scholarly journals Atmospheric chemistry and physics in the atmosphere of a developed megacity (London): an overview of the REPARTEE experiment and its conclusions

2012 ◽  
Vol 12 (6) ◽  
pp. 3065-3114 ◽  
Author(s):  
R. M. Harrison ◽  
M. Dall'Osto ◽  
D. C. S. Beddows ◽  
A. J. Thorpe ◽  
W. J. Bloss ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Urban Atmosphere ◽  
Trace Gas ◽  
Chemical Components ◽  
Chemical Transformations ◽  
Specific Chemical ◽  
Gas Dispersion ◽  
Wide Range

Abstract. The REgents PARk and Tower Environmental Experiment (REPARTEE) comprised two campaigns in London in October 2006 and October/November 2007. The experiment design involved measurements at a heavily trafficked roadside site, two urban background sites and an elevated site at 160–190 m above ground on the BT Tower, supplemented in the second campaign by Doppler lidar measurements of atmospheric vertical structure. A wide range of measurements of airborne particle physical metrics and chemical composition were made as well as measurements of a considerable range of gas phase species and the fluxes of both particulate and gas phase substances. Significant findings include (a) demonstration of the evaporation of traffic-generated nanoparticles during both horizontal and vertical atmospheric transport; (b) generation of a large base of information on the fluxes of nanoparticles, accumulation mode particles and specific chemical components of the aerosol and a range of gas phase species, as well as the elucidation of key processes and comparison with emissions inventories; (c) quantification of vertical gradients in selected aerosol and trace gas species which has demonstrated the important role of regional transport in influencing concentrations of sulphate, nitrate and secondary organic compounds within the atmosphere of London; (d) generation of new data on the atmospheric structure and turbulence above London, including the estimation of mixed layer depths; (e) provision of new data on trace gas dispersion in the urban atmosphere through the release of purposeful tracers; (f) the determination of spatial differences in aerosol particle size distributions and their interpretation in terms of sources and physico-chemical transformations; (g) studies of the nocturnal oxidation of nitrogen oxides and of the diurnal behaviour of nitrate aerosol in the urban atmosphere, and (h) new information on the chemical composition and source apportionment of particulate matter size fractions in the atmosphere of London derived both from bulk chemical analysis and aerosol mass spectrometry with two instrument types.

scholarly journals Atmospheric chemistry and physics in the atmosphere of a developed megacity (London): an overview of the REPARTEE experiment and its conclusions

2011 ◽  
Vol 11 (11) ◽  
pp. 30145-30271 ◽  
Author(s):  
R. M. Harrison ◽  
M. Dall'Osto ◽  
D. C. S. Beddows ◽  
A. J. Thorpe ◽  
W. J. Bloss ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Urban Atmosphere ◽  
Trace Gas ◽  
Chemical Components ◽  
Chemical Transformations ◽  
Specific Chemical ◽  
Gas Dispersion ◽  
Wide Range

Abstract. The Regents Park and Tower Environmental Experiment (REPARTEE) comprised two campaigns in London in October 2006 and October/November 2007. The experiment design involved measurements at a heavily trafficked roadside site, two urban background sites and an elevated site at 160–190 m above ground on the BT Tower, supplemented in the second campaign by Doppler lidar measurements of atmospheric vertical structure. A wide range of measurements of airborne particle physical metrics and chemical composition were made as well as measurements of a considerable range of gas phase species and the fluxes of both particulate and gas phase substances. Significant findings include (a) demonstration of the evaporation of traffic-generated nanoparticles during both horizontal and vertical atmospheric transport; (b) generation of a large base of information on the fluxes of nanoparticles, accumulation mode particles and specific chemical components of the aerosol and a range of gas phase species, as well as the elucidation of key processes and comparison with emissions inventories; (c) quantification of vertical gradients in selected aerosol and trace gas species which has demonstrated the important role of regional transport in influencing concentrations of sulphate, nitrate and secondary organic compounds within the atmosphere of London; (d) generation of new data on the atmospheric structure and turbulence above London, including the estimation of mixed layer depths; (e) provision of new data on trace gas dispersion in the urban atmosphere through the release of purposeful tracers; (f) the determination of spatial differences in aerosol particle size distributions and their interpretation in terms of sources and physico-chemical transformations; (g) studies of the nocturnal oxidation of nitrogen oxides and of the diurnal behaviour of nitrate aerosol in the urban atmosphere, and (h) new information on the chemical composition and source apportionment of particulate matter size fractions in the atmosphere of London derived both from bulk chemical analysis and aerosol mass spectrometry with two instrument types.

scholarly journals Phytochemical Constituents Propolis Flavonoid, Immunological Enhancement, Anti-porcine Parvovirus Activities of isolated from the Propolis

2020 ◽  
Author(s):  
Xia Ma ◽  
zhenhuan guo ◽  
zhiqiang zhang ◽  
xianghui li ◽  
yizhou lv ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Underlying Mechanism ◽  
Chemical Components ◽  
Porcine Parvovirus ◽  
Wide Range ◽  
Inhibition Antibody ◽  
Antibody Titers ◽  
Phytochemical Constituents ◽  
Immune Enhancement ◽  
Negative Ionization

Propolis was widely used in health preservation and disease healing, it contains many ingredients. The previous study had been revealed that the propolis has a wide range of efficacy, such as antiviral, immune enhancement, anti-inflammatory and so on, but its antiviral components and underlying mechanism of action remain unknown. In this study, we investigated the chemical composition, and anti-PPV and immunological enhancement of Propolis Flavonoid(PF). Chemical composition of PF was distinguished by UPLC-Q/TOF-MS/MS analysis.The presence and characterized of 26 major components was distinguished in negative ionization modes.To evaluate the effects of PF used as adjuvant on the immune response porcine parvovirus (PPV). Thirty Landrace-Yorkshire hybrid sows were randomly assigned to 3 groups, and the sows in adjuvant groups were intramuscular injected PPV vaccine with 2.0 mL PF adjuvant (PA), oilemulsion adjuvant (OA), respectively. After that, serum hemagglutination inhibition antibody titers, IgM and IgG subclasses, eripheral lymphocyte proliferation activity, and concentrations of cytokines were measured. Results indicated an enhancing effect of PA on IgM, IL-2, IL-4, IFN-γ and the IgG subclass responses. These findings suggested that PA could significantly enhance the immune responses. Furthermore, we screened the chemical components the effective of anti-PPV, Ferulic acid have an excellently anti-PPV effective.

scholarly journals Chemical composition of nanoparticles from α-pinene nucleation and the influence of isoprene and relative humidity at low temperature

2021 ◽  
Author(s):  
Lucía Caudillo ◽  
Birte Rörup ◽  
Martin Heinritzi ◽  
Guillaume Marie ◽  
Mario Simon ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Relative Humidity ◽  
Gas Phase ◽  
Particle Formation ◽  
Oxidation Products ◽  
Mixed System ◽  
Chemical Information ◽  
New Particle Formation ◽  
Detection Scheme ◽  
Wide Range

Abstract. New Particle Formation (NPF) from biogenic organic precursors is an important atmospheric process. One of the major species is α-pinene, which upon oxidation, can form a suite of products covering a wide range of volatilities. A fraction of the oxidation products is termed Highly Oxygenated Organic Molecules (HOM). These play a crucial role for nucleation and the formation of Secondary Organic Aerosol (SOA). However, measuring the composition of newly formed particles is challenging due to their very small mass. Here, we present results on the gas and particle phase chemical composition for a system where α-pinene was oxidized by ozone, and for a mixed system of α-pinene and isoprene, respectively. The measurements took place at the CERN Cosmics Leaving Outdoor Droplets (CLOUD) chamber at temperatures between −50 °C and −30 °C and at low and high relative humidity (20 % and 60 to 100 % RH). These conditions were chosen to simulate pure biogenic new particle formation in the upper free troposphere. The particle chemical composition was analyzed by the Thermal Desorption-Differential Mobility Analyzer (TD-DMA) coupled to a nitrate chemical ionization time-of-flight mass spectrometer. This instrument can be used for particle and gas phase measurements using the same ionization and detection scheme. Our measurements revealed the presence of C8-10 monomers and C18-20 dimers as the major compounds in the particles (diameter up to ~ 100 nm). Particularly, for the system with isoprene added, C5 (C5H10O5-7) and C15 compounds (C15H24O5-10) are detected. This observation is consistent with the previously observed formation of such compounds in the gas phase. However, although the C5 and C15 compounds do not easily nucleate, our measurements indicate that they can still contribute to the particle growth at free tropospheric conditions. For the experiments reported here, most likely isoprene might enhance growth at particle sizes larger than 15 nm. Besides the chemical information regarding the HOM formation for the α-pinene (plus isoprene) system, we report on the nucleation rates measured at 1.7 nm and found that the lower J1.7nm values compared with previous studies are very likely due to the higher α-pinene and ozone mixing ratios used in the present study

scholarly journals Technical note: A new comprehensive SCAVenging submodel for global atmospheric chemistry modelling

2006 ◽  
Vol 6 (3) ◽  
pp. 565-574 ◽  
Author(s):  
H. Tost ◽  
P. Jöckel ◽  
A. Kerkweg ◽  
R. Sander ◽  
J. Lelieveld
Keyword(s):  
Chemical Composition ◽  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Aerosol Particles ◽  
Trace Gases ◽  
Precipitation Chemistry ◽  
Technical Note ◽  
Transport Processes ◽  
New Method

Abstract. We present the new scavenging scheme SCAV, simulating the removal of trace gases and aerosol particles by clouds and precipitation in global atmospheric chemistry models. The scheme is quite flexible and can be used for various purposes, e.g. long term chemistry simulations as well as detailed cloud and precipitation chemistry calculations. The presence of clouds can substantially change the chemical composition of the atmosphere. We present a new method of mechanistically coupling gas phase, aerosol, cloud and precipitation chemistry, which enables studies of feedbacks between multiphase chemistry and transport processes.

scholarly journals Chemical composition of nanoparticles from <i>α</i>-pinene nucleation and the influence of isoprene and relative humidity at low temperature

2021 ◽  
Vol 21 (22) ◽  
pp. 17099-17114
Author(s):  
Lucía Caudillo ◽  
Birte Rörup ◽  
Martin Heinritzi ◽  
Guillaume Marie ◽  
Mario Simon ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Gas Phase ◽  
Experimental Studies ◽  
Particle Growth ◽  
Oxidation Products ◽  
Detection Scheme ◽  
Phase Measurements ◽  
Mixing Ratios ◽  
Wide Range ◽  
Low Mass

Abstract. Biogenic organic precursors play an important role in atmospheric new particle formation (NPF). One of the major precursor species is α-pinene, which upon oxidation can form a suite of products covering a wide range of volatilities. Highly oxygenated organic molecules (HOMs) comprise a fraction of the oxidation products formed. While it is known that HOMs contribute to secondary organic aerosol (SOA) formation, including NPF, they have not been well studied in newly formed particles due to their very low mass concentrations. Here we present gas- and particle-phase chemical composition data from experimental studies of α-pinene oxidation, including in the presence of isoprene, at temperatures (−50 and −30 ∘C) and relative humidities (20 % and 60 %) relevant in the upper free troposphere. The measurements took place at the CERN Cosmics Leaving Outdoor Droplets (CLOUD) chamber. The particle chemical composition was analyzed by a thermal desorption differential mobility analyzer (TD-DMA) coupled to a nitrate chemical ionization–atmospheric pressure interface–time-of-flight (CI-APi-TOF) mass spectrometer. CI-APi-TOF was used for particle- and gas-phase measurements, applying the same ionization and detection scheme. Our measurements revealed the presence of C8−10 monomers and C18−20 dimers as the major compounds in the particles (diameter up to ∼ 100 nm). Particularly, for the system with isoprene added, C5 (C5H10O5−7) and C15 compounds (C15H24O5−10) were detected. This observation is consistent with the previously observed formation of such compounds in the gas phase. However, although the C5 and C15 compounds do not easily nucleate, our measurements indicate that they can still contribute to the particle growth at free tropospheric conditions. For the experiments reported here, most likely isoprene oxidation products enhance the growth of particles larger than 15 nm. Additionally, we report on the nucleation rates measured at 1.7 nm (J1.7 nm) and compared with previous studies, we found lower J1.7 nm values, very likely due to the higher α-pinene and ozone mixing ratios used in the present study.

scholarly journals Towards an advanced atmospheric chemistry-enabled ESM with dynamic land surface processes: Part I - Linking LPJ-GUESS (v4.0) with EMAC modelling system (v2.53)

2018 ◽  
Author(s):  
Matthew Forrest ◽  
Holger Tost ◽  
Jos Lelieveld ◽  
Thomas Hickler
Keyword(s):  
Atmospheric Chemistry ◽  
Land Surface ◽  
General Circulation ◽  
Trace Gas ◽  
Earth System ◽  
Dynamic Global Vegetation Model ◽  
Gas Emissions ◽  
Trace Gas Emissions ◽  
Wide Range ◽  
Global Vegetation

Abstract. Earth System Models (ESMs) are invaluable tools that have emerged from decades of research modelling the earth system. Central to this development has been the coupling of previously separate model types, such as ocean, atmospheric and vegetation models, to provide interactive feedbacks between these earth system components. Here we present the initial steps of coupling LPJ-GUESS, a dynamic global vegetation model, to EMAC, an atmospheric chemistry enabled atmosphere-ocean general circulation model. The LPJ-GUESS framework includes a comparatively detailed tree-individual based model of vegetation dynamics, a crop and managed-land scheme, a nitrogen cycle and a choice of fire models; and hence represents many important terrestrial biosphere processes and provides a wide range of prognostic trace gas emissions from vegetation, soil and fire. When development is complete, these trace gas emissions will form key inputs to the state-of-art atmospheric chemistry representations in EMAC allowing for bi-directional chemical interactions of the surface with the atmosphere. % At this point, the full model will be a complete ESM with a fully prognostic land surface and detailed atmospheric chemistry, and will become a powerful tool for investigating land-atmosphere interactions such as: the methane cycle and lifetime and the atmospheric chemistry of reduced carbon; fire effects and feedbacks; future nitrogen deposition rates and fertilisation scenarios; ozone damage to plants; and the contribution of biogenic volatile organic compounds to aerosol load and, via cloud condensation nuclei activation, to cloud formation (e.g., bioprecipitation cycles). Initial results show that the one-way, on-line coupling from EMAC to LPJ-GUESS gives a good description of the global vegetation patterns and reasonable agreement with a suite of remote sensing datasets.

scholarly journals Modeling interfacial liquid layers on environmental ices

2011 ◽  
Vol 11 (18) ◽  
pp. 9971-9982 ◽  
Author(s):  
M. H. Kuo ◽  
S. G. Moussa ◽  
V. F. McNeill
Keyword(s):  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Low Temperatures ◽  
Freezing Point ◽  
Triple Junctions ◽  
Ice Crystal ◽  
Freezing Point Depression ◽  
Chemical Interactions ◽  
Interfacial Layers ◽  
Wide Range

Abstract. Interfacial layers on ice significantly influence air-ice chemical interactions. In solute-containing aqueous systems, a liquid brine may form upon freezing due to the exclusion of impurities from the ice crystal lattice coupled with freezing point depression in the concentrated brine. The brine may be segregated to the air-ice interface where it creates a surface layer, in micropockets, or at grain boundaries or triple junctions. We present a model for brines and their associated liquid layers in environmental ice systems that is valid over a wide range of temperatures and solute concentrations. The model is derived from fundamental equlibrium thermodynamics and takes into account nonideal solution behavior in the brine, partitioning of the solute into the ice matrix, and equilibration between the brine and the gas phase for volatile solutes. We find that these phenomena are important to consider when modeling brines in environmental ices, especially at low temperatures. We demonstrate its application for environmentally important volatile and nonvolatile solutes including NaCl, HCl, and HNO3. The model is compared to existing models and experimental data from literature where available. We also identify environmentally relevant regimes where brine is not predicted to exist, but the QLL may significantly impact air-ice chemical interactions. This model can be used to improve the representation of air-ice chemical interactions in polar atmospheric chemistry models.

scholarly journals CHEMICAL CONVERSIONS OF REDUCED CARBON COMPOUNDS AND NITROGEN OXIDES IN THE CRAMPED AERODYNAMIC CONDITIONS OF THE URBAN ATMOSPHERE

2021 ◽  
Vol 57 ◽  
pp. 111-117
Author(s):  
Vadim A. Zaytsev ◽  
Keyword(s):  
Nitrogen Oxides ◽  
Reaction Rates ◽  
Urban Atmosphere ◽  
Chemical Transformations ◽  
Stiff System ◽  
Rosenbrock Method ◽  
Wide Range ◽  
Carbon Compounds ◽  
High Concentrations ◽  
Kinetics Of

The kinetics of chemical transformations of the most significant pollutants in the cramped aerodynamic conditions of the urban atmosphere is considered, i.e. in the gaps between rows of wide buildings with significant height. High concentrations created in those areas lead to sufficiently high values of reaction rates. The process is described by a stiff system of differential equations, the solution of which is performed by Rosenbrock method. The effect of reduced carbon compounds and nitrogen oxides in a wide range of their concentrations on the rate of formation of a highly toxic secondary pollutant is investigated. In the course of numerical experiments, conditions are determined that correspond to its maximum value. In that case, the transfer of substances from the reaction zone does not have time to occur.

scholarly journals Technical note: A new comprehensive SCAVenging submodel for global atmospheric chemistry modelling

2005 ◽  
Vol 5 (6) ◽  
pp. 11157-11181 ◽  
Author(s):  
H. Tost ◽  
P. Jöckel ◽  
A. Kerkweg ◽  
R. Sander ◽  
J. Lelieveld
Keyword(s):  
Chemical Composition ◽  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Aerosol Particles ◽  
Trace Gases ◽  
Precipitation Chemistry ◽  
Technical Note ◽  
Transport Processes ◽  
New Method

Abstract. We present the new scavenging scheme SCAV, simulating the removal of trace gases and aerosol particles by clouds and precipitation in global atmospheric chemistry models. The scheme is quite flexible and can be used for various purposes, e.g. long term chemistry simulations as well as detailed cloud and precipitation chemistry calculations. The presence of clouds can substantially change the chemical composition of the atmosphere. We present a new method of mechanistically coupling gas phase, aerosol, cloud and precipitation chemistry, which enables studies of feedbacks between multiphase chemistry and transport processes.

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