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地球观测站的研究人员将从2010年（美国、荷兰和德国）的各种大西洋GEOTRACES巡航中选择的全深度剖面中获得人为放射性核素239Pu、240Pu、237Np和137Cs的总浓度。这将允许在GEOSECS大约37年后对这些人为放射性核素进行大致的描述。感兴趣的同位素除了是瞬态示踪剂外，还表现出一系列的Kd值（沉积物水分布系数，Pu Np,Cs）和地球化学行为，并提供了一种解决不同放射性污染源的方法。这将使团队能够解决诸如平流（新的水团示踪剂），源和汇（特征同位素特征）等过程，以及在一系列对比区域中与清除和粒子动力学相关的过程。计划中的美国、德国和荷兰GEOTRACES巡行横断面区域，这些区域代表了影响tei的全套物理和生物地球化学过程。通过比较放射性核素分布、同位素组成、库存和颗粒活性（Pu）与保守（Cs和Np）的库存比率，我们将了解这些核素的清除和运输速率的一阶信息，这些信息与GEOTRACES通过研究其他TEIs获得的信息是补充的。自从GEOSECS——第一个也是唯一一个产生钚和137Cs全球海洋分布的研究——以来，方法得到了改进，所需的体积更小，不仅提供了更高的灵敏度，而且提供了更多的信息（即，质谱技术能够测量240Pu/239Pu原子比，而传统的α光谱法则不能）。在可能的情况下，研究小组将把2010年测量的分布与1972-1973年测量的分布进行比较，以提供一个大约40年的视角来研究控制这些污染物的命运和运输的过程。除了提供大西洋中Pu和137Cs浓度的最新基线外，他们还将提供237Np以及240Pu/239Pu同位素组成的信息，这些信息尚未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，并将从整个大西洋的许多地点获得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相关的一个重要问题是社会对化石燃料作为主要能源的严重依赖。尽管解决方案肯定是复杂的，但核能能源比例的增加是可能的。从这项建议中获得的资料将有助于评估今后由于日益依赖核能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.