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Title: BIODEGRADATION OF ATRAZINE IN AQUATIC ECOSYSTEMS

Author
item RUPASSARA, INDU - UNIV OF ILLINOIS
item LARSON, RICHARD - UNIV OF ILLINOIS
item SIMS, GERALD

Submitted to: Environmental Bioremediation and Biodegradation Symposium
Publication Type: Proceedings
Publication Acceptance Date: 6/18/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: Atrazine has been the most widely used herbicide in the USA since the 1960's for selective pre- and post-emergence control of weeds in crops such as maize, sorghum, corn, sugarcane and pineapple. Carry-over of atrazine to drinking water and non-target organisms has become a major concern due to its possible health risks. Investigation of naturally occurring aquatic plants and associated microbial degraders to enhance the rate of degradation may help reduce herbicide concentrations in surface water. We examined degradation of atrazine in aquatic systems in the presence of hornwort (Ceratophyllum demersum), a green alga, and reed canarygrass (Phalaris arundinaceae), and associated microorganisms. We observed that hornwort had greater potential to reduce atrazine concentrations than did reed canarygrass, though a fungus isolated from reed canarygrass appeared to be an effective atrazine degrader. The results show promise for the use of plants to reduce herbicide concentrations (phytoremediation), which will provide possible options for managing waterways in agricultural production areas in order to reduce negative effects of agriculture on the environment.

Technical Abstract: Degradation of atrazine in aquatic systems in the presence of hornwort (Ceratophyllum demersum), green algae and reed canarygrass (Phalaris arundinaceae), and associated microorganisms has been studied. First half lives of atrazine in the presence of hornwort and green algae were 5 days and 8 days respectively, while reed canarygrass did not demonstrate degradability. However, a fungus, associated with reed canarygrass seeds degraded atrazine with a half life of 4.5 days after an initial lag period of two weeks. The study with hornwort plant has shown that the degradation process was light dependent and the major metabolite was identified as deethylatrazine. Hornwort incubated in the presence of 1 mg/L 14C atrazine became radioactive. Microscopic autoradiography indicated that radioactivity was present within the plant tissues, with larger densities in mature areas of the plant including stems. Involvement of epiphytes in the degradation process was not clearly observable. Hornwort plant extract, after exposing the plant to 14C atrazine for 30 days contained atrazine (70% of the total radioactivity) and a major metabolite (22% of total) with the same retention time as atrazine-glutathione conjugate standard.