Key factors controlling radiocesium sorption and fixation in river sediments around the Fukushima Daiichi Nuclear Power Plant. Part 1: Insights from sediment properties and radiocesium distributions
| Autor: | Kazuki Iijima, Yosuke Akagi, Tomofumi Sato, Yukio Tachi, Motoki Terashima, Hideji Nakane, Kenso Fujiwara, Makoto Kawamura |
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| Rok vydání: | 2019 |
| Předmět: |
Geologic Sediments
Water Pollutants Radioactive Environmental Engineering 010504 meteorology & atmospheric sciences Weathering 010501 environmental sciences Silt 01 natural sciences Japan Rivers Radiation Monitoring Cation-exchange capacity Environmental Chemistry Kaolinite Fukushima Nuclear Accident Soil Pollutants Radioactive Organic matter Waste Management and Disposal 0105 earth and related environmental sciences chemistry.chemical_classification Sediment Sorption Pollution chemistry Cesium Radioisotopes Environmental chemistry Nuclear Power Plants Environmental science Clay minerals |
| Zdroj: | The Science of the total environment. 724 |
| ISSN: | 1879-1026 |
| Popis: | In order to elucidate the radiocesium transport behaviors in natural environment, we systematically investigated sediments from the highly contaminated rivers of Ukedo and Odaka around the Fukushima Daiichi Nuclear Power Plant. We focused on determining the key factors controlling the radiocesium sorption and fixation, such as variations in the particle size, clay mineralogy, and organic matter (OM). The distribution patterns of the 137Cs concentration and particle size fractions were found to be similar for the two rivers, indicating that both clay and silt fractions contributed almost equally to the Cs sorption. The clay mineralogical composition evaluated using X-ray diffraction analysis showed that the relative contents of micaceous minerals were higher in the Ukedo River samples, whereas the relative contents of smectite and kaolinite were higher in the Odaka River samples. This implies that the sediments in both rivers were likely at different weathering stages due to the different geological settings in both catchments. The effects of OM on the sediment properties were also investigated by comparing the cation exchange capacity (CEC) and the radiocesium interception potential (RIP) of the two samples both with and without OM present. The CEC values were controlled by both the clay minerals and OM, and the RIP values increased significantly in the absence of OM. Such trends were correlated to the total organic carbon values, which may be used to understand the direct and indirect roles of OM in the sorption and fixation of Cs. These key differences in river sediment were attributed to the differences in the geological settings and weathering stages. These properties may contribute to the different sorption and fixation behaviors of radiocesium. In the second part paper, we further examined these behaviors and identified key factors by investigating their relationship to the sediment properties of both rivers. |
| Databáze: | OpenAIRE |
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