Quantifying Surface Area in Muds from the Antarctic Dry Valleys: Implications for Weathering in Glacial Systems

量化南极干谷泥浆的表面积：对冰川系统风化的影响

• 批准号: 1543344
• 负责人: Gerilyn Soreghan
• 金额: $ 35.18万
• 依托单位: University of Oklahoma Norman Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2022-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1543344&HistoricalAwards=false
• 关键词: Quantifying; Surface; Area; Muds; Antarctic

As glaciers creep across the landscape, they can act as earthmovers, plucking up rocks and grinding them into fine sediments. Glaciers have moved across the Antarctic landscape over thousands to millions of years, leaving these ground-up sediments in their wake. This study builds on pilot discoveries by the investigators that revealed remarkably large and variable measurements of surface area in glacially-derived fine-grained sediments found in the McMurdo Dry Valleys (MDV), one of the few landscapes on the Antarctic continent not currently covered by ice. Surface area is key to chemical weathering, the process by which rock is converted to soils as ions are carried away in streams and groundwater. These chemical weathering processes are also one of the primary means by which the Earth system naturally removes carbon dioxide from the atmosphere. Hence, high surface areas observed in sediments implies high "weatherability" which in turn translates to more potential carbon dioxide removed from the atmosphere. Therefore, chemical weathering in high surface area glacial sediments may have significant impacts on Earth's carbon cycle. The researchers will measure the chemical and physical properties of sediments previously collected from the Dry Valleys to understand what factors lead to production of sediment with high-surface area and potential "weather ability" and investigate how sediment produced in these glacial systems could ultimately impact Earth's carbon budget. Results from this research will help scientists (including modelers) refine predictions of the effects of melting glaciers- and attendant exposure of glacial sediment? on atmospheric carbon levels. These results may also contribute to applied research efforts on development of carbon-dioxide removal technologies utilizing principles of rock weathering. In addition to the scientific benefits, this research will involve several students at the undergraduate, graduate, and post-doctoral levels, including science education undergraduates, thus contributing to training of the next-generation STEM workforce.Physical weathering produces fresh surfaces, greatly enhancing specific surface area (SSA) and reactive surface area (RSA) of primary minerals. Quantifying SSA and RSA of sediments is key to determining dissolution and leaching rates during natural weathering, but few data exist on distribution of sediment SA, particularly in glacial and fluvial systems. Pilot data from glacial stream systems in Taylor Valley and Wright Valley (located in the MDV) exhibit remarkably high and variable values in both SSA and RSA, values that in some cases greatly exceed values from muds in temperate glacial systems. This discovery motivates the current research, which aims to investigate the hypothesis that high and variable SAs of muds within Wright and Taylor Valleys reflect textural and/or compositional inheritance from the differing depositional settings within the MDV, biologic controls, dust additions, and/or pedogenic processes. These hypotheses will be tested by sedimentologically, mineralogically, and geochemically characterizing muds from glacially derived sediment deposited in various environments (cold vs. wet based glaciation; fluvial, lacustrine, dust, and drift deposits) and of varying age (Miocene to Modern) from the MDV and quantifying variation of SA and reactivity. Comparisons with analyzed muds from temperate glacial systems will enable polar-temperate comparisons. Analyses will focus on muds of previously collected sediment from the MDVs. Grain size and SSA will be measured by Laser Analysis and N2 adsorption BET, respectively. After carbonate removal, samples will be re-analyzed for SSA, and muds characterized geochemically. Mineralogy and bulk chemistry will also be assessed on co-occurring sand fractions, and textural attributes documented. SSA-normalized dissolution experiments will be used to compare solutes released from sediments to determine RSAs. Results will be integrated with the various sedimentologic and geochemical analyses to test the posed hypotheses. Ultimately, this research should shed light on how weathering in Antarctic systems contributes to global carbon cycling.

随着冰川蔓延到整个景观时，它们可以充当土方，拔出岩石并将其磨成细小的沉积物。 冰川已经在数千到数百万年的时间里遍及南极景观，使这些地面沉积物留在了它们之后。这项研究建立在研究人员的试点发现的基础上，该发现揭示了在麦克穆尔多干谷（MDV）中发现的冰川衍生的细颗粒沉积物（MDV）的表面积的大量测量值，这是南极洲目前未覆盖的冰的少数几个景观之一。 表面积是化学风化的关键，当离子在溪流和地下水中移走时，岩石转化为土壤的过程。这些化学风化过程也是地球系统自然从大气中去除二氧化碳的主要手段之一。因此，在沉积物中观察到的高表面积意味着高“气化性”又转化为从大气中去除的更多潜在二氧化碳。因此，高表面积冰川沉积物中的化学风化可能会对地球的碳循环产生重大影响。研究人员将测量以前从干山谷收集的沉积物的化学和物理性质，以了解哪些因素会导致用高表面区域和潜在的“天气能力”产生沉积物，并研究这些冰川系统中产生的沉积物如何最终影响地球的碳预算。这项研究的结果将有助于科学家（包括建模者）完善对冰川融化和随时随地接触冰川沉积物的影响的预测？在大气碳水平上。这些结果还可能有助于利用岩石风化原理的二氧化碳去除技术开发的应用研究工作。除了科学的好处外，这项研究还将涉及本科，研究生和博士后水平的几名学生，包括科学教育本科生，从而有助于培训下一代STEM劳动力的培训。物理风化会产生新鲜的表面，从而产生新鲜的表面，从而极大地增强了特定表面积（SSA）和反应性表面积（SSA）和反应性的表面积（RSA）（RSA）（RSA）。量化沉积物的SSA和RSA是确定自然风化过程中溶解和浸出速率的关键，但是很少有关于沉积物SA分布的数据，尤其是在冰川和河流系统中。来自Taylor Valley和Wright Valley（位于MDV中）的冰川流系统的试验数据在SSA和RSA中均显示出很高和可变的值，在某些情况下，值大大超过了温带冰川系统中泥浆的值。这一发现激发了当前的研究，该研究旨在调查赖特和泰勒山谷内泥浆的高和可变的SAS的假设反映了MDV内不同沉积环境，生物控制，灰尘，粉尘，灰尘和/或Pedenicenic过程中不同沉积环境的质地和/或组成遗传。这些假设将通过沉积学，矿物学上和地球化学来测试，以表征来自各种环境中沉积的冰川衍生沉积物的泥浆（冷与湿的冰川；河流，湖泊，湖泊，灰尘，灰尘和漂移沉积物）和不同年龄（中新世至现代）的MDV和量化和量化的变量。与来自温带冰川系统的分析泥浆的比较将实现极性比较。分析将集中于MDV先前收集的沉积物的泥浆。晶粒尺寸和SSA将分别通过激光分析和N2吸附下注来测量。去除碳酸盐后，将对SSA进行重新分析样品，并以地球形式进行泥浆。还将评估矿物学和散装化学因素以及记录的纹理属性。 SSA归一化的溶解实验将用于比较从沉积物释放的溶质以确定RSA。结果将与各种沉积学和地球化学分析集成，以检验姿势的假设。最终，这项研究应阐明南极系统中的风化如何有助于全球碳循环。

项目成果

Significance of the Terrestrial Sink in the Biogeochemical Sulfur Cycle

• DOI: 10.1029/2021gl097009
• 发表时间: 2022
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Y. Joo;M. Sim;M. E. Elwood Madden;G. Soreghan

Cyanobacterial weathering in warming periglacial sediments: Implications for nutrient cycling and potential biosignatures

变暖的冰缘沉积物中的蓝藻风化：对营养循环和潜在生物特征的影响

• DOI: 10.1002/ppp.2133
• 发表时间: 2021
• 期刊: Permafrost and Periglacial Processes
• 影响因子: 5
• 作者: Demirel‐Floyd, Cansu;Soreghan, Gerilyn S.;Madden, Megan E. Elwood
• 通讯作者: Madden, Megan E. Elwood

Effects of Mass Wasting on the Physiochemical Properties of Fluvial Sediments in Puerto Rico Following Hurricane Maria

飓风玛丽亚后大规模浪费对波多黎各河流沉积物理化性质的影响

• DOI: 10.1029/2021jf006509
• 发表时间: 2022
• 期刊: Journal of Geophysical Research: Earth Surface
• 作者: Webb, N. D.;Regmi, N. R.;Soreghan, G. S.;Elwood Madden, A. S.;Sylvester, J.;Cartagena Colon, F.;Demirel‐Floyd, C.;Elwood Madden, M. E.
• 通讯作者: Elwood Madden, M. E.