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| Titel |
Microbial Growth and Coexistence on Diffusion-limited Unsaturated Rough Surfaces |
| VerfasserIn |
G. Wang, D. Or |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250021792
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| Zusammenfassung |
| Microbial activity in unsaturated soils plays an important role in biochemical nutrient
cycling, bioremediation, and dispersal of pathogenic microorganisms. Quantitative
description of microbial activity in unsaturated soils is hindered by complexity
of pore space and hydration dynamics. Microbes in unsaturated soils live in an
environment dominated by presence of numerous solid- and gas-liquid interfaces,
where nutrient distribution and flux pathways are dynamically shaped by liquid
configuration. We propose a model for considering effects of nutrient diffusive
fluxes under various hydrations and pore space conditions on microbial growth and
coexistence of two competing bacterial species. Simulation results show that hydration
limitation to nutrient diffusive fluxes enhance microbial coexistence and are in good
agreement with available experimental results. Effective nutrient diffusion coefficients on
rough surfaces is significantly affected by liquid configuration and by connectivity
(expressed as percolation probability) of the surface roughness network. The aqueous
network is dynamically controlled by matric potential where effective diffusion
coefficient varied from 0.46 mm2/hr to 0 and percolation probability varied from 0.76 to
0.21 when matric potential varies from -0.01 to -5 kPa, respectively. For matric
potential values of -2.0 kPa and lower, two competing microbial species coexisted
indefinitely supported by limited nutrient flux and within fragmented liquid clusters with
percolation probability 0.37. Coexistence was limited to 90 hrs at -1.2 kPa with
increasing percolation probability to 0.52 (effective diffusion coefficient of 0.19
mm2/hr). No coexistence was observed at matric potential of -0.01 kPa, the stronger
species rapidly expanded and dominated the entire domain. Pore scale and roughness
microhydrology may play an important role in the large microbial diversity found in soil. |
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