A comparison between 210Pb and 210Po activity concentration on Sediment Dating

Abstract

Records stored in natural archives, such as lake sediments, are used in environmental programs for the assessment of changing erosion rates in a catchment arising from disturbances, and to monitor pollution by heavy metals and other contaminants. Accurate sediment chronologies are important to interpret those practices. One of the most important means to date recent sediments is through 210Pb. This radionuclide occurs naturally as one of the 238U decay series. It is widely distributed on the earth due to its formation from radium in the ground or from radon that emanates to the atmosphere or decays to 210Pb. The 210Pb is deposited as particulates and falls into lakes where it is scavenged from the water column and deposited on the basins. Excess of 210Pb is measured through gamma spectrometry technique. However, this technique has a low sensibility and small values are difficult to detect or need to be analyzed for a long time. 210Po is a decay product of 210Pb and its determination through alpha spectrometry is more sensitive and faster. The aim of this paper is to compare both radionuclides activity concentration in lakes sediments cores to evaluate the use of 210Po in dating of locals with low levels of 210Pb.