Speciation of cesium in tree tissues and its implication for uptake and translocation of radiocesium in tree bodies
Speciation of cesium in tree tissues and its implication for uptake and translocation of radiocesium in tree bodies
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树木组织中铯的形态及其对树体放射性铯吸收和转运的影响
DOI：
10.1016/j.scitotenv.2020.142598
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发表时间：
2021
影响因子：
9.8
通讯作者：
Tanaka Kazuya,Kanasashi Tsutomu,Takenaka Chisato,Takahashi Yoshio
中科院分区：
文献类型：
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作者：
Tanaka Kazuya,Kanasashi Tsutomu,Takenaka Chisato,Takahashi Yoshio
自切尔诺贝利和福岛核电站事故以来，广泛的研究集中在放射性铯在森林系统中的分布和循环。然而，直接化学形态分析的Cs光谱方法是有限的稳定Cs以及放射性铯在树木中的丰度低。在这项研究中，我们调查了133 Cs掺杂树皮，边材，心材，针，分支样品采集在福岛扩展X射线吸收精细结构（EXAFS）的Cs的配位结构。我们调查了福岛的四种代表树种，柳杉、赤松、锯齿栎和五加。EXAFS光谱表明，Cs吸附作为外层复杂的所有部分的四个物种，静电结合带负电荷的功能基团的组成部分树组织。这些结果得到了支持的提取实验中，超过98.5%的吸附Cs解吸从每个树种的所有部分，使用1 M CH3COONH4。在超纯水、NaCl和KCl溶液中，进行了铯在植物细胞壁的重要组分纤维素上的吸附实验。考虑到树木汁液的组成，纤维素和溶液的Kd值不足以固定Cs。总体而言，这项研究的结果是一致的，与以前的实地观察表明，放射性铯是易位在移动的形式的代谢活跃的树木部分。
Since the Chernobyl and Fukushima nuclear power plant accidents, extensive research has focused on the distribution and cycle of radiocesium in forest systems. Nevertheless, direct chemical speciation analyses of Cs by spectroscopic methods are limited by the low abundances of stable Cs as well as radiocesium in trees. In this study, we investigated coordination structures of Cs in133Cs-doped bark, sapwood, heartwood, needle, and branch samples of trees collected in Fukushima by extended X-ray absorption fine structure (EXAFS) spectroscopy. We examined four representative tree species in Fukushima,Cryptomeria japonica,Pinus densiflora,Quercus serrata, andEleutherococcussciadophylloides. EXAFS spectra suggested that Cs was adsorbed as an outer-sphere complex on all parts of the four species, with electrostatic binding to negatively charged functional groups in components of tree tissues. These results were supported by extraction experiments where more than 98.5% of the sorbed Cs was desorbed from all parts of each tree species using 1 M CH3COONH4. Sorption experiments of Cs on cellulose, an important component of plant cell walls, were carried out in ultrapure water, NaCl, and KCl solutions. TheKdvalues for cellulose and solutions were not high enough to fix Cs, considering the composition of sap in trees. Overall, the results of this study are consistent with previous field observations indicating that radiocesium is translocated in mobile form to metabolically active tree parts.