We published this paper about Fukushima disaster.

It will be interesting idea to measure marine sediment cores, not only in Mediterranean Sea but worldwide.

Best regards,

Dear Jan. Thank you very much for your paper. Yes the idea is to measure Cs 137 in marine sediments in order to assess the presence of a peak (as for Chernobyl disaster). I'm interested in mediterranean cores as we have some samples from the Tyrrhenian sea. I presume that the Fukushima atmospheric release  was much lower than Chernobyl one so the question could be: can we see this in cores? Where?

Dear Sergio,

As you can see,I-131, Cs-134 and Cs-137 concentration in our area and also in Europe were very small. But maybe it can be seen in cores, especially in seas around Japan and in Pacific (if I remember correctly, currents and winds were in direction to Canada and USA at that time).  I am not sure that there is much difference of Cs-137 in sediments in Mediterranean Sea from Fukushima. But,even if in experiment we prove that situation,it is also a success :)

Dear Sergio,

the release from the Fukushima Daiichi reactors occurred both, to the atmosphere and by direct discharges into coastal waters. The atmospheric releases could be detected worldwide in the northern hemisphere and even in Europe and the Mediterranean region. There are a number of papers describing the dispersion and deposition in Europe, e.g. Masson et al., 2011: tracking of airborne radionuclides from the damaged Fukushima Daiichi NPP by European networks. Environ. Sci. Technol., 45, 7670-7677. doi: 10.1021/es2017158.

We were able to detect the Fukushima derived typical isotopic ration in air and even seawater in Monaco: Pham et al., 2012: Detection of Fukushima Daiichi nuclear power plant accident radioactive traces in Monaco. J. Environ. Radioactivity, 114, 131-137.

I expect a signal in the sediments also of the Mediterranean Sea, however, this signal will be extremely weak and might not be detectable in the future. In addition, the signal from Cs-134 will soon disappear due to the relative short half-live of only 2 years. Bioturbation in the sediment will lead to vertical dilution of the signal in the sediments and will further weaken the potential signal. You would need a very good stratagy for the sampling technique to collect this peak with sufficient material in preferrably undisterbed sediments, extremely low detection limits with long counting times of large gamma-detectors.

Good luck for your work!

Dear Hartmut, thank you very much for your suggestions. We will have some data in short so we could consider a strategy if it's possible.

Sergio, There' are many sources of Cs-137 in the Meditteranian and many journal articles citing measurement thereof. I'll post a sample of such. There are many medical and industrial radiographic uses of Cs-137; the disposal of such is often leaking or outright dumping in to the sea. Dr. T. Douglas Reilly, physics (gamma-ray spectroscopy)t, retired from LANL, EURATOM, USDOE, and IAEA. Sample of articles:

137 Cs surface concentrations ranged between 4.2 and 5.5 Bq m -3 over the entire basin (Fukai et al., 1980) including the Adriatic sea (Franic and Bauman, 1993). The profiles showed subsurface maxima in the..." 

Estimation of the Adriatic Sea water turnover time using fallout 90Sr as a radioactive tracer · Aug 2005 · Journal of Marine Systems  Zdenko Franić  This was clearly the case for the vertical profiles in the Thyrrhenian Sea during 1977 (Fukai et al., 1980) and the Catalan Sea during 1991 (Molero et al., 1995): although the profile shapes were correct, 

Long-term box modelling of 137Cs in the Mediterranean Sea

Full-text · Article · Jun 2002 · Journal of Marine Systems

 J.A. Sanchez-Cabeza  M. Ortega  J. Merino  P. Masqué 15Citations 

"... in the period 1970–82, different authors (Ballestra, Bojanowski, Fukai, & Vas, 1984; Fukai, Ballestra, & Vas, 1980; Kautsky, 1977 ) found average concentrations in the water column of 5.4 ± 2.1 Bq m 3 in the surface..."  Modelling of Mediterranean system-changes under climate variations and human impact National Academy of Sciences of Ukraine Abstract: The one-and-a-half dimension multilayer Lagrangian model LATOX was developed to model the environmental pollution of deep stratified lakes and semi-enclosed seas. This model is used to simulate changes in the system of the Mediterranean seas, forced by the changes of climate and anthropogenic factors. It incorporates the submodels of the Black Sea, Azov Sea, Marmara Sea and the western and eastern Mediterranean. Simple submodels of the Kerch, Bosphorus,…

I do not think you can obtain the peak of 137Cs from the Fukushima Nuclear Accident in Mediterranean Sea. The final 137Cs signal in the sediment depended on atmospheric deposition flux of 137Cs (1Bq/m2 in total for 137Cs). However, the 137Cs inventory of 137Cs is about 1000Bq/m2 in the upper core sediment (70cm) from global fallout and Chernobyl Nuclear Accident. Therefore, the 137Cs signal from FNA will be diluted in the 137Cs background. But you can easly detect signal of FNA in Japan due to high atmospheric deposition flux of 137Cs.  

Thanks!

Wuhui Lin. 

I agree with most of the previous answers in that it will be practically impossible to detect FNA-originating 137Cs in sediments from the Mediterranean, due to the small amount deposited and the high "background" of 137Cs from bomb test fallout and Chernobyl.

As Hartmut points out, FNA-originating 137Cs could be identified by the accompanying 134Cs early after the emission, but with the decay of 134Cs the origin of 137Cs becomes unclear.

We were able to detect FNA-related depositions in Germany in 2011 in several environmental media (see publication link). From the data we estimated a regional deposition of 137Cs and 134Cs of about 0.2 Bq/m^2 each. Sediment traps in small rivers showed about 2 Bq/kg of 137Cs, but no 134Cs (D.T. below 0.1 Bq/kg), proving that this 137Cs in recent sediments was mainly from old sources.

Yours, Helmut

http://dx.doi.org/10.1016/j.jenvrad.2011.06.003

Dear Helmut,

thank you very much for your suggestion. As we are using sediment traps too, it could be interesting to repeat your approach also in our coastal area in order to compare the results. We have now first results from two cores in the tyrrhenian sea and there is no evidence of Cs137 related to fukushima.