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  • hydroxyl radical  (2)
  • nitrogen oxides  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Atmospheric chemistry of carbon disulphide (1983)
    Springer
    Journal of atmospheric chemistry 1 (1983), S. 65-86 
    Details
    ISSN: 1573-0662
    Keywords: Atmospheric oxidation ; carbon disulphide ; carbonyl sulphide ; sulphur cycle ; kinetic studies ; hydroxyl radical ; oxygen atom ; photolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The oxidation of carbon disulphide has been studied under conditions which are likely to pertain in the atmosphere. The quantum yield for direct photo-oxidation of CS2 in air at 1 atm pressure, using near UV radiation was 0.012, with OCS as a major product. The rate coefficient (k 1) for the reaction of OH with CS2, was determined from measurements of OCS formation in the near UV photolysis of HONO−CS2−O2−N2 mixtures. k 1 was dependent on oxygen concentration rising from ≤4×10-14 cm3 molecule-1 s-1 at O2≤15 Torr to (2.0±1.0)×10-12 cm3 molecule-1 s-1 at 1 atm air and 300 K. Equimolar amounts of carbonyl sulphide and sulphur dioxide were the major reaction products. The concentration of carbon disulphide in the ambient atmosphere was measured and the concentration to be expected in the background atmosphere was estimated. Rate and concentration data were used to show that carbon disulphide oxidation represents a major source for atmospheric carbonyl sulphide. It can also serve as an alternate source for atmospheric sulphur dioxide in addition to that produced from hydrogen sulphide and dimethyl sulphide. A consideration of atmospheric concentrations and rate data for these trace sulphur gases suggests that the natural sulphur budget is much smaller than the yearly amounts of sulphur dioxide emitted from anthropogenic sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00113980
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  • 2
    Electronic Resource
    Electronic Resource
    Studies of Oxidant Production at the Weybourne Atmospheric Observatory in Summer and Winter Conditions (1999)
    Springer
    Journal of atmospheric chemistry 33 (1999), S. 111-128 
    Details
    ISSN: 1573-0662
    Keywords: Weybourne Atmospheric Observatory ; ozone production ; peroxy radicls ; nitrogen oxides ; peroxy acetyl nitrate ; oxidant (O3+NO2)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Detailed studies have been made of the behaviour of gases and radicals involved in the production of oxidants at the Weybourne Atmospheric Observatory in both summertime and wintertime conditions. In June 1995 the range of meteorological conditions experienced varied such that ozone destruction was observed in clean northerly air flows reaching Weybourne down the North Sea from the Arctic, and ozone production was observed in varying degrees in air with different loadings of nitrogen oxides and other precursors. The transition point for ozone destruction to ozone production occurred at a nitric oxide concentration of the order of 50 pptv. Plumes of polluted air from various urban areas in the U.K. were experienced in the June campaign at Weybourne. Quantitative studies of ozone production in a plume from the Birmingham conurbation on 18 June 1995 showed that the measurement of ozone production agreed well with calculated production rates from the product of the nitric oxide and peroxy radical concentrations (r2=0.9). In wintertime conditions (October–November 1994) evidence was also found for oxidant production, defined as the sum of O3+NO2. At this time of year the peroxy radical concentrations (RO2) were much lower than observed in the summertime and the nitric oxide (NO) was much higher. There was still sufficient RO2 during the day, however, for a slow accumulation of oxidant. Confirmatory evidence for this comes from the diurnal co-variance of (O3+NO2) with PAN, an excellent tracer of tropospheric photochemistry. The same type of covariance occurs in summer between PAN and ozone. The results obtained in these series of measurements are pertinent to understanding the measures necessary to control production of regional photochemical air pollution, and to the production of ozone throughout the northern hemisphere in winter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005969204215
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  • 3
    Electronic Resource
    Electronic Resource
    Tropospheric Box-Modelling and Analytical Studies of the Hydroxyl (OH) Radical and Related Species: Comparison with Observations (1999)
    Springer
    Journal of atmospheric chemistry 33 (1999), S. 183-214 
    Details
    ISSN: 1573-0662
    Keywords: hydroxyl radical ; troposphere ; modelling ; steady state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Calculated and observed hydroxyl (OH) fields are presented. Calculated OH was obtained in three ways using (1) a photochemical box-model (2) a simple OH steady state approach and (3) a variant on (2) – the ‘multiple equation steady state’ approach which assumes steady state for OH, HO2 and RO2 and hence obtains three simultaneous, non linear, equations. All three methods used data collected in June 1995 during the Weybourne Atmospheric Observatory Summer Experiment (WAOSE'95). Julian Days 169, 178, 179 and 180 displayed especially good data capture and were consequently chosen for study. The two steady state methods are essentially driven purely by observations and derive OH from the ratio of the relevant source and sink terms. The box-model was constrained where possible to observations; remaining unmeasured volatile organic compounds (VOCs) were initialised to an arbitrary low value of 10 ppt. Agreement between theory and experiment was usually around 50% and often better than this value, especially on J169, though discrepancies of up to a factor of 3 were occasionally apparent. Despite the inherent scatter, neither the box-model nor the simple steady state method were found to consistently over-estimate OH (a common feature of many numerical approaches) although this did occur to a certain extent using the multiple equation steady state approach, probably due to breakdowns in the steady state approximation. More data spread was evident in the box-model approach compared with the other methods. An analysis of the major sources and sinks of OH is presented for the three methods of calculation. Calculated and observed peroxy radicals are also presented. Calculated peroxy radicals were generally lower than that observed at night yet higher, sometimes by up to a factor of 7, during the day. Possible explanations for this result are explored.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006009901180
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  • 4
    Electronic Resource
    Electronic Resource
    Reactive Nitrogen Compounds at Spitsbergen in the Norwegian Arctic (1997)
    Springer
    Journal of atmospheric chemistry 28 (1997), S. 209-225 
    Details
    ISSN: 1573-0662
    Keywords: PAN ; NOy ; Arctic measurements ; nitrogen oxides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Simultaneousindependent measurements of NOy and NOx(NOx= NO + NO2) by high-sensitivitychemiluminescence systems and of PAN (peroxyacetylnitrate) and PPN (peroxypropionyl nitrate) by GC-ECDwere made at Spitsbergen in the Norwegian Arcticduring the first half year of 1994. The average mixingratio of the sum of PAN and PPN (denoted PANs)increased from around 150 pptv in early winter to amaximum of around 500 pptv in late March, whereasepisodic peak values reached 800 pptv. This occurredsimultaneously with a maximum in ozone which increasedto 45–50 ppbv in March–April. The average NOxmixing ratio was 27 pptv and did not show any cyclethrough the period. The NOy mixing ratio showeda maximum in late March, while the difference betweenNOy and PAN decreased during spring. This is anindication of the dominance of PAN in the NOybudget in the Arctic, but possible changes in theefficiency of the NOy converter could alsocontribute to this. Although most PAN in theArctic is believed to be due to long range transport,the observations indicate local loss and formationrates of up to 1–2 pptv h-1 in April–May.Measurements of carbonyl compounds suggest thatacetaldehyde was the dominant, local precursor ofPAN.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005883323285
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