High-resolution ¹²⁹I bomb peak profile in an ice core from SE-Dome site, Greenland

¹²⁹I in natural archives, such as ice cores, can be used as a proxy for human nuclear activities, age marker, and environmental tracer. Currently, there is only one published record of ¹²⁹I in ice core (i.e., from Fiescherhorn Glacier, Swiss Alps) and its limited time resolution (1-2 years) prevents the full use of ¹²⁹I for the mentioned applications. Here we show ¹²⁹I concentrations in an ice core from SE-Dome, Greenland, covering years 1956-1976 at a time resolution of ∼6 months, the most detailed record to date. Results revealed ¹²⁹I bomb peaks in years 1959, 1962, and 1963, associated to tests performed by the former Soviet Union, one year prior, in its Novaya Zemlya test site. All ¹²⁹I bomb peaks were observed in winter (1958.9, 1962.1, and 1963.0), while tritium bomb peaks, another prominent radionuclide associated with nuclear bomb testing, were observed in spring or summer (1959.3, and 1963.6; Iizuka et al., 2017). These results indicate that ¹²⁹I bomb peaks can be used as annual and seasonal age markers for these years. Furthermore, we found that ¹²⁹I recorded nuclear fuel reprocessing signals and that these can be potentially used to correct timing of estimated ¹²⁹I releases during years 1964-1976. Comparisons with other published records of ¹²⁹I in natural archives showed that ¹²⁹I can be used as common age marker and tracer for different types of records. Most notably, the 1963 ¹²⁹I bomb peak can be used as common age marker for ice and coral cores, providing the means to reconcile age models and associated trends from the polar and tropical regions, respectively.