Special issue of Journal of Environmental Radioactivity on 2nd International Conference on Po and radioactive Pb isotopes

摘要

Daughter products of radon isotopes (~(222)Rn, ~(220)Rn and ~(219)Rn) originating from the ~(238)U-~(235)U-~(232)Th decay chains have been widely utilized as tracers and chronometers in our understanding of the earth and near-earth surface processes. Of the 33 Pb isotopes (~(182-214)Pb) that occur in nature and that are produced inside the laboratory, only 4 are stable (~(204)Pb, ~(206)Pb, ~(207)Pb and ~(208)Pb). Of these 29 radioactive Pb isotopes, four radioactive isotopes are produced from the ~(238)U (~(214)Pb, T_(1/2) = 26.8 min; ~(210)Pb, T_(1/2) = 22.3 yr), ~(235)U (~(211)Pb, T_(1/2) = 36.1 min) and ~(232)Th series (~(212)Pb, T_(1/2) = 10.64 h) (Porcelli and Baskaran, 2011). Due to low abundance and relatively short half-life, ~(211)Pb is of less importance as a tracer. There are 27 Po isotopes (~(192-218)Po) all of which are radioactive that occur in nature or produced inside the laboratory and the longest-lived radionu-clide that occur in nature is ~(210)Po (T_(1/2) = 138.38 d). Six of these 27 radioactive isotopes are produced from the ~(238)U (~(218)Po, T_(1/2) = 3.10 min; ~(214)Po, T_(1/2) = 164 μs; ~(210)Po, T_(1/2) = 138.38 d), ~(235)U (~(215)Po, T_(1/2) = 1.78 ms) and ~(232)Th series (~(216)Po, T_(1/2) = 0.145 s; ~(212)Po, T_(1/2) = 0.299 μs) (Porcelli and Baskaran, 2011).