State Research Institute Center for Physical Sciences and Technology, Vilnius, Lithuania.
State Research Institute Nature Research Centre, Vilnius, Lithuania.
PLoS One. 2020 Aug 17;15(8):e0237605. doi: 10.1371/journal.pone.0237605. eCollection 2020.
The vertical distribution of radiocarbon (14C) was examined in the bottom sediment core, taken from Lake Drūkšiai, which has served as a cooling pond since 1983 for the 26 years of the Ignalina Nuclear Power Plant (INPP) operation using two RBMK-1500 reactors (Russian acronym for"Channelized Large Power Reactor"). 14C specific activity was measured in alkali-soluble and -insoluble fractions of the sediment layers. Complementary measurements of the 210Pb and 137Cs activity of the samples provided the possibility to evaluate the date of every layer formation, covering the 1947-2013 period. In addition, 14C distribution was examined in the scales of pelagic fish caught between 1980 and 2012. Our measurements reveal that, during the period 1947-1999, the radiocarbon specific activity in both fractions exhibits a parallel course with a difference of 5 ± 1 pMC (percent of modern carbon) being higher in alkali-soluble fraction, although 14C specific activity in both fractions increased by 11.4-13.6 pMC during the first 15 years of plant operation. However, during the 2000-2009 period, other than previously seen, a dissolved inorganic carbon (DIC) → aquatic primary producers → sediments 14C incorporation pattern occurred, as the radiocarbon specific activity difference between alkali-soluble and -insoluble fractions reached 94, 25, and 20 pMC in 2000, 2006, and 2008, respectively. Measurements in different sediment fractions allowed us to identify the unexpected organic nature of 14C contained in liquid effluences from the INPP in 2000-2009. The discrepancy between 14C specific activity in fish scales samples and DIC after 2000 also confirmed the possibility of organic 14C contamination. Possible reasons for this phenomenon might be industrial processes introduced at the INPP, such as the start of operation of the cementation facility for spent ion exchange resins, decontamination procedures, and various maintenance activities of reactor aging systems and equipment.
放射性碳（14C）的垂直分布在取自 Drūkšiai 湖的底部沉积物核心中进行了研究，自 1983 年以来，该湖一直作为 Ignalina 核电站（INPP）的冷却池，使用两座 RBMK-1500 反应堆（俄语为“Channelized Large Power Reactor”）运行了 26 年。在沉积物层的碱可溶和不可溶部分测量了 14C 的比活度。对样品中 210Pb 和 137Cs 活度的补充测量提供了评估每个层形成日期的可能性，涵盖了 1947-2013 年期间。此外，还检查了 1980 年至 2012 年间捕获的浮游鱼类鳞片中的 14C 分布。我们的测量结果表明，在 1947-1999 年期间，两种分数中的放射性碳比活度呈平行变化，尽管在工厂运行的前 15 年中，两种分数中的 14C 比活度增加了 11.4-13.6 pMC，但碱可溶分数中的差异高 5±1 pMC（现代碳的百分比）。然而，在 2000-2009 年期间，除了以前看到的情况外，发生了溶解无机碳（DIC）→水生初级生产者→沉积物 14C 掺入模式，因为碱可溶和不可溶分数之间的放射性碳比活度差异分别在 2000、2006 和 2008 年达到 94、25 和 20 pMC。对不同沉积物分数的测量使我们能够识别出 INPP 液体流出物中包含的放射性碳的意外有机性质，这种情况发生在 2000-2009 年。2000 年后鱼鳞片样本和 DIC 之间的 14C 比活度差异也证实了有机 14C 污染的可能性。这种现象的可能原因可能是 INPP 引入的工业过程，例如开始运行用于处理用过的离子交换树脂的胶结设施、去污程序以及反应堆老化系统和设备的各种维护活动。
