A Ten-Year Biomonitoring Study of Atmospheric Deposition of Trace Elements at the Territory of the Republic of Belarus

For the third time since 2005 atmospheric deposition of trace elements in Belarus was monitored by the moss technique widely used in Europe for air pollution studies. Samples of moss species of Hylocomium splendens and Pleurozium schreberi were collected at 86 sites over the Gomel, Vitebsk and Minsk Regions in the summer of 2015. A total of 30 elements were determined by epithermal neutron activation analysis. Studying of the temporal trends in Belarus was undertaken with the results obtained in previous moss surveys in 2005/2006 and 2010/2011. Comparison with the analogous data from the neighbouring countries showed relatively low contamination levels in Belarus for the most heavy and toxic elements. The results of survey 2010/2011 showed that, except Cr, other element concentrations reduce or are at the same levels.

Determination of uranium in tree bark samples by epithermal neutron activation analysis

In this study uranium (U) concentrations were determined in certified reference materials (CRMs) and in tree bark samples collected in “Cidade Universitária Armando de Salles Oliveira” (CUASO) USP, São Paulo. The barks were collected from different species namely Poincianella pluviosa and Tipuana tipu. These bark samples were cleaned, dried, grated and milled for the analyses by epithermal neutron activation analysis method (ENAA). This method consists on irradiating samples and U standard in IEA-R1 nuclear reactor with thermal neutron flux of 1.9 x 1012 n cm-2 s-1 during 40 to 60 seconds depending on the samples’ matrices. The samples and standard were measured by gamma ray spectroscopy. U was identified by the peak of 74.66 keV of 239U with half life of 23.47 minutes. Concentration of U was calculated by comparative method. For analytical quality control of U results, certified reference materials were analyzed. Results obtained for CRMs presented good precision and accuracy, with |Z score| ≤ 0.39. Uranium concentrations in tree barks varied from 83.1 to 627.6 ng g-1 and the relative standard deviations of these results ranged from 1.8 to 10 %.