Production of high-purity 229Th for analyses of U- and Th-series isotopes in geological materials

EAR-0346052PietruszkaU和Th衰变系列的短暂中间子体同位素已被证明是最近地球过程的性质和时间尺度的重要示踪物。目前这些同位素的应用范围很广，从第四纪地质年代学到地下水水文学，从海洋化学到活火山下的岩浆作用。这些测量最重要的实验室工具之一是高纯度Th-229同位素示踪剂，它既可用于确定Th的丰度，也可用于通过质谱仪测定样品的Th同位素比率。不幸的是，目前还没有商业上可用的高纯度Th-229来满足铀和Th系列同位素研究界目前和未来的需求。该项目将通过与橡树岭国家实验室的科学工作人员合作，确保高纯度Th-229的长期来源。使用这种新的高纯度Th-229示踪剂进行的研究将包括对社会具有明确益处的各种专题，例如了解第四纪晚期的气候和海平面变化、破译活火山的岩浆作用、评估长期储存放射性废物的潜在地点以及确定放射性核素在地下水中的运移。这些研究人员使用的Th-229示踪剂的纯度对数据质量有深远的影响，因此，这样的项目的结果也是如此。这对于使用等离子体电离质谱仪进行测量的未来潜力是一个特别重要的问题，它使地质材料的U和Th系列同位素分析的准确度和精密度达到极限成为可能。最终，该项目还将促进这些研究人员教授和培训地球化学领域的本科生，特别是研究生的能力。

EAR-0346052PietruszkaThe short-lived intermediate daughter isotopes of the U- and Th-decay series have proven to be important tracers of the nature and time scales of recent Earth processes. Current applications of these isotopes range widely from Quaternary geochronology to groundwater hydrology to ocean chemistry to magmatic processes beneath active volcanoes. One of the most important laboratory tools for these measurements is a high-purity Th-229 isotopic tracer, which is used both to determine the abundance of Th and, often, the Th isotope ratio of a sample by mass spectrometry. Unfortunately, there is no commercially available supply of high-purity Th-229 that will meet the current and future demands of the U- and Th-series isotope research community. This project will secure a long-term source of high-purity Th-229 through collaboration with the scientific staff of the Oak Ridge National Laboratory. The research conducted using this new high-purity Th-229 tracer will include diverse topics of unambiguous benefit to society, such as understanding climate and sea level change during the late Quaternary, deciphering magmatic processes at active volcanoes, evaluating potential sites for long-term storage of radioactive waste, and characterizing the transport of radionuclides in groundwater. The purity of the Th-229 tracer used by these researchers has a profound impact upon data quality, and thus, the outcome of projects such as these. This is an issue of particular importance for the future potential of measurements using plasma ionization mass spectrometry, which makes it possible to push the limits of accuracy and precision for U- and Th- series isotopic analyses of geological materials. Ultimately, this project will also promote the ability of these researchers to teach and train undergraduate and, especially, graduate students in the field of geochemistry.***