NATURALLY-OCCURRING GAMMA-EMITTING ISOTOPES, RADON RELEASE AND PROPERTIES OF PARENT MATERIALS OF SASKATCHEWAN SOILS

of parent materials of Saskatchewan soils. Can. J. Soil Sci. 74: 47-53 . Mineral composition of the parent material is a major factor control ling natural radioactivity of soils. The objective of this study was t o investigate the relationship between the natural radioactivity of 18 till and six lacustrine parent materials and their properties measure d during soil surveys. Gamma spectroscopy was used to estimate K-40 an d daughters of U-238 and Th-232; neutron activation analysis was used to determine total U; and alpha counting was used to measure Rn-222 re lease from the soil. The amounts of the various radioisotopes were pos itively correlated with each other and with clay content; the correlat ion with sand content was negative: and the correlations with silt and inorganic C content were generally not significant. Adding the fine/t otal clay ratio as a further independent variable considerably improve d the correlation between K-40 and clay content. The data suggested co nsiderable disequilibrium in the U-238 decay chain, which appeared to be in part related to the mode of deposition of the parent materials. Soil survey information - in particular. texture - thus appears a read ily available tool for preliminary screening of terrestrial radiation in Saskatchewan.