Vegetation fires and release of radioactivity into the air

摘要

Naturally-occurring radionuclides, such as those of the uranium and thorium series, as well as artificial radionuclides, are accumulated in plants generally in low concentrations. Summer vegetation fires release these natural and man-made radionuclides into the atmosphere. Concentrations of uranium isotopes ~(238)U, ~(235)U, ~(234)U, ~(232)Th, ~(230)Th, ~(226)Ra, ~(210)Pb and ~(210)Po were measured in smoke from wild vegetation fires. It is shown that radionuclide concentrations in smoke particles are enhanced about 100 times in comparison with the vegetation of the area and with reference aerosols. Smoke particles were particularly enriched in ~(210)Po, and displayed ~(210)Po/~(210)Pb activity concentration ratios always above unity and up to 12, while in common aerosols ~(210)Po/~(210)Pb is always <1. Inhaled smoke particles from vegetation and forest fires may contribute to enhanced radiation doses in the human lung.