Behaviour of Lead-210 in continental environment: Comparison with stables isotopes of lead

Lead-210 is a natural radioactive isotope and a decay product of the Uranium-238 decay chain found in the natural environment along with Radon-222 and Polonium-210. Lead-210 contribution to the internal exposure of man through ingestion is 20% but represents 70% of the internal exposure of man through inhalation due to the uranium and thorium decay series. Transfer of lead-210 in the environment has been relatively poorly studied when compared to other radionuclides (Caesium-137, Strontium-90, Cobalt-60, Tritium, Carbon-14, etc.) even if we register a recent increase in the number of scientific publications. Therefore, this study reviews experimental data concerning the transfers of Lead-210 in the different compartments (atmosphere, freshwaters, sediments, soils, plants, animals) of continental environments (terrestrial and freshwater) from its natural sources. Moreover, it compares these data with those concerning the stable isotopes of lead. Indeed, stable lead is found in all the terrestrial and freshwater ecosystems but with an important variation in its concentration according to location and sampling type. Such a global contamination of the environment is mainly due to its industrial use. Lead toxicity is coming from its physiological behaviour similar to those of essential elements such as calcium and magnesium. A list of transfer factors for Lead-210 and stable isotopes of lead between the different compartments of the terrestrial and freshwater ecosystems is provided. The main conclusion of this review is that the behaviours of Lead-210 and stable isotopes of lead are quite similar in terrestrial environments although some discrepancies are noted in freshwater environments. The nature of these discrepancies is discussed