LA 
could be definitely detected by the biological 
working group participating in this "Meteor" 
cruise, there must have been at least low 
quantities of active fallout products in the 
water layers between 800 m depth and the bottom 
in 1966 as well. 
In the year 1968, the activity concentration 
values of 15708 as well as those of 905 in the 
surface water has receded to about two-thirds of 
the 1966 values, At the three stations with 
depth profiles, taken at about 50 nautical miles 
apart, the 13708 vertical distribution in the 
upper water layers showed a varying trend (Fig, 
108). 
At one station —- with relatively high, down 
to 100 m depth, constant activity concentration 
initial values —- a quick reduction in concentra=- 
tion took place down to 500 m. The second station, 
with lower surface values, gave a shallower re- 
duction in concentration down to 500 m depth. At 
the third station with the lowest concentration 
values at the surface, the values remained practi- 
cally constant down to 500 m depth. In that depth, 
the activity concentrations of all three stations 
are almost the same, The further fall in concen- 
tration, downwards to deeper layers, then contin- 
ues largely parallel. From 1,000 m down to 4,000 m 
depth the concentration values practically do not 
change any more, The vertical distribution of the 
900g activity concentrations is similar to that 
of the 13708 (Fig. 109). 
Even if, as a result of the then insufficient 
practical knowledge, the depth measurement values 
from the year 1966 have only a limited relevance, 
one can still assert with confidence that also