Collaborative Research: US GEOTRACES GP17-OCE: Shipboard Measurements of Dissolved Aluminum, Iron, and Manganese – Tracing Inputs to the South Pacific Gyre and Southern Ocean

国际研究项目GEOTRACES的目标是了解海洋中微量化学元素及其同位素的分布。海洋中微量元素的重要性在于它们作为海洋浮游植物必需的微量营养素（如铁），作为毒物（如铅），以及作为过去和现在海洋过程的示踪剂（如钍）的作用。在这个项目中，两种微量营养素微量元素（铁和锰）和大气尘埃沉积示踪剂（铝）的溶解浓度将在东南太平洋和邻近的南大洋的一次研究巡航中采集的海水样本中进行测量，以便更好地了解这些微量营养素的输入及其对这些地区生物过程的影响。化学分析将在海上近乎实时地进行，从而提供初步数据，为巡航取样策略和其他调查人员进行的分析提供信息。该项目涉及两个美国实验室，将支持一名研究生和一名本科生的研究。美国GEOTRACES GP17-OCE考察队将把重点放在沿横断面穿越南太平洋环流和南大洋太平洋部分的微量元素和同位素分布上，在那里，向海洋表面提供的溶解铁（DFe）和锰（DMn）被认为调节了初级生产和相关的碳和营养元素循环。研究人员将在船上和巡航后对溶解铝（DAl）、DFe和DMn进行测量，以限制(1)该海洋区域尘埃沉积的大小，以及DAl和DMn作为风成铁输入示踪剂的保真度；(2)深海DAl和DFe异常的成因及其对深海元素来源的启示；(3)深海热液DFe排放的来源和去向及其在支持南大洋初级生产中的作用。项目结果，加上GP17-OCE项目合作者对其他微量化学物质的测量，将促进对控制海洋中DAl、DFe和DMn的库存和分布的过程及其未来变化轨迹的理解。该奖项反映了美国国家科学基金会的法定使命，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。

The goal of the international research program GEOTRACES is to understand the distributions of trace chemical elements and their isotopes in the oceans. The importance of trace elements in the ocean lies in their roles as essential micronutrients for marine phytoplankton (e.g., iron), as toxicants (e.g., lead), and as tracers of past and present oceanic processes (e.g., thorium). In this project, the dissolved concentrations of two micronutrient trace elements (iron and manganese) and a tracer of atmospheric dust deposition (aluminum) will be measured in seawater samples collected during a research cruise in the southeastern Pacific Ocean and adjacent Southern Ocean, in order to better understand the inputs of these micronutrients and their impact on biological processes in these regions. Chemical analyses will be performed at sea in near real-time, thus providing a first glimpse of data that will inform the cruise sampling strategy and the analyses performed by other investigators. The project involves two US laboratories, and will support the research of a graduate and undergraduate student. The U.S. GEOTRACES GP17-OCE expedition will focus on the distribution of trace elements and isotopes along a transect crossing the South Pacific Gyre and the Pacific sector of the Southern Ocean, where the supply of dissolved iron (DFe) and manganese (DMn) to the surface ocean is thought to regulate primary production and associated cycling of carbon and nutrient elements. The investigators will undertake shipboard and post-cruise measurements of dissolved aluminum (DAl), DFe and DMn in order to constrain (1) the magnitude of dust deposition to this ocean region and the fidelity of DAl and DMn as tracers of aeolian iron inputs; (2) the origin of deep-ocean DAl and DFe anomalies, and their implications for deep sources of these elements; and (3) the source and fate of hydrothermal DFe emissions from the deep ocean and their role in supporting Southern Ocean primary production. Project results, complemented by measurements of other trace chemical species made by collaborators on GP17-OCE, will advance the understanding of the processes that control the oceanic inventories and distributions of DAl, DFe and DMn, and their trajectories of future change.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.