Kunduzbayeva A Ye, Lukashenko S N, Kabdyrakova A M, Larionova N V, Magasheva R Yu, Bakirova G A
Branch "Institute of Radiation Safety and Ecology" of the NNC RK, Kurchatov, Kazakhstan.
Russian Institute of Radiology and Agroecology, Obninsk, Russia.
J Environ Radioact. 2022 Aug;249:106867. doi: 10.1016/j.jenvrad.2022.106867. Epub 2022 May 3.
This paper reports the speciation of Cs, Am, Sr and Pu in the soil samples of the Experimental Field (EF). The EF is a testing ground of the Semipalatinsk nuclear weapons test site used for surface and atmospheric tests. The study revealed low mobility of artificial radionuclides in the EF site soils. The revealed high radionuclide concentrations in soil mainly exist in tightly bound form. On average, the content of the tightly bound form of Cs was revealed to be below 98%, that of Sr - 94%, Am - 89%, and Pu - 98%. The radionuclides occurrence forms were analyzed in correlation with the physicochemical parameters of soils. Reliable relationships have been established between the content of carbonates and the content of the exchangeable, acid-soluble and strongly bound Sr forms in soils, as well as the content of the water-soluble salts and the content of the strongly bound Pu form in the soil. Similarly, we compared the distributions of the radionuclides speciation and their stable isotopes with their analogous elements in the soil. Unlike Cs and Sr, which are in a tightly bound form in the soils of the Experimental Field site, the main content of soil "competitors" of the Cs radionuclide - K and Cs is observed in an exchange form, less significantly in an acid-soluble form. The alkaline earth metals (analogous elements for Sr) are mainly observed as a composition of the exchangeable and acid-soluble forms. The results allow to conclude that there is no equilibrium distribution of the physicochemical forms of radionuclides introduced into the soil and the natural presence forms of their stable analogs in the soil. Such equilibrium distribution can only be achieved at a complete isotopic exchange in phases and soil components, which under the conditions of the Experimental Field is not possible in the near future. It can be concluded that the behavior of the studied radionuclides in soils is stipulated by the initial form delivered by the fallouts from tests at the EF site.
本文报道了实验场（EF）土壤样品中铯（Cs）、镅（Am）、锶（Sr）和钚（Pu）的形态。实验场是塞米巴拉金斯克核武器试验场用于地表和大气试验的一个试验场地。研究表明，人工放射性核素在实验场场地土壤中的迁移性较低。土壤中检测到的高放射性核素浓度主要以紧密结合的形式存在。平均而言，铯紧密结合形式的含量低于98%，锶为94%，镅为89%，钚为98%。分析了放射性核素的存在形态与土壤理化参数的相关性。已在土壤中碳酸盐含量与可交换态、酸溶态和强结合态锶的含量之间，以及水溶性盐含量与土壤中强结合态钚的含量之间建立了可靠的关系。同样，我们比较了放射性核素形态及其稳定同位素与土壤中类似元素的分布情况。与实验场场地土壤中以紧密结合形式存在的铯和锶不同，铯放射性核素在土壤中的主要“竞争元素”——钾和铯，主要以交换态存在，酸溶态的含量较少。碱土金属（锶的类似元素）主要以可交换态和酸溶态的形式存在。结果表明，引入土壤中的放射性核素的物理化学形态与其稳定类似物在土壤中的天然存在形态不存在平衡分布。这种平衡分布只有在相和土壤成分中完全同位素交换时才能实现，而在实验场的条件下，近期内是不可能实现的。可以得出结论，所研究的放射性核素在土壤中的行为是由实验场试验沉降物带来的初始形态决定的。
