Shifts of radiocesium vertical profiles in sediments and their modelling in Japanese lakes
Autor: | Koichi Kamiya, Hiroyuki Arai, Yuichi Onda, Eiji Komatsu, Takehiko Fukushima |
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Rok vydání: | 2018 |
Předmět: |
Hydrology
Environmental Engineering 010504 meteorology & atmospheric sciences Sediment 010501 environmental sciences 01 natural sciences Pollution Model application Wind wave Environmental Chemistry Environmental science Waste Management and Disposal Sediment core Vertical shift 0105 earth and related environmental sciences Trophic level |
Zdroj: | Science of The Total Environment. 615:741-750 |
ISSN: | 0048-9697 |
Popis: | Vertical profiles of radiocesium concentrations were measured in sediment cores collected at various times after the 2011 Fukushima nuclear accident in five Japanese lakes (Hinuma, Kasumigaura, Kitaura, Onogawa and Sohara) with different morphological and trophic characteristics in order to investigate the sedimentation-diffusion processes. In lakes where sediments had high porosities and experienced considerable wave action due to shallowness, we observed rapid penetration of radiocesium to a certain depth just after the accident, followed by downward movement of the peak depths. In contrast, gradual downward transfers of distinct peaks were found in other types of lakes. A one-dimensional differential sediment model with water-sediments interaction processes was constructed to describe the vertical shift of radiocesium profiles. Our proposed submodels relating to the length scales of the mixing using wind-induced stress and porosity of sediments were constructed based on one measurement of the vertical distribution of radiocesium in three lakes (Hinuma, Kasumigaura and Sohara). This model was then validated using samples from those lakes in different years, as well as from two other lakes. Good agreement was obtained. We discuss our findings, the limits of model application, and future research targets. |
Databáze: | OpenAIRE |
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