The use of vegetation to enhance bioremediation of soils in Iowa contaminated with pesticide wastes

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Project Period: 
Project Investigator(s): 
JR Coats, TA Anderson, Pesticide Toxicology Laboratory, Department of Entomology, Iowa State University

(This is a continuation of a previously CHEEC funded study on pesticide contamination. See FY 1992.) Evidence for enhanced microbial degradation of xenobiotic chemicals in the rhizosphere, a zone of increased microbial activity at the root-soil interface, continue to accrue, suggesting that vegetation may play an important role in facilitating bioremediation of contaminated surface soils. For sites tainted with pesticide wastes, such as at agrochemical dealerships, establishing vegetation may be problematic because of the presence of herbicide mixtures at concentrations several fold above field application rates. Nonetheless, herbicide-tolerant plants exist that can survive in these environments, and they are ideal candidates for testing the influence of rhizosphere microbial communities on the degradation of pesticide waste. Laboratory experiments have tested whether a commodity plant such as soybeans could survive in soil from a pesticide-contaminated site containing a mixture of three predominant herbicides, atrazine, metolachlor, and trifluraline, and if its presence could enhance biodegradation. Although soybean survival in this soil was high, its presence did not enhance the degradation of the chemicals. Tests with nonvegetated soils and rhizosphere soils from Kochia sp., a herbicide-tolerant plant, showed enhanced degradation of these chemicals in rhizosphere soil. Also, Kochia sp. seedlings have emerged from rhizosphere soils spiked with additional concentrations of the three test chemicals, indicating the ability of these plants to survive in soils containing high concentrations of herbicide mixtures.


Anderson TA, Kruger EL, Coats JR; Biological Degradation of Pesticide Wastes in the Root Zone of Soils Collected at an Agrochemical Dealership; in Bioremediation through Rhizoshpere Technology. American Chemical Society. 1994; Chapter 16:199-209

Anderson TA, Kruger EL, Coats JR; Rhizosphere Microbial Communities of Herbicide-Tolerant Plants as Potential Bioremedials of Soils Contaminated with Agrochemicals; in Bioremediation of Pollutants in Soil and Water. American Society for Testing and Materials. 1995; 149-157

Anderson TA, Coats JR; Screening Rhizosphere Soil Samples for the Ability to Mineralize Elevated Concentrations of Atrazine and Metolachlor. Journal of Science and Health. 1995; B30(4):473-484

Anderson TA, Kruger EL, Coats JR; Enhanced Degradation of a Mixture of Three Herbicides in the Rhizosphere of a Herbicide-Tolerant Plant. Chemosphere. 1994;28(8):1551-1557

Anderson TA, Coats JR; The Role of the Rhizosphere in Facilitating Biological Degradation of Hazardous Organic Chemicals; in Bioremediation Science and Technology. Soil Society of America 1995

Perkovich BS, Anderson TA, Kruger EL, Coats JR; Enhanced Mineralization of 14C-atrazine in Kochia Scoparia Rhizosphere Soil from a Pesticide-Contaminated Site. Pesticide Science. 1996; 46(4):391-396.