GEOTRACES Peru-Tahiti section: Measurement of 7Be as a Tracer of Upper Ocean Processes

在海洋中，微量元素的功能多种多样，如营养物质，人类活动的污染物，甚至是当前和过去海洋过程的方便示踪剂。它们的生物地球化学循环对海洋碳循环和生态系统动力学以及全球气候变化具有重要影响。 海洋中影响微量元素分布和行为的许多过程无法直接观测，因此使用各种地球化学示踪剂对其速率和途径提供重要约束。Berlene-7（Be 7）是一种宇宙成因的（即，由于其半衰期（53.3天），可用于研究季节性时间尺度上发生的环境过程。这一时间尺度对生物生产、营养再生和大气沉积等研究都很重要。在这个项目中，来自迈阿密大学的一个研究小组将于2013年对秘鲁到塔希提岛的美国GEOTRACES断面沿着的水柱Be 7进行测量。国际GEOTRACES计划的使命（美国计划是其中的一个组成部分）是“确定控制海洋中关键微量元素和同位素分布的过程和量化通量，并确定这些分布对不断变化的环境条件的敏感性。“作为多机构的美国GEOTRACES太平洋运动的一部分，迈阿密团队将解决GEOTRACES科学计划内制定的关键任务。 具体而言，它们将：（1）对影响所测微量元素分布的基本迁移过程提供现实的估计;它们将使用Be 7的水柱测量值作为物理过程的示踪剂，例如重新分布生物活性物种的混合和上升流;以及（2）开发和应用新的Be 7方法，以量化参与该活动的其他研究团队测量的TEI的大气沉积。沿巡航轨迹沿着的表层沃茨和低层大气中Be 7的测量将提供有关TEI的大气输入的估计。进入全球海洋的大气输入是许多化学物种的重要预算组成部分，但很难限制。这项工作产生的数据将用于对气溶胶沉积模型和微量元素的大气输入进行地面实况调查。更广泛的影响：拟议的工作是为了支持GEOTRACES计划，因此有助于该计划的许多广泛的知识目标。提供相关TEIs大气输入估计值的能力是一个重要的例子，它将在GEOTRACES之外的未来对该领域做出广泛贡献，包括了解人类活动对海洋的影响。研究生的教育和培训将是这项研究的重要组成部分。

In the ocean, trace elements function variously as nutrients, as contaminants from human activity, and even as convenient tracers of current and past oceanographic processes. Their biogeochemical cycling has major impacts on the ocean carbon cycle and ecosystem dynamics as well as on global climate change. Many processes influencing the distribution and behavior of trace elements in the ocean cannot be directly observed, so consequently a variety of geochemical tracers are used to provide important constraints on their rates and pathways. Beryllium-7 (Be7) is a cosmogenic (i.e., produced in the upper atmosphere) radionuclide that, because of its half-life (53.3d), can be used in the study of environmental processes occurring over seasonal timescales. This timescale is important to studies of biological production, nutrient regeneration, and atmospheric deposition, to name a few. In this project, a research team from the University of Miami will make measurements of water column Be7 along the U.S.GEOTRACES transect from Peru to Tahiti in 2013. The mission of the International GEOTRACES Program (of which the US program is a component) is "to identify processes and quantify fluxes that control the distributions of key trace elements and isotopes in the ocean, and to establish the sensitivity of these distributions to changing environmental conditions." As part of the multi-institutional U.S.GEOTRACES Pacific campaign, the Miami team will address key tasks formulated within the GEOTRACES Science Plan. Specifically, they will: (1) provide realistic estimates of the underlying transport processes influencing measured trace elements of interest (TEI) distributions; they will use water column measurements of Be7 as a tracer of physical processes, such as mixing and upwelling, which redistribute biologically active species; and (2) develop and apply new Be7 methods for quantifying the atmospheric deposition of TEIs measured by other research teams participating in the campaign. Measurements of Be7 in the surface waters and in the lower atmosphere along the cruise track will provide estimates of the atmospheric input of relevant TEIs. The atmospheric input into the global ocean is an important budgetary component of numerous chemical species, yet is very difficult to constrain. The data generated in this work will be available to allow ground-truthing of aerosol deposition models and the atmospheric input of trace elements. Broader impacts: The proposed work is in support of the GEOTRACES program, and as such contributes to many of the broad intellectual objectives of that program. The ability to provide estimates of the atmospheric input of relevant TEIs is an important example, and one that will contribute widely to the field in the future beyond GEOTRACES, including understanding anthropogenic impacts on the oceans. Education and training of graduate students will be essential components of this research.