|Smith Jr, Sammie|
Submitted to: Environmental Toxicology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2005
Publication Date: 9/15/2005
Citation: Bouldin, J.L., Farris, J.L., Moore, M.T., Smith Jr, S., Cooper, C.M. 2005. Evaluated fate and effects of atrazine and lambda-cyhalothrin in vegetated and unvegetated microcosms. Environmental Toxicology. 20:487-498. Interpretive Summary: Pesticide runoff from agricultral fields can contaminate downstream rivers, lakes, and streams. Aquatic plants in drainage ditches can sorb these pesticides, thereby reducing the concentration of pesticides entering downstream water systems. Experiments showed that small ditches with plants sorbed more pesticides than small ditches without plants. This demonstrated the importance of vegetation in ditches and other structures which carry pesticide runoff from fields to rivers, lakes, and streams.
Technical Abstract: Contaminants such as nutrients, metals, and pesticides can interact with constructed wetlands and existing drainage ditches used as agricultural best management practices. Our research has shown that macrophyte presence and hydrologic regime aid in transfer and transformation of pesticides associated with agricultural runoff. This study consisted of applications of both atrazine (triazine herbicide) and lambda-cyhalothrin (pyrethroid insecticide) to unvegetated and vegetated microcosms to measure fate and effects of pesticides applied at suggested field application rates. Exposures focused on monocultures of Ludwigia peploides (water primrose) and Juncus effusus (soft rush). Pesticide sorption was evident through atrazine and lambda-cyhalothrin concentrations in plant tissue as high as 2461.4 and 86.5 ug/kg, respectively. Toxicity was measured in water from unvegetated microcosms through 28 d and in Chironomus tentans (midge larvae) exposed to sediments collected from 3 h to 56 d in microcosms receiving the pesticide combination. Comparative survival of test organisms from this study suggests that effective mitigation of pesticides from runoff can be dependent upon macrophyte contact and vegetative attributes associated with ditches.