Botanical survey and screening of plant species which accumulate 226Ra from contaminated soil of uranium waste depot

A geobotanical study was performed of the wild plants growing in the area of the old uranium mill tailings waste depot of a former uranium ore reprocessing factory in South Bohemia and the distribution of Ra-226 in selected plants was determined. The distribution of Ra-226 in contaminated soil was found to be extremely variable (from 7 to 32 Bq Ra-226 g(-1) of DW). The differences in plant distribution were caused by factors of disturbance, soil properties (nutrients and salt content, water supply), and successional stage. No direct relation was proved between plant species characteristics and their radioactivity content. The results showed a great range of variation in the accumulation of Ra-226 by the plant species found. The highest activity of Ra-226 was found in Potentilla reptans (4.09 Bq Ra-226 g(-1), of DW), Mentha arvensis (4.00 Bq Ra-226 g(-1) of DW), and Daucus carota (3.70 Bq Ra-226 g-1 of DW). About half of the plant species are used as medicinal plants and some of them are accumulators of Ra-226. However, no plants suitable for phytoextraction of Ra-226 contaminated substrates were discovered. (C) 2007 Elsevier Masson SAS. All rights reserved.