A 1.4 million year record of black carbon and biomass burning in the eastern Arctic from the Lake El'gygytgyn and other sediment cores (P2C2)

该奖项资助了一种测量湖泊沉积物岩芯中黑碳的新方法，该方法建立在测量冰川冰芯中黑碳的成熟技术的基础上。黑碳（BC）是一种主要的气候强迫因子，产生于生物质的不完全燃烧。在气候变暖的气候模式预测中，野火排放是关键的未知数，特别是大规模生物质燃烧和BC排放与气候强迫的关系。冰芯BC方法的发展改变了人们对极地BC的认识；该项目将进一步发展沉积物-岩心BC方法，并将其应用于提供额外的记录，将时间和空间覆盖范围扩大到其他地区，包括开发过去~ 140万年北极BC的详细湖泊-沉积物记录，从而扩展对气候和生物质燃烧联系的理解。这将使我们能够在全球范围内更长期地了解气候、人类活动和生物质燃烧之间的联系，并将二氧化碳作为一种强迫因子进行量化。BC总量反映区域到半球的生物质燃烧排放，而不是局部的生物质燃烧。考虑到北极东部冰芯位置的稀疏性，这种新的湖泊沉积物方法在俄罗斯北极地区的应用将使该地区过去生物质燃烧和BC强迫的广泛分布记录成为可能，有可能改变对强迫情景的理解。对El'gygytgyn湖样本的分析将把生物质燃烧记录延长到比冰芯或木炭记录更早的时间。这种长期的BC记录的发展和跨学科解释将极大地扩展生物质燃烧和BC在空间和时间上的仪器记录-通过广泛的气候状态和强迫情景-符合美国国家科学基金会气候变化古视角（P2C2）计划的目标。该项目将利用北极东部存档的湖泊沉积物样本，并使用这种新方法：(1)开发与北极东部生物质燃烧有关的约2000年的BC记录，以确定该地区气候、人类活动、BC和生物质燃烧之间的联系；(2)通过比较El’gygytgyn湖沉积物岩芯上~15万年的BC通量和颗粒质量与格陵兰NEEM冰芯约12万年的BC记录，评价湖泊沉积物法测量不同气候状态下BC的有效性；(3)通过建立El'gygytgyn湖在过去约140万年（跨越海洋同位素阶段（MIS） 1至MIS 45）的详细沉积物BC记录，量化和理解北极东部长期和大尺度气候变化、BC和生物质燃烧之间的联系。为了实现该项目的目标，将对俄罗斯北极地区的一系列较短、高时间分辨率的湖泊岩心以及较深、低时间分辨率的湖泊岩心（包括El'gygytgyn湖岩心的上部~60 m）的湖泊沉积物样本进行BC浓度和颗粒质量测量。对过去16万年E湖沉积物岩心进行的初步BC测量显示，冰期气候与大尺度气候（如日照、温室气体浓度）密切相关，但与全新世间冰期的气候-植被-火灾关系不同。该奖项由极地项目办公室和地球科学部共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award funds a new method for measuring black carbon in lake-sediment cores, which builds on a well-established technique for measuring black carbon in glacial ice cores. Black carbon (BC) is a primary climate forcing agent resulting from incomplete combustion of biomass. Wildfire emissions are critical unknowns in climate-model predictions under a warming climate, particularly the relationship of large-scale biomass burning and BC emissions to climate forcing. Development of the ice-core BC method has transformed understanding of BC in polar regions; this project will further develop the sediment-core BC method and apply it to provide additional records that will expand temporal and spatial coverage to other regions, including development of detailed lake-sediment records of Arctic BC during the past ~1.4 million years thereby extending understanding of climate and biomass-burning linkages. This will enable worldwide, longer-term understanding of linkages between climate, human activities, and biomass burning, as well as quantification of BC as a forcing agent. BC aggregates reflect regional-to-hemispheric biomass burning emissions rather than local biomass burning. Given the sparsity of ice-coring locations in the eastern Arctic, application of this new lake sediment method in Arctic Russia will enable widely distributed records of past biomass burning and BC forcing in the region, potentially transforming understanding of forcing scenarios through time. Analysis of samples from Lake El'gygytgyn will extend biomass burning records much farther back in time than is possible with ice cores or charcoal records. The development and interdisciplinary interpretation of such long-term BC records will greatly extend instrumental records of biomass burning and BC in space and time - through a broad range of climate states and forcing scenarios - in line with the goals of NSF's Paleo Perspectives on Climate Change (P2C2) program.This project will exploit the availability of archived lake sediment samples from the eastern Arctic and use this new method to (1) develop ~2,000-year-long records of BC, which is related to biomass burning in the eastern Arctic, to determine linkages between climate, human activities, BC, and biomass burning in the region; (2) evaluate the validity of the lake sediment method of measuring BC for different climate states by comparing BC flux and particle mass in the upper ~150,000 years of the Lake El'gygytgyn sediment core with a reprocessed ~120,000-year BC record from the Greenland NEEM ice core; and, (3) quantify and understand linkages between long-term and large-magnitude climate change, BC, and biomass burning in the eastern Arctic by developing a detailed sediment BC record from Lake El'gygytgyn during the past ~1.4 million years (spanning Marine Isotope Stage (MIS) 1 to MIS 45). To meet the goals of this project, BC concentration and particle mass measurements will be made in lake sediment samples from an array of shorter, higher-time-resolution cores from the Russian Arctic, as well as from deeper, lower-time resolution lake cores, including the upper ~60 m of the Lake El'gygytgyn core. Pilot BC measurements from Lake E sediment cores for the past 160,000 years show close correspondence with large-scale climate (e.g., insolation, greenhouse gas concentrations) but suggest different climate-vegetation-fire relationships during the glacial periods than reported for the Holocene interglacial. This award is co-funded by the Office of Polar Programs and the Division of Earth Sciences.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.