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BIOCONVERSION AND MASS TRANSFER OF PESTICIDES IN A MODEL WETLANDS SYSTEM
Description:
The widespread use of agrichemicals over the years has impaired the nation's water quality through contamination of soil and of surface and groundwaters. A constructed wetlands environment has natural restorative processes which are attractive methods for improving water quality while being cost-effective. A selection of pesticides will be examined since their biodegradation is not well understood under anaerobic conditions present in wetlands sediment and soils, namely, denitrifying, iron reducing and methanogenic. The objectives of the proposed investigation are: 1) to examine the biodegradation of atrazine, alachlor, chlorothalanil and dicamba using soil slurry cultures under aerobic, denitrifying, iron reducing and methanogenic conditions; 2) to determine the rate and extent of transformation or degradation under the different oxidation-reduction (O-R) conditions; 3) to characterize the metabolites formed during pesticide transformation; 4) to quantify the chemical mobility (mass transfer rates) and availability of atrazine, alachlor, dicamba and chlordane in field contaminated soils and one reference soil as a function of moisture content, temperature, pH and dominant electron acceptor; 5) to carry out laboratory soil-wetlands microcosm studies to measure the biodegradation rate and extent of target pesticides in field contaminated soils under optimized microbial and chemical mobility conditions. In addition, we will aim to verify the activity in the constructed wetlands environment.
Completion of the project will provide basic information of the fate and behavior of the noted pesticides, identify persistent metabolites and their behavior, and evaluate the natural restorative processes present in a wetlands environment.