Zi 
can be viewed as being largely unchanged. Only one 
station showed a clear decrease in concentration 
between 100 m and 250 m depth (Fig. 113). Below 
500 m down to 1,500 m the decrease in concentration 
progressed in the same manner as in 1972. The one 
deep-water series of that year showed = from 3000 m 
downwards —- extremely low 15708 activity concentration 
values, 905 was not measured during this cruise, 
The fact that fallout products could already 
be found in 1966 down to 5,300 m depth, indicates 
a transportation of those products from the sur- 
face downwards to near-bottom already within 5 to 
10 years. Two model conceptions can be developed 
concerning this transport mechanism:- 
The fallout products are, or become, combined 
With small particles. Therefore, one could 
also expect perhaps a rapid take-up of certain 
elements by plankton or other organisms. 
These particles sink downwards, as they most- 
ly are heavier than water, In this manner, 
a comparatively rapid transportation from 
the sea surface to the bottom would be 
possible, without a comparable transporta- 
tion upwards from the sea bottom taking place. 
The fallout products are in solution and 
are brought downwards by current processes, 
In this case, a corresponding watermass 
must be displaced and in some manner make 
the way free for the instreaming watermass. 
Both mechanisms appear to be possible, the 
second would illustrate the adverse case for a 
dumping of wastes, as it would be linked with a 
relatively rapid vertical transportation from below 
to above. 
2)