scholarly journals 100 Years of Progress in Gas-Phase Atmospheric Chemistry Research

2019 ◽  
Vol 59 ◽  
pp. 10.1-10.52 ◽  
Author(s):  
T. J. Wallington ◽  
J. H. Seinfeld ◽  
J. R. Barker
Keyword(s):  
Climate Change ◽  
Acid Rain ◽  
Gas Phase ◽  
Organic Compounds ◽  
Atmospheric Chemistry ◽  
Reaction Rates ◽  
Tropospheric Chemistry ◽  
Oxides Of Nitrogen ◽  
Chemical Reaction Rates

Abstract Remarkable progress has occurred over the last 100 years in our understanding of atmospheric chemical composition, stratospheric and tropospheric chemistry, urban air pollution, acid rain, and the formation of airborne particles from gas-phase chemistry. Much of this progress was associated with the developing understanding of the formation and role of ozone and of the oxides of nitrogen, NO and NO2, in the stratosphere and troposphere. The chemistry of the stratosphere, emerging from the pioneering work of Chapman in 1931, was followed by the discovery of catalytic ozone cycles, ozone destruction by chlorofluorocarbons, and the polar ozone holes, work honored by the 1995 Nobel Prize in Chemistry awarded to Crutzen, Rowland, and Molina. Foundations for the modern understanding of tropospheric chemistry were laid in the 1950s and 1960s, stimulated by the eye-stinging smog in Los Angeles. The importance of the hydroxyl (OH) radical and its relationship to the oxides of nitrogen (NO and NO2) emerged. The chemical processes leading to acid rain were elucidated. The atmosphere contains an immense number of gas-phase organic compounds, a result of emissions from plants and animals, natural and anthropogenic combustion processes, emissions from oceans, and from the atmospheric oxidation of organics emitted into the atmosphere. Organic atmospheric particulate matter arises largely as gas-phase organic compounds undergo oxidation to yield low-volatility products that condense into the particle phase. A hundred years ago, quantitative theories of chemical reaction rates were nonexistent. Today, comprehensive computer codes are available for performing detailed calculations of chemical reaction rates and mechanisms for atmospheric reactions. Understanding the future role of atmospheric chemistry in climate change and, in turn, the impact of climate change on atmospheric chemistry, will be critical to developing effective policies to protect the planet.

scholarly journals Do organic surface films on sea salt aerosols influence atmospheric chemistry? – a model study

2007 ◽  
Vol 7 (21) ◽  
pp. 5555-5567 ◽  
Author(s):  
L. Smoydzin ◽  
R. von Glasow
Keyword(s):  
Mass Transfer ◽  
Liquid Phase ◽  
Gas Phase ◽  
Aqueous Phase ◽  
Atmospheric Chemistry ◽  
Organic Coating ◽  
Sea Salt ◽  
Tropospheric Chemistry ◽  
Special Focus ◽  
Sea Salt Aerosols

Abstract. Organic material from the ocean's surface can be incorporated into sea salt aerosol particles often producing a surface film on the aerosol. Such an organic coating can reduce the mass transfer between the gas phase and the aerosol phase influencing sea salt chemistry in the marine atmosphere. To investigate these effects and their importance for the marine boundary layer (MBL) we used the one-dimensional numerical model MISTRA. We considered the uncertainties regarding the magnitude of uptake reduction, the concentrations of organic compounds in sea salt aerosols and the oxidation rate of the organics to analyse the possible influence of organic surfactants on gas and liquid phase chemistry with a special focus on halogen chemistry. By assuming destruction rates for the organic coating based on laboratory measurements we get a rapid destruction of the organic monolayer within the first meters of the MBL. Larger organic initial concentrations lead to a longer lifetime of the coating but lead also to an unrealistically strong decrease of O3 concentrations as the organic film is destroyed by reaction with O3. The lifetime of the film is increased by assuming smaller reactive uptake coefficients for O3 or by assuming that a part of the organic surfactants react with OH. With regard to tropospheric chemistry we found that gas phase concentrations for chlorine and bromine species decreased due to the decreased mass transfer between gas phase and aerosol phase. Aqueous phase chlorine concentrations also decreased but aqueous phase bromine concentrations increased. Differences for gas phase concentrations are in general smaller than for liquid phase concentrations. The effect on gas phase NO2 or NO is very small (reduction less than 5%) whereas liquid phase NO2 concentrations increased in some cases by nearly 100%. We list suggestions for further laboratory studies which are needed for improved model studies.

scholarly journals Introductory lecture: atmospheric chemistry in the Anthropocene

2017 ◽  
Vol 200 ◽  
pp. 11-58 ◽  
Author(s):  
Barbara J. Finlayson-Pitts
Keyword(s):  
Human Health ◽  
Atmospheric Chemistry ◽  
Industrial Revolution ◽  
Anthropogenic Activities ◽  
Cost Effective ◽  
Global Scale ◽  
Tropospheric Chemistry ◽  
Atmospheric Composition ◽  
Oxides Of Nitrogen ◽  
Neonicotinoid Pesticides

The term “Anthropocene” was coined by Professor Paul Crutzen in 2000 to describe an unprecedented era in which anthropogenic activities are impacting planet Earth on a global scale. Greatly increased emissions into the atmosphere, reflecting the advent of the Industrial Revolution, have caused significant changes in both the lower and upper atmosphere. Atmospheric reactions of the anthropogenic emissions and of those with biogenic compounds have significant impacts on human health, visibility, climate and weather. Two activities that have had particularly large impacts on the troposphere are fossil fuel combustion and agriculture, both associated with a burgeoning population. Emissions are also changing due to alterations in land use. This paper describes some of the tropospheric chemistry associated with the Anthropocene, with emphasis on areas having large uncertainties. These include heterogeneous chemistry such as those of oxides of nitrogen and the neonicotinoid pesticides, reactions at liquid interfaces, organic oxidations and particle formation, the role of sulfur compounds in the Anthropocene and biogenic–anthropogenic interactions. A clear and quantitative understanding of the connections between emissions, reactions, deposition and atmospheric composition is central to developing appropriate cost-effective strategies for minimizing the impacts of anthropogenic activities. The evolving nature of emissions in the Anthropocene places atmospheric chemistry at the fulcrum of determining human health and welfare in the future.

scholarly journals Partitioning Entropy with Action Mechanics: Predicting Chemical Reaction Rates and Gaseous Equilibria of Reactions of Hydrogen from Molecular Properties

Entropy ◽  
2021 ◽  
Vol 23 (8) ◽  
pp. 1056
Author(s):  
Ivan R. Kennedy ◽  
Migdat Hodzic
Keyword(s):  
Potential Energy ◽  
Maximum Entropy ◽  
Gas Phase ◽  
Chemical Reaction ◽  
Virial Theorem ◽  
Colloidal Particles ◽  
Reaction Rates ◽  
Molecular Properties ◽  
Gas Phase Reactions ◽  
Chemical Reaction Rates

Our intention is to provide easy methods for estimating entropy and chemical potentials for gas phase reactions. Clausius’ virial theorem set a basis for relating kinetic energy in a body of independent material particles to its potential energy, pointing to their complementary role with respect to the second law of maximum entropy. Based on this partitioning of thermal energy as sensible heat and also as a latent heat or field potential energy, in action mechanics we express the entropy of ideal gases as a capacity factor for enthalpy plus the configurational work to sustain the relative translational, rotational, and vibrational action. This yields algorithms for estimating chemical reaction rates and positions of equilibrium. All properties of state including entropy, work potential as Helmholtz and Gibbs energies, and activated transition state reaction rates can be estimated, using easily accessible molecular properties, such as atomic weights, bond lengths, moments of inertia, and vibrational frequencies. We conclude that the large molecular size of many enzymes may catalyze reaction rates because of their large radial inertia as colloidal particles, maximising action states by impulsive collisions. Understanding how Clausius’ virial theorem justifies partitioning between thermal and statistical properties of entropy, yielding a more complete view of the second law’s evolutionary nature and the principle of maximum entropy. The ease of performing these operations is illustrated with three important chemical gas phase reactions: the reversible dissociation of hydrogen molecules, lysis of water to hydrogen and oxygen, and the reversible formation of ammonia from nitrogen and hydrogen. Employing the ergal also introduced by Clausius to define the reversible internal work overcoming molecular interactions plus the configurational work of change in Gibbs energy, often neglected; this may provide a practical guide for managing industrial processes and risk in climate change at the global scale. The concepts developed should also have value as novel methods for the instruction of senior students.

scholarly journals Study of the factors that determine the transfer of water and organic compounds into the gas phase from aqueous solutions in a discharge with a liquid cathode

2021 ◽  
Vol 2100 (1) ◽  
pp. 012025
Author(s):  
A V Chistolinov ◽  
M A Khromov ◽  
R V Yakushin ◽  
M Kh Gadzhiev ◽  
A S Tyuftyaev
Keyword(s):  
Aqueous Solution ◽  
Free Surface ◽  
Aqueous Solutions ◽  
Gas Phase ◽  
Organic Compounds ◽  
Direct Current ◽  
Current Discharge ◽  
Liquid Cathode ◽  
Direct Current Discharge

Abstract A study was performed to investigate the transfer of organic compounds and water from an aqueous solution to the gas phase under the action of a direct current discharge, in which an aqueous solution that contains organic compounds plays the role of a cathode. The effect of the area of the free surface of a liquid in various reactors, as well as the effect of the stirring mode of a solution near the surface of a liquid on the rate of transfer of water and organic compounds under the action of a discharge of this type, have been investigated. It is shown that a change in the area of the free surface of a liquid has no significant effect on the rate of transfer of water and organic compounds from solution to the gas phase under the action of a direct current discharge with a liquid cathode. It is shown that the stirring mode and the temperature of the solution, on the contrary, have a very significant effect on the rate of nonequilibrium transfer of both water and organic compounds from solution to the gas phase under the action of a discharge with a liquid cathode.

scholarly journals Russian studies in the field of atmospheric chemistry in 2015–2018

2019 ◽  
Vol 55 (6) ◽  
pp. 66-78
Author(s):  
I. K. Larin
Keyword(s):  
Climate Change ◽  
Atmospheric Chemistry ◽  
Ozone Layer ◽  
General Assembly ◽  
International Union ◽  
Atmospheric Sciences

A brief overview of the work of Russian scientists in the field of atmospheric chemistry in 20152018, including work on the chemistry of the troposphere, the chemistry of the ozone layer and on the role of chemistry in climate change is presented. Review has been prepared in the Commission on atmospheric chemistry of the meteorology and atmospheric sciences section of the national Geophysics Committee. The report was presented and approved at the XXVII General Assembly of the International Union of Geodesy and Geophysics (IUGG) 1.

scholarly journals A fast stratospheric chemistry solver: the E4CHEM submodel for the atmospheric chemistry global circulation model EMAC

2010 ◽  
Vol 3 (1) ◽  
pp. 321-328 ◽  
Author(s):  
A. J. G. Baumgaertner ◽  
P. Jöckel ◽  
B. Steil ◽  
H. Tost ◽  
R. Sander
Keyword(s):  
Atmospheric Chemistry ◽  
General Circulation ◽  
Circulation Model ◽  
Reaction Rates ◽  
Heterogeneous Reactions ◽  
Tropospheric Chemistry ◽  
Box Model ◽  
Chemical Mechanism ◽  
Global Circulation Model ◽  
Stratospheric Chemistry

Abstract. The atmospheric chemistry general circulation model ECHAM5/MESSy (EMAC) and the atmospheric chemistry box model CAABA are extended by a computationally very efficient submodel for atmospheric chemistry, E4CHEM. It focuses on stratospheric chemistry but also includes background tropospheric chemistry. It is based on the chemistry of MAECHAM4-CHEM and is intended to serve as a simple and fast alternative to the flexible but also computationally more demanding submodel MECCA. In a model setup with E4CHEM, EMAC is now also suitable for simulations of longer time scales. The reaction mechanism contains basic O3, CH4, CO, HOx, NOx, and ClOx gas phase chemistry. In addition, E4CHEM includes optional fast routines for heterogeneous reactions on sulphate aerosols and polar stratospheric clouds (substituting the existing submodels PSC and HETCHEM), and scavenging (substituting the existing submodel SCAV). We describe the implementation of E4CHEM into the MESSy structure of CAABA and EMAC. For some species the steady state in the box model differs by up to 100% when compared to results from CAABA/MECCA due to different reaction rates. After an update of the reaction rates in E4CHEM the mixing ratios in both boxmodel and 3-D model simulations are in satisfactory agreement with the results from a simulation where MECCA with a similar chemistry scheme was employed. Finally, a comparison against a simulation with a more complex and already evaluated chemical mechanism is presented in order to discuss shortcomings associated with the simplification of the chemical mechanism.

Predictive a priori pressure-dependent kinetics

Science ◽  
2014 ◽  
Vol 346 (6214) ◽  
pp. 1212-1215 ◽  
Author(s):  
Ahren W. Jasper ◽  
Kenley M. Pelzer ◽  
James A. Miller ◽  
Eugene Kamarchik ◽  
Lawrence B. Harding ◽  
...  
Keyword(s):  
Pressure Dependence ◽  
Atmospheric Chemistry ◽  
Transition State Theory ◽  
A Priori ◽  
Reaction Rates ◽  
State Theory ◽  
Two Dimensional ◽  
Transfer Rates ◽  
Reaction Systems ◽  
Chemical Reaction Rates

The ability to predict the pressure dependence of chemical reaction rates would be a great boon to kinetic modeling of processes such as combustion and atmospheric chemistry. This pressure dependence is intimately related to the rate of collision-induced transitions in energy E and angular momentum J. We present a scheme for predicting this pressure dependence based on coupling trajectory-based determinations of moments of the E,J-resolved collisional transfer rates with the two-dimensional master equation. This completely a priori procedure provides a means for proceeding beyond the empiricism of prior work. The requisite microcanonical dissociation rates are obtained from ab initio transition state theory. Predictions for the CH4 = CH3 + H and C2H3 = C2H2 + H reaction systems are in excellent agreement with experiment.

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