title: Fringe-controlled biodegradation under dynamic conditions: quasi 2-D flow-through experiments and reactive-transport modeling.
abstract: Biodegradation in contaminated aquifers has been shown to be most pronounced at the fringe of contaminant plumes, where mixing of contaminated water and ambient groundwater, containing dissolved electron acceptors, stimulates microbial activity. While physical mixing of contaminant and electron acceptor by transverse dispersion has been shown to be the major bottleneck for biodegradation in steady-state plumes, so far little is known on the effect of flow and transport dynamics (caused, e.g., by a seasonally fluctuating groundwater table) on biodegradation in these systems. Towards this end we performed experiments in quasi-two-dimensional flow-through microcosms on aerobic toluene degradation by Pseudomonas putida F1. Plume dynamics were simulated by vertical alteration of the toluene plume position and experimental results were analyzed by reactive-transport modeling. We found that, even after disappearance of the toluene plume for two weeks, the majority of microorganisms stayed attached to the sediment and regained their full biodegradation potential within two days after reappearance of the toluene plume. Our results underline that besides microbial growth, also maintenance and dormancy are important processes that affect biodegradation performance under transient environmental conditions and therefore deserve increased consideration in future reactive-transport modeling.
authors.affiliation: University of Tübingen, Center for Applied Geoscience, Hölderlinstr. 12, 72074 Tübingen, Germany.
authors.forename: Dominik
authors.initials: D
authors.lastname: Eckert
authors.affiliation: Helmholtz Center Munich, Institute of Groundwater Ecology, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany.
authors.forename: Petra
authors.initials: P
authors.lastname: Kürzinger
authors.affiliation: Helmholtz Center Munich, Institute of Groundwater Ecology, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Bauer
authors.affiliation: Helmholtz Center Munich, Institute of Groundwater Ecology, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Griebler
authors.affiliation: University of Tübingen, Center for Applied Geoscience, Hölderlinstr. 12, 72074 Tübingen, Germany. Electronic address: olaf.cirpka@uni-tuebingen.de.
authors.forename: Olaf A
authors.initials: OA
authors.lastname: Cirpka
mesh_terms: D000332:Aerobiosis; D001673:Biodegradation, Environmental; D004058:Diffusion; D060587:Groundwater / Q000032:analysis*; D008962:Models, Theoretical; D016958:Pseudomonas putida / Q000378:metabolism*; D013997:Time Factors; D014050:Toluene / Q000378:metabolism*; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D014874:Water Pollutants, Chemical; D014050:Toluene
keywords: Dormancy; Endogeneous respiration; Fringe-controlled biodegradation; Microbial dynamics; Reactive-transport modeling