Measurements of stable carbon isotopes on board GO-SHIP cruises in the South Atlantic Ocean to enhance our ability to quantify anthropogenic CO2 uptake rates by the ocean

在南大西洋 GO-SHIP 游轮上测量稳定碳同位素，以增强我们量化海洋人为二氧化碳吸收率的能力

• 批准号: 2123768
• 负责人: Wei-Jun Cai
• 金额: $ 70.21万
• 依托单位: University of Delaware
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2123768&HistoricalAwards=false
• 关键词: Measurements; stable; carbon; isotopes; board

Rising carbon dioxide concentrations in the atmosphere, global climate change, and the sustainability of the Earth’s biosphere are of great scientific and societal concern. Approximately one-quarter of fossil fuel emissions of carbon dioxide emitted each year are absorbed by the oceans, and it is important to understand where and how fast this process occurs. Stable isotopes of carbon can be used as a “signature” to identify fossil fuel-derived carbon dioxide in the atmosphere and ocean. The investigators have developed a new method for measuring the stable carbon isotope composition of dissolved carbon dioxide rapidly and precisely while at sea. They will measure several thousand samples on two research expeditions to the South Atlantic Ocean. They will compare their measurements to ones made in the same locations approximately ten years earlier, and determine the amount of carbon dioxide absorbed over that time period. The proposed research will enhance ocean carbon research infrastructure, general science education, and public awareness of climate change and environmental issues. The investigators plan to enhance diversity in earth sciences by recruiting underrepresented minority students in the research and have a graduate and an undergraduate student involved in all phases of this project. The team, including the students, will actively disseminate the research results in international, national, regional, local education and outreach activities, and in peer-review journals. In the South Atlantic Ocean, anthropogenic CO2 uptake rates are high and variable as mode and intermediate waters are formed and are sensitive to climate changes. The carbon-13 Suess effect makes delta13C-CO2 in the atmosphere a clearly defined endmember and delta13C-DIC in the ocean a powerful tracer to independently estimate anthropogenic CO2 uptake and storage in the ocean. The team has developed a precise, rapid, and sea-going method to simultaneously measure dissolved inorganic carbon (DIC) concentration (to plus or minus 2 micromol per kilogram) and stable carbon isotope composition (delta13C-DIC) (to plus or minus 0.03 permil) by combining a CO2 extraction device with a Cavity Ring-Down Spectroscopy (CRDS) isotope analyzer. They will use this method aboard GO-SHIP cruises A13.5 and A16S to analyze about 1000 samples onboard the ship and 2000 samples on land for each cruise. Extensive evaluation and comparison of this method with the traditional isotope ratio mass spectrometry (IRMS)-based method will be done. The PIs hypothesize that the formation and the strength of mode and intermediate waters have a strong influence on the lateral transport of anthropogenic carbon and thus the decadal variability of the water column anthropogenic carbon inventory change. As a result, the change in inventory has both meridional and zonal trends, and therefore a combination of A13.5 and A16S will better represent the basin-wide changes. Two objectives will be achieved in testing this hypothesis: (1) Demonstrate that precise and accurate delta13C-DIC data, comparable in quality to IRMS-based data, can be collected via the CRDS-based method, and that large numbers of samples can be analyzed onboard ships and back home with high spatial resolution comparable to other GO-SHIP level 1 parameters such as DIC; (2) Assess the spatial variations and temporal changes of the anthropogenic carbon uptake and storage rates in the South Atlantic Ocean. In particular, the PIs will compare estimated anthropogenic carbon inventories independently from delta13C-DIC and DIC observations from transect A13.5 (2022 vs. 2010 and earlier data) in the eastern basin with those of transect A16S (2024 vs. 2013 and earlier data) in the western basin. They will also compare the basin-wide water column anthropogenic 13C-DIC inventory with the surface ocean anthropogenic 13CO2 uptake flux estimated from air-sea carbon isotope disequilibrium, the difference being anthropogenic carbon carried by lateral transport.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.

大气中二氧化碳浓度的上升、全球气候变化和地球生物圈的可持续性是科学和社会关注的重大问题。每年大约有四分之一的化石燃料排放的二氧化碳被海洋吸收，重要的是要了解这一过程发生在哪里以及速度有多快。碳的稳定同位素可以作为一种“标志”，用于识别大气和海洋中化石燃料产生的二氧化碳。研究人员开发了一种新方法，可以在海上快速准确地测量溶解二氧化碳的稳定碳同位素组成。他们将在南大西洋的两次研究考察中测量数千个样本。他们将把他们的测量结果与大约十年前在同一地点进行的测量结果进行比较，并确定在这段时间内吸收的二氧化碳量。拟议的研究将加强海洋碳研究基础设施，普通科学教育以及公众对气候变化和环境问题的认识。研究人员计划通过招募研究中代表性不足的少数民族学生来增强地球科学的多样性，并让一名研究生和一名本科生参与该项目的所有阶段。该团队，包括学生，将积极传播研究成果在国际，国家，区域，地方教育和推广活动，并在同行评审期刊。在南大西洋，人为CO2吸收率很高，并随着模态和中间沃茨的形成而变化，对气候变化很敏感。碳-13 Suess效应使得大气中的delta 13 C-CO2成为明确定义的端元，海洋中的delta 13 C-DIC成为独立估计海洋中人为CO2吸收和储存的强大示踪剂。该团队开发了一种精确，快速和航海的方法，通过将CO2提取设备与腔衰荡光谱（CRDS）同位素分析仪相结合，同时测量溶解无机碳（DIC）浓度（± 2 μ mol/kg）和稳定碳同位素组成（delta 13 C-DIC）（± 0.03 permil）。他们将在GO-SHIP巡航A13.5和A16 S上使用这种方法，每次巡航分析船上约1000个样本和陆地上的2000个样本。将对该方法与传统的基于同位素比质谱（IRMS）的方法进行广泛的评价和比较。PI假设模式和中间沃茨的形成和强度对人为碳的横向输送有很大的影响，因此水柱人为碳清单变化的年代际变化。因此，库存的变化具有纬向和纬向趋势，因此A13.5和A16 S的组合将更好地代表流域范围的变化。验证这一假设的两个目的是：（1）证明通过基于CRDS的方法可以收集到与基于IRMS的数据质量相当的精确和准确的delta 13 C-DIC数据，并且可以在船上和回家时以与其他GO-SHIP 1级参数（如DIC）相当的高空间分辨率分析大量样品;（2）评估南大西洋人为碳吸收和储存率的空间变化和时间变化。特别是，PI将比较估计的人为碳清单，独立于东部流域断面A13.5（2022年与2010年及更早的数据）和西部流域断面A16 S（2024年与2013年及更早的数据）的delta 13 C-DIC和DIC观测。他们还将比较流域范围内的水柱人为13 C-DIC清单与海-气碳同位素不平衡估计的表层海洋人为13 CO2吸收通量，差异是横向运输携带的人为碳。该奖项反映了NSF的法定使命，并被认为值得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来支持。

项目成果

Performance evaluations and applications of a δ13C-DIC analyzer in seawater and estuarine waters

海水和河口水域中Ύ´13C-DIC分析仪的性能评估和应用

• DOI: 10.1016/j.scitotenv.2022.155013
• 发表时间: 2022
• 期刊: Science of The Total Environment
• 影响因子: 9.8
• 作者: Deng, Xue;Li, Qian;Su, Jianzhong;Liu, Chun-Ying;Atekwana, Eliot;Cai, Wei-Jun
• 通讯作者: Cai, Wei-Jun

Ocean Ventilation Controls the Contrasting Anthropogenic CO 2 Uptake Rates Between the Western and Eastern South Atlantic Ocean Basins

海洋通风控制南大西洋盆地西部和东部的人为 CO 2 吸收率对比

• DOI: 10.1029/2021gb007265
• 发表时间: 2022
• 期刊: Global Biogeochemical Cycles
• 影响因子: 5.2
• 作者: Gao, Hui;Cai, Wei‐Jun;Jin, Meibing;Dong, Changming;Timmerman, Amanda H. V.
• 通讯作者: Timmerman, Amanda H. V.