Advanced Radiocarbon Dating and Molecular-Level Tools for Evaluating Marine Carbon Cycling in the Canadian Arctic

用于评估加拿大北极海洋碳循环的先进放射性碳测年和分子水平工具

• 批准号: RGPIN-2020-06501
• 负责人: Walker, Brett
• 金额: $ 2.55万
• 依托单位: University of Ottawa
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=718350
• 关键词: Advanced; Radiocarbon; Dating; Molecular; Level

The marine carbon cycle plays an important role in regulating Earth's climate on timescales of years to millennia. The Canadian Arctic is warming at nearly double the rate as the rest of the planet, and as a result, Arctic seas will undergo unprecedented change in coming decades. These changes include: increased water temperatures, acidification and hypoxia that directly affect how ecosystems function. Marine carbon takes many forms, from large particulate detritus to small dissolved organic carbon (DOC) molecules and dissolved inorganic carbon salts (DIC; primarily as bicarbonate). This proposal aims to address fundamental knowledge gaps in our understanding of the Canadian Arctic marine carbon cycle. The proposed research will couple advanced stable carbon (13C) and radiocarbon (14C) isotopic measurements together with dissolved microbial biomarker analysis and nuclear magnetic resonance spectroscopy in order to quantify carbon sources, transformations and cycling rates within three Canadian Arctic regions: Baffin Bay, the Canadian Archipelago and Hudson Bay/Foxe Basin. The core research questions are: (1) What are the distributions and 14C-ages of marine DIC and DOC in the Canadian Arctic? (2) What are the residence times and ventilation ages of Canadian Arctic water masses? (3) What are the main sources of carbon persisting in these regions? and (4) to what extent does DOC biomolecular and chemical composition ultimately determine its biological availability to heterotrophic bacteria and its long-term persistence (i.e. 14C-age) in Arctic waters? These questions will be examined in field and lab-based studies conducted by 4 MSc students, 3 PhD students and 6-8 undergraduate students, recruited and trained using approaches designed to maximize equity, diversity and inclusion. Our results will advance our understanding of marine carbon cycling dynamics within the Canadian Arctic and improve our ability to predict carbon stocks and fluxes. This work will also help advance our ability to parametrize and incorporate DOC biogeochemical cycling into future Arctic Earth System Models. The research will take advantage of new and existing collaborations with world-renowned researchers within Canada and abroad. This research will integrate the use of two National Research Facilities, the André E. Lalonde Accelerator Mass Spectrometry Laboratory and Amundsen Science further building Canada's profile as a leader in carbon cycle research in a period of rapid Arctic climate change. I have played a leading role in developing and improving marine 14C methods that have helped us quantify rates of organic carbon cycling in the ocean. My interdisciplinary background in the fields of chemical oceanography, isotope geochemistry, and accelerator mass spectrometry make me uniquely qualified to lead the proposed research program.

海洋碳循环在调节地球气候方面发挥着重要作用，时间尺度从几年到几千年。加拿大北极变暖的速度几乎是地球其他地区的两倍，因此，北冰洋将在未来几十年经历前所未有的变化。这些变化包括：水温升高、酸化和缺氧，这些都直接影响生态系统的运行。海洋碳有多种形式，从大颗粒碎屑到小的溶解有机碳(DOC)分子和溶解的无机碳盐(DIC；主要是重碳酸盐)。这项建议旨在解决我们对加拿大北极海洋碳循环理解方面的基本知识空白。 拟议的研究将结合先进的稳定碳(13C)和放射性碳(14C)同位素测量以及溶解微生物生物标记物分析和核磁共振光谱分析，以量化加拿大北极三个地区的碳源、转化和循环速率：巴芬湾、加拿大群岛和哈德逊湾/福克斯盆地。核心研究问题是：(1)海洋DIC和DOC在加拿大北极的分布和14C年龄是什么？(2)加拿大北极水团的停留时间和通风年龄是什么？(3)这些地区持续存在的碳的主要来源是什么？以及(4)DOC的生物分子和化学组成在多大程度上最终决定了它对异养细菌的生物有效性和它在北极水域的长期持久性(即14C-AGE)？这些问题将由4名硕士学生、3名博士生和6-8名本科生进行实地和基于实验室的研究，招募并使用旨在最大限度地实现公平、多样性和包容性的方法进行培训。 我们的结果将促进我们对加拿大北极海洋碳循环动力学的理解，并提高我们预测碳储量和碳通量的能力。这项工作还将有助于提高我们将DOC生物地球化学循环参数化并纳入未来北极地球系统模型的能力。这项研究将利用与加拿大国内外世界知名研究人员的新的和现有的合作。这项研究将整合安德烈·E·拉隆德加速器质谱学实验室和阿蒙森科学这两个国家研究设施的使用，进一步巩固加拿大作为快速北极气候变化时期碳循环研究领先者的形象。 我在开发和改进海洋14C方法方面发挥了领导作用，这些方法帮助我们量化了海洋中有机碳循环的速度。我在化学海洋学、同位素地球化学和加速器质谱学领域的跨学科背景使我唯一有资格领导拟议的研究计划。