Biological Elimination Rates of Radioisotopes by Mallards Contaminated at a Liquid Radioactive Waste Disposal Area

Abstract

The biological elimination of nine gamma-emitting radioisotopes was studied in mallards (Anas platyrhynchos) which were released onto liquid radioactive waste pounds in southeastern Idaho. After 68, 75 or 145 days, the ducks were removed from the contaminated environment and placed in metabolic cages. Whole-body and feces-urine counts were made for 51 days and then the ducks were sacrificed and dissected for tissue analyses. The biological elimination of radioisotopes were fit to two compartment models using non-linear least squares estimation. Fecal-urine data substantiated two-compartment elimination of all radionuclides. Biological half-lives in mallards were 10 days (131I), 22 days (140Ba), 86 days (51Cr), 32 days (58Co), 26 days (75Se), 67 days (65Zn), 10 days (134Cs), 67 days (60Co) and 11 days (137Cs). Body burdens in ducks were at 90% of equilibrium with the radioactive waste pond water at the time of removal from the waste ponds. Tissue distribution of radionuclides on the day of removal from the ponds showed gut to have the highest concentrations followed by feather, liver and muscle. After 51 days in metabolic cages, feather had the greatest radionuclide concentrations followed by liver, muscle and gut. Liver contained the greatest variety of radionuclides and muscle the smallest. Biological elimination rates for the major dose-contributing nuclides (134Cs and 137Cs) to humans consuming contaminated waterfowl tissue indicate that the dose to man could be reduced substantially due to the rapid elimination of these radionuclides by mallards. Contaminated waterfowl would receive most of the internal dose in the first month after leaving the contaminated environment indicating that long-term doses would be inconsequential.

Comparison of Two Freshwater Turtle Species as Monitors of Environmental Contamination

“…A comparison of the biological half-life of '37Cs in turtles to that in several other taxa revealed that it was greater than that for birds (Fendley et al 1977, Halford et al 1983 and wild mammals (Jenkins et al 1969). The longer retention of 13'Cs in turtles is consistent with the slower metabolic rate in the poikilothermic turtles.…”

Idaho National Engineering and Environmental Laboratory Site Environmental Report for Calendar Year 1997

“…Radionuclides may have many different isotopes, which are shown by a superscript to the left of the symbol. This number is the atomic weight of the isotope (the number of protons and neutrons in the nucleus of the atom), Radionuclide symbols used in this report are shown in the following Ten-year Summary of Particulate Matter Concentrations (1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997) The Idaho National Engineering and Environmental Laboratory (INEEL), a 2,300 -@2 U.S. Department of Energy site on the Snake River Plain of Idaho, employs 8,100 people, They work on nationally important nuclear energy, systems engineering, and environmental technology problems. The INEEL was founded in 1949 and occupies a mostly undeveloped site of sagebrush desert.…”

Guidance Manual for Conducting Screening Level Ecological Risk Assessments at the INEL

“…Halford and Markham 197S). Halford et al (1982b). The biological elimination of nine gamma-emitting radioisotopes was studied in wing-clipped mallards held on a liquid radioactive waste pond at the INEL.…”