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| Titel |
Analysis on radiocesium concentration in rivers that have catchment areas affected by the fallout from Fukushima Daiichi Nuclear Power Plant |
| VerfasserIn |
Keisuke Taniguchi, Kazuya Yoshimura, Aya Sakaguchi, Masayoshi Yamamoto, Yuichi Onda |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250094716
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| Publikation (Nr.) |
 EGU/EGU2014-10146.pdf |
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| Zusammenfassung |
| Due to Fukushima Daiichi Nuclear Power Plant accident, radioactive materials including
Cs-134 and Cs-137 were widely distributed in surrounded area. The radiocesiums have been
transported in river networks. This study showed the monitoring results of radiocesium
concentration in river waters and suspended sediments in Abukuma river basin and smaller
coastal river catchments.
The monitoring started at 6 sites from June 2011. Subsequently, additional 24
monitoring sites were installed between October 2012 and January 2013. Flow and
turbidity (for calculation of suspended sediment concentration) were measured at
each site, while suspended sediments and river water were collected every one
or half month to measure Cs-134 and Cs-137 activity concentrations by gamma
spectrometry.
Activity concentrations of Cs-134 and Cs- 137 on suspended sediments were generally
decreasing at all sites. The decreasing rate changed lower at about one year later from the
accident. Activity concentration in river waters also showed the same tendency although there
are only few data within 1 year from the accident.
Activity concentrations measured at the same day are proportional to the mean catchment
inventory. Therefore, the activity concentration can be normalized by the mean catchment
inventory. The normalized activity can be fitted to following double exponential
function:
[At] = 1.551 exp (-5.265t) + 0.069 exp (-0.266 t), where t [year] is the time from the
accident.
There is no time evolution of Kd between suspended sediments and river water. Instead,
Kd was varied spatially. Although the reason of the spatial variation is not clear for now,
geology of the catchment (i.e. mineral composition of suspended particles) seems to relate to
the variation. |
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