Samuel V. Panno, Keith C. Hackley, Walton R. Kelly, and Hue Hwa Hwang

Illinois State Geological Survey and Illinois State Water Survey

Abstract

The sources of nitrate (NO₃^--N) in groundwater of the shallow karst aquifer in southwestern Illinois’ sinkhole plain is being examined, and the results of sampling nine of 10 selected karst springs are presented. Anomalously high concentrations of NO₃^- in spring water from the study area are evidence that sources other than soil organic matter probably have contributed additional NO₃^- to the shallow karst aquifer. Bacterial species present in the spring water suggest an influx of waste products from livestock, humans, and/or wildlife. Isotopic data were most definitive and suggest that the sources of NO₃^- in spring water from the study area are dominated by N-fertilizer and soil organic matter.