RAPID: Anthropogenic radionuclides in the Atlantic Ocean 4 decades after GEOSECS

在这个项目中，哥伦比亚大学Lamont-Dougherty地球天文台的研究人员将获得2010年(美国、荷兰和德国)各种大西洋地球轨道巡航中选定的全深度剖面中人为放射性核素239Pu、240Pu、237Np和137Cs的总浓度。这将使我们能够在GEOSECS后大约37年对这些人为放射性核素进行概括性的描述。感兴趣的同位素除了是瞬时示踪剂外，还表现出一系列Kd值(沉积物水分配系数、Pu Np、Cs)和地球化学行为，并提供了解决不同来源的放射性污染的手段。这将使该小组能够处理平流(新的水团示踪剂)、源和汇(特征同位素特征)等过程，以及与一系列对比区域的清扫和粒子动力学有关的过程。计划中的美国、德国和荷兰的GEOTRACES巡航横跨代表了一整套影响TEI的物理和生物地球化学过程的地区。通过比较放射性核素的分布、同位素组成、库存和粒子反应性(Pu)与保守性(Cs和Np)的库存比，我们将了解到关于这些核素的清除和传输速率的一级信息，这些信息是对GEOTRACES研究其他TEI获得的补充。自从GEOSECS--第一项也是唯一一项研究--提供全球钚和137Cs的海洋分布的研究以来，方法得到了改进，要求体积更小，不仅提供更好的灵敏度，而且提供更多的信息(即，质谱仪技术能够测量240Pu/239Pu原子比；传统的阿尔法光谱分析不能)。在可能的情况下，该小组将把2010年测量的分布与1972-1973年测量的分布进行比较，对控制这些污染物的命运和迁移的过程提供大约40年的视角。除了提供大西洋中钚和137Cs浓度的最新基线外，它们还将提供关于237Np以及240Pu/239Pu同位素组成的信息，这些信息还没有在这个尺度上测量过。更广泛的影响：该项目将是一项国际合作，将从大西洋各地的许多地点产生宝贵的环境放射性核素数据，否则将无法获得这些数据。与人为气候变化和可持续性有关的一个重要问题是，社会严重依赖化石燃料作为主要能源。尽管解决方案肯定会很复杂，但核能发电的比例很可能会提高。从这项提议中获得的信息将有助于评估由于未来对核能的依赖程度增加而可能释放的核素的命运。

In this project, researchers at the Lamont-Dougherty Earth Observatory of Columbia University will obtain the total concentrations of the anthropogenic radionuclides 239Pu, 240Pu, 237Np, and 137Cs in selected full-depth profiles from the various Atlantic GEOTRACES cruises occurring in 2010 (US, Netherlands, and Germany). This will allow the broad brush characterization of these anthropogenic radionuclides some 37 years after GEOSECS. The isotopes of interest, in addition to being transient tracers, exhibit a range of Kd values (sediment water distribution coefficients, Pu Np ,Cs), and geochemical behaviors as well as provide a means to resolve different sources of radioactive contamination. This will allow the team to address processes such as advection (new water mass tracers), sources and sinks (characteristic isotopic signatures), as well as processes related scavenging and particle dynamics across a range of contrasting regions. The planned US, German, and Dutch GEOTRACES cruises transect regions that represent a full suite of physical and biogeochemical processes that affect TEIs. By comparing radionuclide distributions, isotopic composition, inventories, and inventory ratios of particle reactive (Pu) to conservative (Cs and Np), we will learn first order information about rates of scavenging and transport of these nuclides that is complimentary to that gained through study of other TEIs by GEOTRACES.Since GEOSECS, -- the first and only study to produce a view of the global oceanic distributions of plutonium and 137Cs -- methods have improved requiring less volume and providing not only better sensitivity but additional information (i.e., mass spectrometric techniques are capable of measuring the 240Pu/239Pu atom ratio; traditional alpha spectrometry is not). Where possible, the team will compare distributions measured in 2010 to those measured in 1972-1973 providing a ca. 40-year perspective on processes that control the fate and transport of these contaminants. In addition to providing updated baselines for Pu and 137Cs concentrations in the Atlantic, they will also provide information on 237Np as well as the 240Pu/239Pu isotopic composition, which have not been measured at this scale. Broader Impacts: This project will be an international collaboration and will yield valuable environmental radionuclide data from a number of locations throughout the Atlantic that would not be obtained otherwise. An important problem related to both anthropogenic climate change and sustainability is societal heavy reliance on fossil fuels as the main source of energy. Although the solution will certainly be complex, an increase in the proportion of energy derived from nuclear power is likely. The information gained from this proposal will be useful in assessing the fate of nuclides that might be released as a result of increased reliance on nuclear power in the future.