This paper reports the results of investigations on the radioecological state of bottom sediments of the Ob–Yenisei shoal area and Ob and Yenisei estuaries. Materials were obtained in two periods: 1995–2001 and 2014–2019 during seven expeditions on the R/V Akademik Boris Petrov, Professor Shtokman, and Akademik Mstislav Keldysh. Resampling of bottom sediment cores at key-points in areas of increased radiocesium activity and subsequent analysis of the radionuclide distribution made it possible to establish positive trends in the change of the radiation state of the regional ecosystem. The total degradation of the Ob radiocesium overactivity zone and quite significant degradation of the Yenisei zone (primarily the most polluted) were revealed. Comparison of current max-positions of specific activity in the vertical distribution of ¹³⁷Cs in sediment cores made it possible to determine the sedimentation rate in the distal and proximal facies of the Yenisei estuary: 4.7–5.8 and 3.2–3.7 mm/year, respectively. The established changes that have occurred over ~20 years prove the ability of the Kara Sea ecosystem to self-purify. Pollutant diffusion and assimilation by bottom sediments play a significant role in the self-regeneration of the ecosystem. This is most intense in zone of influence of the river–sea geochemical barrier.

本文报告了Ob-Yenisei浅滩区以及Ob和Yenisei入海口底部沉积物的放射生态状态的调查结果。资料是在两个阶段获得的：1995-2001年和2014-2019年是在R / V Akademik Boris Petrov，Shtokman教授和Akademik Mstislav Keldysh的七次考察中获得的。在放射性铯活动增加的地区的关键点对底部沉积物核心进行重新采样，并随后对放射性核素分布进行分析，从而有可能在区域生态系统的辐射状态变化中确立积极趋势。揭示了Ob放射性铯过度活性区的总降解和叶尼塞区的相当明显的降解（主要是污染最严重的区域）。在¹³⁷的垂直分布中当前比活的最大位置的比较沉积物芯中的Cs使得确定叶尼塞河河口远端和近端相的沉积速率成为可能：分别为4.7-5.8和3.2-3.7 mm /年。大约20年以来发生的既定变化证明了卡拉海生态系统的自我净化能力。底部沉积物的污染物扩散和吸收在生态系统的自我再生中起着重要作用。这在河海地球化学屏障的影响区最为强烈。