Radionuclides produced by 20th-century human nuclear activities from 1945 (e.g., atmospheric nuclear explosions and nuclear-fuel reprocessing) made significant impacts on earth's surface environments. Long-lived shallow-water corals living in tropical/subtropical seas incorporate the anthropogenically-produced radionuclides, including ¹²⁹I and ¹⁴C, into their skeletons, and provide time series records of the impacts of nuclear activities. Here, we present ¹²⁹I/¹²⁷I and Δ¹⁴C time series records of an annually-banded modern coral skeleton from Rowley Shoals, off the northwestern coast of Australia, in the far eastern Indian Ocean. The ¹²⁹I/¹²⁷I and Δ¹⁴C records, covering the period 1930s−1990s, exhibit distinct increases caused by the nuclear activities, and their increasing profiles are clearly different from each other. The first distinct ¹²⁹I/¹²⁷I increase occurs from 1955 to 1959, followed by a decrease in 1960–1963. The increase is probably due to US atmospheric nuclear explosions in Bikini and Eniwetok Atolls in 1954, 1956 and 1958. The ¹²⁹I produced in those nuclear tests would be transported by the North Equatorial Current, a portion of which passes through the Indonesian Throughflow and then reaches Rowley Shoals. This initial increase from 1955 is, however, absent in the Δ¹⁴C record, which shows a distinct increase from 1959 and its peak around the mid-1970s, followed by a gradual decrease. This absence and the 4-year-delayed Δ¹⁴C increase are likely due to dilution of explosion-produced ¹⁴C with natural carbon (by seawater mixing and air-sea gas exchange) being much more intense than that of explosion-produced ¹²⁹I with natural iodine (by the same processes), suggesting that the ¹²⁹I/¹²⁷I ratio is a more conservative anthropogenic tracer in surface ocean waters, as compared to Δ¹⁴C. The second ¹²⁹I/¹²⁷I increase is contemporaneous with a rapid Δ¹⁴C increase during 1964–1967, followed by a rapid ¹²⁹I/¹²⁷I decrease in 1968–1969; the increases can be ascribed to very large atmospheric nuclear explosions conducted in the former Soviet Union in 1961–1962. The third ¹²⁹I/¹²⁷I increase appears between 1969/1970 and 1992, which can be attributed to airborne ¹²⁹I released from nuclear-fuel reprocessing facilities in Europe, the former Soviet Union and the US. The coral ¹²⁹I/¹²⁷I and Δ¹⁴C time series records, combined with previous studies, enhance our understanding of the behavior of anthropogenic ¹²⁹I and ¹⁴C in the global ocean and atmosphere.

1945 年以来 20 世纪人类核活动（例如大气核爆炸和核燃料后处理）产生的放射性核素对地球表面环境产生了重大影响。生活在热带/亚热带海洋中的长寿命浅水珊瑚珊瑚的骨骼中掺入了人为产生的放射性核素，包括¹²⁹ I和¹⁴ C，并提供了核活动影响的时间序列记录。在这里，我们展示了¹²⁹ I/ ¹²⁷ I 和 Δ ¹⁴ C 时间序列记录，该记录来自远东印度洋澳大利亚西北海岸的 Rowley Shoals 的年带状现代珊瑚骨架。在¹²⁹ I / ¹²⁷ I和Δ1930-1990 年代的¹⁴ C 记录显示出由核活动引起的明显增加，并且它们的增加剖面明显不同。第一次明显的¹²⁹ I/ ¹²⁷ I 增加发生在 1955 年至 1959 年，随后在 1960 年至 1963 年减少。增加可能是由于美国在 1954 年、1956 年和 1958 年在比基尼和埃尼威托克环礁的大气核爆炸。这些核试验中产生的¹²⁹ I 将通过北赤道流运输，其中一部分通过印度尼西亚的贯通流，然后到达罗利浅滩。然而，从 1955 年开始的这种初始增加在 Δ ¹⁴C 记录，显示从 1959 年开始明显增加，并在 1970 年代中期达到峰值，然后逐渐减少。这种缺失和延迟 4 年的 Δ ¹⁴ C 增加可能是由于爆炸产生的¹⁴ C 被天然碳稀释（通过海水混合和海气交换）比爆炸产生的¹²⁹ I强烈得多与天然碘（通过相同的过程），表明¹²⁹ I/ ¹²⁷ I 比率是表层海水中更保守的人为示踪剂，与 Δ ¹⁴ C相比。第二次¹²⁹ I/ ¹²⁷ I 增加与快速增长同时发生Δ ¹⁴期间1964至1967年Ç增加，随后迅速¹²⁹ I / ¹²⁷在1968 - 1969年我减少; 增加可归因于 1961 年至 1962 年在前苏联进行的非常大的大气核爆炸。第三次¹²⁹ I/ ¹²⁷ I 增加出现在 1969/1970 和 1992 年之间，这可以归因于从欧洲、前苏联和美国的核燃料后处理设施中释放的空中¹²⁹ I。珊瑚¹²⁹ I / ¹²⁷ I和Δ ¹⁴ C时间系列的记录，与以前的研究相结合，提升我们人类的行为的理解¹²⁹我和¹⁴C 在全球海洋和大气中。