The comparative kinetics of Ca, Sr, And Ra in a freshwater turtle, Trachemys scripta
The accumulation of {sup 45}Ca, {sup 47}Ca, {sup 88}Sr, and {sup 226}Ra was studied in the yellow-bellied slider, a common freshwater turtle of the Southeastern US. The author was particularly interested in testing the hypothesis of competitive inhibition, a concept whereby decreasing the intake of a stable dietary element increases the absorption and retention of chemically similar radionuclides. He established four specific hypotheses and examined the processes of absorption and elimination as a function of stable dietary calcium (2 and 20 mg g{sup {minus}1}), season (summer, fall, winter and spring), and age and sex of the animals (hatchlings, juveniles, adult males, adult females, and gravid females). Turtles were gavaged with radionuclides and the gamma-emitting isotopes were detected during serial whole-body counts performed on the live animals for up to 480 d. The analysis of the beta-emitting {sup 45}Ca was accomplished by chemical separation procedures. Data were fit to a two-component exponential retention model by nonlinear regression. The 10-fold reduction in dietary Ca did not affect the elimination rate constants, and increased the assimilation of Sr and Ra only within juveniles. For all animals the absorption of Ca was significantly greater than Sr, and likewise, Sr was greater than Ra. Mean absorptions were generally higher than values reported for other organisms. Unlike many other organisms, absorption rates did not decline at maturity. He suspects that high Ca demands in constructing and maintaining the massive shell, necessitated by the turtle's survival strategy, may contribute to the high absorption, as well as the lack of a decline at maturity. Elimination rate constants were greatest in the summer and declined to levels that were generally not distinguishable from zero in the spring, winter, and fall seasons.
- Research Organization:
- Colorado State Univ., Fort Collins, CO (United States)
- OSTI ID:
- 5543381
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CALCIUM 45
BIOLOGICAL ACCUMULATION
CALCIUM 47
RADIUM 226
STRONTIUM 88
TURTLES
CONTAMINATION
AGE DEPENDENCE
COMPARATIVE EVALUATIONS
FRESH WATER
SEASONAL VARIATIONS
SEX DEPENDENCE
WATER POLLUTION
WHOLE-BODY COUNTING
ALKALINE EARTH ISOTOPES
ALPHA DECAY RADIOISOTOPES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CALCIUM ISOTOPES
CARBON 14 DECAY RADIOISOTOPES
COUNTING TECHNIQUES
DAYS LIVING RADIOISOTOPES
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
HEAVY ION DECAY RADIOISOTOPES
HEAVY NUCLEI
HYDROGEN COMPOUNDS
INTERMEDIATE MASS NUCLEI
ISOTOPES
NUCLEI
OXYGEN COMPOUNDS
POLLUTION
RADIOISOTOPES
RADIUM ISOTOPES
REPTILES
STABLE ISOTOPES
STRONTIUM ISOTOPES
VARIATIONS
VERTEBRATES
WATER
YEARS LIVING RADIOISOTOPES
560162* - Radionuclide Effects
Kinetics
& Toxicology- Animals
Plants
Microorganisms
& Cells