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首页> 外文学位 >Radionuclide transport in forest ecosystems: Modeling approaches and safety evaluation.
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Radionuclide transport in forest ecosystems: Modeling approaches and safety evaluation.

机译：森林生态系统中的放射性核素运输：建模方法和安全性评估。

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Concentrations of heavy metals in the environment have been increasing for several centuries as a result of industrial operations. Particularly, the introduction of radionuclides from man-made nuclear sources has posed a new challenge to the natural environment. The Chernobyl NPP accident in 1986 led to radionuclide contamination in most countries of Eastern and Western Europe. The fate and transport of these radionuclides, as well as associated risks to public health, are a growing concern. Radionuclides incorporated in natural and agricultural products and consumed as foodstuff, construction materials, etc. can contribute significantly to the human dose. Agricultural ecosystems can be relatively well handled by appropriate remedial action, but countermeasures for natural and semi-natural ecosystems have not been comprehensively developed and applied. Contamination in these ecosystems will continue to pose a danger in times to come.; This study presents a generic dynamic model, FORESTPATH, that describes the major kinetic processes and pathways of radionuclide movement in forests and natural ecosystems and which can be used to predict future radionuclide concentrations. The model calculates the time-dependent radionuclide concentrations in different compartments of the forest ecosystem based on the information available on residence half-times in two forest types: coniferous and deciduous. Results of model simulations show that forests can efficiently accumulate the activity released in the environment and that the understory, tree and organic layer are the major sink compartments contributing to the human radiation dose. The FORESTPATH model reproduces well the radionuclide cycling pattern found in the literature for deciduous and coniferous forests. Variability analysis has been used to assess the relative importance of specific parameter values in the generic model performance.; The FORESTPATH model was successfully applied in a general evaluation of remedial policies for contaminated forests. Deposition patterns and remediation schedules are both important in planning efficient countermeasures. FORESTPATH can be used as the core of a decision-support system for site remediation and planning.; Given their high complexity, traditional sampling programs often provide only limited and fragmented information for the natural ecosystems. A model-directed sampling program which implies a close feedback between sampling and modeling has been developed and is now being applied by an international team of USA, EU and CIS members in the Chernobyl NPP Exclusion Zone. More than 200 samples were collected and analyzed to gain data on the radionuclide partition in compartments of Chernobyl forests. Results of both 1994 and 1995 sampling programs have enabled the FORESTPATH model to be validated.
机译：由于工业运作，环境中重金属的浓度已经增加了几个世纪。特别是，从人造核源引入放射性核素对自然环境提出了新的挑战。 1986年的切尔诺贝利核电站事故在东欧和西欧的大多数国家导致了放射性核素的污染。这些放射性核素的命运和运输以及对公共健康的相关风险，日益引起人们的关注。掺入天然和农产品中并作为食品，建筑材料等消费的放射性核素可显着增加人体剂量。通过适当的补救措施可以相对良好地处理农业生态系统，但是尚未全面开发和应用针对自然和半自然生态系统的对策。这些生态系统中的污染将在未来一段时间内继续构成危险。这项研究提出了一个通用的动力学模型FORESTPATH，该模型描述了森林和自然生态系统中放射性核素运动的主要动力学过程和途径，可用于预测未来放射性核素的浓度。该模型根据关于两种森林类型（针叶和落叶树种）的居留半衰期的可用信息，计算森林生态系统不同隔室中随时间变化的放射性核素浓度。模型模拟的结果表明，森林可以有效地积累环境中释放的活性，而林下，树木和有机层是影响人类辐射剂量的主要汇聚区。 FORESTPATH模型很好地再现了文献中发现的落叶和针叶林的放射性核素循环模式。变异性分析已用于评估通用模型性能中特定参数值的相对重要性。 FORESTPATH模型已成功地应用于对受污染森林的补救政策的一般评估中。沉积方式和修复时间表对于规划有效的对策都很重要。 FORESTPATH可以用作网站修复和规划的决策支持系统的核心。鉴于其高度复杂性，传统的采样程序通常只为自然生态系统提供有限且分散的信息。已经制定了一个模型指导的采样程序，该程序暗示了采样和建模之间的紧密反馈，并且美国，欧盟和独联体成员在切尔诺贝利NPP禁区的国际团队现在正在应用该程序。收集并分析了200多个样品，以获取有关切尔诺贝利森林分区中放射性核素分区的数据。 1994年和1995年采样程序的结果使FORESTPATH模型得以验证。

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