Retention of ingested 110mAg by a freshwater fish, Salmo trutta L.

Abstract

The accumulation kinetics were followed on 19 fingerling trout fed 5 days a week, with 110mAg labelled rations. Nine trout, placed in individual compartments, received 3 to 4 living juvenile carp as daily food ration, while the 10 remaining others held in group, received diced fresh carp. Consumption of 25 daily food intake, distributed over a 34-day period, resulted in a very slow 110mAg uptake, at a relatively high level with regard to the radionuclide concentration in the ingested preys. The 110mAg trophic transfer factor reached a value of 0.117 at the end of the uptake phase. Its development was described by a power function that revealed a possibility of biomagnification of the radionuclide during its transfer between the two superposed levels after about 500 days. The retention factor was observed to remain roughly constant in time at a value in the order of 0.1. At the end of the accumulation phase, the 110mAg organotropism, investigated on the group of trout, showed a very high concentration in the liver which accounted for 63% of the total radioactivity in the fish. Immediately following the accumulation period (34 days), the 9 lonely individuals were fed according the same methodology than during the uptake phase, but with non-labelled rations. After 27 days, their radioactivity level and the 110mAg distribution in the tissues were not significatively different from those obtained at the end of the uptake phase.