Comparative kinetics of 47Ca, 85Sr and 226Ra in the freshwater turtle, Trachemys scripta

• Published in: Journal of environmental radioactivity 1992, Vol.16 (1), p.25-47
• Main Authors: Hinton, Thomas G., Ward Whicker, F., Pinder, John E., Ibrahim, Shawki A.
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on vertebrates; Fundamental and applied biological sciences. Psychology; Reptilia. Amphibia
• ISSN: 0265-931X; 1879-1700
• DOI: 10.1016/0265-931X(92)90052-U

The kinetics of 47Ca, 85Sr and 226Ra were compared in the yellow-bellied slider, a common freshwater turtle of the southeastern USA. The absorption and elimination processes were examined as a function of stable dietary Ca (2 and 20 mg g −1, season (summer, fall, winter and spring), age and sex of the animals (hatchlings, juveniles, adult males, adult females and gravid females). Turtles were gavaged with radionuclides and serial whole-body analyses were performed on the live animals for up to 480 days. Absorption results: Only in the juvenile age class did reduced dietary Ca cause a significant increase in 85Sr absorption (p < 0·03). The absorption of 85Sr and 226Ra in the adult male, adult female and hatchling groups was unaffected by dietary Ca. Mean absorption (± SE) was greater than that which has been reported for other organisms and significantly differed among isotopes ( Ca: 77 ± 3%; Sr: 40 ± 2%; Ra: 21 ± 2%; p < 0·0·001). The high absorption values were not restricted to immatures, but continued into maturity. Elimination results: Elimination rates were not affected by the dietary treatment, nor were isotopic differences in elimination observed. Annual mean (± SE) elimination rate constants (year −1), pooled among animal groups, were 0·22 ± 0·07 for 85Sr and 0·26 ± 0·18 for 226Ra. Retention was strongly affected by season (p < 0·02), with the greatest elimination occurring in the summer and declining to levels that were not distinguishable from zero in the winter.