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项目的目标是了解海洋中微量化学元素及其同位素的分布。该项目将在即将到来的两次美国GEOTRACES探险中进行稀有气体浓度、氦和氧同位素丰度以及氚的测量，分别前往南太平洋、南大洋和阿蒙森海。稀有气体和同位素示踪剂将用于确定热液喷吐、冰川融水和海冰形成对该地区水团的贡献。冰川融化和海冰形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深水的性质。深层热液的上涌可以向南大洋的表层水输送铁等有限的微量营养素，从而提高初级生产力。深埋热液柱可能通过德雷克通道输出热液微量元素和同位素（TEIs）通量。该项目将支持研究生、教师专业发展和公众宣传。在GEOTRACES GP17-OCE考察期间，该团队将测量氦-3、氦浓度和氖浓度。在GP17-ANT探险队中，他们将测量所有五种惰性气体、氦-3、水的稳定同位素组成和氚的浓度。具体目标包括(1)研究热液通道输入整个南太平洋,(2)量化其他hydrothermally-sourced TEI通量和扫气率,(3)量化的输入雪和海冰融化与铁和其他TEI阿蒙森海,(4)跟踪冰架泵机制在阿蒙森海,并检查向北传播的传播融水和TEI冰封开放南太平洋边缘海。此外，由于有证据表明并非所有流入南大洋的热液都已被发现，这些考察有可能扩大对其他热液系统的认识，这些系统对水柱的生物地球化学非常重要。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 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.