Kasar S, Mishra S, Sahoo S K, Kavasi N, Omori Y, Arae H, Sorimachi A, Aono T
Environmental Radionuclides Research Group, National Institutes for Quantum and Radiological Science and Technology (QST), 4-9-1Anagawa, Chiba, 263-8555, Japan.
Environmental Radionuclides Research Group, National Institutes for Quantum and Radiological Science and Technology (QST), 4-9-1Anagawa, Chiba, 263-8555, Japan; Environmental Monitoring and Assessment Division, Bhabha Atomic Research Centre, Mumbai, 400085, India.
J Environ Radioact. 2021 Jul;233:106617. doi: 10.1016/j.jenvrad.2021.106617. Epub 2021 Apr 15.
Various radionuclides including fission products and heavy nuclides were released into the environment during the Fukushima Daiichi Nuclear Power Station (FDNPS) accident. The dissolution followed by migration of deposited radionuclides of Cs, Sr and U on soils could take place to the local environment. Therefore, it is necessary to determine sorption-desorption coefficients of U in soil-water system around the FDNPS from a migration viewpoint. The determination of sorption coefficient K(S) as well as desorption coefficient K(D) for U has been carried out in the present study using a laboratory batch method. Stable U was used for sorption from simulated ground water onto contaminated soil samples collected from Okuma Town, Fukushima. Different soil parameters were measured to understand their effects on sorption and desorption processes. The obtained K(S) and K(D) values of U were compared with values of K(S) and K(D) of Cs and Sr and K(S)-U in known Fukushima accident contaminated soils reported in the literature for better understanding. It was observed that K(S)-U varied from 160 to 5100 L/kg, whereas K(D)-U ranged from 200 to 11000 L/kg. K(D) was higher than K(S) for U in these soils implying irreversibility of the sorption process. Pearson's correlation of K(S) values suggested that U sorption is affected by various soil parameters. However, desorption is decided by the nature of U species formed in sorption process and soil parameters like pH, presence of carbonates, Ca ions, clay minerals etc. to some extent. The comparison between K(S) and K(D) values for Cs, Sr and U revealed that unsorbed Sr could migrate farther than unsorbed Cs or U under the present experimental conditions. Both sorption and desorption studies are of great importance to understand migration of metal ions from contaminated sites to local uncontaminated areas.
在福岛第一核电站事故期间，包括裂变产物和重核素在内的各种放射性核素被释放到环境中。沉积在土壤上的铯、锶和铀等放射性核素会发生溶解，随后迁移到当地环境中。因此，从迁移的角度来看，有必要确定福岛第一核电站周边土壤 - 水系统中铀的吸附 - 解吸系数。本研究采用实验室批量法测定了铀的吸附系数K(S)和解吸系数K(D)。使用稳定的铀从模拟地下水中吸附到从福岛大熊町采集的受污染土壤样品上。测量了不同的土壤参数，以了解它们对吸附和解吸过程的影响。将获得的铀的K(S)和K(D)值与文献中报道的已知福岛事故污染土壤中铯和锶的K(S)和K(D)值以及K(S)-U进行比较，以便更好地理解。观察到K(S)-U在160至5100 L/kg之间变化，而K(D)-U在200至11000 L/kg之间。在这些土壤中，铀的K(D)高于K(S)，这意味着吸附过程具有不可逆性。K(S)值的皮尔逊相关性表明，铀的吸附受各种土壤参数的影响。然而，解吸在一定程度上取决于吸附过程中形成的铀物种的性质以及土壤参数，如pH值、碳酸盐的存在、钙离子、粘土矿物等。铯、锶和铀的K(S)和K(D)值的比较表明，在当前实验条件下，未吸附的锶比未吸附的铯或铀迁移得更远。吸附和解吸研究对于理解金属离子从污染场地向当地未受污染区域的迁移都非常重要。
