Collaborative Research: US GEOTRACES GP17-ANT: Answering key questions in marine particle trace element biogeochemistry in the Amundsen Sea

合作研究：US GEOTRACES GP17-ANT：回答阿蒙森海海洋颗粒微量元素生物地球化学的关键问题

• 批准号: 2220306
• 负责人: Robert Sherrell
• 金额: $ 19.49万
• 依托单位: Rutgers University New Brunswick
• 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: 2022-11-01 至 2025-10-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2220306&HistoricalAwards=false
• 关键词: Collaborative; Research; US; GEOTRACES; GP17

The goal of the international GEOTRACES program is to understand the distributions of trace chemical elements and their isotopes in the oceans. This project will generate a dataset of 40 trace elements on suspended particles and surface sediment samples collected on the GEOTRACES GP17-ANT cruise to the Amundsen Sea, West Antarctica. The Amundsen Sea hosts the most productive polynya per unit area in all of Antarctica, with biological carbon uptake ten times higher than the average for the Southern Ocean. Over the past 30 years, this region has become a primary locus of increased freshwater input, as the fastest melting glaciers in West Antarctica deliver huge and increasing volumes of freshwater to the Amundsen Sea. The major contribution of this region to global sea level rise is well documented, but the impact of accelerated additions of meltwater and associated chemical constituents on the biogeochemistry of the Antarctic shelf waters, and in particular on the cycling of trace elements, has not received comprehensive investigation. Hypotheses addressing four key components of the biogeochemical system in the Amundsen Sea will be tested, and results will closely mesh with complementary efforts proposed by other GP17-ANT investigators. The project will support a graduate student and several undergraduate interns, with a focus on broadening participation in STEM. The investigators will also work with established programs to create meaningful out-of-school science experiences for middle and high school students.The aim of the project is to quantify and interpret the distributions of particulate trace elements in approximately 500 samples covering a large swath of the Amundsen Sea shelf, including waters influenced by five major ice shelves, and in the adjacent iron-limited Southern Ocean waters bounded by 100°W and 135°W, and south of 67°S. The investigators will use size-fractionated sample collection, total acid digestion and weak acid leaching, and well-established mass spectrometric methods to determine concentrations and probe the physico-chemical state of the particulate trace elements. The team will use the new data to investigate the following issues: 1) the role of phytoplankton, with a focus on Phaeocystis and diatoms, dominant taxa on the Amundsen Sea shelf, in driving element cycling in the upper water column while experiencing variable degrees of iron stress; 2) the “meltwater pump” which generates vigorous and particle-rich outflow from ice shelf cavities; 3) the bottom nepheloid layer of resuspended sediments as a reaction zone that determines the composition of the sedimentary paleo-record and also modulates of chemical fluxes at the sediment-water boundary; and 4) the rare earth elements (REE), which the team proposes carry unique geochemical information about terrigenous particle provenance among the geologically diverse glacial drainage regions, and also includes a labile particulate fraction whose magnitude and inter-element ratios may serve as a relative index of element scavenging intensity that can be applied to predict regions of maximal scavenging for other particle-reactive elements.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.

国际 GEOTRACES 计划的目标是了解海洋中微量化学元素及其同位素的分布，该项目将生成由 GEOTRACES GP17-ANT 巡航中收集的悬浮颗粒和表面沉积物样本中的 40 种微量元素组成的数据集。南极洲西部的阿蒙森海拥有整个南极洲单位面积生产力最高的冰间湖，其生物碳吸收量比南大洋平均水平高十倍。过去 30 年来，该地区已成为淡水输入量增加的主要场所，因为南极洲西部融化速度最快的冰川向阿蒙森海输送了大量且不断增加的淡水。该地区对全球海平面上升的主要贡献是有据可查的。但融水和相关化学成分的加速添加对南极陆架水域生物地球化学的影响，特别是对微量元素循环的影响，尚未得到全面的假设研究。将测试阿蒙森海生物地球化学系统的四个关键组成部分，其结果将与其他 GP17-ANT 研究人员提出的补充工作紧密结合。该项目将支持一名研究生和几名本科生实习生，重点是扩大参与范围。研究人员还将与已建立的项目合作，为中学生和高中生创造有意义的校外科学体验。该项目的目的是量化和解释涵盖约 500 个样本的颗粒微量元素的分布。大的阿蒙森海陆架的大片地区，包括受五个主要冰架影响的水域，以及以西经 100° 和 135°W 以及南纬 67° 以南为界的邻近铁限制南大洋水域，调查人员将使用尺寸分级。样品采集、总酸消化和弱酸浸出，以及成熟的质谱方法来确定浓度并探测颗粒微量元素的物理化学状态，该团队将使用新数据来进行研究。研究以下问题：1）浮游植物（重点关注阿蒙森海陆架上的主要类群棕囊藻和硅藻）在经历不同程度的铁胁迫时驱动上部水体元素循环的作用2）“融水”； 3) 重悬浮沉积物的底部霞石层作为反应区，决定了沉积物的成分沉积古记录以及沉积物-水边界的化学通量的调节；4）稀土元素（REE），该团队认为稀土元素携带着有关地质多样化的冰川流域中的陆源颗粒来源的独特地球化学信息，并且包括不稳定颗粒部分，其大小和元素间比率可作为元素清除强度的相对指数，可用于预测其他颗粒反应元素的最大清除区域。该奖项通过使用基金会的智力价值和更广泛的影响审查标准进行评估，NSF 的法定使命被认为值得支持。