Pore Water Velocity and Residence Time Effects on the Degradation of 2,4-D during Transport
| Autor: | H. M. Gaber, and Bhabani S. Das, Heiko W. Langner, Jon M. Wraith, Warren L. Jones, William P. Inskeep |
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| Rok vydání: | 1998 |
| Předmět: | |
| Zdroj: | Environmental Science & Technology. 32:1308-1315 |
| ISSN: | 1520-5851 0013-936X |
| Popis: | Model predictions of fate and transport of organic solutes in soils and groundwater are sensitive to assumptions concerning rates of microbial degradation. We studied the independent effects of residence time (RT) and pore water velocity (ν) on the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) by employing a series of unsaturated soil column experiments (continuous pulse concentration = 1 mg L-1) with varying column lengths and ν. While 2,4-D degradation under batch conditions was best described by a logistic rate expression, analysis of the 2,4-D breakthrough curves (BTCs) showed that (i) observed 2,4-D degradation rates were consistent with a first-order kinetic model and (ii) a single set of independently determined rate parameters from batch experiments could not describe 2,4-D degradation for all transport conditions. Apparent first-order degradation rate constants obtained from column data were found to be independent of column RT, but increased with decreasing ν, especially at ν < 1 cm h-1.... |
| Databáze: | OpenAIRE |
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