Fallout 137Cs and 90Sr in Trout from Mountain Lakes in Colorado

Abstract

Abstract

Concentrations of 137Cs and 90Sr were measured in trout from 51 mountain lakes in Colorado during the period 1965–1970. 137Cs levels ranged from 116 to 5802 pCi/kg wet muscle while 90Sr values ranged from 6 to 238 pCi/g bone ash. A yearly decrease in 137Cs levels was observed with the rate of decrease becoming smaller through the sampling period. The temporal trend was fit by a model employing a fallout “rate” factor and a “cumulative deposition” factor. Radionuclide concentrations generally were higher at the more northerly latitudes. Trout from lakes in certain watersheds were much higher in 137Cs than trout from other regions. Trout from montane and alpine lakes contained much more 137Cs and 90Sr than fish from waters at lower elevations. Dissolved calcium was significantly related to 90Sr values in trout, but potassium had no demonstrable effect on 137Cs values. A trophic relationship of 3.26 was found for 137Cs between large trout and small trout which presumably were the prey. General lake characteristics associated with relatively high 137Cs and 90Sr burdens in trout are described.