Isotopic studies of the natural sources of radium in groundwater in Illinois. Final technical completion report
Stable and radioactive isotopes in groundwater were studied in an investigation of the natural geologic sources of high concentrations of /sup 226/Ra and /sup 228/Ra in confined aquifers in the Cambrian and Ordovician bedrock of northern Illinois. The covariation of delta/sup 18/O values (-6.6 to -7.9/sup 0/ //sub 00/) that are similar to contemporary meteoric water. However, a source of recharge related to glaciation is required for groundwater in confined aquifers of the Cambrian and Ordovician that is significantly depleted in /sup 18/O (delta/sup 18/O values range to -12.7/sup 0///sub 00/ and are less than -9/sup 0///sub 00/ over large regions). The covariation of delta/sup 34/S and delta/sup 18/O in dissolved sulfates determined a mixing line between two sources: oxidation of sulfide minerals and dissolution of marine evaporites. Dissolved sulfates from evaporite sources are present in large concentrations in confined aquifers but are of a different isotopic composition than evaporites of Cambrian or Ordovician age. Glaciation may be important with regard to recharge of the sulfates. The /sup 234/U//sup 238/U activity ratio in groundwater from the Cambrian and Ordovician are unexpectedly high; values range from 2.1 to 40.7. The lowest ratios occur in primary recharge zones. In confined aquifers values are greater than 20 over large regions. Alpha recoil damage is a mechanism that contributes to the disequilibrium. However, the regional variation in activity ratios and in /sup 234/U concentrations supports the concept that glacial recharge has contributed to the high ratios. Radiological and geochemical mechanisms that partition /sup 238/U, /sup 234/U and /sup 230/Th on the sandstone matrix are important to the dissolved /sup 226/Ra concentration. 38 references, 11 figures.
- Research Organization:
- Illinois Univ., Urbana (USA). Water Resources Center
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 6441927
- Report Number(s):
- UILU-WRC-84-187; ON: DE85000073
- Country of Publication:
- United States
- Language:
- English
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54 ENVIRONMENTAL SCIENCES
58 GEOSCIENCES
580400 -- Geochemistry-- (-1989)
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALKALINE EARTH ISOTOPES
ALPHA DECAY RADIOISOTOPES
AQUIFERS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
DATA
ECOLOGICAL CONCENTRATION
EVEN-EVEN NUCLEI
EXPERIMENTAL DATA
FEDERAL REGION V
GEOLOGIC STRATA
GEOLOGIC STRUCTURES
GROUND WATER
HEAVY NUCLEI
HYDROGEN COMPOUNDS
ILLINOIS
INFORMATION
ISOTOPE RATIO
ISOTOPES
LIGHT NUCLEI
NORTH AMERICA
NUCLEI
NUMERICAL DATA
ORIGIN
OXYGEN 18
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
RADIOECOLOGICAL CONCENTRATION
RADIOISOTOPES
RADIUM 226
RADIUM 228
RADIUM ISOTOPES
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
STABLE ISOTOPES
SULFUR 34
SULFUR ISOTOPES
URANIUM 234
URANIUM 238
URANIUM ISOTOPES
USA
WATER
YEARS LIVING RADIOISOTOPES