Date of Award

6-1994

Degree Name

Master of Science

Department

Geosciences

First Advisor

Dr. Thomas Straw

Second Advisor

Dr. Alan Kehew

Third Advisor

Dr. Richard Passero

Access Setting

Masters Thesis-Open Access

Abstract

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.

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Geology Commons

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