25 
Appendix 
An Intercomparison of Radionuclide Analyses in a Baltic Sea Sediment Sample 
Results of the HELCOM MORS-PRO intercom 
parison on Baltic Sea Sediment 2000 
Tarja K. Ikaheimonen and Vesa-Pekka Vartti 
STUK - Radiation and Nuclear Safety Authority 
Helsinki, Finland 
Introduction 
As a part of the HELCOM MORS-PRO work, the 
MORS Group arranged an intercomparison exer 
cise of radionuclide analyses using a sediment 
sample taken from the Baltic Sea. The sediment 
sample was taken by STUK on 21 June 1999 
at the Station EB1 in the Bothnian Sea (latitude 
61°04.00’ N, longitude 19°43.78’ E, at a depth 
of 130 m). The sampling was carried out with an 
Aquarius Box Corer (surface area of 18 cm x 18 
cm). Fourteen parallel sediment cores were taken 
to achieve the target amount of 60 kg wet weight. 
The top layer (0-10 cm) of each core was sliced 
and used for the exercise. The material was sent 
to IAEA-MEL, which contracted with EUROLYO 
Ltd. for the freeze-drying and homogenization of 
the sample. 
Aliquots of the homogenized sediment sample, 
Baltic Sea Sediment 2000, were delivered to the 
MORS Group in June 2000. Gamma-emitting 
nuclides, natural radionuclides, and transuranic 
elements were requested to be analysed. 
Participants 
Altogether eight laboratories from Denmark, 
Estonia, Finland, Germany, Latvia, Poland, and 
Sweden participated in the intercomparison as 
listed in Table A1. 
Analytical results 
All laboratories analysed the sediment sample 
for K-40 and Cs-137. Nine other gamma-emitting 
nuclides were also analysed, and of these, Cs- 
134, Pb-210, Ra-226, Th-228, Th-232, U-238, and 
Co-60 were analysed by more than one labora- 
Laboratory 
Country 
Code 
Rise National Laboratory, Roskilde 
Denmark 
RISO/DK 
Estonian Radiation Protection Centre, Tallinn 
Estonia 
ERPC/ES 
STUK - Radiation and Nuclear Safety Authority, Helsinki 
Finland 
STUK/FI 
Federal Maritime and Hydrographic Agency, Hamburg 
Germany 
DHIG/GE 
Federal Research Centre for Fisheries Institute of Fisheries Ecology, Hamburg 
Germany 
BFFG/GE 
Ministry of Environmental Protection and Regional Development of Latvia, Riga 
Latvia 
LVEA/LV 
Central Laboratory for Radiological Protection, Warsaw 
Poland 
CLOR/PO 
Swedish Radiation Protection Institute, Stockholm 
Sweden 
SSI/SW 
Table A1. 
Laboratories par 
ticipating in the 
intercomparison 
exercise. 
Lab.code 
K-40 
Uncert. 
Cs-137 
Uncert. 
Cs-134 
Uncert. 
RISO/DK 
998 
100 
1020 
102 
9.2 
1.0 
ERPC/ES 
1100 
80 
1220 
53 
9.2 
0.9 
STUK/FI 
980 
59 
1060 
53 
9.8 
1.0 
DHIG/GE 
991 
8.4 
1140 
5.82 
9.97 
0.47 
BFFG/GE 
1000 
24 
1100 
27 
9.95 
0.28 
LVEA/LV 
795 
24 
988 
20 
9.30 
1.58 
CLOR/PO 
1050 
48 
1060 
21 
- 
- 
SSI/SW 
1130 
17 
1200 
20 
11.9 
1.9 
Mean 
1006 
101 
1098 
82 
9.9 
0.94 
Table A2. 
Results for artificial 
gamma-emitting 
radionuclides in 
Bq kg -1 d.w. with 
an uncertainty of 
1 sigma and the 
arithmetic means 
with the standard 
deviation (in the 
Uncert. column). 
Long-lived radionuclides in the seabed of the Baltic Sea