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Title:Hydrogeolic and geochemical studies of selected natural radioisotioes and barium in groundwater in Illinois
Author(s):Gilkeson, Robert H.; Cartwright, Keros; Cowart, James B.; Holtzman, Richard B.
Contributor(s):Illinois State Geological Survey; Florida State University; Argonne National Laboratory
Water resource development
Water resource development--Illinois
Aquifer properties
Chemical properties
Glacial events
Sedimentary rocks
Abstract:Dissolved conentrations of the natural radioisotopes ²²²Rn, ²²⁶Ra, ²²⁸Ra, ²³⁰Th, ²³²Th, ²³⁴U and ²³⁸U and the element Ba²⁺ were investigated in a study of high concentrations of ²²⁶Ra, ²²⁸Ra, and Ba²⁺ in groundwater from the Cambrian and Ordovician bedrock of northern Illinois. The high radium and barium concentrations are naturally present in the major aquifers--the sandstone bedrock; therefore, remedial well construction measures will not lower the concentrations. The combined concentrations of ²²⁶Ra and ²²⁸Ra range from 2.3 to 50.2 pCi/L; the majority of analyses exceed the limit in the drinking water regulations of 5.0 pCi/L. The ²²⁶Ra/²²⁸Ra activity ratio ranges from 0.2 to 41.0; a ²²⁶Ra analysis has no validity for predicting the ²²⁸Ra concentration. Important controls on dissolved ²²⁶Ra concentrations are secondary U on the sandstone matrix and the ionic strength of groundwater. The distribution of accessory minerals that contain ²³²Th is believed to be an important control on dissolved ²²⁸Ra concentrations. Locally the dissolved ²²⁶Ra and ²²⁸Ra concentrations are affected by dissolution-precipitation of secondary barite. Dissolved concentrations of ²²²Rn and U are less than proposed drinking water regulations. The extreme enrichment in the ²³⁴U that occurs widespread in groundwater from the Cambrian and Ordovician bedrock is unique and problematic. The enrichment may reflect recharge of uranium to the bedrock by glacial processes. Dissolved Ba²⁺ concentrations range from <0.01 to 22.4 mg/L. The high Ba²⁺ concentrations occur in groundwater that is depleted in dissolved SO₄²⁻ by anaerobic microbial reactions. A map presents the distribution of Ba²⁺ in groundwater from the Cambrian and Ordovician bedrock in northeastern Illinois.
Issue Date:1983-05-01
Publisher:University of Illinois at Urbana-Champaign. Water Resources Center
Genre:Report (Grant or Annual)
Sponsor:U.S. Department of the Interior
U.S. Geological Survey
Rights Information:Copyright 1983 held by the authors
Date Available in IDEALS:2016-09-28

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