Assessment of vertical radiocesium transfer in soil via roots
| Autor: | Shinta Ohashi, Wataru Sakashita, Masabumi Komatsu, Shigeto Ikeda, Yoshiki Shinomiya, Tomoyuki Saitoh, Satoru Miura, Akio Akama, Shinji Kaneko |
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| Rok vydání: | 2020 |
| Předmět: |
Bamboo
010504 meteorology & atmospheric sciences Health Toxicology and Mutagenesis Soil science Forests 010501 environmental sciences 01 natural sciences Soil Nutrient Japan Radiation Monitoring Forest ecology Fukushima Nuclear Accident Soil Pollutants Radioactive Environmental Chemistry Waste Management and Disposal Diel vertical migration Ecosystem 0105 earth and related environmental sciences Forest floor General Medicine Pollution Deciduous Cesium Radioisotopes Litter Environmental science Soil horizon |
| Zdroj: | Journal of Environmental Radioactivity. 222:106369 |
| ISSN: | 0265-931X |
| DOI: | 10.1016/j.jenvrad.2020.106369 |
| Popis: | Several years after the Fukushima Daiichi Nuclear Power Plant accident, the surface mineral soil layer is believed to be the main reservoir of radiocesium (137Cs) in forest ecosystems in Japan. Dissolved 137Cs combines with clay minerals in the soil, and hence, it is not expected to easily infiltrate over time. However, previous studies have indicated that 137Cs derived from the older global fallout migrated deeper than that of the Chernobyl accident, and this cannot be explained by only the dissolved 137Cs vertical migration in the soil. Considering the carbon and nutrient dynamics in the forest floor, the 137Cs transfer process in soil via roots may alter its vertical distribution on a decadal scale. Therefore, in this study, we investigated the 137Cs activity concentrations in both roots and soil matrix, by considering four (0–20 cm) or six (0–30 cm) mineral soil layers taken at every 5 cm at seven study sites dominated by one of the six plant species (three coniferous forests, one deciduous forest, two deciduous forests covered by Sasa, and one bamboo forest) in eastern Japan in 2013. Comparing the results of 137Cs activity concentrations between roots and soil matrix taken at the same soil layer, roots at the surface (0–5 cm) layer often showed lower values than the soil matrix. However, roots deeper than 5 cm had higher activity concentrations than the soil matrix, conversely. The 137Cs inventories ratio of roots to soil matrix are about 1% at the 0–5 and 5–10 cm soil layer, and about 2% at the soil layers deeper than 10 cm. These results suggest that decomposition of root litter little affect the short-term vertical migration of 137Cs in the forest soil. However, it indicates that continuous production and mortality of roots with relatively high 137Cs activity concentrations have an important role for changing the vertical distribution of 137Cs on time scale of decades, particularly at deeper soil layers. |
| Databáze: | OpenAIRE |
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