title: Method to determine 226Ra in small sediment samples by ultralow background liquid scintillation.
abstract: (210)Pb dating of sediment cores is a widely used tool to reconstruct ecosystem evolution and historical pollution during the last century. Although (226)Ra can be determined by gamma spectrometry, this method shows severe limitations which are, among others, sample size requirements and counting times. In this work, we propose a new strategy based on the analysis of (210)Pb through (210)Po in equilibrium by alpha spectrometry, followed by the determination of (226)Ra (base or supported (210)Pb) without any further chemical purification by liquid scintillation and with a higher sample throughput. Although gamma spectrometry might still be required to determine (137)Cs as an independent tracer, the effort can then be focused only on those sections dated around 1963, when maximum activities are expected. In this work, we optimized the counting conditions, calibrated the system for changing quenching, and described the new method to determine (226)Ra in small sediment samples, after (210)Po determination, allowing a more precise determination of excess (210)Pb ((210)Pb(ex)). The method was validated with reference materials IAEA-384, IAEA-385, and IAEA-313.
authors: Institute of Environmental Science and Technology, and Physics Department, Autonomous University of Barcelona, ES-08193 Bellaterra, Spain. joanalbert.sanchez@uab.cat
authors: Joan-Albert
authors: JA
authors: Sanchez-Cabeza
authors: Laval Liong Wee
authors: LL
authors: Kwong
authors: Maria
authors: M
authors: Betti
mesh_terms: D019015:Geologic Sediments / Q000737:chemistry*; D007856:Lead Radioisotopes / Q000032:analysis; D011059:Polonium / Q000032:analysis; D011883:Radium / Q000032:analysis*; D012588:Scintillation Counting / Q000379:methods*; D013051:Spectrometry, Gamma
chemical_list: D007856:Lead Radioisotopes; D011059:Polonium; D011883:Radium