Experimental Studies on the Biokinetics of Plutonium and Americium in the Cephalopod Octopus vulgaris

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Abstract
Radiotracer experiments using the photon-emitters 237Pu and 241Am were performed to examine uptake, tissue distribution and retention of Pu and Am in the cephalopod O. vulgaris C. A 2 wk exposure in contaminated sea water resulted in twice as much 23Pu being taken up by whole octopus as 241Am. Immediately following uptake 41% and 73% of the 237Pu and 241Am, respectively, were located in the branchial hearts. Depuration rates for both radionuclides were identical; .apprx. 46% of both radionuclides initially incorporated were associated with a long-lived compartment which turned over slowly (Tb1/2 [half life] = 1.5 yr). Longer exposures to 241Am increased the size of the slowly exchanging 241Am pool in the octopus. After 2 mo. depuration, the majority of the residual activity of both radionuclides was in the branchial hearts. On the average, 33% of the 241Am ingested with food was assimilated into tissues, primarily the hepatopancreas. Different whole-body 241Am excretion rates were observed at different times following assimilation and were related to transfer processes taking place within internal tissues, most notably between hepatopancreas and the branchial hearts. Relationships between circulatory and excretory functions of these 2 organs were discussed and a physiological mechanism proposed to explain the observed patterns of 241Am excretion in O. vulgaris.