Depuration and uptake kinetics of I, Cs, Mn, Zn and Cd by the earthworm (Lumbricus terrestris) in radiotracer-spiked litter
- Atomic Energy of Canada Ltd., Pinawa, Manitoba (Canada). Whiteshell Labs.
The relative depuration and uptake kinetics of contaminants should be known to interpret appropriately the use of organisms such as earthworms in environmental bioassays and monitoring. For example, 14-d earthworm bioassays should be interpreted with the knowledge that some contaminants will continue to accumulate in tissues for months. The radiotracers {sup 125}I, {sup 134}Cs, {sup 54}Mn, {sup 65}Zn, and {sup 109}Cd were applied to deciduous litter and specimens of Lumbricus terrestris were exposed, either to litter alone or to litter on the top of soil columns. Depuration was monitored for 120 d and uptake, in a separate experiment, for 20 d. Both depuration and uptake were described using two-phase, first-order statistical models. Cut clearance had a mean half-time of 1.4 d. The mean half-time for physiological depuration decreased from I (210 d) > Cd (150 d) > Zn (69 d) > Mn (40 d) > Cs (24 d). Both the depuration and the uptake experiments were necessary to resolve even partially the multiphase processes. Earthworm/soil dry weight concentration ratios decreased from Cd > Zn > I {ge} Cs {ge} Mn. The very slow kinetics indicate that tissue concentrations will increase continuously for a long time, with important implications for subsequent food-chain transfers.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 563988
- Journal Information:
- Environmental Toxicology and Chemistry, Vol. 16, Issue 10; Other Information: PBD: Oct 1997
- Country of Publication:
- United States
- Language:
- English
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