Radiotracers in Studies of Trace Metal Behavior in Mesocosms: Advantages and Limitations

Abstract

Radioisotopes have been used to study the movement and transformation of chemicals in natural systems for at least three decades, and from an oceanic scale to that of laboratory animals or the human body. For obvious reasons, radioisotopes cannot be added at will to open, natural ecosystems. Enclosed ecosystems are therefore ideal for this technique. Radioisotopes have been used extensively in laboratory-scale bioaccumulation studies (e.g., International Atomic Energy Agency 1975, and references therein). Few, however, have used isotopes other than 14 C in mesocosms which simulate or isolate part of a natural aquatic ecosystem (e.g., Brungs 1967, Hesslein et al. 1980, Adler et al. 1980, Santschi et al. 1980c). The methodology we use at the Marine Ecosystems Research Laboratory (MERL), at the University of Rhode Island, Narragansett, R.I., U.S.A., will serve to illustrate the advantages and drawbacks of radiotracer experiments in enclosed ecosystems.