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| Titel |
A numerical modeling approach to assess the impact of heterogeneity on bioavailability and total biodegradation |
| VerfasserIn |
Mehdi G. Gharasoo, Florian Centler, 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 |
250040503
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| Zusammenfassung |
| Natural porous media like soils and aquifers are characterized by heterogeneities at various
scales. While macro-scale heterogeneities can be resolved by REV-based models of
the subsurface, heterogeneities at the scale of pore assemblies can not be resolved
by such model approaches. As a consequence effective reaction rates used e.g. to
describe the biodegradation of contaminants might be a function of such pore-scale
heterogeneities. However, it is not known to which extent these heterogeneneities affect
the bioavailability of chemical species to the microorganisms and thus the total
biodegradation rates. The specific objective of this project is to assess and model these
bioavailability effects and their impact on total contaminant biodegradation in porous
media resulting from structural heterogeneity at the pore scale. By using a numerical
modeling approach it is the aim to obtain a better and quantitative understanding of the
bioavailability of biodegradable compounds in porous media, and to derive a quantitative
link between pore scale heterogeneity of the medium and effective biodegradation
rates.
Therefore, a reactive transport model for two-dimensional, water-saturated pore networks
has been developed. The model is capable of simulating water flow, solute transport and
biogeochemical reactions in pore structures of different heterogeneities. The intra pore
bioavailability is defined by a linear exchange model making use of recent results from
theoretical analyses of single pore systems. The bioavailability of biodegradable species and
their effective degradation rates at the scale of pore networks is assessed for various spatially
heterogeneous pore network realizations following a given pore size distribution and
geo-statistical spatial correlation function.
Simulation results for homogeneous networks are in agreement with continuum scale
modeling results considering the same intra pore bioavailability. For heterogeneous pore
networks, simulation results indicate a decrease of bioavailability/effective biodegradation
rates with increasing heterogeneity of the pore structure. This may lead towards finding
effective rate laws for biodegradation as a function of the heterogeneity of a porous
medium.
Keywords: biodegradation, pore network, reactive transport models, bioavailability,
pore-scale heterogeneity |
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