Sorbonne Universités UPMC Univ Paris 06, Institut d'Ecologie et des Sciences de l'environnement de Paris (iEES), case 120, 4 place Jussieu, 75 252 Paris cedex 05, France.
National Institute for Environmental Science, Fukushima Branch, 10-2 Fukasaku, Miharu, Tamura, Fukushima 963-7700, Japan.
Sci Total Environ. 2018 Jan 15;612:1079-1090. doi: 10.1016/j.scitotenv.2017.07.205. Epub 2017 Sep 7.
The Fukushima nuclear accident in Japan resulted in the deposition of radiocesium over forested and rural landscapes northwest of the power plant. Although there have been several investigations into the dynamics of contaminated river sediment, less attention has been paid to the sources of deposited particulate matter in dams and reservoirs. In the Fukushima Prefecture, there are 10 significant dams and over a 1000 reservoirs for both agricultural and surface water management. These reservoirs may have trapped a significant volume of radiocesium-contaminated sediment. Therefore, characterizing the sources of contaminated particulate matter is important for the ongoing management of contamination in the region. Accordingly, the composition of particulate matter deposited in the Mano Dam reservoir, approximately 40km northwest of the power plant, was investigated with the analyses and modelling of carbon and nitrogen stable isotope ratios (δC and δN), total organic carbon (TOC) and total nitrogen (TN) concentrations. Four sediment cores, with lengths ranging 29-41cm, were sampled in the Mano Dam. Source samples from 46 forest soils, 28 cultivated soils and 25 subsoils were used to determine the source contributions of particulate matter. Carbon and nitrogen parameters were analyzed on all samples and a concentration-dependent distribution modelling approach was used to apportion source contributions. Three of the four cores sampled in the Mano Dam reservoir had distinct radiocesium peaks representative of the initial post-accident wash-off phase. Cultivated sources were responsible for 48±7% of the deposited fine particulate matter whereas forests were modelled to contribute 27±6% and subsoil sources 25±4%. Ongoing decontamination of cultivated sources in the Fukushima region should result in a decrease of contaminated matter deposition in reservoirs.
日本福岛核事故导致放射性铯沉积在核电站西北部的森林和农村景观中。尽管已经有几项关于受污染河流沉积物动力学的研究，但对水坝和水库中沉积的颗粒物的来源关注较少。在福岛县，有 10 座重要的大坝和 1000 多个用于农业和地表水管理的水库。这些水库可能截留了大量放射性铯污染的沉积物。因此，表征受污染颗粒物的来源对于该地区正在进行的污染管理非常重要。因此，研究了距离核电站西北约 40 公里的丸山大坝水库中沉积的颗粒物的来源，分析和模拟了碳和氮稳定同位素比值（δC 和 δN）、总有机碳（TOC）和总氮（TN）浓度。在丸山大坝采集了四个长度在 29-41cm 之间的沉积物岩芯。从 46 个森林土壤、28 个耕作土壤和 25 个底土中采集了源样本，以确定颗粒物的源贡献。对所有样本进行了碳和氮参数分析，并使用浓度相关的分布建模方法分配源贡献。在丸山大坝水库采集的四个岩芯中的三个都有明显的放射性铯峰值，代表初始事故后冲刷阶段。耕作源对沉积的细颗粒物的贡献为 48±7%，而森林被建模为贡献 27±6%，底土源贡献 25±4%。福岛地区正在进行的耕作源去污工作应导致水库中污染物质沉积的减少。
