SREL Reprint #0715




Relative Mobilization of Zinc, Cerium, and Americium from Sediment in an Aquatic Microcosm

John P. Giesy and Richard A. Geiger



The effect of rooted aquatic macrophytes on the relative mobility of 65Zn,  144Ce, and 241Am from sediment was investigated in sediment water microcosms.  The presence of macrophytes resulted in a greater total above sediment biomass and reduced seston and aufwuchs biomass.  Macrophytes also increased the total mass of all three elements in the above-sediment components.  This increase was not caused solely by increased biomass into which the isotopes could partition since concentrations of all three isotopes were increased in the water, seston, and aufwuchs as a result of the presence of macrophytes.  The ratio of Am to 144Ce was the same in seston, aufwuchs, and macrophytes when macrophytes were present.  The presence of macrophytes caused a reduction of Am relative to 144Ce in the water, seston, and aufwuchs.  The dynamics of 65Zn were different from those of 144Ce and 241Am.  The ratio of 241Am to 65Zn was approximately sevenfold greater in seston, aufwuchs, and macrophytes than in sediments or water, with macrophytes causing a significant increase in this ratio only in water.  Even though the sediments contained a large quantity of stable zinc, the observed behavior of 65Zn could not be attributed to isotope dilution.  Rather 65Zn seems to be restricted from uptake by biota, relative to 241Am and 144Ce.  The microcosms studied here were sufficient to study the relative mobility of trace elements from sediments, as well as specific pathways of mobilization, but were not useful for measuring the rate and absolute magnitude of elemental fluxes from sediments, which could be extrapolated to larger systems.


SREL Reprint #0715

Giesy, J.P. and R.A. Geiger. 1980. Relative mobilization of zinc, cerium, and americium from sediment in an aquatic microcosm. p. 304-318. In Microcosms in Ecological Research, edited by J.P. Giesy Jr. CONF 781101. U.S. Department of Energy Symposium Series 52.

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