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  • 1
    ISSN: 1573-0662
    Keywords: nonmethane hydrocarbons ; isoprene ; tropical atmosphere ; oil field emissions ; potential ozone formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The levels of low molecular weight hydrocarbons were measured at pristine sites and rural locations affected by hydrocarbon emissions from oil and gas producing fields in Venezuela. At the clean sites, lower concentrations of C2 to C6 alkanes were observed, whereas, in comparison with remotes sites, very much higher levels were measured at the polluted sites. Alkenes present relatively high concentrations, with isoprene being the most abundant, all over the study region. The main sources of alkenes are likely to be natural, mainly from vegetation. The levels of alkanes recorded at the clean sites and the alkene levels found everywhere in the region are in agreement with the values reported for other clean sites in the tropics. The increase of ozone production capacity due to the anthropogenic emissions of alkanes from oil and gas fields was estimated. Due to the presence in the atmosphere of important amounts of naturally emitted isoprene, ethene and propene, which makes a substantial contribution to the reactivity of the hydrocarbon mixture, a small increase (〈5%) was estimated to occur in the capacity of the ozone production at a regional scale during the rainy season.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-0662
    Keywords: Savannah atmosphere ; vegetation burning ; soluble particles ; particles size distributions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The results presented are the first complete analysis of inorganic soluble ions in a tropical savannah region. Atmospheric particles were collected in six rural Venezuelan savannah sites. Concentrations and size distribution of NO3 −, SO4 2-, CI−, PO4 3-, NH4 +, Na+, K+, Ca2+ and Mg2+ were determined in samples collected with Hi Vol samplers equipped with five-stage cascade impactors. Concentrations were higher in the dry season, with a maximum during the burning periods. Using Na+ as a reference, the results show a deficit of Cl− and, with the exception of Mg2+, an enrichment of all other ions with respect to marine aerosols. Significant variations were observed in particle-size distribution between different periods. Various pairs of ions present similar size distributions: SO4 2- and NH4 +; Cl− and Na+; PO4 3- and K+; Ca2+, Mg2+ and NO3 −; indicating that the ions were produced by the same source and/or were involved in similar atmospheric processes. Possible primary sources, the gas-to-particle atmospheric process, environmental implication of long-range transport of nutrients during dry seasons, etc., are discussed.
    Type of Medium: Electronic Resource
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