文摘
up>210up>Pb dating of sediment cores is a widely used tool to reconstruct ecosystem evolution and historical pollution during the last century. Although up>226up>Ra can be determined by γ 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 up>210up>Pb through up>210up>Po in equilibrium by α spectrometry, followed by the determination of up>226up>Ra (base or supported up>210up>Pb) without any further chemical purification by liquid scintillation and with a higher sample throughput. Although γ spectrometry might still be required to determine up>137up>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 up>226up>Ra in small sediment samples, after up>210up>Po determination, allowing a more precise determination of excess up>210up>Pb (up>210up>Pbub>exub>). The method was validated with reference materials IAEA-384, IAEA-385, and IAEA-313.
