46 
In 1970, the influence of the radioactive waste 
waters of the nuclear fuel reprocessing plant near 
Cherbourg upon the 15708 activity concentration values 
in the southern North Sea was already making itself 
felt. The further distribution from the English Channel 
as far as into the Iberian Basin with altogether lower 
surface concentrations, largely corresponds with that 
of 1968 (Fig. 116). 
In 1972, the 137c8 distribution (Fig. 117) shows 
a completely different picture. Compared with 1970, the 
surface values were still somewhat reduced. On the other 
hand, at 12 of 15 stations, in the region of Biscay and 
the Iberian Basin, the activity concentration values at 
500 m resp. 1,000 m depths lay clearly above those at 
the surface. They exceeded those values by 1.5 to 4.4 
times. To date, we habe no certain explanation for this 
unprecedented phenomenon observed in 1972 (with the 
axception of one Mediterranean station in 1970). 
In 1974, there again appeared a pronounced 
uniform distribution of 15708 in the Iberian Basin 
(Fig. 118). The surface values had receded further. 
The activity concentration values in the region between 
the surface and 500 m depth lay relatively close to 
one another. The concentrations were again clearly 
lower only at 1,000 m depth, and their levels stood 
out well in contrast to those of the upper water layers. 
B 
2.3 Summary 
The measurement values! deviation range between 
individual stations lying comparatively close to one 
another, and also in the repition of a station within 
the period of a few days - in individual cases - can 
be surprisingly large. For that reason, in order to 
obtain an exact picture of the relationships in the 
Iberian Basin, the investigations must be carried out