Radon in a fractured bedrock aquifer: Relationships with rock type and distribution of parent radionuclides

Conference · Wed Jan 01 04:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:6060312

Folger, P F; Wanty, R B; Day, W; Frishman, D; Taylor, T ^[1]; Poeter, E ^[2]

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1. Geological Survey, Denver, CO (United States). Denver Federal Center
2. Colorado School of Mines, Golden, CO (United States)

Ground-water samples collected from 35 domestic water wells in the Elk Creek drainage 30 miles southwest of Denver, Colorado, show a strong relationship between dissolved Rn-222 concentration and host-rock lithology. Wells completed in Precambrian Pikes Peak Granite (Ypp) average 11,000 pCi/L, whereas wells completed in Precambrian migmatitic rocks (Xm) average 4,000 pCi/L. Geophysical logs of three boreholes completed in the same rock type (Ypp) show significant differences in natural gamma traces and correspondingly different radon concentrations. One well shows a monotonous gamma response with depth, averaging 500 counts per second (cps); water from this well contains 5,300 pCi/L Rn-222. Water from the second well contains 11,000 pCi/L and the third well contain over 20,000 pCi/L. If Rn-222 parent radionuclides are homogeneously distributed along fracture walls, then Rn-222 concentration should decrease with an increasing water-volume-to-rock surface-area ratio. An inverse relationship between transmissivity and Rn-222 concentration is not observed for these 3 wells. The 2 wells with 5,300 pCi/L and 20,000 pCi/L Rn-222 in water have transmissivities of 26 and 75 gallons per day per foot (gpd/ft), respectively, whereas transmissivity for the well with 11,000 pCi/L is 195 gpd/ft. Single-well pumping tests on 29 other wells belie a systematic correlation between transmissivity and Rn-222 concentration, suggesting that local heterogeneous accumulations of Rn-222 parent radionuclides on fracture walls may strongly affect Rn-222 concentration in these wells.

• OSTI ID: 6060312
• Report Number(s): CONF-921058--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 24:7
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540230* -- Environment
Terrestrial-- Radioactive Materials Monitoring & Transport-- (1990-)
58 GEOSCIENCES
580000 -- Geosciences
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALKALINE EARTH ISOTOPES
ALPHA DECAY RADIOISOTOPES
AQUIFERS
CARBON 14 DECAY RADIOISOTOPES
CHEMISTRY
COLORADO
CORRELATIONS
DEVELOPED COUNTRIES
ECOLOGICAL CONCENTRATION
ELECTROMAGNETIC RADIATION
ELEMENTS
ENVIRONMENTAL TRANSPORT
EVEN-EVEN NUCLEI
FLUIDS
GAMMA RADIATION
GASES
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOLOGY
GROUND WATER
HEAVY ION DECAY RADIOISOTOPES
HEAVY NUCLEI
HYDROGEN COMPOUNDS
IONIZING RADIATIONS
ISOTOPES
LITHOLOGY
MASS TRANSFER
NONMETALS
NORTH AMERICA
NUCLEI
OXYGEN COMPOUNDS
PETROLOGY
RADIATIONS
RADIOECOLOGICAL CONCENTRATION
RADIOISOTOPES
RADIUM 226
RADIUM ISOTOPES
RADON
RARE GASES
SOIL CHEMISTRY
SPONTANEOUS FISSION RADIOISOTOPES
URANIUM 238
URANIUM ISOTOPES
USA
WATER
WATER WELLS
WELLS
YEARS LIVING RADIOISOTOPES