Karst Groundwater Contaminants in Western Illinois

Wei Zheng, ISTC senior research chemist, worked with colleagues from the Illinois Natural History Survey (INHS) as well as other divisions of the Prairie Research Institute (PRI) on a project titled “Karst Groundwater Contaminants in Western Illinois: Comparison of Current Conditions with Historical Data,” which ended in April 2014. As a follow-up to earlier studies by INHS in 2000, the objective of this study was to provide data to help address the following questions:

  1. Have land use practices become safer for the environment and is this reflected in the water quality of our shallow karst aquifers?
  2. Or have increasing encroachment upon natural lands and potentially more intensive agricultural practices overshadowed any improvements in how we treat the environment?
two researchers with hard hats and headlamps sample water inside a cave

In short, how good a job has been done in the face of increasing development to protect shallow karst groundwater quality? Results from the water quality data indicated that the karst system was widely but moderately contaminated by land use activities. Field water chemistry data collected during the present study were roughly comparable to values from 2000.

The PPCPs analyzed for were all from human sources; no veterinary pharmaceuticals or hormones were included in this study. The number of detections and combined concentration were positively correlated with chloride (Cl-), suggesting septic discharge as the source of both. The prevalence of human bacteria also suggested septic system contamination. The correlation between PPCPs and Nitrate measured as Nitrogen (NO3--N) was weaker than for Chloride (Cl-), suggesting an additional source of NO3--N, probably synthetic fertilizer and soil organic matter.

Dr. Zheng and other colleagues are conducting additional studies on karst groundwater in the state. This project was funded by a National Great Rivers Research and Education Center grant received by Steve Taylor of INHS and others at the Institute. The final project report is published as Illinois Natural History Survey Technical Report 2014(22).