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Abstract
The present work illustrates the effect of some environmental parameters such as contact time, effect of different concentration of potassium, calcium ions and the effect of competition on the uptake and accumulation of 85Sr and 134Cs within various organs and tissues namely; muscles, bone, liver and gills of the Nile catfish Clarias lazera which breeds in Ismailia Canal. The release of the these radionuclides from the contaminated fish has been also tested. These radionuclides were used in this study because of their biological significance and for their presence in the reactor coolant waters. The parameters used for the evaluation of radionuclides within the selected organs and tissues were the Concentration Factor (C.F) and the Accumulated Activity (A.A) Bq.g-1. The release of the 85Sr and 134Cs isotopes used in this study from the radiocontaminated fish after treatment with fresh and non-radioactive FICW was calculated as Percent Released (%Rs). The results showed that the Nile catfish Clarias lazera was found to concentrate the radionuclides 85Sr and 134Cs from the aquatic environment and the rate of uptake increased by increase of exposure time in different steps. The internal distribution of these radionuclides in the different organs and tissues of the fish due to the uptake from the aquatic environment followed the order.
For 85Sr: bone > gills > liver > muscles.
For 134Cs: liver > gills > muscles > bone .
The accumulation of 85Sr within the studied organs is inversely proportional to the Ca++ ion concentration in water and did not significantly affected by K+ ion concentration. The uptake and the accumulation of 134Cs is inversely proportional to the K+ ion concentration and did not significantly affected by Ca++ ion concentration in water. The presence of 134Cs decreased the uptake of 85Sr and the presence of 85Sr decreased the uptake of 134Cs. The release of 85Sr from the whole fish was faster during the first two days than that obtained for 134Cs.
From the obtained data it was possible to calculate the dose delivered to any person eating contaminated fish.