Biogeosciences Discuss., 10, 4127-4156, 2013
www.biogeosciences-discuss.net/10/4127/2013/
doi:10.5194/bgd-10-4127-2013
© Author(s) 2013. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Biogeosciences (BG). Please refer to the corresponding final paper in BG.
Does the Fukushima NPP disaster affect the caesium activity of North Atlantic Ocean fish?
G. Kanisch and M.-O. Aust
Thünen Institute of Fisheries Ecology, Marckmannstraße 129b, 20539 Hamburg, Germany

Abstract. Fillet samples of marine fish collected from the East/West Greenland current (GC) and from the Baltic Sea (BS), have been investigated by gamma-ray spectrometry within the regular German monitoring program. In samples of the second half of 2011 134Cs traces have been detected, suggested to originate from the Fukushima fallout being deposited in March/April 2011 over the northern North Atlantic and accumulated by fish. The radionuclide 134Cs (half-live 2 yr) was indeed detected with quite small activities at about 0.0036 Bq kg−1 w.w. Existing box-models describing the transport of Cs within seawater boxes of the NE Atlantic allowed estimating that 134Cs contributions from other sources, i.e. from the Chernobyl fallout and from discharges by the two major European nuclear reprocessing plants, both were negligible around Greenland, while for the Chernobyl fallout a small 134Cs background contribution to BS fish was estimated. Model results confirmed the level of 134Cs measured in BS fish and showed its maximum to have occurred in winter 2011/2012 followed by a continuous decrease. It was also determined that 134Cs activity, but not that of 134Cs, showed a significant negative correlation with sampling depth (150–400 m) of GC fish; this strengthens our Fukushima fallout assumption. As a result, the Fukushima fallout in these sea areas only marginally enhanced (GC: 4%; BS: 0.1%) pre-Fukushima levels of individual dose rates received by human fish consumers; the addition was around 0.001 μSv following the consumption of 10 kg fish per year, which is not expected to cause concern according to present guidelines for radiation protection.

Citation: Kanisch, G. and Aust, M.-O.: Does the Fukushima NPP disaster affect the caesium activity of North Atlantic Ocean fish?, Biogeosciences Discuss., 10, 4127-4156, doi:10.5194/bgd-10-4127-2013, 2013.
 
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