COMPARISONOFDIFFERENTMETHODSFOR210PbDETERMINATIONIN.pdf

COMPARISON OF DIFFERENT METHODS FOR 210 Pb DETERMINATION IN ENVIRONMENTAL SAMPLES D C Lauria1 • L L Carvalho • C C Conti Instituto de Radioproteção e Dosimetria-Comissão Nacional de Energia Nuclear (IRD/CNEN), Rio de Janeiro, RJ, Brazil. ABSTRACT. Liquid scintillation counting (LSC), gamma spectrometry, and total beta counting are methods for determining 210Pb concentration in environmental samples. In this research, we investigated a fast, simple method to determine 210Pb by LSC in environmental samples; the method is capable of estimating concentrations higher than 20 mBq/L for liquid samples. Environmental samples were analyzed by the proposed methodology, and results were compared with other methods on the basis of accuracy, lower limit of detection, time consumption, and sample type. INTRODUCTION 210Pb is one of the most radiotoxic products of the uranium decay chain, presenting a rather long half-life (T1/2 = 22.3 yr). When absorbed into the human body, 210Pb concentrates in bone tissue with a very long biological half-life. Because of its metabolic and dosimetric characteristics, 210Pb is an important isotope from the point of view of radiation protection. The value of its ingestion dose con- version factor is the highest among the naturally occurring radionuclides (IAEA 1996). Determining 210Pb concentration in environmental samples on a routine basis is thus one of the most important subjects when monitoring nuclear installations such as those involved in uranium mining and mill- ing. Moreover, tap water regulations also include natural radioactivity; thus, determining the 210Pb content in aqueous samples (e.g tap and mineral water) has gained importance. 210Pb determination is also very important for studying sediment chronology in surface water. Methods for determining radionuclides for monitoring purposes usually require low detection limits, and depending on the situation, quicker methods are necessary to help in the decision proce