Effects of water chemistry and temperature on radiocesium dynamics in rainbow trout,Oncorhynchus mykiss

Abstract

We determined the effects of temperature ($ and 16°C) and water concentrations of potassium (0.01-3.4 mmolK), sodium (0.4-3.0 mmol/L), and calcium (8.3-2.9 mmol/L) on the dynamics of ' 3 7~s in rainbow trout (Oncorhyrechles mykiss). Trout were fed food labelled with 1 3 7~s , and " 3 7~s retention was monitored by whole body gamma counting (70 d). Assimilation of " 7~s did not vary significantly over the range of concentrations of Kt, ~a ' , and Ca2' employed, with an average value of 65 & 3% (meankSE). The elimination of 1 3 7~s was significantly affected by K', with the elimination rate constant of trout held at the highest K' concentration (0.021 k 0.801 d-' at K+ of 3.4 mmol/L) roughly double that observed in trout at lower R + (0.011 f 0.001 d-' at Kf 2 0.3 mmo1K). Elimination of 1 3 7~s was also significantly affected by temperature, with the increase in elimination rate over the range of 8 and 16°C corresponding to a Q,, of ~1 . 7 . Although the effect of K+ on accumulation of ' 3 7~s in trout was statistically significant, this effect, by itself, can explain only a small fraction of the broad range of ' 3 7~s concentration ratios reported for wild fish.RCsumC : Nous avons mesure les effets de la temperature (8 et 16°C) et des concentrations dans l'eau du potassium (0,01-3,4 mmolBL), du sodium (0,4-3,0 m o K ) et du calcium (0,3-2,9 m o U L ) sur la dynamique du 1 3 7~s chez la truite arc-en-ciel (Owsrhynchus mykiss). Nous avons nourri les truites avec des aliments marquks au ' 3 7~s et mesure la retention de cet Clement par comptage des radiations gamma sur l'ensemble du corps (70 d). L'assirnilation du 1 3 7~s ne variait pas de fagon significative dans la plage des concentrations de KT9 ~a + et Ca" employkes, la valeur moyenrse se situant ii 65 2 3% (moyenne 2 ET). Lklimination du ' 3 7~s etait affectee de facon significative par K ' , la constante du taux d'elimination chez les truites maintenues ii la plus forte concentration de #+ (0,021 f 0,001 d-', M+ de 3,4 mmolk) Ctant grossitrement le double de celle qui a Ctt5 observee chez des trnites ii des concentrations plus faibles de K + (0,011 -t 0,001 d-I, K+ 5 0,3 mmol/L). L'tlimination du ' 3 7~s etait aussi affectbe de fagon significative par la temperature, l'accroissement du taux d9$limination sur la plage de 8-16°C correspondant B un Q,, de =1,4. Bien que l'effet de K+ sur l'accumulation du 137Cs chez les truites ait Ct6 statistiquement significatif, cet effet, en lui-meme, ne peut expliquer qu9une petite fraction de la large plage de concentrations de '"CS signalees pour les poissons sauvages.[Iiaduit par la Redaction] MntreductionCesium-1 37 ( L 3 7~s ) is of particular concern among the radionuclides released to the aquatic environment by nuclear operations and weapons testing, because of its high yield in uramium-235 fission, its relatively long half-life ((30 years), and its tendency to accumuhk in aquatic biota (Vmderplong et aB. 1975;

ACCUMULATION OF 137Cs BY LARVAE OF THE MIDGE CHIRONOMUS RIPARIUS FROM SEDIMENT: EFFECT OF POTASSIUM

“…Cocchio et al [14] found a significant effect of increasing K ϩ concentration on 137 Cs elimination by rainbow trout (O. mykiss) with the elimination rate constant at a K ϩ concentration of 3.4 mmol/L being double of that at a K ϩ concentration of 0.3 mmol/L. After an exposure time of 167 h, no significant differences in accumulation of radiocesium were observed among the treatments.…”

“…For each 10-fold difference in K, bioaccumulation of radiocesium increases about 3.5-fold. Cocchio et al [14], however, found that K concentration could explain only a small fraction of the variation in 137 Cs accumulation in rainbow trout (Oncorhynchus mykiss). Cocchio et al [14], however, found that K concentration could explain only a small fraction of the variation in 137 Cs accumulation in rainbow trout (Oncorhynchus mykiss).…”

“…This is contrary to what is found in other studies on the effect of competing ions on metal accumulation. Cocchio et al [14] found a significant effect of increasing K ϩ concentration on 137 Cs elimination by rainbow trout (O. mykiss) with the elimination rate constant at a K ϩ concentration of 3.4 mmol/L being double of that at a K ϩ concentration of 0.3 mmol/L. Chowdhurry et al [40], who studied carp (Cyprinus carpio), found an increase in uptake rate constant for Sr 2ϩ with decreasing Ca 2ϩ concentration but a decrease in the elimination rate constant.…”

“…When organisms are exposed to water only, a direct effect has been demonstrated for several organisms, showing a decreased cesium uptake with increasing potassium * To whom correspondence may be addressed (bervoets@ruca.ua.ac.be). concentration [11][12][13][14]. In soil-or sediment-dwelling organisms, however, it is uncertain to what extent potassium has either a direct effect on cesium uptake (by competing for the same uptake mechanisms) or an indirect one by changing the distribution of the radionuclide between the solid and the liquid phase.…”

Influence of temperature on silver accumulation and depuration in rainbow trout

“…It was predicted that net Ag depuration would be faster in warmer fish, because metabolic processes increase with temperature (MacLeod & Pessah, 1973; Burel et al ., 1996). The predicted response has been reported in other experiments where rainbow trout, brown trout Salmo trutta L. and stone loach Noemacheilus barbatulus (L.) showed increased elimination rates of Cs and Cd at higher temperatures (Douben, 1989; Ugedal et al ., 1992; Cocchio et al ., 1995). In the present study, only the gills and plasma of ‘warm’ rainbow trout showed a hint of faster, initial Ag elimination compared to ‘cold’ fish [Fig.…”