Bioaccumulation and retention of Po-210 and Pb-210 in two species of mosses from the zone of influence of the former radium-extracting plants

The presented study was aimed at assessing the ability to accumulate and retain 210 Po and 210 Pb in two species of the mosses Sphagnum girgensohnii Russow and Pleurozium schreberi (Willd. ex Brid.) Mitt. Mosses were collected in the zone of influence of the former radium-extracting plants (Komi Republic, Russia). 210 Po and 210 Pb activity concentrations in S. girgensohnii varied from 131 ± 15.4 to 221 ± 18.3 Bq kg −1 , and from 164 ± 18.6 to 309 ± 26.1 Bq kg −1 respectively. In P. schreberi corresponding activity concentrations ranged from 107 ± 18.8 to 328 ± 29.2 Bq kg −1 and from 117 ± 13.2 to 399 ± 31.1 Bq kg −1 . Activity concentrations of 210 Po and 210 Pb in autumn were higher than in summer. In the young parts of the mosses, they were lower than in the old parts. To assess the ability to retain accumulated radionuclides, watersoluble (distilled H 2 O), exchangeable (1 M CH 3 COONH 4 ), and acidsoluble (0.1 M H 2 SO 4 ) fractions of 210 Po and 210 Pb were isolated from the studied mosses by the method sequential extraction. It was revealed that these fractions in total contained up to 26% of 210 Po and 39% of 210 Pb. The results showed that the studied moss species are a good biogeochemical barrier and long-term storage for 210 Pb and 210 Po.