Tracing Glacial-interglacial Changes in the Dust Source to Antarctica using Helium Isotopes

Winckler/0636898该奖项支持一个研究南极冰芯尘埃来源的项目。 大气气溶胶在全球地球化学循环和地球气候系统中起着重要的作用。从南极冰芯中提取的记录告诉我们，在冰川期，从大气到冰盖的灰尘沉积量是间冰期的15-20倍，这增加了灰尘可能是冰川-间冰期时间尺度上气候变化的关键因素的可能性。 通过表征来自南美洲、南非和澳大利亚的潜在源区以及巴塔哥尼亚的新鲜冰川粉，该项目将确定间冰期粉尘是否来自不同的地理区域（例如，澳大利亚）或来自南美洲风化较严重的源区。该项目的智力价值在于，它将有助于重建与气候有关的灰尘沉积速率变化，并在灰尘的来源方面，它将对源区的水文和植被以及将灰尘运送到档案地点的大气环流的性质提供关键限制。 在最近的一项试点研究中发现，从南极洲德龙宁毛德地的冰中提取的尘埃中的4 He/Ca比率在冰川到全新世之间发生了巨大的变化，表明尘埃输送到南极洲的来源发生了变化。 该项目更广泛的影响是，氦同位素和钙测量提供了丰富的信息，然后可以转化为粉尘气候模型的关键输入。改进后的模型能够准确地重建古尘埃分布，这将有助于我们预测尘埃变化对未来气候变化的反应。这些信息将有助于提高我们对地球气候系统的综合认识，并反过来使决策者更好地了解最易受气候变化干扰的过程和条件，从而制定更有意义的气候变化政策。 该项目将支持双硕士地球和环境科学新闻计划的研究生。 首席研究员负责管理拉蒙的岩石惰性气体实验室。她在这个设施的领导作用影响本科生和研究生的培训，以及访问科学家。

Winckler/0636898This award supports a project to study dust sources in Antarctic ice cores. Atmospheric aerosols play an important role both in global biogeochemical cycles as well as in the climate system of the Earth. Records extracted from Antarctic ice cores inform us that dust deposition from the atmosphere to the ice sheet was 15-20 times greater during glacial periods than during interglacials, which raises the possibility that dust may be a key player in climate change on glacial-interglacial timescales. By characterizing potential source areas from South America, South Africa, and Australia as well as fresh glacial flour from Patagonia, the project will determine if the interglacial dust was mobilized from a distinct geographical region (e.g., Australia) or from a more heavily weathered source region in South America. The intellectual merit of the project is that it will contribute to reconstructing climate-related changes in the rate of dust deposition, and in the provenance of the dust, it will provide critical constraints on hydrology and vegetation in the source regions, as well as on the nature of the atmospheric circulation transporting dust to the archive location. In a recent pilot study it was found that there is a dramatic glacial to Holocene change in the 4He/Ca ratio in the dust extracted from ice from Dronning Maud Land, Antarctica, indicating a shift in the source of dust transported to Antarctica. The broader impacts of the project are that Helium isotopes and calcium measurements provide a wealth of information that can then be turned into critical input for dust-climate models. Improved models, which are able to accurately reconstruct paleo dust distribution, will help us to predict changes in dust in response to future climate variability. This information will contribute to an improvement of our integrated understanding of the Earth's climate system and, in turn, will better inform policy makers of those processes and conditions most susceptible to perturbation by climate change, thereby leading to more meaningful climate-change policy. The project will support a graduate student in the dual masters Earth and Environmental Science Journalism program. The lead-PI manages the rock noble gas laboratory at Lamont. Her leadership role in this facility impacts the training of undergraduate and graduate students as well as visiting scientists.