Natural Radioactivity and Radon Exhalation in Phosphate Fertilizers

摘要

~(238)U, ~(232)Th, ~(226)Ra,~(222)Rn and ~(40)K activity concentrations in fertilizer samples collected from a local market were determined. Radon activity concentrations ranged from 0.04-252 Bq kg~(-1) and were comparable with low activity concentrations ranges reported previously. Radon exhalation rates and effective ~(226)Ra concentration were determined using CR-39 solid-state nuclear track detectors. Effective ~(226)Ra concentrations ranged from 4.27-33.93 Bq kg~(-1). Two different ~(222)Rn exhalation rates were determined; area dependent exhalation rates (0.044-0.351 Bq m~(-2) h~(-1)) and mass dependent exhalation rates (0.023-0.180) Bq kg~(-1) h~(-1)). Even without secular equilibrium, strong correlations were generally apparent among uranium concentrations, effective ~(226)Ra concentrations and ~(222)Rn exhalation rates in samples with high concentrations of uranium. ~(232)Th and ~(40)K concentrations ranged from 0-44.6 and 0.08-127 n-g/g, respectively.