Date of Award
Master of Science
Geological and Environmental Sciences
Dr. W. Thomas Straw
Dr. Alan Kehew
Dr. Richard Passero
Masters Thesis-Open Access
Nitrate concentrations in excess of U.S. EPA standards have been documented for farm wells in an area where hog production and row crops are the predominant forms of agribusiness. The aquifer serving this area is in glacial deposits of interbedded sand, clay, gravel and till. The upper, unconfined, sand and gravel unit of the aquifer is connected to a flow-through wetland. Five well nests, with wells at various depths, were installed in and around the wetland. Samples were taken from the wells in both winter and summer to establish temporal and spatial changes in ground-water quality parameters.
Concentrations of nitrate, sulfate, calcium, magnesium, potassium, and sodium are lower downgradient than in upgradient wells. Changes in concentrations may be due to denitrification, plant uptake, dilution, sorption, changes in redox potential or ion exchange. Conditions become more reducing as ground water encounters wetland organic sediments where organisms act as mediators for electron transfer.
Betts, "The Effects of a Wetland on Ground-Water Quality in an Agriculturally Impacted Aquifer" (1994). Master's Theses. 3962.