Evaluation of sulfate reduction at experimentally induced mixing interfaces using small-scale push-pull tests in an aquifer-wetland system

Kneeshaw, T. A.; McGuire, J. T.; Smith, E. W.; Cozzarelli, I. M.

Abstract:

This paper presents small-scale push-pull tests designed to evaluate the kinetic controls on SO42 - reduction in situ at mixing interfaces between a wetland and aquifer impacted by landfill leachate at the Norman Landfill research site, Norman, OK. Quantifying the rates of redox reactions initiated at interfaces is of great interest because interfaces have been shown to be zones of increased biogeochemical transformations and thus may play an important role in natural attenuation. To mimic the aquifer-wetland interface and evaluate reaction rates, SO42 --rich anaerobic aquifer water (??? 100 mg / L SO42 -) was introduced into SO42 --depleted wetland porewater via push-pull tests. Results showed SO42 - reduction was stimulated by the mixing of these waters and first-order rate coefficients were comparable to those measured in other push-pull studies. However, rate data were complex involving either multiple first-order rate coefficients or a more complex rate order. In addition, a lag phase was observed prior to SO42 - reduction that persisted until the mixing interface between test solution and native water was recovered, irrespective of temporal and spatial constraints. The lag phase was not eliminated by the addition of electron donor (acetate) to the injected test solution. Subsequent push-pull tests designed to elucidate the nature of the lag phase support the importance of the mixing interface in controlling terminal electron accepting processes. These data suggest redox reactions may occur rapidly at the mixing interface between injected and native waters but not in the injected bulk water mass. Under these circumstances, push-pull test data should be evaluated to ensure the apparent rate is actually a function of time and that complexities in rate data be considered. ?? 2007 Elsevier Ltd. All rights reserved.

Genre:

Article

ProdID:

70031354

Citation Author:

Kneeshaw, T. A.; McGuire, J. T.; Smith, E. W.; Cozzarelli, I. M.

Citation Contributing Office:

Citation Datum:

Citation Day:

Citation Edition:

Citation Editor:

Citation End Page:

2629

Citation Issue:

Citation Keywords:

Citation Language:

English

Citation Larger Work Title:

Applied Geochemistry

Citation LatN:

Citation LatS:

Citation LonE:

Citation LonW:

Citation Month:

Citation No Pagination:

Citation Number Of Pages:

Citation Online Only Flag:

Citation Phsyical Description:

Citation Projection:

Citation Public Comments:

Citation Publisher:

Citation Series:

Citation Series Code:

Citation Series Number:

Citation Search Results Text:

Evaluation of sulfate reduction at experimentally induced mixing interfaces using small-scale push-pull tests in an aquifer-wetland system; 2007; Article; Journal; Applied Geochemistry; Kneeshaw, T. A.; McGuire, J. T.; Smith, E. W.; Cozzarelli, I. M.