15 
Using the radioactivity, chlorinity, and MPN data from the 
subsurface samples taken at the profile stations, one can cal- 
culate dilutions and expected MPN"s as was done with the surface 
data. For these calculations, all subsurface samples were 
grouped together independent of depth or location and geometric 
means were calculated. For any comparisons made, only samples 
that were determinate for both parameters being compared were 
used. Thus, out of a total of 21 subsurface samples examined, 
ten were indeterminate for dilutions calculated either from 
radioactivity or chlorinity and only eleven could be used for 
determining the geometric means. The results obtained are 
presented in Table II. 
The calculations do not have the same degree of validity 
as they do for surface samples for several reasons. First, 
radioactivity was measured by lowering the probe through the 
water column and not on the actual samples brought to the sur- 
face for coliform analysis since these samples were too small. 
Because of the non-homogeneous nature of the water mass and 
drift of the ship around the station location during sampling, 
the actual radioactivity of a sample could have differed greatly 
from that read from a depth curwe. Second, dilutions of greater 
than about 1/300 calculated from chlorinities are certainly 
grossly inexact, and dilutions of greater than 1/2000 are com- 
pletely indeterminate. The data presented above should be 
viewed with these limitations in mind. 
From the data in Table II, it can be seen that a greater 
dilution of the tagged effluent occurs than one would calculate 
from chlorinity, indicating, as with the surface samples, that 
