Collaborative Research: Cosmogenic Radionuclides in the WAIS Divide Ice Core

WELTEN/0636964该奖项支持一个为期两年的项目，该项目使用加速器质谱仪(AMS)测量南极冰样中的宇宙源放射性核素10Be、26Al和36Cl的浓度。该项目是未来对WAIS深冰芯多达1000个独立冰样进行放射性核素分析的初步研究。由于这些冰芯研究涉及大量样品，以及及时分析宇宙成因放射性核素的重要性，我们提议在普渡大学建立第二条化学分离线，与加州大学伯克利分校开发的Siple Dome和GISP-2冰芯化学分离线相同。在对12-16个测试冰样进行了全面的实验室间比较后，我们将使用两条提取线来测量来自WAIS分水岭的浅冰芯中的宇宙源放射性核素。预计两条化学分离线的使用将使样品吞吐量增加两倍，并确保普渡大学AMS及时分析宇宙源放射性核素。该项目的学术价值在于，这些测量将使科学家能够区分局部和全球影响。通过测量不同地点冰芯中的几种放射性核素，可以弄清放射性核素绝对浓度及其比率的变化是由于大气环流、沉积机制和积雪速率等局部效应的变化，还是由于太阳活动和地球磁场强度的变化，这是影响大气中宇宙核素全球产生率的主要过程。最后，将WAIS浅冰芯中的26Al/10Be比值与GISP2冰芯中测得的26Al/10Be比值进行比较，将证明这一比值是否可以作为古老南极冰的绝对计时器。该项目的更广泛影响包括组成一个多学科合作者小组，以解释来自WAIS分水岭冰芯未来的宇宙放射性核素数据分析；对本科生和研究生进行冰样化学处理和在更广泛的气候变化研究范围内解释宇宙核素数据的参与和培训；向广泛的实验室访客和当地学校的学生解释冰芯和气候变化研究的重要性。

Welten/0636964This award supports a 2-year project to measure the concentrations of the cosmogenic radionuclides, 10Be, 26Al and 36Cl, in Antarctic ice samples using accelerator mass spectrometry (AMS). This project is a pilot study for the future analysis of radionuclides from up to 1000 individual ice samples of the WAIS Divide deep ice core. Because of the large number of samples that are involved in these ice core studies, and the importance of a timely analysis of cosmogenic radionuclides, we are proposing to set up a second chemical separation line, at Purdue University, identical to the one developed at UC Berkeley for the Siple Dome and GISP-2 ice cores. After a thorough interlaboratory comparison on 12-16 test ice samples, we will use both extraction lines to measure cosmogenic radionuclides in a shallow ice core from the WAIS Divide. It is to be expected that the use of two chemical separation lines will increase the sample throughput by a factor of two, and ensure a timely analysis of the cosmogenic radionuclides by AMS at Purdue University. The intellectual merit of the project is that these measurements will enable scientists to separate local from global effects. By measuring several radionculides in ice cores from different locations one can disentangle whether variations in absolute radionuclide concentrations and their ratios are due to local effects such as variations in atmospheric circulation, deposition mechanisms, and snow accumulation rates; or whether they are due to variations in solar activity and geomagnetic field strength, the primary processes influencing the global production rates of cosmogenic nuclides in the atmosphere. Finally, a comparison of the 26Al/10Be ratios in the WAIS Divide shallow core with those measured in the GISP2 ice core will demonstrate if this ratio can be used as an absolute chronometer of old Antarctic ice. The broader impacts of this project include the formation of a multi-disciplinary team of collaborators for the interpretation of future analyses of cosmogenic radionuclide data from the WAIS Divide ice core, the involvement and training of undergraduate and graduate students in the chemical processing of ice samples and interpretation of the cosmogenic nuclide data in the wider scope of climate change research, and explaining the importance of ice core and climate change studies to a wide range of lab visitors and students from local schools.