W6 AM Evaluation of Groundwater Communication with Surface Water and Contributions to Sediment Toxicity
Wednesday, 16 November 2005: 8:00 AM - 11:40 AM in 324-326

(RIC-1117-745260) Herbicide abatement by a riparian wetland system.

Rice, C¹, Bialek, K¹, McCarty, G.¹, Angier, J.², Hively, D.¹, ¹ U.S. Department of Agriculture, Environmental Quality Lab, Beltsville, MD, USA² U.S. Environmental Protection Agency, Office of Pesticide Programs, Crystal City, VA, USA

ABSTRACT- Riparian buffers are touted for their ability to remove agricultural contaminants; however, little is known about the specific processes that function to arrest pesticide movement and transport. Five years of data have been gathered on the movement and fate of atrazine and metolachlor into a riparian wetland that borders an active cornfield in Maryland. Base-flow conditions in the first-order stream connected to this system are entirely groundwater fed. This results in relatively high stream concentrations of certain metabolites of the herbicides, especially metolachlor ethane sulfonic acid. Data will be presented on the relative concentrations of herbicides and their metabolites in the various compartments of the riparian buffer to provide better understanding of contaminant movement and fate in this first-order riparian ecosystem.

Key words: riparian buffer, pesticides, metolachlor ethane sulfonic acid, pesticide fate