Water Resources Research Act Program

Details for Project ID 2017IL333B

Diurnal and Seasonal Variation in Groundwater Nitrate-N Concentration in a Riparian Buffer Zone

Institute: Illinois
Year Established: 2017 Start Date: 2017-03-01 End Date: 2018-02-28
Total Federal Funds: $10,000 Total Non-Federal Funds: $20,000

Principal Investigators: Eric Peterson

Abstract: Within agricultural areas of the US Midwest, nonpoint source nutrient export contributes to elevated nitrate (NO3-) concentrations in surface waters and to the development of the hypoxic zone in the Gulf of Mexico. Development of best management practices (BMPs) to remediate excess nonpoint source nutrients in surface waters includes the diversion of tile-drain water through riparian buffer zones (RBZ), which have been shown to remove NO3-. The proposed project examines how concentrations with the RBZ change over the course of a day and over the course of a year. The project addresses four objectives: 1) Do NO3- concentrations vary over a 24-hour period in each season? As vegetation processes are controlled by photosynthesis, uptake will be a function of solar intensity and should vary accordingly. 2) Does daily mean NO3- concentration vary seasonally? Seasonal variation associated with NO3- import, NO3- export, vegetative uptake, and denitrification will control the concentration of NO3-. 3) Does the mean daily timing of maximum and minimum NO3- concentration (i.e., phase) vary seasonally? The change in peak solar intensity hours between seasons should result in duration of the rising and failing NO3- concentrations. 4) Does the magnitude of mean difference between daily maximum and minimum (i.e., amplitude) NO3- vary seasonally? Twenty-four hour samplings will occur every two-weeks to examine how concentrations vary over a day and subsequently the seasons. Measured nitrate as nitrogen (NO3-N) will be statically analyzed for both diurnal variation and seasonal variation to determine the mechanisms involved in the reduction of NO3-N concentrations in water moving through the RBZ. The project serves as one facet of a larger collaborative project with the City of Bloomington to identify BMPs designed to improve the water supply for the city. The BMPs focus on the reduction of nutrients exported from agricultural fields to the surface water bodies of the area. Identified BMPs will be transferable to other agricultural areas of the state and region. The project will directly involve one Hydrogeology M.S. Program student and one undergraduate Geology student from Illinois State University. Both students will be involved in the water sampling and analyses, and they will be involved in the dissemination and outreach aspects of the work.