Collaborative Research: US GEOTRACES GP17-OCE and GP17-ANT: Properties and processes impacting other trace element and isotope cycles using noble gas and stable isotope tracers

国际GEOTRACES计划的目标是了解微量化学元素及其同位素在海洋中的分布。该项目将在美国即将进行的两次对南太平洋、南大洋和阿蒙森海的GEOTRACES考察中对惰性气体浓度、氦和氧同位素丰度以及氚进行测量。惰性气体和同位素示踪剂将用于确定热液喷发、冰川融水和海冰形成对该区域水团的贡献。冰川融化和海冰生成被认为是南极大陆架微量元素循环的重要驱动因素。这些过程也有助于确定南大洋来源的深水的性质。深源热液的上涌可将铁等有限的微量营养素输送到南大洋的表层沃茨，从而提高初级生产力。较深的热液羽流可能通过德雷克海峡输出热液微量元素和同位素（TEI）通量。在GEOTRACES GP 17-OCE考察期间，该团队将测量氦-3、氦浓度和氖浓度。在GP 17-ANT探险中，他们将测量所有五种惰性气体的浓度，氦-3，水的稳定同位素组成和氚。具体目标包括：（1）研究整个南太平洋的热液输入路径，（2）量化其他热液源TEI通量和清除率，（3）量化阿蒙森海与铁和其他TEI相关的雪和海冰融化输入，（4）追踪阿蒙森海冰架泵机制，并研究了向北扩散的融水和TEI从冰覆盖的边缘海到开放的南大洋的传播。此外，由于有证据表明，并非所有的热液输入到南大洋已被发现，探险有可能扩大知识的额外的热液系统，重要的水柱的地球化学，是location.This奖项反映了NSF的法定使命，并已被认为是值得的支持，通过评估使用基金会的知识价值和更广泛的影响审查标准。

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 undertake measurements of noble gas concentrations, helium and oxygen isotope abundances, and tritium on two upcoming U.S. GEOTRACES expeditions to the South Pacific, Southern Ocean, and Amundsen Sea. The noble gas and isotope tracers will be used to determine the contributions of hydrothermal venting, glacial meltwater, and sea ice formation to the water masses of the region. Glacial melt and sea ice production are considered important drivers of trace element cycling on the Antarctic continental shelf. These processes also help establish the properties of Southern Ocean-sourced deep water. Upwelling of deep-sourced hydrothermal water could deliver limiting micronutrients such as iron to the surface waters of the Southern Ocean, driving enhanced primary productivity. Deeper-lying hydrothermal plumes may export fluxes of hydrothermal trace elements and isotopes (TEIs) through the Drake Passage. The project will support a graduate student, teacher professional development, and public outreach.During the GEOTRACES GP17-OCE expedition, the team will measure helium-3, helium concentration, and neon concentration. On the GP17-ANT expedition, they will measure the concentrations of all five noble gases, helium-3, the stable isotope composition of water, and tritium. Specific aims include (1) to study pathways for hydrothermal inputs throughout the South Pacific, (2) to quantify other hydrothermally-sourced TEI fluxes and scavenging rates, (3) to quantify the inputs of snow and sea ice melt in relation to iron and other TEIs in the Amundsen Sea, (4) trace the ice shelf pump mechanism in the Amundsen Sea, and examine the spread of northward spread of meltwater and TEIs from the ice-covered marginal seas to the open Southern Ocean. In addition, since there is evidence that not all the hydrothermal inputs to the Southern Ocean have been discovered, the expeditions have the potential to expand knowledge of where additional hydrothermal systems, important to the biogeochemistry of the water column, are located.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.