NOAA/WDS Paleoclimatology - Kure Atoll, Hawaiian Archipelago Radiocarbon Data from 1939-2002 AD

Corals of the Hawaiian Archipelago are well situated in the North Pacific Gyre (NPG) to record how bomb-produced radiocarbon (14C) has been sequestered and transported by the sea. While this signal can be traced accurately through time in reef-building corals and used to infer oceanographic processes and determine the ages of marine organisms, a comprehensive and validated record has been lacking for the Hawaiian Archipelago. In this study, a coral core from Kure Atoll in the Northwestern Hawaiian Islands was used to create a high-resolution bomb 14C record for the years 1939–2002, and was then used with other 14C measurements in fish otoliths and seawater to explore differences and similarities in the bomb 14C signal throughout the Hawaiian Archipelago. The Kure Atoll sample series produced a well-defined bomb 14C curve that, with some exceptions, was similar to other coral 14C records from the Hawaiian Archipelago. Subtle differences in the coral 14C records across the region may be explained by the large-scale ocean circulation patterns and decadal cycles of the NPG. The most rapid increase of 14C, in the 1950s and 1960s, showed similar timing across the Hawaiian Archipelago and provides a robust basis for use of bomb 14C dating to obtain high precision age determinations of marine organisms. Reference otoliths of juvenile fish demonstrated the use of the post-peak 14C decline period as a viable reference in the age validation of younger and more recently collected fishes, and effectively extended the utility of bomb 14C dating to the latest 30 years.

夏威夷群岛（Hawaiian Archipelago）的造礁珊瑚栖息于北太平洋环流（North Pacific Gyre, NPG）中，可有效记录大气核爆产生的放射性碳（radiocarbon, ¹⁴C）在海洋中的固存与运移过程。尽管通过造礁珊瑚（reef-building corals）的时序记录可精准追踪该放射性碳信号，进而反演海洋学过程并测定海洋生物的年代，但夏威夷群岛地区始终缺乏经过全面验证的相关数据集。
本研究以夏威夷群岛西北部的库雷环礁（Kure Atoll）获取的珊瑚岩芯（coral core）为材料，构建了1939年至2002年的高分辨率核爆放射性碳记录；随后结合鱼类耳石（otoliths）与海水的其他放射性碳检测数据，探究了整个夏威夷群岛区域内核爆放射性碳信号的异同。库雷环礁的样品序列得到了清晰的核爆放射性碳曲线，除少数例外情况外，其与夏威夷群岛其他珊瑚的放射性碳记录趋势一致。该区域内珊瑚放射性碳记录的细微差异，可通过北太平洋环流的大尺度海洋环流模式与年代际周期加以解释。1950至1960年代放射性碳浓度的快速上升阶段，在整个夏威夷群岛区域内出现时间一致，为利用核爆放射性碳测年（bomb ¹⁴C dating）高精度测定海洋生物年代提供了可靠依据。幼鱼的参考耳石样本证明，核爆放射性碳峰值后的衰减阶段可作为近期采集的幼龄鱼类年代验证的有效参照，从而将核爆放射性碳测年的应用范围有效拓展至近30年。