title: Effects of bioaugmentation on sorption and desorption of benzene, 1,3,5-trimethylbenzene and naphthalene in freshly-spiked and historically-contaminated sediments.
abstract: This work investigated the frequently observed "rebounds" of contaminants of concern in groundwater systems. Specifically, influences of bioaugmented microorganisms on the sorption and desorption of representative petroleum constituents [benzene, 1,3,5-trimethylbenzene and naphthalene (BTN)] were studied in freshly-spiked and historically-contaminated sediments. Capable microorganisms were enriched and supplemented to contaminated sediments to enhance biodegradation of petroleum hydrocarbons. In freshly-spiked sediments, when petroleum-degrading microorganisms were added, concentrations of dissolved petroleum constituents appeared to increase initially, and 12.4, 14.0 and 20.0 mg/kg of benzene, 1,3,5-trimethylbenzene and naphthalene, respectively desorbed from the sediments into the water phase. In the historically-contaminated sediments, the augmentation of petroleum-degrading microorganisms led to the desorption of 0.023-0.059, 0009-0.016, and 1.731-2.763 mg/L of previously sequestrated BTN into the water phase, and also triggered the desorption of 0.051-0.223, -0.133-2.630, and 2.324-1.200 mg/kg of previously sequestrated BTN as the methanol extraction quantity. The mechanisms of the enhanced desorption at the presence of microbes remain to be determined; however, we presumed that microbially produced constituents such as biosurfactants and cell mass could have attributed to the partition of petroleum compounds from the sediments. Findings from this study may partially explain "rebounds" of certain petroleum constituents into the groundwater during in situ bioremediation practice, although such immediate rebounds sometimes are weak, and the desorbed constituents can be eventually biodegraded under proper biogeochemical conditions.
authors.affiliation: State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin 300072, PR China; School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, PR China.
authors.forename: YueHua
authors.initials: Y
authors.lastname: Li
authors.affiliation: State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin 300072, PR China; School of Civil Engineering, Tianjin University, Tianjin 300072, PR China. Electronic address: liangchen@tju.edu.cn.
authors.forename: Liang
authors.initials: L
authors.lastname: Chen
authors.affiliation: Research Institute of Safety and Environment Technology, China National Petroleum Corporation, Beijing 102206, PR China.
authors.forename: YuLong
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Beijing Key Laboratory of Water Resources and Environmental Engineering, China University of Geosciences, Beijing 100083, PR China.
authors.forename: Fei
authors.initials: F
authors.lastname: Liu
authors.affiliation: Advanced Environmental Technologies, LLC, Fort Collins, CO 80525, USA.
authors.forename: Paul H
authors.initials: PH
authors.lastname: Fallgren
authors.affiliation: Advanced Environmental Technologies, LLC, Fort Collins, CO 80525, USA.
authors.forename: Song
authors.initials: S
authors.lastname: Jin
mesh_terms: D065966:Absorption, Physicochemical; D001554:Benzene / Q000737:chemistry / Q000378:metabolism; D001555:Benzene Derivatives / Q000737:chemistry / Q000378:metabolism*; D001673:Biodegradation, Environmental; D019015:Geologic Sediments / Q000737:chemistry; D006838:Hydrocarbons / Q000378:metabolism; D009281:Naphthalenes / Q000737:chemistry / Q000378:metabolism*; D010578:Petroleum / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*
chemical_list: C482494:1,3,5-trimethylenebenzene; D001555:Benzene Derivatives; D006838:Hydrocarbons; D009281:Naphthalenes; D010578:Petroleum; D014874:Water Pollutants, Chemical; C031721:naphthalene; D001554:Benzene
keywords: Aged petroleum hydrocarbons; Bioaugmentation; Groundwater; Rebound; Sediments; Sorption and desorption