Echoes of a Cold War

• Published in: Continental shelf research 2024-12, Vol.283, p.105347, Article 105347
• Main Authors: Rusakov, Valeriy Y., Lukmanov, Ruslan A., Soktoev, Bulat R., Mishan'kin, Andrey Y.
• Format: Article
• Language: English
• Subjects: 137Cs contamination; 210Pb dating; Kara sea; Novaya zemlya archipelago; Nuclear weapons testing
• ISSN: 0278-4343
• DOI: 10.1016/j.csr.2024.105347

The Kara Sea was an area of radionuclide contamination as a result of nuclear weapons testing, since it is located in close proximity to the nuclear test site on the Novaya Zemlya archipelago. The vertical distribution of 137Cs and 210Pb in 15 sediment cores from the sea made it possible to reconstruct the chronology of 137Cs entry into marine sediments. The reconstruction was based on the age-depth model RUS2023 (Rusakov et al., 2024) for 210Pbex, taking into account the grain-size composition and sorption capacity of sediments. Our study showed that higher 137Cs concentrations in sediments of the Novaya Zemlya Trough correspond to the time of active nuclear weapons testing in 1961–63 (about 9.0 ± 1.6 Bq kg‒1), as well as in estuarine sediments of the Yenisei Bay in 1986 (85.2 ± 3.2 Bq kg‒1). The abnormally high flux in 1980s represents the superposition of 137Cs fluxes as a result of global fallout (Chernobyl trace) and as a result of the release of radionuclide from regional source located in the Yenisei River catchment. Both of these events are associated with increased the sedimentation and mass accumulation rates of marine sediments. In 1961‒63, this was a consequence of the release of sediment into the atmosphere due to nuclear explosions, and in the 1980s, as a result of an increase in sediment supply with river runoff. Currently, against the backdrop of a decrease in sediment fluxes into the sea, Novaya Zemlya and Yenisei River remain the main sources of 137Cs supply to marine sediments. Background values for recent sediments in the Kara Sea are