Submitted to: Agronomy Society of America, Crop Science Society of America, Soil Science Society of America Meeting
Publication Type: Abstract Only
Publication Acceptance Date: September 12, 2004
Publication Date: November 18, 2004
Citation: Rice, C., Bialek Kalinski, K.M., Angier, J., Mccarty, G.W. 2004. Persistance of herbicide breakdown products in a riparian buffer system [abstract]. Agronomy Society of America, Crop Science Society of America, Soil Science Society of America Meeting. CD-ROM 6532. Technical Abstract: The effectiveness of a forested riparian buffer at removing herbicides was studied. The riparian system contains a first-order stream that receives groundwater and surface runoff from a nearby cornfield that is treated yearly with a pre-emergent mix of metolachlor and atrazine. The fate of the parent compounds and their degradation products has been followed for several years. For the two herbicides, the sulfonated degradatioin product of metolachlor, metolachlor ethane sulfonic acid (MESA) is by far the most abundant, which is followed by the oxygenated degradate of metolachlor, metolachlor oxanilic acid (MEOA). MESA typically averages 500 to 1000x higher in concentration than its parent (and most other pesticide products) in the buffer zone. For atrazine the most commonly measured metabolite is CIAT (also called DEA) followed by CEAT and hydroxy atrazine. Over most of the year these metabolites are more abundant than either of the parent compounds except for a 1-2 week period following spraying when spikes in parent compound are observed in the stream. These spikes coincide with the first few rainfall events following spraying. There appears to be a particular persistence of MESA in this riparian ecosystem.