Radiocesium distribution in sugi (Cryptomeria japonica) in Eastern Japan: translocation from needles to pollen
Radiocesium distribution in sugi (Cryptomeria japonica) in Eastern Japan: translocation from needles to pollen
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DOI：
10.1016/j.jenvrad.2014.06.018
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发表时间：
2015-01-01
影响因子：
2.3
通讯作者：
Umemura, Mitsutoshi
中科院分区：
文献类型：
--
作者：
Kanasashi, Tsutomu;Sugiura, Yuki;Umemura, Mitsutoshi
通过测量不同年龄针叶、雄花和花粉中的Cs-137浓度，我们评估了2012年11月至2013年2月日本东部杉（柳杉）林的放射性铯污染，包括福岛的80个站点和其他地区（东北和关东越）的35个站点。在广阔的地理区域内，福岛第一核电站事故发生时出现的针状物所含的Cs-137浓度远远高于事故后出现的针状物。这一结果，连同使用放射自显影术对Cs-137分布的视觉分析，表明一些来自直接沉降物的Cs-137残留在旧针的表面上。由于我们也检测到Cs-137在年轻的针叶和雄花，我们得出结论，Cs-137被转移到杉针叶的尖端。雄花中的Cs-137浓度高于当前生长（2012年）针叶中的浓度，并与之呈正相关。雄花和花粉的~（137）Cs浓度也呈正相关关系，二者的~（137）Cs浓度几乎一致。这些结果表明，Cs-137从老针叶向幼针叶、雄花和花粉的向顶转运发生。然而，与三个不同年龄的针中Cs-137浓度相关的结果与切尔诺贝利事故后4年多进行的类似研究的结果不同。这表明，在福岛第一核电站事故后2年，在杉树林中的Cs-137的分布尚未达到稳定状态。(C)2014爱思唯尔有限公司版权所有。
We assessed the radiocesium contamination of sugi (Cryptomeria japonica) forests in eastern Japan from November 2012 to February 2013, including 80 sites in Fukushima and 35 sites in other regions (Tohoku and Kanto-Koshinetsu), by measuring the Cs-137 concentrations in needles of different ages, male flowers, and pollen. Over a wide geographic area, needles that were present at the time of the Fukushima Dai-ichi Nuclear Power Plant accident contained much higher Cs-137 concentrations than needles that emerged after the accident. This result, together with visual analysis of Cs-137 distribution using autoradiography, indicated that some of the Cs-137 derived from direct fallout remained on the surface of the older needles. Since we also detected Cs-137 in younger needles and male flowers, we concluded that Cs-137 was translocated toward the tips of sugi needles. The Cs-137 concentration in male flowers was higher than and positively correlated with that in the currently growing (2012) needles. Also, a positive relationship was observed between the Cs-137 concentration of male flowers and pollen, and they were found to be nearly identical Cs-137 concentration. These results indicate the occurrence of acropetal translocation of Cs-137 from old needles to young needles, male flowers and pollen. However, the results as related to Cs-137 concentration in the needles of three different ages differed from the results of similar studies conducted more than 4 y after the Chernobyl accident. This suggests that, 2 y after the Fukushima Dai-ichi NPP accident, the distribution of Cs-137 in the sugi forests has not yet reached a steady state. (C) 2014 Elsevier Ltd. All rights reserved.