Activity concentration of natural radionuclides (238U, 226Ra, 232Th, 228Ra and 40K) in lettuce cultivated in soil amended with niobium tailings

Abstract

This study evaluates the possible agricultural application of calcium carbonate derived from niobium extraction. This carbonate is stored in dams, and it is enriched with radionuclides from 232Th series, which imposes restrictions on its use. Activity concentration evaluation in soil was performed before the tillage of lettuce (Lactuca sativa L.) and the soil–plant transfer factor was determined. Results showed the dilution factor applied to the carbonate in the soil causes insignificant increments in soil activity concentration. In cultivated lettuce, high activity concentrations of 228Ra and 226Ra were found independently when using either the control or carbonate amended soil.