title: Impact of imposed anaerobic conditions and microbial activity on aqueous-phase solubility of polycyclic aromatic hydrocarbons from soil.
abstract: The influence of anaerobic conditions on aqueous-phase polycyclic aromatic hydrocarbon (PAH) bioavailability was investigated in laboratory microcosms. Highly aged (>70 years), PAH-contaminated soil was incubated under anaerobic conditions by using various anaerobic headspaces, anaerobic headspaces with an oxygen-scavenging complex (titanium(III) citrate) in the aqueous phase, or anaerobic headspaces with electron-acceptor amendments in the aqueous phase. Incubation of soil solely under anaerobic conditions resulted in increased aqueous concentrations of all PAHs tested (fluoranthene, pyrene, benz[a]anthracene, and benzo[a]pyrene). Benz[a]anthracene and benzo[a]pyrene extractable concentrations were above aqueous solubility, by as much as an order of magnitude for the latter. The degree of solubility increase observed was a function of molecular weight of the PAH regardless of initial soil concentration, suggesting formation of stable PAH-soluble organic matter associations. The soil samples incubated aerobically for 90 d before imposition of anaerobic conditions did not release PAHs to the aqueous phase. Methanogenic organisms and sulfate-reducing bacteria were seen to have the most significant effect on increases in aqueous-phase PAHs. Polycyclic aromatic hydrocarbons made more soluble under anaerobic conditions was available to be degraded or transformed under aerobic conditions.
authors.affiliation: US Air Force Counterproliferation Center, Maxwell AFB, Alabama 36112-6427, USA.
authors.forename: Tasha L
authors.initials: TL
authors.lastname: Pravecek
authors.forename: Russell F
authors.initials: RF
authors.lastname: Christman
authors.forename: Frederic K
authors.initials: FK
authors.lastname: Pfaender
mesh_terms: D000693:Anaerobiosis; D001551:Benz(a)Anthracenes / Q000032:analysis / Q000378:metabolism; D001564:Benzo(a)pyrene / Q000032:analysis / Q000378:metabolism; D001673:Biodegradation, Environmental; D001682:Biological Availability; D016166:Free Radical Scavengers / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis / Q000378:metabolism*; D012987:Soil; D012995:Solubility; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*
chemical_list: D001551:Benz(a)Anthracenes; D016166:Free Radical Scavengers; D011084:Polycyclic Aromatic Hydrocarbons; D012987:Soil; D014874:Water Pollutants, Chemical; D001564:Benzo(a)pyrene