41 
Z-score of Am-241 
Figure A18. 
Column diagram 
of Z-scores for 
Am-241. 
□ STUK/FI 
■ RISO/DK 
□ CLOR/PO 
□ LVEA/LV 
■ ERPC/ES 
■ DHIG/GE 
■ SS I/S W 
□ BFFG/GE 
Conclusions 
Eight laboratories from seven Baltic Sea countries 
participated in an intercomparison exercise 
carried out during the years 2000-2003 concern 
ing laboratory analyses of artificial and natural 
radionuclides in a sediment sample. All the par 
ticipating laboratories analysed K-40 and Cs-137 
in the sample. In addition, results for several other 
gamma-emitting artificial and natural nuclides, as 
well as alpha-emitting transuranic elements were 
analysed. 
The intercomparison showed that the analytical 
capability in the Baltic Sea countries is on a high 
level; the laboratories are competent to analyse a 
large number of important radionuclides (e.g., Cs- 
137, Cs-134, Pb-210) in the marine environment, 
if needed. In addition, there exists a capability for 
difficult radiochemical analyses of alpha-emitting 
nuclides (Pu and Am isotopes). Sr-90 analyses 
were performed only by one laboratory, which 
was mainly due to the lack of the sample material. 
However, the capability for Sr-90 measurements 
has been demonstrated in other intercomparisons 
(e.g., seawater). 
The results indicate that measurements per 
formed by these laboratories are in quite good 
agreement with each other. When comparing the 
Z-scores (Figures A12-A18), the difference from 
the mean value can be considered to be statisti 
cally significant (|z|>1.96) in only two cases. 
The uncertainties reported with the results varied 
a great deal from each other. Harmonization of the 
uncertainty calculations in the laboratories could 
be a common target in the HELCOM MORS-PRO 
Group. 
Acknowledgement 
The first part of this work was organized by 
Sandor Mulsow, IAEA-MEL. 
Long-lived radionuclides in the seabed of the Baltic Sea