海洋沉积物光释光测年中铀、钍、钾的γ能谱法分析

γ-SPECTROMETRIC DETERMINATION OF U,TH AND K FOR OSL DATING OF MARINE SEDIMENTS

测量样品的放射性核素(^(238)U、^(232)Th和^(40)K)含量并用于计算环境剂量率,是光释光测年方法中非常重要的步骤。本研究比较了电感耦合等离子体质谱和发射光谱法以及高纯锗γ能谱法对一系列海洋沉积物中铀、钍、钾含量的测量结果和环境剂量率计算结果。研究表明,多道高纯锗γ能谱仪测量铀、钍、钾的精确度和准确度较高。不同分析方法得到的测量结果高度一致,通过计算得到的环境剂量率也无显著差别。放射性核素活度浓度和质量浓度的理论比值与实验比值之间差距很小,两种方法几乎没有系统误差。γ能谱法制样更简单,还能了解样品是否处于的放射性平衡状态,是值得推广研究的环境剂量率测量方法。

The measurement of radionuclides(238U,232Th and 40K)is critical in OSL dating for calculation of the environmental dose rate.In this study,we compared the results of the 238U,232Th and 40K contents from the ICP-MS and ICP-OES method and the HPGeγ-ray spectrum method,and the environmental dose rates calculated from the contents are also compared.The results suggest that the environmental dose rates did not differ significantly for the two methods,and the contents of radionuclides are highly consistent.However,for the method ofγ-ray spectrometry,sample preparation is simple and no damage is observed.We may simultaneously measure various radionuclides,and it is easy to know whether the sample is in a radioactive equilibrium state or not.Therefore,the method is highly recommended for measuring the dose rate in OSL dating.