  
Chemical Mechanism ◽  
Subsequent Generation ◽  
North West ◽  
Volatile Organic ◽  
Master Chemical Mechanism ◽  
Photochemical Ozone

Abstract. Kinetic and mechanistic data relevant to the tropospheric degradation of aromatic volatile organic compounds (VOC) have been used to define a mechanism development protocol, which has been used to construct degradation schemes for 18 aromatic VOC as part of version 3 of the Master Chemical Mechanism (MCM v3). This is complementary to the treatment of 107 non-aromatic VOC, presented in a companion paper. The protocol is divided into a series of subsections describing initiation reactions, the degradation chemistry to first generation products via a number of competitive routes, and the further degradation of first and subsequent generation products. Emphasis is placed on describing where the treatment differs from that applied to the non-aromatic VOC. The protocol is based on work available in the open literature up to the beginning of 2001, and some other studies known by the authors which were under review at the time. Photochemical Ozone Creation Potentials (POCP) have been calculated for the 18 aromatic VOC in MCM v3 for idealised conditions appropriate to north-west Europe, using a photochemical trajectory model. The POCP values provide a measure of the relative ozone forming abilities of the VOC. These show distinct differences from POCP values calculated previously for the aromatics, using earlier versions of the MCM, and reasons for these differences are discussed.

scholarly journals Measurement of isoprene nitrates by GCMS

2016 ◽  
Author(s):  
Graham P. Mills ◽  
Glyn D. Hiatt-Gipson ◽  
Sean P. Bew ◽  
Claire E. Reeves
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Hydroxyl Radical ◽  
Chemical Mechanism ◽  
Gas Chromatography Mass Spectrometry ◽  
Nitrate Radical ◽  
Chromatography Mass Spectrometry ◽  
Calibration Methods ◽  
Isoprene Nitrates ◽  
Master Chemical Mechanism

Abstract. An instrument based on gas chromatography/mass spectrometry (GCMS) and the associated calibration methods are described for the speciated measurements of individual isoprene nitrate isomers. Five of the primary isoprene nitrates formed by reaction of isoprene with the hydroxyl radical (OH) in the Master Chemical Mechanism are identified using known isomers on two column phases, and are fully separated on the Rtx-200 column. Three primary isoprene nitrates from the reaction of isoprene with the nitrate radical (NO3) are identified after synthesis from the already identified analogous hydroxy nitrate.

scholarly journals Protocol for the development of the Master Chemical Mechanism, MCM v3 (Part B): tropospheric degradation of aromatic volatile organic compounds

2003 ◽  
Vol 3 (1) ◽  
pp. 181-193 ◽  
Author(s):  
M. E. Jenkin ◽  
S. M. Saunders ◽  
V. Wagner ◽  
M. J. Pilling
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
First Generation ◽  
Companion Paper ◽  
Chemical Mechanism ◽  
Subsequent Generation ◽  
North West ◽  
Volatile Organic ◽  
Master Chemical Mechanism ◽  
Photochemical Ozone

Abstract. Kinetic and mechanistic data relevant to the tropospheric degradation of aromatic volatile organic compounds (VOC) have been used to define a mechanism development protocol, which has been used to construct degradation schemes for 18 aromatic VOC as part of version 3 of the Master Chemical Mechanism (MCM v3). This is complementary to the treatment of 107 non-aromatic VOC, presented in a companion paper. The protocol is divided into a series of subsections describing initiation reactions, the degradation chemistry to first generation products via a number of competitive routes, and the further degradation of first and subsequent generation products. Emphasis is placed on describing where the treatment differs from that applied to the non-aromatic VOC. The protocol is based on work available in the open literature up to the beginning of 2001, and some other studies known by the authors which were under review at the time. Photochemical Ozone Creation Potentials (POCP) have been calculated for the 18 aromatic VOC in MCM v3 for idealised conditions appropriate to north-west Europe, using a photochemical trajectory model. The POCP values provide a measure of the relative ozone forming abilities of the VOC. These show distinct differences from POCP values calculated previously for the aromatics, using earlier versions of the MCM, and reasons for these differences are discussed.

Sign in / Sign up

Export Citation Format

Share Document