The Accumulation and Elimination of Radiocesium by Naturally Contaminated Wood Ducks

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Abstract
The accumulation of radiocesium was studied in hand-reared wood ducks [Aix sponsa] released into a South Carolina [USA] swamp habitat contaminated with production reactor effluents. The uptake of radiocesium by the ducks was described as: In pCi radiocesium/g live body weight = 0.36 .+-. 0.18 (days). There was no effect of sex on uptake rate. The average estimated time required to attain practical equilibrium (0.90 Qe) was 17.3 days, with a range from 10.2-26.8 days. Ducks which were recaptured after attaining equilibrium concentrations in the field (averaging 16.6 pCi radiocesium/g live body weight) showed single-component elimination-rate curves when confined in a semi-natural pen for elimination studies. Radiocesium elimination under penned conditions was described as: In % initial body burden = 4.60-0.13 (days). Elimination-rate and body weight showed a negative linear correlation for the penned birds although there was no effect of sex on loss-rate. Radiocesium biological half-times for the penned ducks averaged 5.6 days with a range from 3.2-9.3 days. Calculations based on biological half-times determined from studies with the penned birds, were successful in accurately predicting both the levels and rates of radiocesium accumulation by free-living birds in the field.