Atmosphere, standard Atmospheric chemistry

NIST Atmospheric Chemistry Group http //www.cstl.nist.gov/div837/837.01/ outputs / standards / StdMat.htm... 

Other common ways of expressing abundances, particularly of solid or liquid particles, is to express them as concentrations in units of micrograms per cubic meter or nanomoles per cubic meter. For purposes of consistency, concentrations expressed in these units should be normalized to standard conditions of temperature and pressure. Because there is some confusion as to what constitutes standard conditions in atmospheric chemistry (273 K and 1.013 bar are commonly used in chemistry and physics and 293 K and 1.013 bar are used in engineering), it is important to define the standard conditions that are assumed when reporting data. This explicit definition is frequently not done. Concentrations expressed in these units can be easily converted to mixing ratios by use of the ideal gas law ... 

M. BCrauss, F.H. Mies, D. Neumann, P.S. Julienne, Application of Quantum Chemistry to Atmospheric Chemistry, National Bureau of Standards, Physical Chemistry Division, Washington, DC, 1976. 

The PRISM standard environments of COSMOS v2 will allow for different model configurations, including atmospheric chemistry. 

FIGURE 4-25a Standard deviations of mass distribution in a Gaussian plume, cry and az, given as a function of both distance downwind from a point source and Pasquill stability categories. Dispersion coefficient as used in this figure means the standard deviation of the plume width or height [L] rather than a Fickian coefficient [L2/T], (From Atmospheric Chemistry and Physics of Air Pollution, by J. H. Seinfeld. Copyright 1986, John Wiley Sons, Inc. Reprinted by permission of John Wiley Sons, Inc.)... 

DOC. 1977. Reaction rate and photochemical data for atmospheric chemistry-1977. Hampson RF Jr, Garvin D, eds. U.S. Department of Commerce, National Bureau of Standards, National Measurement Laboratory, Washington, DC, 107. 

The KPS paper stimulated research in several new directions, and ultimately spawned new fields. Many researchers, including Karplus, got interested in the development of QST of chemical reactions, and this led to accurate quantum descriptions of the H + H2 reaction [8] a decade after the KPS paper. There was also significant interest in the application of QCT methods to gas-phase reactions other than H -f- H2, and in fact this approach is now considered to be a standard research tool for studying gas-phase reaction dynamics of relevance to laser chemistry, combustion chemistry, atmospheric chemistry, and other applications. 

Further details of these processes can be found in standard textbooks on atmospheric chemistry (e.g. Finlayson-Pitts, 2000 Wayne, 2000). 

Nstp is the atmospheric molecular number density at standard temperature and pressure, i.e. 2.56 X 10 cm . This number allows one to express the concentration of a pollutant in parts per billion or parts per million this representation is often preferred in atmospheric chemistry, instead of a notation of molecules per cubic centimetre. 

Timothy J. Wallington was born and educated in England. He received B.A. (1981), M.A. (1982), D.Phil (1983), and D.Sc. (2007) degrees from Corpus Christi College, Oxford University where he studied with Professor R. P. Wayne and Dr. R. A. Cox. He has carried out extensive research on various aspects of atmospheric chemistry and the kinetics and mechanisms of many different transient atmospheric species. He carried out postgraduate research studies at the University of California, Los Angeles (1984-1986) with Professor J. N. Pitts and Dr. R. Atkinson. He was Guest Scientist at the U.S. National Bureau of Standards (1986-1987) with Dr. M. J. Kurylo. He joined the research staff at the Ford Motor Company in 1987 where he is currently a Technical Leader in the Systems Analytics and Environmental Sciences Department. 

The thermodynamics of nitrogen chemistry helps explain why N2 is so abundant in the atmosphere, and yet the element remains inaccessible to most life forms. Table 14-4 shows that most of the abundant elements react with O2 spontaneously under standard conditions. This is why many of the elements occur in the Earth s crust as their oxides. However, N2 is resistant to oxidation, as shown by the positive A Gj for NO2. ... 

Iron or copper complexes will catalyse Fenton chemistry only if two conditions are met simultaneously, namely that the ferric complex can be reduced and that the ferrous complex has an oxidation potential such that it can transfer an electron to H2O2. However, we must also add that this reasoning supposes that we are under standard conditions and at equilibrium, which is rarely the case for biological systems. A simple example will illustrate the problem whereas under standard conditions reaction (2) has a redox potential of —330 mV (at an O2 concentration of 1 atmosphere), in vivo with [O2] = 3.5 x 10 5 M and [O2 ] = 10 11 M the redox potential is +230 mV (Pierre and Fontecave, 1999). 

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