EAGER: Dating Arctic Lake Sediments with Beryllium-10 Markers of Solar Proton Events

北极湖泊沉积物记录通常具有清晰的层，称为叠层，这是由于北极季节的独特性而形成的。在短暂的融化季节，沉积物被流动并通过溪流运送到湖泊中，在那里物质沉积在湖底。随后是漫长的冬季，湖面结冰，细粒物质缓慢沉降。因此，形成了一个每年一次的沉积物对，称为纹管，较粗的物质位于细粒粘土盖层之下。这些有纹的记录提供了有关过去气候和环境变化的宝贵信息。然而，至关重要的是使用独立的方法确认其时间轴，以确保对既定时间表的信心。太阳质子事件（SPE）就是这样一种潜在的独立方法。SPE是在特定的太阳活动期间从太阳释放的高能粒子的爆发。当这些粒子到达地球时，它们可以与大气气体相互作用，产生像10 Be这样的同位素，这些同位素进入陆地表面并最终进入湖泊沉积物。本研究建议使用10 Be异常SPE作为一种工具，用于验证纹记录。通过分析和比较10 Be的浓度在分层沉积物收集从不同的位置在整个分高北极，本研究的目的是确定是否10 Be增加与SPE可以作为一个可靠的方法来确认varved记录年表。如果这种方法得到证实，表明与SPE相关的沉积物10 Be增加可以验证纹层记录，这将是一个变革性的发展，允许在不同的纹层湖泊沉积记录和各种其他记录（如冰芯，树木年轮和湖泊（湖泊相关）记录）之间进行精确比较。最终，这可以大大提高我们对过去气候变化和变异性的理解。该研究计划包括STEM机会，让高中生了解气候变化并更好地了解当地环境。这将涉及一个积极的学习研讨会。该项目还将涉及该大学荣誉学院的学生由于北极融化季节很短，当沉积物被动员起来，然后被河流携带并沉积在湖泊中时，随后是一段很长的时间，当表面冻结和细粒物质沉降到沉积物表面时，许多北极湖泊的沉积物记录都有很好的分层，每年都有一对沉积物（纹管）;一层粗糙的物质被一层细粒的粘土盖覆盖。这些层压层有可能作为一个古时钟（年表）。然而，为了提供对该时钟的信心，需要通过独立的方法进行确认。本研究的重点是这样的确认。研究人员建议确定10 Be异常导致的太阳质子事件（SPE）在一组分层沉积物中收集的湖泊在不同的位置，从分高北极，测试是否10 Be增加与SPE可以用来确认varved记录年表。如果成功，这项工作将代表一个变革性的发展，允许高分辨率比较不同的纹湖沉积记录和冰芯，树木年轮和湖泊沉积物之间。该研究计划包括STEM机会，让高中生了解气候变化并更好地了解当地环境。这将涉及一个积极的学习研讨会。该项目还将涉及来自该大学荣誉学院（英联邦学院）的学生，他们将参与实验室工作并获得研究经验。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Arctic lake sediment records often have clear layers, called laminations, which form due to the uniqueness of the Arctic seasons. During the short melt season, sediments become mobilized and transported into lakes by streams, where the material is deposited on the lake bottom. This is followed by a lengthy winter characterized by lake surface freezing and the slow settling of fine grained material. Consequently, an annual couplet of sediment, referred to as a varve is formed, with coarser material underlying a fine-grained clay cap. These varved records offer valuable information about past climate and environmental changes. However, it is crucial to confirm their timeline using an independent method to ensure confidence in the established time scale. Solar Proton Events (SPEs) are one such potential independent method. SPEs are bursts of high-energy particles released from the Sun during specific solar activities. When these particles reach Earth, they can interact with atmospheric gases, creating isotopes like 10Be, which make their way onto the land surface and eventually into lake sediments. This study proposes to use 10Be anomalies from SPEs as a tool for verifying varve records. By analyzing and comparing 10Be concentrations in laminated sediments collected from various locations across the sub- to high-Arctic, this research aims to determine if 10Be increases associated with SPEs can be used as a reliable method for confirming varved record chronologies. If this method is confirmed, demonstrating that sediment 10Be increases associated with SPEs can verify varve records, it would be a transformative development, allowing precise comparisons between different varved lake sedimentary records and various other records like ice cores, tree rings, and lacustrine (lake-related) records. Ultimately, this could significantly improve our understanding of past climate changes and variability. The research plan includes STEM opportunities for high school students to learn about climate change and to better understand their local environment. This will involve an active learning workshop. The project will also involve students from the University’s Honors College (Commonwealth College) who will participate in lab work and gain research experience.As a consequence of the short Arctic melt season, when sediment is mobilized and then carried by streams and deposited in lakes, followed by a long period when the surface is frozen and fine-grained material settles to the sediment surface, many Arctic lake sediment records are well-laminated, with an annual couplet of sediment (a varve); a layer of coarse material overlain by a fine-grained clay cap. These laminated layers have the potential to serve as a paleo-clock (a chronology). However, to provide confidence in this clock, it needs to be confirmed by an independent method. This study focuses on such a confirmation. The investigator proposes to identify 10Be anomalies resulting from solar proton events (SPEs) in a set of laminated sediments collected from lakes in different locations, ranging from the sub- to high Arctic, to test whether 10Be increases associated with SPEs can be used to confirm varved record chronology. If successful, this work would represent a transformative development, allowing high-resolution comparisons to be made between different varved lake sedimentary records and between ice cores, tree rings, and lake sediments. The research plan includes STEM opportunities for high school students to learn about climate change and to better understand their local environment. This will involve an active learning workshop. The project will also involve students from the University’s Honors College (Commonwealth College) who will participate in lab work and gain research experience.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.