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 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.

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

2003 ◽  
Vol 3 (1) ◽  
pp. 161-180 ◽  
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 Aerosol mass yields of selected biogenic volatile organic compounds – a theoretical study with nearly explicit gas-phase chemistry

2019 ◽  
Vol 19 (22) ◽  
pp. 13741-13758
Author(s):  
Carlton Xavier ◽  
Anton Rusanen ◽  
Putian Zhou ◽  
Chen Dean ◽  
Lukas Pichelstorfer ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Gas Phase ◽  
Organic Compounds ◽  
Chemical Mechanism ◽  
Biogenic Volatile Organic Compounds ◽  
Gas Phase Chemistry ◽  
Mass Load ◽  
Volatile Organic ◽  
Phase Chemistry ◽  
Good Agreement

Abstract. In this study we modeled secondary organic aerosol (SOA) mass loadings from the oxidation (by O3, OH and NO3) of five representative biogenic volatile organic compounds (BVOCs): isoprene, endocyclic bond-containing monoterpenes (α-pinene and limonene), exocyclic double-bond compound (β-pinene) and a sesquiterpene (β-caryophyllene). The simulations were designed to replicate an idealized smog chamber and oxidative flow reactors (OFRs). The Master Chemical Mechanism (MCM) together with the peroxy radical autoxidation mechanism (PRAM) were used to simulate the gas-phase chemistry. The aim of this study was to compare the potency of MCM and MCM + PRAM in predicting SOA formation. SOA yields were in good agreement with experimental values for chamber simulations when MCM + PRAM was applied, while a stand-alone MCM underpredicted the SOA yields. Compared to experimental yields, the OFR simulations using MCM + PRAM yields were in good agreement for BVOCs oxidized by both O3 and OH. On the other hand, a stand-alone MCM underpredicted the SOA mass yields. SOA yields increased with decreasing temperatures and NO concentrations and vice versa. This highlights the limitations posed when using fixed SOA yields in a majority of global and regional models. Few compounds that play a crucial role (>95 % of mass load) in contributing to SOA mass increase (using MCM + PRAM) are identified. The results further emphasized that incorporating PRAM in conjunction with MCM does improve SOA mass yield estimation.

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

<p>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.  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<sub>y</sub>. 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.</p>

scholarly journals Sources of volatile organic compounds and policy implications for regional ozone pollution control in an urban location of Nanjing, East China

2019 ◽  
Author(s):  
Qiuyue Zhao ◽  
Jun Bi ◽  
Zhenghao Ling ◽  
Qian Liu ◽  
Guofeng Shen ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Policy Implications ◽  
Chemical Mechanism ◽  
Effective Control ◽  
Urban Site ◽  
Biogenic Emissions ◽  
Industrial Emissions ◽  
Photochemical Pollution ◽  
Volatile Organic

Abstract. Understanding the composition, temporal variability, and source apportionment of volatile organic compounds (VOCs) is necessary for determining effective control measures to minimize VOCs and its related photochemical pollution. To provide a comprehensive analysis of VOC sources and their contributions to ozone (O3) formation in the Yangtze River Delta (YRD) – a region experiencing highest rates of industrial and economic development in China, we conducted a one-year sampling exercise for the first time at an urban site in Nanjing (JAES site). Alkanes were the dominant group at the JAES site, contributing ~ 53 % to the observed total VOCs, followed by aromatics (~ 17 %), acetylene (~ 17 %), and alkenes (~ 13 %). We identified seasonal variability in TVOCs with maximum and minimum concentrations in winter and summer, respectively. A morning and evening peak and a daytime trough were identified in the diurnal VOCs patterns. We identified the source apportionments of VOCs and their contributions to photochemical O3 formation using the Positive Matrix Factorization (PMF) and observation-based model together with a Master Chemical Mechanism (MCM). The PMF model identified five dominant VOC sources, with highest contributions from diesel vehicular exhausts (34 ± 5 %), followed by gasoline vehicular exhausts (27 ± 3 %), industrial emissions (19 ± 2 %), fuel evaporation (15 ± 2 %) and biogenic emissions (4 ± 1 %). The results from the OBM-MCM model simulation inferred photochemical O3 formation to be VOC-limited at the JAES site when considering both the reactivity and abundance of the individual VOC species in each source category. Further, VOCs from vehicular and industrial emissions were found to be the dominant control on O3 formation, particularly the VOC species m,p-xylene, toluene and propene, which top priorities should be given to the alleviation of photochemical smog. However, when considering the reactivity and abundance of VOC species, the contribution of biogenic emissions to O3 pollution was significantly reduced. Our results therefore highlight the need to consider both the abundance and reactivity of individual VOC species in order to develop effective control strategies to minimize photochemical pollution in Nanjing.

scholarly journals Development of a detailed chemical mechanism (MCMv3.1) for the atmospheric oxidation of aromatic hydrocarbons

2005 ◽  
Vol 5 (3) ◽  
pp. 641-664 ◽  
Author(s):  
C. Bloss ◽  
V. Wagner ◽  
M. E. Jenkin ◽  
R. Volkamer ◽  
W. J. Bloss ◽  
...  
Keyword(s):  
First Generation ◽  
Companion Paper ◽  
Chemical Mechanism ◽  
Degradation Mechanisms ◽  
Photo Oxidation ◽  
New Information ◽  
Benzene Toluene ◽  
Master Chemical Mechanism ◽  
Using Data ◽  
High Yields

Abstract. The Master Chemical Mechanism has been updated from MCMv3 to MCMv3.1 in order to take into account recent improvements in the understanding of aromatic photo-oxidation. Newly available kinetic and product data from the literature have been incorporated into the mechanism. In particular, the degradation mechanisms for hydroxyarenes have been revised following the observation of high yields of ring-retained products, and product studies of aromatic oxidation under relatively low NOx conditions have provided new information on the branching ratios to first generation products. Experiments have been carried out at the European Photoreactor (EUPHORE) to investigate key subsets of the toluene system. These results have been used to test our understanding of toluene oxidation, and, where possible, refine the degradation mechanisms. The evaluation of MCMv3 and MCMv3.1 using data on benzene, toluene, p-xylene and 1,3,5-trimethylbenzene photosmog systems is described in a companion paper, and significant model shortcomings are identified. Ideas for additional modifications to the mechanisms, and for future experiments to further our knowledge of the details of aromatic photo-oxidation are discussed.

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