The project was undertaken to quantify the travel times of waters introduced into a saturated buffer zone (SBZ), which would allow for the calculation of the nitrate reduction within the system. SBZs are a possible best management practice that can be employed to intercept tile drainage water prior to discharge in streams. While the utility of SBZ is not in question, studies have shown that denitrification and plant uptake are removal mechanisms, understanding the travel time (distances) that are needed for the SBZ systems to be effective is not well documented. This work was an attempt to provide data and insight to address this knowledge gap. The results from the tracer test 1) quantified the travel times for waters in a saturated buffer zones situated in glacial materials. The initial calculations conducted prior to the test suggested a travel time of approximately 70 days. After the tracer injection, the down gradient wells had their peak tracer concentrations at 13-15 days, which was the result of a higher than anticipated hydraulic gradient. Despite the shorter time, the data showed that between 38% to 100% of the nitrate introduced from the tile drainage system was removed along the travel path. As the observation wells were different distances from the diversion tile, the results had a linear relationship between distance (time) traveled and nitrate reduction. These data can be used to help develop SBZ systems that provide optimal reduction given limitations of land available.
- PI: Eric Wade Peterson
- PI Institution: Illinois State University
- March 1, 2020 – December 31, 2021