FIELD DRAIN TILE DIVERSION INTO A RIPARIAN BUFFER ZONE EFFECTS ON SPATIAL DISPERSION OF NITRATE IN GROUNDWATER

High amounts of nitrate from agricultural field watershed contaminate the groundwater, creating a consumption hazard. A nitrate level greater than 10 mg/L causes negative health effects for the local population and aquatic organisms. Redirecting agricultural tile water through riparian buffer zones (RBZ) may reduce the amount of nitrate that flows into surface water. We expected that the spatial dispersion of nitrate in the RBZ would be lowest in the wells furthest from the tile diversion box.

This study was conducted in McLean County, Illinois. Samples were taken from the diversion box, the stream, and from the bailed wells. YSI readings were recorded at every sample site. Samples were analyzed on a Dionex ICS 1100 ion Chromatograph to measure the nitrate levels. The nitrate levels at the diversion box were significantly higher than any of the surrounding wells, with concentrations as high as 26 mg/L N. Groundwater nitrate levels varied widely, but were most commonly less than 1 mg/L N. The wells with the lowest nitrate levels were not next to the stream, but were located in the middle clusters.

Watershed from agricultural fields that is diverted into an RBZ, contains lower levels of nitrate in the groundwater and decreases the amount of harmful nitrate contaminants in drinking water.