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

国际地学研究计划的目标是了解海洋中痕量化学元素及其同位素的分布。该项目将在即将进行的两次前往南太平洋、南大洋和阿蒙森海的美国地理追踪探险中测量惰性气体浓度、氦和氧同位素丰度以及氚。稀有气体和同位素示踪剂将用于确定热液喷发、冰川融化和海冰形成对该地区水团的贡献。冰川融化和海冰生产被认为是南极大陆架上微量元素循环的重要驱动因素。这些过程还有助于确定南大洋来源的深水的性质。深源热水的上涌可将铁等微量营养素输送到南大洋表层水域，从而推动初级生产力的提高。较深的热液热柱可能通过德雷克海峡输出大量的热液微量元素和同位素(TEI)。该项目将支持研究生、教师专业发展和公众出行。在GEOTRACES GP17-OCE探险期间，该团队将测量氦-3、氦浓度和霓虹灯浓度。在gp17-ant探险中，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)研究整个南太平洋的热液输入路径，(2)量化其他热液来源的TEI通量和清扫率，(3)量化阿蒙森海雪和海冰融化相对于铁和其他TEI的输入，(4)追踪阿蒙森海的冰架抽水机制，并研究融水和TEI从覆盖冰层的边缘海向北扩散到开放的南大洋的情况。此外，由于有证据表明并非所有南大洋的热液输入都被发现，探险有可能扩大对水柱生物地球化学重要的其他热液系统位于何处的知识。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.