title: Assessment of in-situ bioremediation at a refinery waste-contaminated site and an aviation gasoline contaminated site.
abstract: A combination of geochemical, microbiological and isotopic methods were used to evaluate in-situ bioremediation of petroleum hydrocarbons at one site contaminated with refinery waste and a second site contaminated with aviation gasoline at Alameda Point, California. At each site, geochemical and microbiological characteristics from four locations in the contaminated zone were compared to those from two uncontaminated background locations. At both sites, the geochemical indicators of in-situ biodegradation included depleted soil gas and groundwater oxygen, elevated groundwater alkalinity, and elevated soil gas carbon dioxide and methane in the contaminated zone relative to the background. Radiocarbon content of methane and carbon dioxide measured in soil gas at both sites indicated that they were derived from hydrocarbon contaminant degradation. Direct microscopy of soil core samples using cell wall stains and activity stains, revealed elevated microbial numbers and enhanced microbial activities in contaminated areas relative to background areas, corroborating geochemical findings. While microbial plate counts and microcosm studies using soil core samples provided laboratory evidence for the presence of some microbial activity and contaminant degradation abilities, they did not correlate well with either contaminant location, geochemical, isotopic, or direct microscopy data.
authors.affiliation: Department of Civil and Environmental Engineering, University of California, Berkeley 94720, USA.
authors.forename: Vishvesh K
authors.initials: VK
authors.lastname: Bhupathiraju
authors.forename: Paula
authors.initials: P
authors.lastname: Krauter
authors.forename: Hoi-Ying N
authors.initials: HY
authors.lastname: Holman
authors.forename: Mark E
authors.initials: ME
authors.lastname: Conrad
authors.forename: Paul F
authors.initials: PF
authors.lastname: Daley
authors.forename: Alexis S
authors.initials: AS
authors.lastname: Templeto
authors.forename: James R
authors.initials: JR
authors.lastname: Hunt
authors.forename: Mark
authors.initials: M
authors.lastname: Hernandez
authors.forename: Lisa
authors.initials: L
authors.lastname: Alvarez-Cohen
mesh_terms: D000468:Alkalies / Q000032:analysis; D001359:Aviation; D001419:Bacteria / Q000254:growth & development / Q000378:metabolism; D001673:Biodegradation, Environmental; D002245:Carbon Dioxide / Q000032:analysis; D003264:Containment of Biohazards; D004787:Environmental Pollution / Q000032:analysis; D005742:Gasoline / Q000032:analysis / Q000382:microbiology*; D006256:Hazardous Waste / Q000032:analysis*; D008697:Methane / Q000032:analysis; D010100:Oxygen / Q000032:analysis; D010578:Petroleum / Q000032:analysis / Q000382:microbiology; D014866:Waste Products / Q000032:analysis*
chemical_list: D000468:Alkalies; D005742:Gasoline; D006256:Hazardous Waste; D010578:Petroleum; D014866:Waste Products; D002245:Carbon Dioxide; D008697:Methane; D010100:Oxygen