The Contents and Distributions of Natural Radionuclides 238U, 232Th, 40K in Permafrost Soils of Central Yakutia

Abstract

The present study addresses the contents and distributions of natural radionuclides 238U, 232Th, and 40K in six main types (subtypes) of soils that have developed in friable alluvial sandy deposits within various layers of the topography of the Central Yakutian Plain. The minimum concentrations of these radionuclides are registered in forest soils of the eluvial type that have developed on weathered sandy deposits of the high level, whereas the maximum concentrations are detected in forest pale-yellow and meadow-steppe soils that have developed on loess-like carbonate loams of the middle level and in polymictic sands of the lower level of the plain, respectively. In addition to the structure of soil forming rocks, the soil formation processes in these soils, such as humus accumulation, podsolization, bleaching, and intra-soil clay deposition have a significant effect on the contents and distributions of 238U, 232Th, and 40K. In the soils examined in this study, 40K distribution followed the eluvial and uniform patterns, whereas the intra-profile distribution of 238U and 232Th was more variable, following the accumulative, eluvial, accumulative eluvial, accumulative eluvial-illuvial, and accumulative illuvial patterns. We have revealed statistically significant correlations between 238U and 232Th contents and soil contents of humus, clay, and silt

Keywords

• natural radionuclides
• soil properties
• content
• distribution