The use of plants (directly or indirectly) to remediate contaminated soil or water is known as phytoremediation. This technology has emerged as a more cost effective, noninvasive, and publicly acceptable way to address the removal of environmental contaminants. Plants can be used to accumulate inorganic and organic contaminants, metabolize organic contaminants, and encourage microbial degradation of organic contaminants in the root zone. Widespread utilization of phytoremediation can be limited by the small habitat range or size of plants expressing remediation potential, and insufficient abilities of native plants to tolerate, detoxify, and accumulate contaminants. A better understanding and appreciation of the potential mechanisms for removing contaminants from the root zone and the interaction between plants, microorganisms, and contaminants will be useful in extending the application of phytoremediation to additional contaminated sites.

Pesticide contamination of soil and groundwater at agricultural chemical distribution sites is a widespread problem in the USA. Alternatives to land-farming or solid waste disposal include biostimulation and phytoremediation. This research investigated the ability of compost, corn stalks, corn fermentation byproduct, peat, manure, and sawdust at rates of 0.5% and 5% (w/w) to stimulate biodegradation of atrazine [6-chloro-Nethyl-N′-(1-methyethyl)-1,3,5-triazine-2,4-diamine], metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide], and trifluralin [2,benzenamine] added as a mixture to soil. Initial concentrations were 175±42 mg atrazine kg-1 soil, 182±25 mg metolachlor kg-1 soil, and 165±23 mg trifluralin kg-1soil. After amendment addition, 30% of the atrazine, 33% of the metolachlor, and 44% of the trifluralin was degraded over 245 days, which included 63 days' aging prior to amendment additions. Atrazine degradation was enhanced by 0.5% manure, 5% peat, and 5% cornstalk amendments compared to nonamended soils. Metolachlor degradation was enhanced by all amendments at the 5% level, except for compost and peat. Amendments had no effect on trifluralin degradation. The 5% addition of compost, manure, and cornstalks resulted in significant increases in bacterial populations and dehydrogenase activity. A second experiment compared the persistence of atrazine, metolachlor, and trifluralin applied in a mixture to their persistence in soil individually. A combined average of 123 mg atrazine kg-1 remained in soil treated with the three-herbicide mixture compared to 31 mg atrazine kg-1 remaining in soil treated with atrazine only. Atrazine mineralization and atrazine-degrading microorganisms were suppressed by high concentrations of metolachlor, but not by trifluralin. Abstract Pesticide contamination of soil and groundwater at agricultural chemical distribution sites is a widespread problem in the USA. Alternatives to land-farming or solid waste disposal include biostimulation and phytoremediation. This research investigated the ability of compost, corn stalks, corn fermentation byproduct, peat, manure, and sawdust at rates of 0.5% and 5% (w/w) to stimulate biodegradation of atrazine [6-chloro-N-ethyl, and trifluralin [2,6-dinitro-N, N-dipropyl-4-(trifluoromethyl)benzenamine] added as a mixture to soil. Initial concentrations were 175±42 mg atrazine kg -1 soil, 182±25 mg metolachlor kg -1 soil, and 165±23 mg trifluralin kg -1 soil. After amendment addition, 30% of the atrazine, 33% of the metolachlor, and 44% of the trifluralin was degraded over 245 days, which included 63 days' aging prior to amendment additions. Atrazine degradation was enhanced by 0.5% manure, 5% peat, and 5% cornstalk amendments compared to nonamended soils. Metolachlor degradation was enhanced by all amendments at the 5% level, except for compost and peat. Amendments had no effect on trifluralin degradation. The 5% addition of compost, manure, and cornstalks resulted in significant increases in bacterial popula...

Globalization of markets and the growing world population increase threats of invasive and exotic species and place greater demands on food and fiber production. Pest management in both agricultural and nonagricultural settings employs established practices and new biological, chemical, and management technologies. Pesticides are an essential tool in integrated pest management. Without pesticides a significant percentage of food and fiber crops would be lost, infectious diseases would increase, and valuable native habitats would be devastated. Therefore, it is important to understand the environmental fate of pesticides and assess their potential exposure and associated risks to human health and the environment. This paper summarizes the Advances in Pesticide Environmental Fate and Exposure Assessment symposium held at the 231st National Meeting of the American Chemical Society (Atlanta, GA, 2006). The focus of the symposium was to provide current information on advances in pesticide environmental fate and exposure assessments. Thirty papers were presented on advances ranging from subcellular processes to watershed-scale studies on topics including chemical degradation, sorption, and transport; improved methodologies; use of modeling and predictive tools; exposure assessment; and treatment and remediation. This information is necessary to develop more effective pesticide use and management practices, to better understand pesticide fate and associated exposures and risks, to develop mitigation and remediation strategies, and to establish sound science-based regulations.