Chemical studies on uranium extraction from concentrated phosphoric acid by using PC88A and DBBP mixture

The activity concentration of beryllium-7 (⁷Be), a naturally occurring cosmogenic radionuclide produced in the upper atmosphere, was measured in plants on the Loess plateau of China during the growing season of 2005. The ⁷Be mass activity concentration on July 27 ranged from 34.8 to 147.1 Bq kg⁻¹ in herbaceous plants, from 47.6 to 116.1 Bq kg⁻¹ in subshrubs, and from 15.7 to 56.8 Bq kg⁻¹ in crop plants. The ⁷Be mass and areal activity concentrations of a mixture of herbaceous plants increased from 66.8 to 288.7 Bq kg⁻¹ and from 0.7 to 46.5 Bq m⁻², respectively, during the growing season. On an areal basis, the fraction of ⁷Be in plants in the soil–plant system increased from 0.4 to 8.4% during the growing season. Positive linear correlations were found between the increases of ⁷Be mass and areal activity concentrations in the inter-sampling intervals and the amount of precipitation.