Measuring an Ice-core Proxy for Relative Oxidant Abundances over Glacial-interglacial and Rapid Climate changes in a West Antarctic Ice Core

地球的大气层是一种高度氧化的介质。大气中臭氧等氧化剂的丰富程度强烈影响污染物和温室气体的浓度，对人类健康和福祉产生影响。由于氧化剂没有保存在地质档案中，所以关于氧化剂在过去气候条件变化下如何变化的知识极其有限。该奖项将测量过去5万年来几次主要气候变化期间南极西部冰芯中氧化剂浓度的代用物。这些测量结果将补充格陵兰冰芯的类似测量结果，后者显示了在同一时期的主要气候转变期间大气氧化剂的显著变化。加上来自南极洲的测量结果，研究人员可以检验格陵兰冰芯记录所显示的氧化变化是区域性的还是全球性的。了解氧化剂如何随气候自然变化，将更好地预测气候变暖下未来大气的组成。该奖项将支持测量南极西部冰芯中硝酸盐的同位素组成，作为过去大气中氧化剂浓度的代表。硝酸盐的氮同位素提供了冰芯记录中硝酸盐保存程度的信息，从而有助于解释冰芯记录中观测到的硝酸盐浓度和氧同位素的变化。通过提供末次冰期气候突变事件中氧化变化的空间尺度信息，该项目还可以提高我们对这些突变事件驱动机制的理解。从这个项目中获得的见解将证明对预测平流层环流对气候变化的响应是有价值的，这对气候反馈和对流层组成有很大的影响。此外，本项目收集的关于气候突变事件的机制和反馈的信息将有助于确定未来发生这种对人类产生巨大影响的快速事件的可能性。该奖项将为一名研究生和一名本科生提供培训，并将支持与快速气候变化相关的实践活动的发展，该活动将在华盛顿州西雅图太平洋科学中心举行的年度极地科学周末上使用。

The Earth's atmosphere is a highly oxidizing medium. The abundance of oxidants such as ozone in the atmosphere strongly influences the concentrations of pollutants and greenhouse gases, with implications for human health and welfare. Because oxidants are not preserved in geological archives, knowledge of how oxidants have varied in the past under changing climate conditions is extremely limited. This award will measure a proxy for oxidant concentrations in a West Antarctic ice core over several major climate transitions over the past 50,000 years. These measurements will complement similar measurements from a Greenland ice core, which showed significant changes in atmospheric oxidants over major climate transitions covering this same time period. The addition of measurements from Antarctica will allow researchers to examine if the oxidant changes suggested by the Greenland ice core record are regional or global in scale. Knowledge of how oxidants vary naturally with climate will better inform predictions of the composition of the future atmosphere under a warming climate.This award will support measurements of the isotopic composition of nitrate in a West Antarctic ice core as a proxy for oxidant concentrations in the past atmosphere. The nitrogen isotopes of nitrate provide information on the degree of preservation of nitrate in the ice core record, and thus aid in the interpretation of the observed variability in the observed nitrate concentrations and oxygen isotopes in ice core records. By providing information about the spatial scale of oxidant changes over abrupt climate change events during the last glacial period, this project may also improve our understanding of mechanisms driving these abrupt events. Insight from this project will prove valuable for forecasting the response of stratospheric circulation to climate change, which has large implications for climate feedbacks and tropospheric composition. In addition, the information gleaned from this project on the mechanisms and feedbacks during abrupt climate change events will help determine the likelihood of such rapid events occurring in the future, which would have dramatic impacts on humankind. This award will provide training for one graduate and one undergraduate student, and will support the development of a hands-on activity related to rapid climate change to be used at the annual Polar Science Weekend at the Pacific Science Center in Seattle, WA.