Titre :
|
Effects of a fluctuating water table: column study on redox dynamics and fate of some organic pollutants
|
Auteurs :
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A. Sinke ;
O. Dury ;
J. Zobrist
|
Type de document :
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article/chapitre/communication
|
Année de publication :
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1998
|
Format :
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p. 231-246
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Langues:
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= Anglais
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Catégories :
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EAU
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Mots-clés:
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FLUCTUATION DE NAPPE
;
OXYDO REDUCTION
;
TRANSFERT DE POLLUANT
;
MILIEU POREUX
;
INFILTRATION
;
SORPTION
|
Résumé :
|
The development of the redox conditions has been studied in an initially aerobic column filled with quartz sand coated with ferrihydrite and subjected to a fluctuating water table. The purpose of this study was to evaluate the effect of water table fluctuations on the redox dynamics and the fate of selected organic pollutants. The column that was percolated continuously with electron accepters (O-2, NO3, SO4) and electron donors (acetate and formate), was first operated under saturated conditions resulting in the classical redox zonation. After 4 months of operation, we started to fluctuate the water level and three drainage-imbibition cycles were run each with a total cycle length of 1 month. The pulse of oxygen introduced by lowering the water table caused a partial and temporal oxidation of previously reduced species. To investigate the effect of the changing redox environment on the transport and transformation of organic pollutants, breakthrough experiments were performed with 4-nitrobenzoate and toluene as model pollutants representative for nitro-substituted and volatile aromatics, respectively. The fate of 4-nitrobenzoate and toluene was studied under saturated conditions in short pulse breakthrough experiments and evaluated using the advection-dispersion model. 4-nitrobenzoate was transformed stoichiometrically into 4-aminobenzoate caused by the reduction of the nitrogroup.
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Source :
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Journal of Contaminant Hydrology, vol.33
|