An Evaluation of Variability in the 14co2 Cycle in the UpperOcean

这项研究将检查大西洋和太平洋几个地点的带状珊瑚的年度样本中的碳和氧同位素比率。目标是确定主要温跃层的通风相对于二氧化碳的可变性，并确定过去500年来海洋表面14c的十年时间尺度变化的原因和空间范围。首先，将重建轰炸后时期（1953年至今）赤道和南大西洋带状珊瑚的高精度（+2 /）14c记录。将为这些地点以及北太平洋和南太平洋建立上层海洋的等环流混合模式，与以前使用的模式类似。其次，将从世界海洋的四个地点——北大西洋（佛罗里达）、中北太平洋（夏威夷）、东太平洋（加拉帕戈斯）和西南太平洋（大堡礁）——重建小冰期（公元1400-1850年）的高精度14c记录。将确定在西南太平洋（亚伯拉罕礁）蒙德极小期海面14c的十年时间尺度变化是否为一种海洋现象，并评估这些变化对海面环流和CO2循环的潜在影响。第三，测量北太平洋中部和西南太平洋带状珊瑚的susess效应和18o和13c的变化，以评估化石燃料CO2向海洋的输入。第四，将对化石珊瑚进行高精度的14c测量，这些化石珊瑚已经使用230钍质谱法精确地测定了来自巴布亚新几内亚休恩半岛凸起珊瑚礁的14c。这里的目标是开发一种方法，将从已知年龄的树木年轮（9700日历年BP）中获得的放射性碳年代学扩展到全新世早期和去冰期，当时大气二氧化碳分压大大低于19世纪的水平。

This research will examine carbon and oxygen isotope ratios in annual samples of banded corals from several sites in the Atlantic and Pacific Oceans. The goals are to establish the vriability of the ventilation of the main thermocline with respect to CO2 and to determine the cause and spatial extent of decade time scale changes in surface ocean 1 4 C during the past 500 years. First, high precision (+2 / ) 1 4 C records will be reconstructed for the post-bomb period (1953-present) for banded corals from the equatorial and South Atlantic. Isopycnal mixing models for the upper ocean, similar to that used previously, will be constructed for these locations and for the North and South Pacific. Second, high precision 1 4 C records will be reconstructed for the Little Ice Age (A.D. 1400-1850) from four sites in the world's ocean - North Atlantic (Florida), North Central Pacific (Hawaii), eastern equat Pacific (Galapagos) and Southwest Pacific (Great Barrier Reef). It will be determined whether the decade time scale changes noticed in surface ocean 1 4 C during the Maunder minimum in the Southwest Pacific (Abrahams Reef) were an ocean- wide phenomena, and the potential impact of these changes on surface circulation and on the cycling of CO2 will be assessed. Third, the Suess effect and the changes in 1 8 O and 1 3 C in banded corals from the North Central and Southwestern Pacific will be measured in order to assess the input of fossil fuel CO2 into the ocean. Fourth, high precision 1 4 C will be measured on fossil corals that have been accurately dating using 230 Th by mass spectrometry from the raised reefs of the Huon Peninsula, Papua New Guinea. The goal here is to develop a method to extend the radiocarbon chronology past that available from known-aged tree rings (9,700 calendar yrs BP), into the early Holocene and deglaciation periods when atmospheric pCO2 was substantially lower than nineteenth century levels.