Collaborative Research: Straight to the Source- Mineral Weathering in Snowbanks and Supraglacial Ice, McMurdo Dry Valleys, Antarctica

合作研究：直奔源头——南极洲麦克默多干谷雪堆和冰上冰的矿物风化

• 批准号: 2148066
• 负责人: Anna Bergstrom
• 金额: $ 26.04万
• 依托单位: Boise State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2148066&HistoricalAwards=false
• 关键词: Collaborative; Research; Straight; Source; Mineral

Glacial erosion produces large quantities of sediment that can change the chemistry of surrounding land and ocean ecosystems. While the nutrients underneath glaciers are known to be important for nearby biological communities, comparatively less is known about the chemistry and importance of glacier surfaces and snowpack, which can trap dust - small particles of rock that are deposited by wind and with snowfall. The dust is darker than ice and snow and therefore can warm during sunny periods and melt the surrounding frozen water, generating small amounts of liquid water. During cloudy and cold periods, solar radiation can no longer heat the particles and the liquid water around the dust freezes again. These thawing and freezing cycles can break down the dust and release nutrients, such as iron, which can potentially be used by organisms in the ice or can be transported to streams, lakes, and/or the ocean during periods of high melt. This research will combine computer modeling and laboratory experiments to understand 1) what happens (chemically and physically) to glacier and snowpack dust during freezing and thawing and 2) how to model freezing and thawing of water and dust in glacier ice. Two traveling exhibits exploring the connections between science and art will result from this project, allowing for diverse audiences to connect with the Antarctic continent and understand how small-scale science influences large-scale systems. The results of this study will determine the geochemistry of glacial meltwater due to freezing and thawing, and whether the meltwater contains critical nutrients for surrounding ecosystems.Despite low temperatures and the relative scarcity of liquid water, glacial systems can be a major source of trace metals, nutrients and other weathering products to proglacial and marine systems. While the importance of weathering has been established in subglacial and proglacial environments, less is understood about weathering mechanisms or the composition of major and trace nutrients at the most upstream source: within snow and supraglacial ice. Wind deposits fine-grained sediment on ice surfaces, which can then melt or become incorporated into the ice profile and experience a range of thermal regimes and freeze-thaw conditions. Daily freeze-thaw cycling drives physical and chemical weathering of sediment grains, yet few studies have explicitly examined the frequency and intensity of freeze-thaw cycles and how they control major ion and trace metal release, alteration, and mobility. This interdisciplinary study will use geochemical and energy balance modeling, freeze-thaw experimentation, and scanning electron microscopy to advance knowledge of mineral weathering in ice and snow active layers. Existing samples collected from the McMurdo Dry Valleys of Antarctica, an ecosystem that relies on runoff derived from supraglacial ice and snow melt, will be utilized. Two traveling exhibits exploring the connections between science and art will result from this project, the first focused on connecting the macro-scale Antarctic continent to micro-scale microscopy images, and the second a contemporary art exhibit that will explore the Antarctic continent and our perceptions of scale. Findings from this research will contribute to knowledge of nutrient bioavailability and delivery to proglacial environments and polar oceans, watershed-scale weathering in glacial systems, and the conditions that create microsites for life on glaciers and other icy systems.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.

冰川侵蚀产生大量沉积物，可以改变周围陆地和海洋生态系统的化学成分。虽然众所周知，冰川下方的营养物质对附近的生物群落很重要，但人们对冰川表面和积雪的化学性质和重要性知之甚少，因为它们可以捕获灰尘——风和降雪沉积的小岩石颗粒。这些尘埃比冰和雪颜色更深，因此在阳光明媚的时期会变暖并融化周围的冰冻水，产生少量液态水。在阴天和寒冷时期，太阳辐射不再加热颗粒，尘埃周围的液态水再次冻结。这些解冻和冷冻循环可以分解灰尘并释放营养物质，例如铁，这些营养物质可以被冰中的生物体利用，或者可以在高度融化期间被输送到溪流、湖泊和/或海洋。这项研究将结合计算机建模和实验室实验，以了解 1）冰川和积雪灰尘在冻结和融化过程中会发生什么（化学和物理）；2）如何模拟冰川冰中水和灰尘的冻结和融化。该项目将举办两个探索科学与艺术之间联系的巡回展览，让不同的观众能够与南极大陆建立联系，并了解小规模科学如何影响大规模系统。这项研究的结果将确定由于冰冻和融化而导致的冰川融水的地球化学，以及融水是否含有周围生态系统的关键营养物质。尽管气温较低且液态水相对稀缺，但冰川系统可能是微量金属的主要来源、营养物质和其他风化产物进入冰河前和海洋系统。虽然风化的重要性在冰下和冰前环境中已经得到证实，但人们对风化机制或最上游来源（雪和冰上冰内）主要和微量营养物质的组成了解甚少。风在冰表面沉积细粒沉积物，这些沉积物随后会融化或融入冰剖面并经历一系列热状态和冻融条件。日常冻融循环会驱动沉积物颗粒的物理和化学风化，但很少有研究明确检验冻融循环的频率和强度以及它们如何控制主要离子和痕量金属的释放、改变和迁移性。这项跨学科研究将利用地球化学和能量平衡模型、冻融实验和扫描电子显微镜来增进对冰雪活动层矿物风化作用的了解。将利用从南极洲麦克默多干谷收集的现有样本，该生态系统依赖于冰上冰雪融化产生的径流。该项目将产生两个探索科学与艺术之间联系的巡回展览，第一个侧重于将宏观尺度的南极大陆与微观尺度的显微图像联系起来，第二个当代艺术展览将探索南极大陆和我们的看法规模。这项研究的结果将有助于了解营养物的生物利用度和向冰川前环境和极地海洋的输送、冰川系统中的分水岭规模风化以及在冰川和其他冰冷系统上为生命创造微场所的条件。该奖项反映了 NSF 的法定使命和通过使用基金会的智力优点和更广泛的影响审查标准进行评估，该项目被认为值得支持。