Collaborative Research: The Roles of Seasonality, Silicification, and Alteration in Nitrogen and Silicon Isotope Paleo-proxy Variability

合作研究：季节性、硅化和蚀变在氮和硅同位素古代理变异中的作用

• 批准号: 2218705
• 负责人: Mark Brzezinski
• 金额: $ 90万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2218705&HistoricalAwards=false
• 关键词: Collaborative; Research; Roles; Seasonality; Silicification

The chemistry of fossil diatoms (a type of plankton), specifically their nitrogen and silicon composition, reflects past changes in surface water nutrients and uptake by plants. Changes in sedimentary diatom nitrogen and silicon values from the Southern Ocean record to what degree ocean biology consumed nutrients in the surface ocean through time. These records have been interpreted to document changes in large-scale vertical ocean circulation as well as iron-stimulated biological production. These processes likely worked together to contribute to carbon exchange between the ocean and the atmosphere. The proposed work will address gaps in our understanding of how the diatom proxies record surface nutrient conditions. Specifically, this includes an examination of environmentally controlled effects on physiology that lead diatoms to change how they build their shells and of alteration during sinking and burial as potential influences on the composition of nitrogen and silica. The results will improve reconstructions of nutrient drawdown in the past, highlight optimal geological conditions for robust reconstructions, and increase our understanding of observed spatial and temporal variability in existing diatom nitrogen and silicon isotope records. This work will ultimately improve our understanding of global-scale climate change in the past and contextualize future change. The project will foster the careers of early career scientists, impact education through training of students and incorporation of project results into course work, and translate science methods, goals, and results of this project to novel audiences through art.The proposed work will examine: 1) the relationship between diatom nitrogen and silicon isotope values and surface nutrient uptake during a Southern Ocean spring bloom, 2) primary controls on the spatial variability observed for the relationships between diatom-bound nutrient isotope proxies, macronutrients, and biomass, and 3) possible alteration to isotopic signals occurring during transit to the sediment. The field component includes a transect from 67°S to 54°S to conduct extensive sampling of water and particles. Shipboard incubations combining isotope and novel fluorescent labeling techniques will measure how degree of silicification influences diatom Nitrogen and Silica isotopes. The influence of the loss of lightly silicified taxa and/or fractionation during the dissolution of frustules will be evaluated through laboratory incubations at home institutions. Products of an art-science collaboration will be publicly displayed online and at events. We will broaden participation in STEM at the University of Rhode Island through our participation in the Graduate School of Oceanography’s Research Experience for Undergraduates and the Summer Undergraduate Research Fellowship in Oceanography Program, as well as prioritizing underrepresented groups in recruitment for the project’s graduate student position and at University California Santa Barbara through the Research Experience and Education Facility that focuses on underserved K-12 students.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.

化石硅藻的化学（一种浮游生物），尤其是它们的氮和硅成分，反映了地表水养分和植物吸收的过去变化。从南大洋记录的沉积硅藻氮和硅价值的变化在多大程度上使海洋养分随着时间的流逝而消耗。这些记录已被解释为记录大规模垂直海洋循环以及铁刺激的生物产生的变化。这些过程很可能共同促进了海洋与大气之间的碳交换。拟议的工作将解决我们对硅藻代理如何记录表面养分状况的差距。具体而言，这包括对环境控制对生理学的影响的检查，这会导致硅藻改变它们在下沉和埋葬过程中的壳和改变的方式，因为潜在的影响氮和二氧化硅的组成。结果将改善过去养分缩减的重建，突出显示可靠重建的最佳地质条件，并提高我们对现有硅藻氮和硅同位素记录中观察到的空间和临时变异性的理解。这项工作最终将提高我们对过去的全球气候变化的理解，并将未来的变化背景化。该项目将促进早期职业科学家的职业，通过培训学生来影响教育，并将项目成果纳入课程工作，并将该项目的科学方法，目标和结果转化为新的受众。营养同位素的代理，大量营养素和生物量，以及3）在转移到沉积物期间发生的同位素信号可能改变。该场分量包括从67°S到54°S的样带，以进行大量的水和颗粒采样。将同位素和新型荧光标记技术结合在一起的船上孵化将测量硅化程度如何影响硅氮和二氧化硅同位素。散失的硅胶分类单元和/或分馏过程中的损失的影响将通过家庭机构的实验室孵化来评估。艺术科学合作的产品将在线和活动中公开展示。我们将通过参与海洋学研究生院的本科生和夏季海洋学研究奖学金计划的研究经验，并优先考虑招募项目的研究生研究生职位和加利福尼亚大学圣巴拉拉大学的研究生奖学金和教育的学生，从而拓宽了海洋学本科生的研究经验，并将其优先于招聘人数的研究生和教育的学生招募，我们将扩大参与STEM的参与。任务，并通过评估使用基金会的知识分子和更广泛的影响审查标准，被认为是宝贵的支持。