Time-Series Measurements of the 13C/12C of Dissolved Inorganic Carbon

溶解无机碳 13C/12C 的时间序列测量

• 批准号: 0327006
• 负责人: Paul Quay
• 金额: $ 58.35万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-10-01 至 2007-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0327006&HistoricalAwards=false
• 关键词: Time; Series; Measurements; 13C; 12C

ABSTRACTOCE-0327006The 13C/12C isotopic ratio of dissolved inorganic carbon (DIC) has been shown to be a very useful tracer of anthropogenic CO2 uptake in the ocean (Quay et al., 1992; Heimann and Maier-Reimer, 1996; Sonnerup et al., 2000; Quay et al., 2003). Seasonal changes in the d13C of DIC, coupled with corresponding changes in DIC concentration and pCO2, have been used to close the surface ocean.s carbon budget (Zhang and Quay, 1997; Gruber et al., 1998, Quay and Stutsman, in press). Time- series measurements of d13C, DIC and pCO2, therefore, allow one to separate biological from physical causes for interannual variations in the rate of oceanic CO2 uptake as Gruber et al. (2002) recently demonstrated at BATS. Despite these advantages, there are only two sites in the subtropical N. Atlantic (BATS) and N. Pacific (HOT) oceans where such records exist. This lack of ocean time series records has severely limited our ability to understand the causes of interannual variations in the ocean uptake of anthropogenic CO2 (Quay, 2002). In stark contrast, continuous records of atmospheric CO2 and d13C are being measured at over 100 sites.In this project, researchers at the University of Washington will initiate monthly d13C measurements at a third time-series site (ESTOC) in the eastern subtropical N. Atlantic. The d13C record at ESTOC, which will complement on-going measurements of DIC, pCO2 and alkalinity at the site, offers a very useful comparison to the BATS d13C record. Gruber et al. (2002) concluded that interannual variations in CO2 uptake at Bermuda correlated strongly with sea surface temperature (SST) and the North Atlantic Oscillation (NAO) index of atmospheric circulation. They used their d13C record at BATS to conclude that interannual variations in the rate of net community production (NCP) correlated with NAO. The researchers of this project intend to use the proposed d13C measurements at ESTOC to calculate NCP and determine whether interannual variations in the eastern subtropical N. Atlantic correlate with variations at Bermuda.The research team will also continue its program of d13C measurements at HOT. Our decade-long d13C record at HOT shows that the d13C decrease rate in the surface ocean has doubled since 1995. The DIC increase rate has tripled since 1995. However, this apparent acceleration of anthropogenic CO2 uptake and d13C decrease occurred during a period (post 1998) when salinity is the highest ever measured at HOT and summertime SST has decreased significantly. These dramatic changes at HOT correlate with a shift in the Pacific Decadal Oscillation (PDO) climate index in 1998 from positive (since the late 1970s) to negative. This correlation suggests that changes in physical forcing (e.g., thermocline depth, mixed layer depth, gyre circulation rates) in the N. Pacific may have changed the subtropical ocean.s carbon budget. If so, the situation at HOT may be similar to that found by Gruber et al. (2002) at Bermuda. The team intends to use d13C measurements at HOT to determine whether the accelerated DIC increase is a result of changes in the NCP rate at HOT.The proposed research addresses a major societal issue, that is, how natural variability affects the ocean.s uptake of anthropogenically produced CO2. The largest single human-controlled factor in future climate change is the production of CO2 from fossil fuel combustion and deforestation. The research is expected to yield an ocean d13C data set that will be made available to the broad scientific community and serve as a useful validation test for models predicting future atmospheric CO2 concentrations. The proposed research addresses one of the specific goals of the US Carbon Cycle Science Plan (1999), that is, to better quantify and understand the uptake of anthropogenic CO2 in the oceans. The proposed work enhances infrastructure for research and education in two ways. It establishes collaboration with scientists at the Universidad de Las Palmas in the Grand Canary Islands studying the ocean's carbon cycle. It tests equipment that could be broadly used by the oceanographic community to remotely collect seawater samples for carbon analysis.

ABSTRACTOCE-0327006 溶解无机碳 (DIC) 的 13C/12C 同位素比已被证明是海洋中人为 CO2 吸收的非常有用的示踪剂（Quay 等人，1992 年；Heimann 和 Maier-Reimer，1996 年；Sonnerup 等人，2000 年；Quay 等人，2003 年）。 DIC d13C 的季节性变化，加上 DIC 浓度和 pCO2 的相应变化，已被用来关闭表面海洋的碳预算（Zhang 和 Quay，1997 年；Gruber 等人，1998 年，Quay 和 Stutsman，正在出版）。 因此，d13C、DIC 和 pCO2 的时间序列测量可以将海洋 CO2 吸收率年际变化的生物原因与物理原因区分开来，如 Gruber 等人所述。 （2002）最近在 BATS 上进行了演示。 尽管有这些优势，但在副热带北大西洋 (BATS) 和北太平洋 (HOT) 海洋中只有两个地点存在此类记录。 海洋时间序列记录的缺乏严重限制了我们理解海洋人为二氧化碳吸收年际变化原因的能力（Quay，2002）。 形成鲜明对比的是，正在 100 多个站点测量大气 CO2 和 d13C 的连续记录。在该项目中，华盛顿大学的研究人员将在北大西洋东部副热带的第三个时间序列站点 (ESTOC) 启动每月 d13C 测量。 ESTOC 的 d13C 记录将补充现场持续进行的 DIC、pCO2 和碱度测量，与 BATS d13C 记录进行非常有用的比较。 格鲁伯等人。 （2002）得出的结论是，百慕大二氧化碳吸收量的年际变化与海面温度（SST）和大气环流的北大西洋涛动（NAO）指数密切相关。 他们利用 BATS 的 d13C 记录得出结论，群落净生产率 (NCP) 的年际变化与 NAO 相关。 该项目的研究人员打算使用 ESTOC 提出的 d13C 测量来计算 NCP，并确定东副热带北大西洋的年际变化是否与百慕大的变化相关。研究小组还将继续在 HOT 进行 d13C 测量计划。 我们在 HOT 长达十年的 d13C 记录显示，自 1995 年以来，表层海洋的 d13C 下降率增加了一倍。自 1995 年以来，DIC 增加率增加了两倍。然而，人为 CO2 吸收和 d13C 下降的这种明显加速发生在 HOT 测得的盐度最高且夏季海表温度显着下降的时期（1998 年之后）。 HOT 的这些剧烈变化与 1998 年太平洋年代际振荡 (PDO) 气候指数从正值（自 20 世纪 70 年代末以来）到负值的转变相关。 这种相关性表明，北太平洋物理强迫（例如温跃层深度、混合层深度、环流环流速率）的变化可能改变了副热带海洋的碳预算。 如果是这样，HOT 的情况可能与 Gruber 等人发现的情况类似。 （2002）在百慕大。 该团队打算利用 HOT 的 d13C 测量来确定 DIC 的加速增加是否是 HOT 时 NCP 速率变化的结果。这项研究解决了一个主要的社会问题，即自然变率如何影响海洋对人为产生的 CO2 的吸收。 未来气候变化中最大的单一人类控制因素是化石燃料燃烧和森林砍伐产生的二氧化碳。 该研究预计将产生一个海洋 d13C 数据集，该数据集将提供给广大科学界，并作为预测未来大气二氧化碳浓度的模型的有用验证测试。 拟议的研究涉及美国碳循环科学计划（1999）的具体目标之一，即更好地量化和了解海洋中人为二氧化碳的吸收。 拟议的工作从两个方面增强了研究和教育的基础设施。 它与大加那利群岛拉斯帕尔马斯大学的科学家建立了合作，研究海洋的碳循环。 它测试了海洋学界可以广泛使用的设备，用于远程收集海水样本以进行碳分析。