Collaborative Research: Multiple-isotope Analysis of Nitrate and Sulfate in the West Antarctic Ice Sheet Divide Ice Core

[053852 . 20] thiemens该奖项支持一个项目，该项目将从南极西部冰盖（WAIS）中央冰裂处的深冰芯中，首次完整地记录过去~10万年的硝酸盐和硫酸盐的多种同位素比率。WAIS分裂冰芯将是从南极洲获得的分辨率最高的长冰芯，我们可以期待获得重要的补充信息，包括过去积累速率、温度和化合物（如H2O2、CO和CH4）的准确知识。这些化合物在全球大气化学和气候中起着重要作用。尤其巨大的潜力在于使用多种同位素特征。在硝酸盐和硫酸盐中，由于其前体与臭氧的相互作用，臭氧具有独特的质量无关分馏（MIF） 17O特征。硫酸盐和硝酸盐小样本多同位素组成测量方法的发展，使冰芯连续高分辨率测量首次成为可能。最近的研究表明，这种测量方法可用于测定古大气中羟基辐射状（OH）和臭氧（O3）的浓度，以及分配硫酸盐和硝酸盐的来源。利用这些同位素测量来量化沉积后的变化也有很大的潜力。在头两年，将获得在WAIS分水岭上~100米冰的连续测量，以提供通过百年尺度的季节变化的详细观察。在第三年，测量将在深核的整个可用深度进行（预计此时达到~500米）。该项目的广泛影响包括应用于不同领域，包括大气化学、冰川学、气象学和古气候学。由于硝酸盐和硫酸盐是重要的大气污染物，研究结果也将与全球环境政策直接相关。该项目将与国际极地年（2007-2008）同时进行，并有助于实现国际极地年的目标，其中包括促进跨学科研究，以加强对极地大气化学和气候的了解。

0538520ThiemensThis award supports a project to develop the first complete record of multiple isotope ratios of nitrate and sulfate covering the last ~100,000 years, from the deep ice core planned for the central ice divide of the West Antarctic Ice Sheet (WAIS). The WAIS Divide ice core will be the highest resolution long ice core obtained from Antarctica and we can expect important complementary information to be available, including accurate knowledge of past accumulation rates, temperatures, and compounds such as H2O2, CO and CH4. These compounds play significant roles in global atmospheric chemistry and climate. Especially great potential lies in the use of multiple isotope signatures. The unique mass independent fractionation (MIF) 17O signature of ozone is observed in both nitrate and sulfate, due to the interaction of their precursors with ozone. The development of methods to measure the multiple-isotope composition of small samples of sulfate and nitrate makes continuous high resolution measurements on ice cores feasible for the first time. Recent work has shown that such measurements can be used to determine the hydroxyl radial (OH) and ozone (O3) concentrations in the paleoatmosphere as well as to apportion sulfate and nitrate sources. There is also considerable potential in using these isotope measurements to quantify post depositional changes. In the first two years, continuous measurements from the upper ~100-m of ice at WAIS divide will be obtained, to provide a detailed look at seasonal through centennial scale variability. In the third year, measurements will be made throughout the available depth of the deep core (expected to reach ~500 m at this time). The broader impacts of the project include applications to diverse fields including atmospheric chemistry, glaciology, meteorology, and paleoclimatology. Because nitrate and sulfate are important atmospheric pollutants, the results will also have direct and relevance to global environmental policy. This project will coincide with the International Polar Year (2007-2008), and contributes to goals of the IPY, which include the fostering of interdisciplinary research toward enhanced understanding of atmospheric chemistry and climate in the polar regions.