Kinetic Modeling of Bioavailability for Sorbed‐Phase 2,4‐Dichlorophenoxyacetic Acid

Journal of Environmental Quality - Tập 30 Số 5 - Trang 1523-1527 - 2001
Jeong‐Hun Park1, John P. Giesy2, Xianda Zhao1, Stephen A. Boyd2, Thomas C. Voice1
1Dep. of Civil and Environ. Eng. Michigan State Univ. East Lansing MI 48824
2Dep. of Crop and Soil Science Michigan State Univ. East Lansing MI 48824

Tóm tắt

ABSTRACT

The degradation rate of 2,4‐dichlorophenoxyacetic acid (2,4‐D) was studied in silica–slurry systems to evaluate the bioavailability of sorbed‐phase contaminant. After the silica particles were saturated with 2,4‐D, the system was inoculated with the 2,4‐D–degrading microorganism Flavorbacterium sp. strain FB4. The disappearance rate of 2,4‐D was found to be greater than the rate predicted based upon liquid‐phase 2,4‐D concentrations. A kinetic formulation, termed the enhanced bioavailability model, was developed to describe the desorption and biodegradation processes in this batch system. The approach assumes that 2,4‐D resides in both the liquid and solid phases and degradation occurs via both suspended and attached biomass. All biomass can degrade liquid‐phase 2,4‐D at one rate, while only attached biomass can degrade sorbed 2,4‐D at another rate. An enhanced transformation factor (Ef) was introduced to express the increased biodegradation rate over that expected from the liquid phase only. This approach was able to account for the increased degradation rates observed experimentally. The results provide evidence that desorption to the bulk solution is not prerequisite to degradation, and that sorbed substrate may be available for degradation.

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Thông tin xuất bản

Journal of Environmental Quality

Tập 30 Số 5

1523-1527

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