SCK-CEN, Biosphere Impact Studies Unit, 200 Boeretang, 2400 Mol, Belgium.
J Environ Radioact. 2012 May;107:56-67. doi: 10.1016/j.jenvrad.2011.12.014. Epub 2012 Jan 8.
Considered as one of the most available radionuclide in soil-plant system, ³⁶Cl is of potential concern for long-term management of radioactive wastes, due to its high mobility and its long half-life. To evaluate the risk of dispersion and accumulation of ³⁶Cl in the biosphere as a consequence of a potential contamination, there is a need for an appropriate understanding of the chlorine cycling dynamics in the ecosystems. To date, a small number of studies have investigated the chlorine transfer in the ecosystem including the transformation of chloride to organic chlorine but, to our knowledge, none have modelled this cycle. In this study, a model involving inorganic as well as organic pools in soils has been developed and parameterised to describe the biogeochemical fate of chlorine in a pine forest. The model has been evaluated for stable chlorine by performing a range of sensitivity analyses and by comparing the simulated to the observed values. Finally a range of contamination scenarios, which differ in terms of external supply, exposure time and source, has been simulated to estimate the possible accumulation of ³⁶Cl within the different compartments of the coniferous stand. The sensitivity study supports the relevancy of the model and its compartments, and has highlighted the chlorine transfers affecting the most the residence time of chlorine in the stand. Compared to observations, the model simulates realistic values for the chlorine content within the different forest compartments. For both atmospheric and underground contamination scenarios most of the chlorine can be found in its organic form in the soil. However, in case of an underground source, about two times less chlorine accumulates in the system and proportionally more chlorine leaves the system through drainage than through volatilisation.
考虑到³⁶Cl 是土壤-植物系统中最易获得的放射性核素之一，由于其高迁移性和长半衰期，因此对放射性废物的长期管理具有潜在的关注。为了评估由于潜在污染而导致³⁶Cl 在生物圈中扩散和积累的风险，需要对生态系统中氯的循环动态有适当的了解。迄今为止，只有少数研究调查了生态系统中的氯转移，包括氯化物向有机氯的转化，但据我们所知，尚无模型对该循环进行模拟。在这项研究中，开发了一个涉及土壤中无机和有机库的模型，并对其进行了参数化，以描述松林土壤中氯的生物地球化学命运。通过进行一系列敏感性分析并将模拟值与观测值进行比较，对模型进行了稳定氯的评估。最后，模拟了一系列不同外部供应、暴露时间和来源的污染情景，以估计³⁶Cl 在针叶林不同隔室中的可能积累。敏感性研究支持模型及其隔室的相关性，并强调了影响氯在林分中停留时间的氯转移。与观测值相比，该模型模拟了不同森林隔室中氯含量的实际值。对于大气和地下污染情景，大部分氯以有机形式存在于土壤中。然而，在地下源的情况下，系统中积累的氯减少了约两倍，通过排水而不是通过挥发离开系统的氯比例更高。
