Thiry Yves, Albrecht Achim, Tanaka Taku
Andra, Research and Development Division, 1-7 rue Jean-Monnet, 92298 Châtenay-Malabry cedex, France.
Andra, Research and Development Division, 1-7 rue Jean-Monnet, 92298 Châtenay-Malabry cedex, France.
J Environ Radioact. 2018 Oct;190-191:149-159. doi: 10.1016/j.jenvrad.2018.05.009. Epub 2018 May 21.
The management of vast forested zones contaminated by radiocesium (rCs) following the Chernobyl and Fukushima fallout is of great social and economic concern in affected areas and requires appropriate dynamic models as predictive or questioning tools. Generally, the existing radio-ecological models need less fragmented data and more ecological realism in their quantitative description of the rCs cycling processes. The model TRIPS ("Transfer of Radionuclide In Perennial vegetation Systems") developed in this study privileged an integrated approach which makes the best use of mass balance studies and available explicit experimental data for Scots pine stands. A main challenge was the differentiation and calibration of foliar absorption as well as root uptake in order to well represent the rCs biocycling. The general dynamics of rCs partitioning was simulated with a relatively good precision against an independent series of observed values. In our scenario the rCs biological cycling enters a steady-state about 15 years after the atmospheric deposits. At that time, the simulations showed an equivalent contribution of foliage and root uptake to the tree contamination. But the root uptake seems not sufficient to compensate the activity decline in the tree. The initial foliar uptake and subsequent internal transfers were confirmed to have a great possible impact on the phasing of tree contamination. An extra finding concerns the roots system acting as a buffer in the early period. The TRIPS model is particularly useful in cases where site-specific integrated datasets are available, but it could also be used with adequate caution to generic sites. This development paves the way for simplification or integration of new modules, as well as for a larger number of other applications for the Chernobyl or Fukushima forests once the appropriate data become available. According to the sensitivity analysis that involves in particular reliable estimates of net foliar uptake as well as root uptake not disconnected from rCs exchange reactions in soil.
切尔诺贝利和福岛核事故沉降后，受放射性铯（rCs）污染的大片林区的管理在受影响地区引起了极大的社会和经济关注，需要合适的动态模型作为预测或质疑工具。一般来说，现有的放射生态模型在对rCs循环过程的定量描述中需要更少碎片化的数据和更多的生态现实性。本研究中开发的TRIPS模型（“多年生植被系统中放射性核素的转移”）采用了一种综合方法，该方法充分利用了质量平衡研究和苏格兰松树林现有明确的实验数据。一个主要挑战是区分和校准叶面吸收以及根系吸收，以便很好地描述rCs的生物循环。相对于一系列独立的观测值，rCs分配的一般动态以相对较高的精度进行了模拟。在我们的情景中，rCs生物循环在大气沉降约15年后进入稳态。那时，模拟结果表明叶面吸收和根系吸收对树木污染的贡献相当。但根系吸收似乎不足以补偿树木中放射性活度的下降。最初的叶面吸收和随后的内部转移被证实对树木污染的阶段有很大的可能影响。一个额外的发现涉及根系在早期起到缓冲作用。TRIPS模型在有特定地点综合数据集的情况下特别有用，但在谨慎使用时也可用于一般地点。这一进展为新模块的简化或整合以及一旦有合适数据后对切尔诺贝利或福岛森林的大量其他应用铺平了道路。根据敏感性分析，其中特别涉及对叶面净吸收以及与土壤中rCs交换反应不脱节的根系吸收的可靠估计。
