MRI: Track 3 Acquisition of Helium Recovery Equipment - Closed-cycle Cryotraps for Polar Ice Core Trace Gas Analysis

极地冰芯中的空气是关于大气成分变化的最准确的信息来源。对极地冰芯的测量告诉我们痕量气体如何影响和应对百年和千年时间尺度上的气候变化。极地冰档案包括广泛的气候活性痕量气体（含硫气体，碳氢化合物和卤化化合物），反映了海洋生物群和陆地生态系统的排放。UCI实验室开发了分析技术，从极地档案中提取和分析这些超痕量气体，使研究人员能够重建其大气历史，并了解它们如何受到气候和人类活动的影响。进行中和计划中的项目需要分析南极和格陵兰冰芯的大量样本。封闭循环低温阱的实施将确保能够继续进行这项研究，同时节省分析过程中使用的氦气。极地冰芯中捕获的空气分析需要在超净条件下提取和处理少量空气样本。在UCI的冰核实验室中，目前使用液氦来完成这一工作，液氦是一种易受供应波动和成本迅速增加影响的商品。该项目需要资金购买和安装新的封闭循环低温冷阱系统，从而消除对液氦的需求。封闭循环低温阱的安装将确保运行的连续性，并降低UCI冰芯实验室的长期运行成本。新的低温冷阱将安装在真空管线上，用于从冰芯样品中湿法（融化）和干法（粉碎）提取空气，用于低水平痕量气体分析。冰核实验室积极参与校园和当地少数民族K-12学区的外展活动。该奖项反映了NSF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 air trapped in polar ice cores is the most accurate source of information about the variability in atmospheric composition. Measurements on polar ice cores inform us about how trace gases influence and respond to climate change on centennial and millennial time scales. The polar ice archive includes a wide range of climate-active trace gases (sulfur-containing gases, hydrocarbons, and halogenated compounds) that reflect emissions from oceanic biota and terrestrial ecosystems. The UCI laboratory has developed analytical techniques to extract and analyze such ultra-trace gases from polar archives, allowing researchers to reconstruct their atmospheric histories and understand how they are influenced by climate and human activities. Ongoing and planned projects require the analysis of large numbers of samples from Antarctic and Greenland ice cores. The implementation of closed-cycle cryotraps will ensure the ability to continue this research while conserving helium used in the analytical process.The analysis of air trapped in polar ice cores requires the extraction and manipulation of small air samples under ultra-clean conditions. In the UCI ice core laboratory this is currently done using liquid helium, a commodity subject to fluctuating supply and rapidly increasing costs. This project requests funds to purchase and install new closed-cycle cryogenic cold trap systems, eliminating the need for liquid helium. Installation of the closed-cycle cryotraps will ensure operational continuity and reduce long-term operating costs of the UCI ice core laboratory. The new cold cryotraps will be installed on vacuum lines used for the wet (melting) and dry (shredding) extraction of air from ice core samples for low-level trace gas analysis.The proposed instrumentation will support graduate and undergraduate student training. The ice core laboratory is actively involved in outreach activities both on campus and in local minority K-12 school districts.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.