Submitted to: American Chemical Society National Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 8/24/1999
Publication Date: N/A
Technical Abstract: In the deep Loess Hills along the Missouri River valley of Western Iowa several fields are under study to determine the impact of fertilized corn production on both surface water and groundwater quality. The landscape is characterized by gently sloping ridges, steep side slopes, and well-defined alluvial valleys often with incised channels that usually terminate at an active gully head. Under prevailing weather patterns defined by longterm records, the greater percentage of contaminants leaches through the loess profile to reach shallow water tables than that displaced by surface runoff. The distribution of contaminant concentrations throughout the unsaturated groundwater system is determined largely by landscape positions and tillage practices. Data are presented for metolachlor, atrazine and nitrate. A chromatographic-type conceptual model is proposed based upon both soil properties and characteristic hydraulic conductivity of the loess material. Runoff chemistry generated from late Winter snowmelt exhibits a diurnal freeze-thaw pattern.