~ 26 -

reduction by a factor of 4.9.

The fact that Belle Island was

washed by the water wave from at least one other test device
subsequent to the contamination by wi85 and Henry Island was
not, may account for the greater reduction in activity on
Scaevola leaves at Belle Island.
Four species of algae collected at Belle Island on

August 20 had high levels of yi85 as follows:

Polysiphonia

. Spyridia

1,100,000 d/m/g

1,000,000 d/m/g

Padina

910,000 6/m/g —

Halimeda

600,000 d/m/g

The wi85 activity in the algae samples is related to
the surface area-to-weight ratio in the four species.

Polysi-

phonia and Spyridia are branching, finely divided forms and
have the greatest surface area per unit weight.

fPadina is

flabellate with a smaller surface area and Halimeda is a heavyjointed calcareous form with the least surface area per unit
veight.

The limited data available on the levels of yi8s in

the above algae samples suggest that the contamination is
present mainly on the surface, although a greater number of
samples would be necessary to show with certainty that this

is the case.

The levels of wt85 in the algae were higher

than those in the land plants at the same island (Table 2).

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