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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of atmospheric chemistry 17 (1993), S. 339-351 
    ISSN: 1573-0662
    Keywords: Accommodation coefficient ; annular reactor ; heterogeneous reaction ; nitric acid ; nitrous acid ; nitrogen dioxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A simple and inexpensive procedure is presented for the measurement of gaseous accommodation coefficients upon liquid or solid surfaces. The gas of interest is passed in laminar flow through an annular reactor and the profile of deposition is subsequently determined. The Cooney-Kim-Davies theoretical treatment of deposition in cylindrical systems is adapted to describe uptake on the walls of the annular reactor as a function of accommodation coefficient and diffusion coefficient. The accommodation coefficient (α) of ammonia on oxalic acid is determined in both cylindrical and annular systems and good agreement is found. Uptake of nitrogen dioxide on wet alkaline surfaces yields a value for α of 2.5×10−4, and on solely wet surfaces a value of 8.7×10−5. Nitric and nitrous acids deposit to aqueous sodium carbonate/glycerol surfaces with values of α of 1.5 × 10−2 and 4.3×10−3, respectively.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 10 (1996), S. 69-73 
    ISSN: 0268-2605
    Keywords: trimethyl-lead ; reference material ; homogeneity ; stability ; rainwater ; road dust ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This study was conducted to develop certified reference materials containing trimethyl-lead (TriML) in environmental matrices. A detailed description of the process to prepare candidate artificial rainwater and road dust reference materials, which includes pretreatment, homogenization and bottling procedures, is described. The homogeneity was assessed by comparing the variations within a bottle and between different bottles. The results demonstrated that the distribution of TriML in the same material is homogeneous. The stability of TriML in these materials was verified on the day of preparation and after 1, 3, 6 and 12 months. The results showed no significant difference between the initial TriML concentration and the concentration after 12 months' storage in candidate artificial rainwater kept at room temperature and in road dust stored at -20°C and 4°C, based on a statistical analysis of the results. At 37°C, however, TriML was shown to be unstable: this highlighted the need to store the materials in the dark, preferably at 4°C. TriML in both of the candidate reference materials was hence concluded to be stable for at least 12 months under the appropriate storage conditions.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 7 (1993), S. 567-575 
    ISSN: 0268-2605
    Keywords: alkyl-lead ; rainwater ; gas chromatography/atomic absorption spectroscopy ; temporal trends ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Concentrations of tetra-, tri and di-alkyl-lead compounds in rain have been measured at rural and urban sites in England. The measurements are compared with similar data collected in the early 1980s, prior to a 72% reduction in the emission of lead from combustion of leaded petrol. Whilst concentrations of inorganic lead have fallen broadly in line with emissions of automotive lead, alkyl-lead concentrations in rain have fallen by only 50% or less, and thus the ratio of alkyl-lead to inorganic lead in rain has increased appreciably. The reason for this phenomenon is unclear. The data suggest that lead in rainwater would fall to approximately 2 μg dm-3 if automotive lead emissions fell to zero.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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