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Isotopic fractionation by transverse dispersion: Flow-through microcosms and reactive transport modeling study.
Environ. Sci. Technol. 44, 6167-6173 (2010)
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 at the 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 coupled to 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.
Impact Factor
Scopus SNIP
Web of Science
Times Cited
Times Cited
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4.630
2.620
48
61
Anmerkungen
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Publikationstyp
Artikel: Journalartikel
Dokumenttyp
Wissenschaftlicher Artikel
Schlagwörter
Organic contaminants; Natural attenuation; Rayleigh equation; Porous-medium; Biodegradation; Carbon; Degradation; Aquifer; Diffusion; Quantification
Sprache
englisch
Veröffentlichungsjahr
2010
HGF-Berichtsjahr
2010
ISSN (print) / ISBN
0013-936X
e-ISSN
1520-5851
Zeitschrift
Environmental Science & Technology
Quellenangaben
Band: 44,
Heft: 16,
Seiten: 6167-6173
Verlag
ACS
Verlagsort
Washington, DC
Begutachtungsstatus
Peer reviewed
Institut(e)
Institute of Groundwater Ecology (IGOE)
POF Topic(s)
20403 - Sustainable Water Management
Forschungsfeld(er)
Environmental Sciences
PSP-Element(e)
G-504300-002
PubMed ID
20704214
Scopus ID
77956541129
Erfassungsdatum
2010-10-08