|SREL Reprint #0354|
Accumulation and Redistribution of Radiocaesium by
Migratory Waterfowl Inhabiting a Reactor Cooling Reservoir
L. Brisbin, Jr., R. A. Geiger, M. H. Smith
Accumulation and redistribution of radiocaesium by
migratory waterfowl in habiting a reactor cooling reservoir.
Changes in whole-body burdens of radiocaesium were
studied in monthly samples of American coots (Fulica americana)
and other species of migratory waterfowl inhabiting a 2800-acre reactor cooling
reservoir on the AEC Savannah River Plant near Aiken, South Carolina, USA.
In October newly arrived coots averaged between 4-8 pCi radiocaesium/g
live weight and approximated a 505-50 sex ration.
Between October and January the sex ratio of the coots rose steadily to a
maximum of 87% males as the females continued to move on to more southerly
wintering grounds. In the
predominantly male population remaining on the reservoir, radiocaesium body
burdens continued to rise at a rate of approximately 2-3 pCi/g per bird per
month, to a maximum of between 15-20 pCi/g.
From February through April the predominantly male
population of coots began to leave for northern breeding grounds and were
apparently replaced by populations that had wintered further to the south and
had a higher percentage of females. As
a result, the sex ratio began to decline until it once again approximated 50-50
in the late spring. Since these
spring transient birds had not wintered on the reservoir, they had lower
radiocaesium contents. Thus, the
average body burden of the coot population began to decline to a level closely
approximating that of the first birds to arrive in fall.
Simply sampling the first and last coots seen on the reservoir would have
failed to detect the radioisotopes build-up shown by the winter resident birds.
In any given month, the radiocaesium content of the
coots was generally higher than that of any of nine other species of waterfowl
and aquatic birds sampled. The
higher body burdens of the coots may be related to their tendency to rely
heavily upon submerged aquatic plants as a food resource.
Migratory waterfowl may remove up to 3.75 x 10-5 Ci of
radiocaesium from the reservoir each year and redistribute it elsewhere along
their migratory pathways. The
radiocaesium levels found in these birds do not indicate any present health
hazard to the general public who may use them for food.
SREL Reprint #0354
Brisbin, I.L., Jr., R.A. Geiger, and M.H. Smith. 1973. Accumulation and redistribution of radiocaesium by migratory waterfowl inhabiting a reactor cooling reservoir. In Environmental Behaviour of Radionuclides Released in the Nuclear Industry, p. 373-384. Vol. SM 172/72. International Atomic Energy Agency. Vienna.