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| Titel |
Cesium, iodine and tritium in NW Pacific waters – a comparison of the Fukushima impact with global fallout |
| VerfasserIn |
P. P. Povinec, M. Aoyama, D. Biddulph, R. Breier, K. Buesseler, C. C. Chang, R. Golser, X. L. Hou, M. Ješkovský, A. J. T. Jull, J. Kaizer, M. Nakano, H. Nies, L. Palcsu, L. Papp, M. K. Pham, P. Steier, L. Y. Zhang |
| 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. 8 ; Nr. 10, no. 8 (2013-08-15), S.5481-5496 |
| Datensatznummer |
250085298
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| Publikation (Nr.) |
 copernicus.org/bg-10-5481-2013.pdf |
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| Zusammenfassung |
| Radionuclide impact of the Fukushima Dai-ichi nuclear power plant accident on
the distribution of radionuclides in seawater of the NW Pacific Ocean is
compared with global fallout from atmospheric tests of nuclear weapons.
Surface and water column samples collected during the Ka'imikai-o-Kanaloa
(KOK) international expedition carried out in June 2011 were analyzed for
134Cs, 137Cs, 129I and 3H. The 137Cs, 129I and
3H levels in surface seawater offshore Fukushima varied between
0.002–3.5 Bq L−1, 0.01–0.8 μBq L−1, and
0.05–0.15 Bq L−1, respectively. At the sampling site about 40 km
from the coast, where all three radionuclides were analyzed, the Fukushima
impact on the levels of these three radionuclides represents an increase above
the global fallout background by factors of about 1000, 50 and 3,
respectively. The water column data indicate that the transport of Fukushima-derived
radionuclides downward to the depth of 300 m has already occurred.
The observed 137Cs levels in surface waters and in the water column are
compared with predictions obtained from the ocean general circulation model,
which indicates that the Kuroshio Current acts as a southern boundary for the
transport of the radionuclides, which have been transported from the
Fukushima coast eastward in the NW Pacific Ocean. The 137Cs inventory in
the water column is estimated to be about 2.2 PBq, what can be regarded as a
lower limit of the direct liquid discharges into the sea as the seawater
sampling was carried out only in the area from 34 to 37° N, and from
142 to 147° E. About 4.6 GBq of 129I was deposited in the NW
Pacific Ocean, and 2.4–7 GBq of 129I was directly discharged as liquid
wastes into the sea offshore Fukushima. The total amount of 3H released
and deposited over the NW Pacific Ocean was estimated to be 0.1–0.5 PBq.
These estimations depend, however, on the evaluation of the total
137Cs activities released as liquid wastes directly into the sea, which
should improve when more data are available. Due to a suitable residence
time in the ocean, Fukushima-derived radionuclides will provide useful
tracers for isotope oceanography studies on the transport of water masses
during the next decades in the NW Pacific Ocean. |
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