title: Push-pull tests to quantify in situ degradation rates at a phytoremediation site.
abstract: Nine push-pull tests (PPTs) were performed to determine in-situ aerobic respiration rates at a creosote-contaminated site and to assess the contribution of hybrid poplar trees to the remediation of polynuclear aromatic hydrocarbons (PAH) in groundwater. PPTs were conducted by injecting a solution containing dissolved oxygen and naphthalene (reactive tracers) with bromide (nonreactive tracer) into wells constructed in a shallow unconfined aquifer. The objective of this study was to determine seasonal variation and spatial differences (contaminated versus uncontaminated areas and treed versus untreed areas) in the rate of consumption of dissolved oxygen. First-order aerobic respiration rates varied from 0.0 (control well) to 1.25 hr(-1), which occurred at a planted area in early summer (June). Rates measured in winter at treed areas were greater by a factor of 3-5 when compared to winter rates determined at nontreed areas of the site. Rates at treed regions were found to increase by over 4 times in summer relative to winter at the same location.
authors.affiliation: Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg 24061-0105, USA.
authors.forename: Mark T
authors.initials: MT
authors.lastname: Pitterle
authors.forename: Rikke G
authors.initials: RG
authors.lastname: Andersen
authors.forename: John T
authors.initials: JT
authors.lastname: Novak
authors.forename: Mark A
authors.initials: MA
authors.lastname: Widdowson
mesh_terms: D001673:Biodegradation, Environmental; D010944:Plants / Q000378:metabolism*; D011083:Polycyclic Compounds / Q000737:chemistry*; D014874:Water Pollutants, Chemical
chemical_list: D011083:Polycyclic Compounds; D014874:Water Pollutants, Chemical