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  • Analytical Chemistry and Spectroscopy  (2)
  • hydrocarbons  (1)
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  • 1
    ISSN: 1572-9729
    Keywords: anaerobic ; biodegradation ; BTEX ; fuel ; hydrocarbons ; Seal Beach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Enhanced anaerobic biodegradation of groundwater contaminated by fuel hydrocarbons has been evaluated at a field experiment conducted at the Naval Weapons Station, Seal Beach, California. This experiment included the establishment of three different remediation zones in situ: one zone was augmented with sulfate, one was augmented with sulfate and nitrate, and the third was unaugmented. This enables a comparison of hydrocarbon biodegradation under sulfate-reducing, sequential denitrifying/sulfate-reducing, and methanogenic conditions, respectively. In general, the results from the field experiment are: (1) Certain fuel hydrocarbons were removed preferentially over others, but the order of preference is dependent upon the geochemical conditions; and (2) In the zones that were augmented with sulfate and/or nitrate, the added electron acceptors were consumed quickly, indicating that enhancement via electron acceptor injection accelerates the biodegradation process. More specifically, in the sulfate-reducing zone, sulfate was utilized with an apparent first-order rate coefficient of approximately 0.1 day-1. In the combined denitrifying/sulfate-reducing zone, nitrate was utilized preferentially over sulfate, with an apparent first-order rate coefficient of 0.1–0.6 day-1. However, the data suggest that slow sulfate utilization does occur in the presence of nitrate, i.e., the two processes are not strictly sequential. With regard to the aromatic BTEX hydrocarbons, toluene was preferentially removed under intrinsic conditions; biodegradation of benzene was slow if it occurred at all; augmentation with sulfate preferentially stimulated biodegradation of o-xylene; and ethylbenzene appeared recalcitrant under sulfate-reducing conditions but readily degradable under denitrifying conditions.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Residues of octylphenol polyethoxylates (OPEO) are frequently found in wastewater effluents. OPEO are commonly used surfactants. The polyethoxy chain of OPEO may be shortened or carboxylated during biological wastewater treatment and the aromatic ring chlorinated or brominated during wastewater disinfection with chlorine. Mass spectral data obtained using electron ionization (EI) and chemical ionization (CI) are presented which positively characterize these residues. For CI, methane was used as the reactant gas and protonated molecular ions were observed. The most prominent ions formed under EI resulted from benzylic cleavage while the prominent ions formed under CI resulted from alkyl ion displacement and olefin displacement. EI and CI mass spectra are summarized and fragmentation mechanisms are proposed. Response factors are presented for quantitative analysis by single ion monitoring.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 1016-1020 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The chemical ionization (CI) mass spectra of propylated linear alcohol polyethoxy carboxylates (LAEC) and polyethylene glycol dicarboxylates (PEGDC) have been determined. Olefin displacement of the alkyl chain from the [M + H]+ ions of propylated LAEC formed the protonated polyethoxy carboxyl propyl ester, which then underwent a characteristic fragmentation by first losing water and then ethylene oxides. The fragmentation pattern for PEGDC [M + H]+ ions was similar to that of LAEC, except that the initial steps were displacement of one terminal propyl formate (HCOOC3H7) followed by a neutral loss of CH2O. Strong peaks due to protonated molecules were observed in both LAEC and PEGDC. Product-ion mass spectra obtained from chemical ionization gas chromatographic/triple-stage quadrupole mass spectrometric studies supported the proposed fragmentation mechanisms.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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