Publication Date


Document Type


First Advisor

Kaufman, Ron (Professor of geology)

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Geology


Water--Pollution--Illinois--De Kalb County; Nitrates


This study investigates the temporal variation of nitrate concentrations in ground and surface waters of DeKalb County, Illinois, and examines the presence or absence of a layer at the top of the phreatic zone contaminated by elevated concentrations of nitrate. Between December 1986 and May 1987, 239 ground and surface water samples from 16 wells and 5 surface water sites in DeKalb County, Illinois, were collected and analyzed for temperature, pH, and nitrate concentrations on a biweekly basis. Concentrations of calcium, magnesium, sodium, potassium, sulfate, chloride, and bicarbonate were determined monthly. Surface water concentrations of nitrate were typically above the U.S. Environmental Protection Agency's maximum contaminant level (MCL--45 parts per million [ppm]) throughout the County. Some groundwaters in susceptible areas and associated with anthropogenic influences were found to be contaminated above background level (about 13 ppm) and one site (G03) was consistently above the MCL. Other groundwater sites (G07 and G16) showed peaks of nitrate concentrations far above normal levels, probably reflecting slower plant uptake in the late winter and leaching caused by late spring rainfall. Recently drilled/ deeper wells had low nitrate concentra- t ions. The steady decrease in nitrate concentrations in natural waters from the surface down to deeper wells supports the existence of a contaminated layer near the top of the local phreatic zone. Nitrate concentrations have peaks in some sites coinciding with late winter and the recharge event at the end of the sampling period, but the biweekly sampling schedule may have missed other major peaks in nitrate concentrations.


Bibliography: pages [115]-129.


xi, 211 pages




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