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| Titel |
Concentration and vertical flux of Fukushima-derived radiocesium in sinking particles from two sites in the Northwestern Pacific Ocean |
| VerfasserIn |
M. C. Honda, H. Kawakami, S. Watanabe, T. Saino |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 6 ; Nr. 10, no. 6 (2013-06-03), S.3525-3534 |
| Datensatznummer |
250018267
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| Publikation (Nr.) |
 copernicus.org/bg-10-3525-2013.pdf |
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| Zusammenfassung |
| At two stations in the western North Pacific, K2 in the subarctic gyre and S1
in the subtropical gyre, time-series sediment traps were collecting sinking
particles when the Fukushima Daiichi Nuclear Power Plant (FNPP1) accident
occurred on 11 March 2011. Radiocesium (134Cs and 137Cs) derived
from the FNPP1 accident was detected in sinking particles collected at 500 m
in late March 2011 and at 4810 m in early April 2011 at both stations. The
sinking velocity of 134Cs and 137Cs was estimated to be 22 to
71 m day−1 between the surface and 500 m and >180 m day−1
between 500 m and 4810 m. 137Cs concentrations varied from 0.14 to
0.25 Bq g−1 dry weight. These values are higher than those of surface
seawater, suspended particles, and zooplankton collected in April 2011.
Although the radiocesium may have been adsorbed onto or incorporated into
clay minerals, correlations between 134Cs and lithogenic material were
not always significant; therefore, the form of the cesium associated with the
sinking particles is still an open question. The total 137Cs inventory
by late June at K2 and by late July at S1 was 0.5 to 1.7 Bq m−2 at
both depths. Compared with 137Cs input from both stations by April 2011,
estimated from the surface 137Cs concentration and mixed-layer depth and
by assuming that the observed 137Cs flux was constant throughout the
year, the estimated removal rate of 137Cs from the upper layer
(residence time in the upper layer) was 0.3 to 1.5% yr−1 (68 to
312 yr). The estimated removal rates and residence times are comparable to
previously reported values after the Chernobyl accident (removal rate:
0.2–1%, residence time: 130–390 yr). |
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