Following the Trail of Fukushima Tracers: Transport Pathways, Spreading and Mixing in the North Pacific

该项目的目标是利用2011年一次性释放的放射性同位素（特别是铯）提供的信息（137 Cs，半衰期约为30年，134 Cs，半衰期约为2年）和锶（90锶，29年半衰期），以更好地了解途径，北太平洋的水的混合和输送。PI将分析2013年纬向CLIVAR 30°N断面的表面剖面样本中的锶;并获取和分析沿着2015年纬向CLIVAR线150°W处的上层水柱铯（Cs）和锶（Sr）剖面。这些观测，沿着过去两年半收集的海洋铯和碘数据，将与卫星、漂流物和浮子观测、海洋模型分析和大气模拟结果相结合，以阐明自同位素释放以来4年期间将发生的水平扩散和垂直混合的细节。智力优势：铯和锶的观测和分析，特别是当与其他观测到的属性和数值模型相结合，将提供一个独特的窗口，从其中查看水团的形成和时间尺度的转换在北太平洋。这项调查旨在更好地了解福岛放射性同位素在北太平洋释放和沉积的命运-它们在被引入后2至4年的范围和深度。虽然海洋中的放射性水平被认为是不危险的，但它在哪里以及确切的数量，仍然是那些生活在北太平洋海岸并在其沃茨捕鱼的人特别感兴趣的话题。与此同时，有人问这个独特的示踪剂可以说海洋平流和扩散过程。PI打算使用观测结果来改进他们自己的模型模拟，并验证不同社区的建模工作，预测美国西海岸沃茨的放射性同位素污染。关于福岛同位素混合和扩散的可变性得出的结论将与那些试图了解物理过程对生物生产、营养循环和二氧化碳吸收的作用的人有关，因为这套真正独特的十年尺度示踪剂将揭示流域尺度上层海洋混合和平流过程的速率和模式。为了通过多种示踪剂分析最大限度地提高拟议样品的科学效益，并与从事福岛衍生同位素工作的其他实验室建立更紧密的联系，并支持年轻研究人员的教育，来自巴塞罗那大学P. Masque实验室的一名研究生将被邀请在WHOI度过两个学期，以测量北太平洋水文样品中的90 Sr放射性。在该项目的第一个夏天，WHOI暑期学生研究员（三年级本科生）将被邀请参加该项目的观测部分，通过分析水文学，浮子剖面或测高。进一步与日本同行开展国际合作，并协助开发降低检测限的新方法。青山将应邀从东京访问WHOI同位素实验室。此外，还将建立一个公布结果的公共网站。该小组的所有成员都打算通过以下方案继续开展工作，在各级开展外联活动：利用巡航观测指导当地初中和高中学生参加科学博览会项目、课堂参观和公共外联演讲、访谈和会谈。

The goal of this project is to use the information provided by the one-time, 2011 release of radio isotopes, and in particular, cesium (137Cs, ~30-year half-life and 134Cs, ~2-year half-life) and strontium (90Sr, 29-year half-life) from the Dai-ichi Fukushima nuclear power plants in northern Japan to better understand the pathways, mixing and transport of water in the North Pacific Ocean. The PIs will analyze surface & profile samples from the 2013 zonal CLIVAR 30°N transect for strontium; and obtain and analyze upper water column cesium (Cs) and strontium (Sr) profiles along the 2015 meridional CLIVAR line at 150°W. These observations, along with ocean cesium and iodine data collected over the last two and a half years, will be combined with satellite, drifter and float observations, an ocean model analysis and atmospheric modeling results to illuminate the details of the horizontal spread and vertical mixing that will have taken place over the 4 year period since the release of the isotopes. Intellectual Merit: The Cs and Sr observations and analysis, particularly when combined with other observed properties and numerical models, will provide a unique window from which to view water mass formation and the temporal scale of transformation within the North Pacific. This investigation seeks to better understand the fate of Fukushima radioisotopes released and deposited in the North Pacific -- how far and how deeply they range 2 to 4 years after being introduced. Although levels of this radioactivity in the ocean are not considered dangerous, the questions of where it is, and exactly how much there is, remain topics of particular interest to those who live on North Pacific shores and fish in its waters. At the same time it is asked what this unique tracer can say about ocean advection and diffusion processes. The PIs intend to use the results from the observations to improve their own model simulation and to validate disparate community modeling efforts forecasting radioisotope contamination of waters off the US west coast. Conclusions drawn concerning the variability in the mixing and spreading of Fukushima isotopes will be relevant to those seeking to understand the role of physical processes on biological production, nutrient cycling and CO2 uptake as this truly unique set of decadal-scale tracers will reveal the rates and patterns of basin-scale upper-ocean mixing and advective processes.Broader Impacts: To maximize the scientific benefit of the proposed samples through multi-tracer analysis, as well as to develop stronger ties with other labs working with Fukushima derived isotopes, and support the education of a young researcher, a graduate student from P. Masque's University of Barcelona lab will be invited to spend two semesters at WHOI to measure 90Sr activities in the North Pacific hydrographic samples. During the 1st summer of the project, a WHOI summer student fellow (3rd year undergraduate) will be invited to participate in the observational component of the project through analyses of hydrography, float profiles or altimetry. To further international collaboration with Japanese colleagues and assist in the development of new methods for reducing detection limits M. Aoyama will be invited to visit the WHOI isotope lab from Tokyo. In addition, a public website will be created on which results will be posted. All members of the group intend to engage in outreach at various levels through their continued work with the following programs: mentoring of local middle and high school students using cruise observations for science fair projects, classroom visits and public outreach presentations, interviews and talks.