Arsenic and Uranium in Glacial Aquifers in the
Lower Illinois River Basin
Kelly L. Warner and William S. Morrow
The Lower Illinois River Basin in central Illinois is
one of 59 basins that are part of the U.S. Geological Survey National Water-Quality
Assessment program. Sixty wells sampled in the deep (greater than 200 feet
below land surface) and shallow (less than 200 ft below land surface) glacial
aquifers had detections of 15 of the 17 trace elements analyzed. The deep
glacial aquifer had higher concentrations of arsenic than the shallow aquifer.
Dissolved arsenic concentrations ranged from no detection to 84 ug/L. Arsenic
concentrations appear to be related to geologic controls and redox conditions.
Arsenic concentrations vary with distance from recharge areas. Uranium
concentrations ranged from no detection to 17 ug/L with the most detections
in the shallow glacial aquifer. The source of uranium may be anthropogenic.
U.S. Geological Survey
221 N. Broadway
Urbana, IL 61801
(217) 344-0037
klwarner@usgs.gov, wsmorrow@usgs.gov