Reverse and Submarine Weathering in Glacially Influenced Arctic Fjords

受冰川影响的北极峡湾的逆风化和海底风化

• 批准号: 2338157
• 负责人: Laura Wehrmann
• 金额: $ 65.63万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-02-01 至 2027-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2338157&HistoricalAwards=false
• 关键词: Reverse; Submarine; Weathering; Glacially; Influenced

When mineral particles reach the ocean floor, they often undergo biological or chemical transformations that turn them into new mineral phases and also result in the uptake from or release of elements to the surrounding seawater. One set of these reactions involve silicate minerals, which are composed of silica and oxygen and a range of other elements, such as iron and aluminum. These seafloor reactions are important because they affect the chemical composition of the ocean and its pH. In this project, we aim to study these reactions in Arctic fjords. Fjords are long, narrow ocean inlets that were formed by glaciers moving over the landscape in the past. Many fjords still have glaciers located at their inner end today which deliver meltwater and sediment to fjord waters. Climate change is resulting in the rapid melting of these glaciers. We are interested in understanding the specific silicate mineral reactions that are occurring, what elements they are taking up or releasing, and how climate change may affect these processes. We will collect seafloor sediment samples for this project from Kongsfjorden, Svalbard, and analyze them using a range of chemical methods. Additionally, we will carry out laboratory incubation studies where we will add silicate minerals formed by ocean algae to fjord sediments and observe what happens to them. Over long time scales, the inputs of major and minor elements to the ocean by rivers and hydrothermal vents has to be balanced by removal mechanisms of these elements in the marine realm in order for ocean chemistry to remain relatively constant. A long-debated process that sequesters elements in ocean seafloor sediments and affects seawater pH is reverse weathering which involves the transformation of biogenic silica, such as diatom frustules, to new silicate (clay) minerals. Many aspects of this process still remain unknown, such as reaction rates and products, and global distribution. Previous studies of this process have focused mainly on tropical coastal ocean systems. Coastal polar regions, including glacially influenced fjords, likely represent another hotspot of reverse weathering because they receive high inputs of key “ingredients”: biogenic silica and reactive iron and aluminum oxide minerals. At the same time, climate change drives the retreat of Arctic glaciers and is expected to strongly modify sediment delivery to and carbon cycling in these fjords. This project will fill key gaps in our knowledge of the pathways and products of the reactions involving silicate minerals in sediments and the impacts of these processes on the removal of dissolved ions from seawater in glacially influenced fjords. We will collect sediment samples for this project from Kongsfjorden, Svalbard, and analyze them using a range of geochemical techniques. Additionally, we will carry out incubation studies using diatom frustules and fjord sediments. The outcomes of this study will help accurately constrain the possible impacts that climate change in rapidly changing Arctic coastal environments has on larger scale oceanic processes and construct predictive models of elemental cycling and biogeochemical responses in the future ocean.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.

当矿物颗粒到达海底时，它们经常经历生物学或化学转化，这些变化将它们变成新的矿物相，并导致元素或释放到周围海水的吸收。这些反应中的一组涉及硅树脂矿物质，这些矿物质由二氧化硅和氧气组成，以及一系列其他元素，例如铁和铝。这些海底反应很重要，因为它们会影响海洋及其pH值的化学成分。在这个项目中，我们旨在研究北极峡湾中的这些反应。峡湾是长而狭窄的海洋入口，过去是冰川过去在景观上移动的。今天，许多峡湾仍然有冰川位于其内端，这些峡谷为峡湾水域提供了融化和沉积物。气候变化导致这些冰川的迅速融化。我们有兴趣了解发生的特定有机硅矿物反应，它们所占据或释放的元素以及气候变化如何影响这些过程。我们将从Svalbard的Kongsfjorden收集该项目的海底沉积物样品，并使用一系列化学方法分析它们。此外，我们将进行实验室孵化研究，在其中添加由海藻形成的硅酮矿物质到峡湾沉积物中，并观察它们发生了什么。在长期的尺度上，必须通过去除海洋领域中这些元素的机制来平衡河流和水热通风孔的主要和次要元素的输入，以使海洋化学保持相对恒定。一个长期的过程，隔离了海底沉积物中的元素并影响海水pH值，这是反向风化，涉及生物二氧化硅（例如硅藻果子）转化为新的硅胶（粘土）矿物质。该过程的许多方面仍然未知，例如反应率和产品以及全球分布。对这一过程的先前研究主要集中在热带沿海海洋系统上。沿海极性区域，包括受冰川影响的峡湾，可能代表了另一个反向风化的热点，因为它们获得了关键的“成分”的高输入：生物二氧化硅以及反应性铁和氧化铝矿物质。同时，气候变化驱动了北极冰川的撤退，预计将在这些峡湾中强烈改变沉积物的递送和碳循环。该项目将填补我们对涉及沉积物中硅树脂矿物的途径和产物的途径的关键空白，以及这些过程对去除冰川影响峡湾中海水溶解离子的影响。我们将从Svalbard的Kongsfjorden收集该项目的沉积物样品，并使用一系列地球化学技术分析它们。此外，我们将使用硅藻葬礼和峡湾沉积物进行孵化研究。这项研究的结果将有助于准确限制北极沿海环境中攀爬变化的可能影响，对大规模的海洋过程有变化，并构建了未来海洋中元素循环和生物地球化学响应的预测模型。该奖项奖反映了NSF的法定任务，并通过评估基金会的智力效果来表现出对基金会的支持。