those which had been carried out before this accident. Therefore, 
the measurement results were only obtainable after a longer delay. 
After the decay of the short-lived disturbing nuclides, the routine 
method could again be used circa 2 1/2 months after the accident. 
The results of the Sr 90 analyses indicate that the activity part of 
Sr 90 in the Fallout from Chernobyl was only very slight. They lie, 
aot only in the analysis results from the North Sea, but also in 
those of the Baltic Sea, within the variation range of the measure- 
ments already previously available. For that reason, in the further 
Investigations determination of Sr 90 was only carried out now and 
then. 
4.2.5 
Iransuranics 
The great expenditure of work and time for the determination of the 
ä-particle emitting Transuranics (Plutonium, Americium, and Curium) 
hindered the analysis of a larger number of samples. The increase of 
the Plutonium concentration in seawater, nevertheless, could only be 
described as significant in the first days after the accident. 
Pu 139 was determined in the region of Fehmarnbelt with circa 
4 uBq/l before the accident. After the accident, the measurement 
value was 20uBq/1 (Table 3). On 09.06. and 10.06. still only 
concentrations between 1.4 uBq/1 and 5.2 uBq/l1 were found in the 
western Baltic Sea. The limit of detection of the process lies some- 
what at 1 upBq/l. 
The transuranic nuclide Np 239 was clearly gamma-spectroscopically 
detected on 3rd May in a smear test sample of 2nd May from a ship 
coming out of the Baltic Sea. Np 239 decays, with a half-life time 
of 2.35 days, to Pu 239. 
Am 241 was only insignificantly increased, simultaneously however 
the nuclide Cm 242 could be detected for the first time in the Bal- 
ctic Sea. In the marine hydrosphere, this nuclide was hitherto un- 
equivocally only to be found in the vieinity of nuclear fuel repro- 
cessing plants - e., g. introduced by the nuclear fuel reprocessing 
plant Sellafield Works. It is remarkable that, the activity concen- 
tration of Cm 242 ascertained in the Baltic Sea exceed by far those 
of the Plutonium activity concentrations. As maximum concentration, 
232 uBq/l was found at the position Fehmarnbelt. 
Corresponding to their chemical behaviour in the sea, it is to be 
expected that the transuranic elements in shallow seas - the North 
Sea and the Baltic Sea are to be considered as such - in a few weeks 
will be adsorbed on particulate matter in water, and thereby removed 
from the water column by sedimentation. These highly radio toxic 
elements, therefore, in future must also be more intensively moni- 
tored in the sediments,