GEOTRACES Pacific Meridional Transect: Measurement of chlorofluorocarbons and sulfur hexafluoride

GEOTRACES 太平洋经线横断面：氯氟碳化合物和六氟化硫的测量

• 批准号: 1737041
• 负责人: Rana Fine
• 金额: $ 52.82万
• 依托单位: University of Miami
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1737041&HistoricalAwards=false
• 关键词: GEOTRACES; Pacific; Meridional; Transect; Measurement

The goal of the international GEOTRACES program is to understand the distributions of trace chemical elements and their isotopes in the oceans. The National Science Foundation is supporting a U.S. GEOTRACES sampling expedition in the Pacific Ocean in 2018, that will conduct full ocean depth at sites extending south from Alaska to Tahiti. The purpose of this project is to measure the concentrations of chlorofluorocarbon (CFC) compounds and of sulfur hexafluoride (SF6) along this transect of stations. These gas measurements can be used to determine the "ages" of water parcels and the rates of important oceanographic and biogeochemical processes. Such information is essential to the interpretation of the trace element and isotope data that will be gathered as part of GEOTRACES. The trace gas concentrations, ventilation ages, and rate data will all be made available to other investigators within six months of collection, forming an important foundation for the GEOTRACES Pacific program.The project team will measure CFC-11, CFC-12, and SF6 concentrations aboard the 2018 Pacific Meridional Transect. Beyond the concentration measurements, the project has the following specific objectives: 1) Calculate tracer ages and identify the relative extent of ventilation and dilution of thermocline and intermediate water masses within which Trace Elements and their Isotopes (TEIs) reside across different circulation regimes, 2) Calculate rates of biochemically important processes (including apparent oxygen utilization and denitrification rates) and distinguish between the contributions from physical and biogeochemical processes across the different circulation regimes, 3) Put tracer and hydrographic GEOTRACES data into context of larger space and time scales using historical tracer, hydrographic, ARGO CTD and oxygen data. The CFC and SF6 tracer data will contribute to interpretation of the key GEOTRACES trace elements and isotopes by characterizing physical processes, which can affect trace element speciation and internal cycling. Calculated tracer ages are the backbone of this project and are the primary service for other GEOTRACES PIs. Tracer ages will be used to address each of the objectives. As tracer ages are an important part of the contribution to the GEOTRACES program, uncertainties will be estimated for the ages related to internal ocean variability and effects of mixing due to non-stationarity of the atmospheric transients.

国际 GEOTRACES 计划的目标是了解海洋中微量化学元素及其同位素的分布。美国国家科学基金会正在支持 2018 年美国在太平洋进行的 GEOTRACES 采样考察，该考察将在从阿拉斯加向南延伸到塔希提岛的地点进行全海洋深度测量。该项目的目的是测量沿该站横断面的氯氟碳化合物 (CFC) 化合物和六氟化硫 (SF6) 的浓度。这些气体测量可用于确定水块的“年龄”以及重要海洋和生物地球化学过程的速率。这些信息对于解释作为 GEOTRACES 一部分收集的痕量元素和同位素数据至关重要。痕量气体浓度、通风年龄和速率数据将在收集后六个月内提供给其他调查人员，为 GEOTRACES Pacific 计划奠定重要基础。项目团队将测量 CFC-11、CFC-12 和 SF6 2018 年太平洋经线横断面的浓度。除了浓度测量之外，该项目还有以下具体目标： 1) 计算示踪剂年龄并确定温跃层和中间水团的通风和稀释的相对程度，其中微量元素及其同位素 (TEI) 驻留在不同的循环状态中，2 ) 计算重要生化过程的速率（包括表观氧利用率和反硝化速率），并区分不同循环状态下物理和生物地球化学过程的贡献，3) 将示踪剂和水文 GEOTRACES 数据置于使用历史示踪剂、水文学、ARGO CTD 和氧气数据实现更大的空间和时间尺度。 CFC 和 SF6 示踪剂数据将通过表征物理过程来解释关键的 GEOTRACES 痕量元素和同位素，这会影响痕量元素形态和内部循环。计算的示踪剂年龄是该项目的支柱，也是其他 GEOTRACES PI 的主要服务。示踪剂年龄将用于实现每个目标。由于示踪剂年龄是对 GEOTRACES 计划贡献的重要组成部分，因此将估计与内部海洋变化和由于大气瞬变的非平稳性导致的混合影响相关的年龄的不确定性。