Impact of fertilizers on the uptake of 226Ra, 232Th, and 40K by potgrown rice plants

Fertilizers usually enhance potassium (K) content and other naturally occurring radioactive materials in agricultural fields that eventually enter the human food chain through plants. In this study, potgrown rice plants planted in soil that is relatively high in natural radioactive content was used to estimate the individual influence of fertilizer applications on the uptake of 226Ra, 232Th, and 40K using gammaray spectrometry. Three types of common fertilizers used in rice cultivation (with percentages) 17.5N:15.5P:10K, 17N:3P:25K+2MgO, and 46N (i.e., urea) were separately added to the pottedrice plants which were in three different growth stages: emergence stage (10 days), maximum tillering stage (40 days), and initiation stage (70 days). Fertilizers at various concentrations (0, 100, 200, 300, and 400 mg kg^–1) were applied in the first stage of plant growth, whereas only 200 mg kg^–1 fertilizer was applied in the second and third stages. Results showed that the uptake of 226Ra, 232Th, and 40K by rice grains was affected by different concentrations of fertilizer and its application time. However, these findings suggested insignificant health risk related to the ingestion dose of grains treated with selected fertilizers.