SCALING NITRATE AND CHLORIDE ACROSS AN AGRICULTURAL WATERSHED

Nutrients such as chloride and nitrogen have led to the degradation of water quality in recent years, especially in agricultural streams. This study seeks to understand how drainage area size and discharge affect the concentrations of nitrate and chloride in an agricultural stream. Filtered water samples and discharge measurements were taken once per week from eight different sites along the agricultural stream Money Creek, near Bloomington, Illinois. The drainage area of the eight sites ranged from 6.40 km2 to 77.26 km2. We processed these samples through a Dionex-Ion Chromatography to reveal the concentrations of nitrate and chloride in each filtered sample. The concentrations of nitrate along the stream all remained relatively constant and independent of both discharge and drainage area size, with the values remaining approximately 15.0 mg/l. However, the concentrations of chloride increased as both drainage area and discharge increased, with these concentrations ranging from 19.50 mg/l to 31.18 mg/l. This study shows that increasing drainage area and discharge has no effect on nitrate concentrations and that as they increase so does chloride concentrations in an agricultural stream, which this trend can be applied to similar streams.