Isotopic fractionation by transverse dispersion: Flow-through microcosms and reactive transport modeling study
Rolle M, Chiogna G, Bauer R, Griebler C, Grathwohl P (2010)
Publication Type: Journal article
Publication year: 2010
Journal
Book Volume: 44
Pages Range: 6167-6173
Journal Issue: 16
DOI: 10.1021/es101179f
Abstract
Flow-through experiments were carried out to investigate the role of transverse dispersion on the isotopic behavior of an organic compound during conservative and bioreactive transport in a homogeneous porous medium. Ethylbenzene was selected as model contaminant and a mixture of labeled (perdeuterated) and light isotopologues was continuously injected in a quasi two-dimensional flow-through system. We observed a significant fractionation of ethylbenzene isotopologues during conservative transport at steady state. This effect was particularly pronounced atthe plume fringe and contrasted with the common assumption that physical processes only provide a negligible contribution to isotope fractionation. Under the experimental steady state conditions, transverse hydrodynamic dispersion was the only process that could have caused the observed fractionation. Therefore, the measured isotope ratios at the outlet ports were interpreted with different parameterizations of the transverse dispersion coefficient. A nonlinear compound-specific parameterization showed the best agreement with the experimental data. Successively, bioreactive experiments were performed in two subsequent stages: a first oxic phase, involving a single strain of ethylbenzene degraders and a second phase with aerobic and anaerobic (i.e., ethylbenzene oxidation coupledto nitrate reduction) degradation. Significant fractionation through biodegradation occurred exclusively due to the metabolic activity of the anaerobic degraders. We performed analytical and numerical reactive transport simulations of the different experimental phases which confirmed that both the effects of physical processes (diffusion and dispersion) and microbially mediated reactions have to be considered to match the observed isotopic fractionation behavior. © 2010 American Chemical Society.
Authors with CRIS profile
Involved external institutions
Eberhard Karls Universität Tübingen
Germany (DE)
Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt (HMGU) / Helmholtz Munich
Germany (DE)
Germany (DE)
Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt (HMGU) / Helmholtz Munich
Germany (DE)
How to cite
APA:
Rolle, M., Chiogna, G., Bauer, R., Griebler, C., & Grathwohl, P. (2010). Isotopic fractionation by transverse dispersion: Flow-through microcosms and reactive transport modeling study. Environmental Science & Technology, 44(16), 6167-6173. https://doi.org/10.1021/es101179f
MLA:
Rolle, Massimo, et al. "Isotopic fractionation by transverse dispersion: Flow-through microcosms and reactive transport modeling study." Environmental Science & Technology 44.16 (2010): 6167-6173.
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