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| Titel |
Analysis of Carbon and Hydrogen Isotope Signals obtained by Reactive Transport Simulations of a Benzene Biodegradation Scenario |
| VerfasserIn |
Florian Centler, Anko Fischer, Hans-H. Richnow, Martin Thullner |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250041066
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| Zusammenfassung |
| Compound-specific stable isotope analysis (CSIA) has been established as a viable tool for
the evaluation of in situ biodegradation. Isotope signatures can be interpreted by means of the
Rayleigh equation to quantify microbially mediated processes leading to the degradation of
organic contaminants. Beyond quantification, isotope data from more than one element can
be combined to identify and distinguish distinct biodegradation pathways. The Rayleigh
approach, however, was originally developed for closed systems. This assumption does not
necessarily hold true for field sites at which not only biodegradation, but also abiotic
non-destructive processes like diffusion, dispersion, volatilization, and sorption can lead to a
decrease in contaminant concentration. This makes the interpretation of isotope signals from
field sites challenging. In order to evaluate the explanatory power of the Rayleigh
approach, we analyze isotope fractionation data obtained from a multi-dimensional
reactive transport simulation. We employ the versatile reactive transport simulator
GeoSysBRNS to simulate the simultaneous fractionation of carbon and hydrogen
isotopes in a hypothetical benzene plume scenario in a two-dimensional aquifer.
Biodegradation of benzene occurs via an aerobic and an anaerobic degradation
pathway, which results in a typical redox zonation within the aquifer. With benzene
concentrations and isotope signals for carbon and hydrogen available at every location of the
simulation domain, the explanatory power of one and two-dimensional isotope data
analysis can be thoroughly assessed. The influence of abiotic processes affecting
contaminant concentration in the aquifer as well as the effect of vertical mixing
in measuring wells on the isotope signal and its interpretation are investigated. |
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