Investigation of Past Variations In Surface Ocean Radiocarbon During The Holocene

小行星9314691 这项持续研究的主要目标是构建时间 使用来自化石和活珊瑚的年度珊瑚带，在过去的表层海水状态中进行高精度14 C的历史研究。这些数据，再加上稳定的氧和碳同位素测量（18 O和13 C），揭示了重要的信息，14 CO2在海洋上层的循环和空气和海洋之间的交换14 CO2。 将进行四个实验：1）使用热电离质谱法使用230 Th绝对定年的化石珊瑚序列来确定14 C的十年时间尺度变化是否存在于古代海洋中。 将研究瓦努阿图和佛罗里达比斯坎国家公园珊瑚的两个时间段。 这将允许在全新世存在的极端热条件下比较两个主要洋流（分别是南赤道洋流和墨西哥湾流）中的14 C：小冰期和高温期。 2)确定小冰期后期（公元1680-1730年）北太平洋14 C十年时间尺度变化的存在与否，并将此记录与西南太平洋获得的记录进行比较，其中大的14 C变化与古代厄尔尼诺事件相关。 还将研究北大西洋的珊瑚，以检查14 C的变化在世界范围内的程度。 3)将在北方太平洋的三个地点测量Suess效应（自19世纪末以来，主要由于不含14 C的化石燃料CO2导致14 C降低），在那里没有发现可测量的Suess效应。 赤道大西洋是目前温带和热带海洋中唯一没有原子弹爆炸后14 C记录的地方。 它的重要性参数示踪剂渗透到大西洋不能夸大。 有限数量的高精度14 C分析将B加速器质谱（AMS）技术进行，每个样品都有多个石墨靶分析。 剩余的样品（75%）将在UCI放射性碳实验室使用传统的气体计数技术进行高精度测量。

9314691 DRUFFEL The major goal of this continuing research is to construct time histories of high-precision 14C in past surface ocean water regimes using annual coral bands from fossil and living corals. These data, when coupled with stable oxygen and carbon isotope measurements (18 O and 13C), reveal important information regarding the cycling of 14CO2 in the upper ocean and the exchange of 14CO2 between air and sea. Four experiments will be conducted 1) To determine whether decade time-scale variations in 14C were present in ancient oceans using fossil coral sequences that have been absolutely dated using 230 Th by thermal ionization mass spectrometry. Two time periods will be studied in corals from Vanuatu and from Biscayne National Park, Florida. This will allow for the comparison of 14C in two major ocean currents (the South Equatorial Current and the Gulf Stream, respectively), during extreme thermal conditions that existed in the Holocene: the Little Ice Age and the Hypsithermal. 2) To determine the presence or absence of decade time-scale variations in 14C in the North Pacific during the late Little Ice Age (AD 1680-1730), and compare this record to that obtained from the southwestern Pacific where large 14C variations correlated with ancient El Nino events. Corals from the North Atlantic will also be studied, to examine the extent to which the 14C variability was world-wide. 3) The Suess effect (lowering of 14C due mainly to 14C-free fossil fuel CO2 since late 1800s) will be measured at three sites in the northern Pacific, where no measurable Suess effect was found 4)Collection and high-precision 14C analyses are proposed for a coral from Fernando de Noronha. The equatorial Atlantic is presently the only location in the temperate and tropical oceans for which a post-bomb 14C record is not available. Its importance for parameterizing tracer penetration into the Atlantic cannot be overstated. A limited number of high-precision 14C analyses will b e made using Accelerator Mass Spectrometry (AMS) techniques, with multiple graphite target analysis for each sample. The remainder of the samples (75%) will be measured to high- precision at the UCI Radiocarbon Laboratory using conventional, gas-counting techniques.