GEOTRACES GP-17 OCE: Measurement of 7Be as a Tracer of Upper Ocean Processes

GEOTRACES GP-17 OCE：测量 7Be 作为上层海洋过程的示踪剂

• 批准号: 2147723
• 负责人: Mark Stephens
• 金额: $ 27.61万
• 依托单位: Florida International University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2147723&HistoricalAwards=false
• 关键词: GEOTRACES; GP; 17; OCE; Measurement

The International GEOTRACES Program was established to identify processes and quantify fluxes that control the distributions of key trace elements and their isotopes in the ocean as these chemical species play important roles as nutrients, as tracers of current and past oceanographic processes, and as contaminants derived from human activity. This is a proposal to make measurements of one such species (the radioactive isotope Beryllium-7) in the water column and on aerosols during the US GEOTRACES GP17-OCE section of the South Pacific and Southern Oceans. Beryllium-7 is a tracer that, because of its half-life (53.3 days), allows the study of processes such as biological production, nutrient regeneration, and atmospheric deposition, which occur over seasonal time scales and shallow depths (200m). The data will be used to derive important biogeochemical rate information pertinent to interpreting sources and transformations of the extensive suite of trace elements and isotopes that will be measured during the expedition. The proposed work will measure beryllium-7 in the surface waters and in the lower atmosphere to provide estimates of the atmospheric input of relevant trace elements and isotopes. The atmospheric input into the global ocean is an important budgetary component of numerous chemical species, but there is little-to-no data from this region. Determination of the atmospheric input and its variability will allow observation of the oceanic response to this flux along the cruise track. The water column measurements of beryllium-7 will be used as a tracer of physical processes, such as mixing and upwelling, which redistribute biologically active species. The rate of oxygen utilization (OUR) within the upper thermocline will also be determined by water column measurements of beryllium-7 coupled with hydrographic data and observed oxygen distributions. Accurate characterization of this process within 200m of the euphotic zone, where carbon utilization is most intense, has been difficult owing to limitations of other available techniques which are characterized by multiyear to decadal timescales that likely miss the rapid organic matter remineralization occurring along shallow isopycnal surfaces. The seasonal timescale of beryllium-7 will allow for estimation of OUR within the shallow water just beneath the euphotic zone, where the most significant remineralization occurs. This research will support undergraduate researchers in a minority serving institution.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

建立国际GEOTRACES计划的目的是确定控制海洋中关键微量元素及其同位素分布的过程和量化通量，因为这些化学物质作为营养物、当前和过去海洋过程的示踪剂以及人类活动产生的污染物发挥着重要作用。这是一项在美国GEOTRACES GP 17-OCE南太平洋和南大洋部分期间对水柱和气溶胶中的一种此类物质（放射性同位素BER 14 -7）进行测量的建议。铍-7是一种示踪剂，由于其半衰期（53.3天），可以研究生物生产，营养再生和大气沉积等过程，这些过程发生在季节性时间尺度和浅层（200米）。 这些数据将用于获得重要的地球化学速率信息，以解释考察期间将测量的大量微量元素和同位素的来源和转化。拟议的工作将测量地表沃茨和低层大气中的铍-7，以提供有关微量元素和同位素进入大气的估计数。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，但该地区的数据很少或根本没有。确定大气输入量及其变化性，就可以观测海洋对沿着巡航轨迹的这种通量的反应。对铍-7水柱的测量将被用作物理过程的示踪剂，例如重新分布生物活性物种的混合和上升流。上部温跃层内的氧利用率（OUR）也将通过对铍-7的水柱测量以及水文数据和观测到的氧分布来确定。 在透光层200米范围内，碳的利用是最强烈的，这一过程的准确表征，一直是困难的，由于其他可用的技术，其特点是多年到十年的时间尺度，可能会错过快速的有机质再矿化发生沿着浅等密度面的限制。铍-7的季节性时间尺度将允许在真光层下面的浅水中估计OUR，其中发生最显着的非矿化。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。