| Abstract
| - A novel combination of noninvasive imaging with anoxygen sensitive fluorescent indicator was developed toinvestigate the biodegradation processes occurring at thefringe of a solute plume, where the supply of oxygenwas limited. A thin transparent porous matrix (156 × 120× 3 mm) was made from quartz plates and quartz sand (212−300 μm) and enriched with acetate-degrading bacteria.A degrading plume developed from a continuous acetatesource in the uniform flow field containing dissolved oxygen.Ruthenium (Π)-dichlorotris(1,10-phenanthroline) (Ru(phen)3Cl2), a water-soluble fluorescent dye, was used asan indicator of dissolved oxygen. The fluorescenceintensity was dependent on the concentration of oxygenbecause the dissolved oxygen acted as collisional quencher.The oxygen distribution was interpreted from imagesrecorded by a CCD camera. These two-dimensionalexperimental results showed quantitatively how the oxygenconcentrations decreased strongly at the narrow plumefringe and that oxygen was depleted at the core of the plume.Separately, dispersivity was measured in a series ofnonreactive transport experiments, and biodegradationparameters were evaluated by batch experiments. Two-dimensional numerical simulations with MT3D/RT3D usedthese parameters, and the predicted oxygen distributionswere compared with the experimental results. Thismeasurement method provides a novel approach toinvestigate details of solute transport and biodegradationin porous media.
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