Looking for Evidence of Stratospheric Ozone Depletion in Ice at South Pole

平流层中臭氧的丰富是对地表紫外线辐射的主要控制，这对地球上的生命有着重要的影响。平流层臭氧还通过改变大气环流模式影响地球气候系统，对海洋碳循环和海冰范围产生影响。有人提出，距今18,000年前的最后一次冰川期的结束与持续200多年的平流层臭氧耗竭有关，这是由山上的一系列大喷发造成的。南极洲西部的塔卡河火山。这种臭氧消耗可能通过改变大气环流模式，减少南极海冰面积，并增加南大洋的碳排放，加速了最后一次冰川盛期的结束。该项目将测试一种通过测量南极浅冰样中硝酸盐的氮同位素来确定过去地表紫外线辐射水平的新方法。这项研究利用南极洲上空的现代臭氧空洞来测试和校准这个潜在的替代品，或替代过去的南极臭氧空洞。雪中硝酸盐的氮同位素组成对紫外线诱导的光解离程度高度敏感。这一特征使测量冰芯中的氮同位素成为平流层臭氧丰度的潜在替代品(或替代品)，平流层臭氧丰度是地球表面紫外线辐射水平的最大决定因素。过去地表紫外线辐射水平的替代物将提供一种手段来检验这样一种假设，即西南极一系列平流层规模的火山喷发导致的200年臭氧空洞可能在18KYR前引发了南极冰川的快速消融。我们建议通过高分辨率测量以前从南极钻探的浅冰芯顶部10米处的硝酸盐氮同位素，来测试使用硝酸盐氮同位素作为过去地表紫外线辐射水平的替代品。这块冰中包含的时期是1950-2004年的共同纪元(C.E.)，这将使研究人员能够检查和校准著名的现代臭氧空洞下的硝酸盐同位素浓缩。这将使未来两年在南极冰芯钻探的新冰芯对18KYR之前火山喷发期的样品进行类似测量的效用。这个项目在南极没有实地工作。

The abundance of ozone in the stratosphere is the dominant control on surface ultra-violet radiation, which has important implications for life on Earth. Stratospheric ozone also impacts the Earth's climate system by altering atmospheric circulation patterns, with implications for the ocean carbon cycle and sea ice extent. It has been proposed that the end of the last glacial period, 18,000 years before present, was associated with a period of depleted stratospheric ozone that lasted over 200 years and was caused by a series of large eruptions from the Mt. Takahe volcano in West Antarctica. This ozone depletion may have hastened the end of the last glacial maximum by changing atmospheric circulation patterns, reducing Antarctic sea ice extent and creating increased carbon emissions from the Southern Ocean. This project will test a new method of determining past surface ultra-violet radiation levels by measuring the nitrogen isotopes of nitrate in shallow South Pole ice samples. This research utilizes the modern-day ozone hole over Antarctica to test and calibrate this potential proxy, or substitute, for past Antarctic ozone holes. The nitrogen isotopic composition of nitrate in snow is highly sensitive to the degree of ultraviolet-induced photo-dissociation of that nitrate. This feature makes the measurement of nitrogen isotopes in ice cores a potential proxy (or substitute) for the ozone abundance in the stratosphere, which is the largest determinant of ultraviolet radiation levels at the Earth's surface. A proxy for past surface ultraviolet radiation levels would provide a means to test the hypothesis that a 200-year ozone hole resulting from a series of stratospheric-scale volcanic eruptions in West Antarctica might have triggered rapid Antarctic de-glaciation 18 kyr ago. We propose to test the use of nitrogen isotopes of nitrate as a proxy for past surface-ultraviolet radiation levels by measuring the nitrogen isotopes of nitrate at high resolution in the top 10 m of a previously drilled shallow ice core from the South Pole. The period contained in this ice is 1950-2004 Common Era (C.E.), which will allow researchers to examine and calibrate the nitrate isotope enrichment under the well-known modern-day ozone hole. This will inform the utility of similar measurements on samples from a period of volcanism 18 kyr before present from a new ice core being drilled at the South Pole ice core over the next two years.There is no field work in Antarctica as part of this project.