Geochemical Characterization of Prince William Sound and Copper River Sediments: A Proxy Development to Assess Climate-Driven Variations in a High-Resolution Sedimentary Record

作为为期两年的博士后研究奖学金的一部分，该项目的重点是通过分析不同环境条件下的时间序列来确定威廉王子湾（PWS）和铜河沉积物的元素组成。这些数据将被用来解释保存的沉积物中包含的核心，其记录延伸到上个世纪，在此期间，相对强大的仪器记录的流量，气候和海洋条件存在的签名。最终，希望这项研究的结果能够对过去几千年的气候驱动因素进行高分辨率的表征。这些知识将进一步了解该系统在过去是如何响应的，并可能提供有关未来气候变化的关键预测信息。此外，这项研究的一个关键外展组成部分是开发一个教学课程，供阿拉斯加农村地区服务不足的人群使用，他们接受科学教育或当前研究的机会有限。该计划的目的是进一步了解科学家如何使用沉积物岩心来确定PWS和北方太平洋的气候趋势，以及随后对渔业分布，生计和商业收获的影响。该项目将在Steven A博士的指导下进行。PWS是一个敏感的亚北极地区，快速变化的气候模式强烈改变水文和海洋条件，对生态和经济产生深远的影响。这项研究旨在利用PWS沉积物中包含的高分辨率环境记录的潜力，这可能使我们能够了解整个全新世河流沉积物分散和/或气候驱动的海洋学模式的变化。以前的X射线荧光（XRF）分析表明，PWS沉积物岩心包含地球化学和沉积学特征，可以潜在地解决不同的源输入。元素比（如Sr/Mn，Zn/S，K/Ca）可以提供区分楚加奇/北方PWS来自铜河上游的沉积物负荷的基础。然而，缺乏关于主要流域内成分变化的信息，也缺乏对受变化的物源/淡水来源影响的季节性变化的了解（例如，雪融化，冰川融化，降雨，楚加奇与兰格尔范围）在铜河流量是关键的环境代用记录的发展。一旦受到限制，这些代理有可能解决气候振荡的次年度到十年的时间尺度。因此，本项目的重点是收集PWS和铜河流域沉积物的代表性样品的高分辨率时间序列，目的是自信地约束沉积物芯XRF记录中观察到的元素变化。悬浮泥沙浓度的元素组成将采用电感耦合等离子体质谱法（ICPMS）测定。还将对样品进行宇宙成因7 Be分析，以检验以下假设：在春季排放/冰川融化期间，普遍使用的近期河流沉积示踪剂在高纬度环境中可能存在问题。

As part of a two-year postdoctoral research fellowship, this project focuses on determining the elemental composition of Prince William Sound (PWS) and Copper River sediments by analyzing a time-series throughout varying environmental conditions. These data will be used to interpret preserved sedimentary signatures contained within cores whose record extends into the last century, the period for which relatively robust instrumental records of discharge, climate, and oceanographic conditions exist. Ultimately, it is hoped the results of this research will allow high-resolution characterization of climatic drivers over the last several millennia. This knowledge will further understanding of how this system has responded in the past, and may provide crucial predictive information concerning future climate variations. Additionally, a key outreach component for this study is the development of a teaching curriculum to be used by underserved populations within rural Alaska who have limited access to science education or current research. The program will aim to further student understanding of how scientists use sediment cores to identify climate trends in PWS and the northern Pacific Ocean, and the subsequent impact on fisheries distribution, subsistence, and commercial harvests. This project will be conducted under the mentorship of Dr. Steven A. Kuehl at the Virginia Institute of Marine Science.The PWS is a sensitive sub-arctic region where rapidly changing climate patterns strongly alter hydrological and oceanographic conditions in ways that have profound ecological and economical implications. This research seeks to exploit the potential for a high-resolution environmental record contained within PWS sediment, which may allow us to understand changing river sediment dispersal and/or climate-driven oceanographic patterns throughout the Holocene. Previous X-ray Fluorescence (XRF) analyses reveal that PWS sediment cores contain geochemical and sedimentological signatures that can potentially resolve varying source input. Elemental ratios (e.g. Sr/Mn, Zn/S, K/Ca) may provide a basis for differentiating Chugach/northern PWS derived sediment loads from those of the upper Copper River. However, there is a paucity of information on compositional variations within the major drainage basins, and understanding seasonal variability influenced by changing provenance/ freshwater sources (e.g., snow melt, glacial melt, and rainfall, Chugach vs. Wrangell Range) in Copper River discharge is critical for the development of environmental proxy records. Once constrained, these proxies have the potential to resolve climatic oscillations on sub-annual to decadal timescales. Therefore, this project focuses on collecting a high-resolution time-series of representative samples of PWS and Copper River basin sediments with the aim to confidently constrain elemental variations observed in sediment core XRF records. Elemental composition of suspended sediment concentrations will be determined using Inductively Coupled Plasma Mass Spectrometry (ICPMS). Samples will also be analyzed for cosmogenic 7Be to test the hypothesis that the ubiquitously used tracer for recent fluvial sedimentation may be problematic in high latitude settings during spring discharge/ glacial melt.