By L. DeWayne Cecil (a), L. Flint Hall (b) and Jaromy R. Green

(a) U.S. Geological Survey, Idaho Falls, Idaho

(b) State of Idaho INEEL Oversight Program, Idaho Falls, Idaho

(c) Garden City Community College, Garden City, Kansas
U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 03-4106


Prepared in cooperation with the U.S. DEPARTMENT OF ENERGY

Complete accessible text of report (737 KB PDF)

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Background concentrations of iodine-129 (129I, half-life = 15.7 million years) resulting from natural production in the earth’s atmosphere, in situ production in the earth by spontaneous fission of uranium-238(238U), and fallout from nuclear weapons tests conducted in the 1950s and 1960s were reevaluated on the basis of 52 analyses of ground- and surface-water samples collected from the eastern Snake River Plain in southeastern Idaho. The background concentration estimated using the results of a subset of 30 ground-water samples analyzed in this reevaluation is 5.4 attocuries per liter (aCi/L; 1 aCi = 10-18 curies) and the 95-percent nonparametric confidence interval is 5.2 to 10.0 aCi/L. In a previous study, a background 129I concentration was estimated on the basis of analyses of water samples from 16 sites on or tributary to the eastern Snake River Plain. At the 99-percent confidence level, background concentrations of 129I in that study were less than or equal to 8.2 aCi/L.

During 1993–94, 34 water samples from 32 additional sites were analyzed for 129I to better establish the background concentrations in surface and ground water from the eastern Snake River Plain that is presumed to be unaffected by wastedisposal practices at the Idaho National Engineering and Environmental Laboratory (INEEL). Surface water contained larger 129I concentrations than water from springs and wells contained. Because surface water is more likely to be affected by anthropogenic fallout and evapotranspiration, background 129I concentrations were estimated in the current research using the laboratory results of ground-water samples that were assumed to be unaffected by INEEL disposal practices.





Purpose and scope

Description of the study area

Previous investigations

Sources of iodine-129 in the eastern Snake River Plain aquifer

Natural sources

Above-ground testing of nuclear devices

Nuclear-fuel reprocessing facilities releases


Methods and quality assurance

Results of iodine-129 analyses

References cited

For additional information write to:


U.S. Geological Survey
INEEL, MS 1160

P.O. Box 2230

Idaho Falls, ID 83403


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Last modified: Thursday, September 01 2005, 02:23:46 PM
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