ff 
nuclear technical accident in the marine environment (nuclear power 
stations, nuclear fuel reprocessing plants, atomic ship's propul- 
sion) can be roughly estimated with the aid of the measurement data. 
In order to be able to make statements concerning the actual extent 
of the effect upon the marine environment, through laboratory inve- 
stigation of water and sediment samples are absolutely necessary. 
Laboratory investigations 
4.2.1 
Total Camma-measurements 
The acidified water samples arriving at the Laboratory from the sea, 
by total Gamma-radiation measurements in 1-1-Marinelli beakers with- 
out further previous treatment, were graded corresponding to their 
contamination. 
The results of the measurements were referred to the time of the 
sampling. For the correction of the sample-taking time, the decay 
curve of a strongly contaminated water sample taken on 3rd May near 
"Borkumriff”" served as basis. 
The scattering of these measurement results and the temporal sequen- 
ces of the investigation samples from the region of the Federal Ger- 
man continental shelf are represented in Figs. 6 and 7. The scatte- 
ring of the measurement values indicates a temporal and locationally 
very different input of the radionuclides from the atmosphere. The 
comparison with data from the adjacent coastal region (data of the 
Land of Schleswig-Holstein) showed that dilution effects of diffe- 
rent intensities - caused by weather influence and different water 
depths —- likewise played a great role with the build-up of the ra- 
dioactivity concentrations in the surface water. The temporal course 
of the input of the radioactivity was determined by the travelling 
through of the rain front at the beginning of May. 
4.2.2 
Gamma-spectroscopic nuclide determinations 
Direct Gamma-spectrometrical measurements carried out on seawater 
samples from the North Sea led to satisfactory results only until 
10th May, and from the Baltic Sea only until 15th May. Afterwards, 
the nuclides in the samples were already so far diluted and decayed 
that the samples could only be measured in concentrated form (after 
concentration by means of evaporation),.