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

该奖项支持一个研究南极冰芯中粉尘源的项目。大气气溶胶在全球生物地球化学循环和地球气候系统中都起着重要作用。从南极冰芯中提取的记录告诉我们，冰期从大气到冰盖的尘埃沉积是间冰期的15-20倍，这增加了在冰期-间冰期时间尺度上尘埃可能是气候变化的关键因素的可能性。通过描述来自南美洲、南非和澳大利亚的潜在来源地区以及来自巴塔哥尼亚的新鲜冰川面粉，该项目将确定间冰期粉尘是来自一个独特的地理区域（如澳大利亚）还是来自南美洲一个风化程度更严重的来源地区。该项目的智力价值在于，它将有助于重建与气候有关的尘埃沉积率变化，并在尘埃来源方面，它将提供对源区水文和植被的关键限制，以及对将尘埃运送到档案地点的大气环流性质的限制。在最近的一项初步研究中发现，从南极洲Dronning Maud地冰中提取的尘埃中的4He/Ca比值在冰期到全新世之间发生了巨大的变化，这表明输送到南极洲的尘埃来源发生了变化。该项目更广泛的影响是氦同位素和钙的测量提供了丰富的信息，这些信息可以转化为尘埃气候模型的关键输入。改进后的模型能够准确地重建古沙尘分布，将帮助我们预测沙尘随未来气候变化的变化。这些信息将有助于提高我们对地球气候系统的综合认识，反过来，也将使决策者更好地了解那些最容易受到气候变化扰动的过程和条件，从而制定更有意义的气候变化政策。该项目将资助一名攻读地球与环境科学新闻学双硕士学位的研究生。首席pi管理着拉蒙特的岩石稀有气体实验室。她在该设施中的领导作用影响了本科生和研究生以及访问科学家的培训。

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.