11
4 Project plan of the Sediment Baseline Study
In 2001 at its sixth meeting, the Project Group
MORS identified the need for a Sediment
Baseline Study as a future activity of the Group to
provide a more detailed description of the spatial
distribution of radionuclides in the Baltic Sea
sediments. The Group noted that especially the
western part of the Baltic Proper had not been
covered in an adequate way in the preceding
studies. Other areas for additional sampling were
also considered.
The Chernobyl fallout is very unevenly distributed
in the Baltic Sea area. During the 20 years since
the accident, the MORS Group has made several
efforts to evaluate the total inventories of the most
important fallout nuclides (especially Cs-137)
bound in the Baltic Sea sediments. With reference
to the existing data, there were huge “white areas”
lacking data especially on the Swedish side of
the Baltic Proper, in the southeastern parts of the
Baltic Proper, and in the Gulf of Riga.
One of the main objectives of the study was
to obtain more information about the amounts
of radionuclides in the sediments of the “white
areas”. In addition to Cs-137, more information
about Sr-90, Tc-99, 1-129, Np-237, and other
transuranic elements was needed. The study
aimed to be arranged cooperatively with the
planned sediment monitoring programme under
HELCOM COMBINE and several national sediment
monitoring programmes being planned, e.g.,
in Sweden.
The study was planned to cover all the sampling
stations listed in the regular monitoring
programme of MORS, with additional stations
as appropriate. The western and southeastern
parts of the Baltic Proper would be the main
target areas in planning for additional samples.
Furthermore, special attention was to be directed
to coastal areas, to areas with hard bottoms,
and to anoxic sediments. The resources among
the Contracting Parties to increase sampling at
additional stations were recognized to be limited.
However, many Contracting Parties announced
that they were prepared to consider their possibilities
to provide additional data.
A more detailed Project Plan for the study was
made in 2002 at the seventh meeting of the
MORS-PRO Group. At that time, the project
period was planned to span three years (2002-2004)
and the general objectives of the project
were defined as follows:
- to provide additional data on radionuclides in
Baltic Sea sediments;
- the sampling and analysis activities should
mainly be based on the permanent HELCOM/
MORS Monitoring Programme. Additional
samples would be taken with the aim of providing
new data from so-called “white areas”,
coastal areas, areas with hard bottoms, and
anoxic sediments;
- special attention should be directed to Sr-90,
Tc-99, 1-129, and Np-237 analyses;
- the sampling and analysis activities would
be coordinated by Finland so that the whole
Baltic Sea area would be covered (as fully as
possible) by new data on Cs-137, Sr-90, Tc-99,
1-129, Np-237, and Pu and Am isotopes.
A preliminary plan of national contributions to the
project was also defined in the MORS-PRO 7
meeting.
Due to the delay in sampling and other problems
that arose in many countries, the eighth meeting
of the Group decided to prolong the duration of
the Study by one year. At the same meeting, a
detailed list of national contributions was updated.
The Ris0 National Laboratory promised to
contribute to the project by analysing about 100
sediment samples taken by the other participants
for Np-237, Tc-99, and transuranics. The ninth
meeting prolonged the timetable of the project
further until 2006.
Long-lived radionuclides in the seabed of the Baltic Sea
