SEPARATION OF SELENIUM SPECIES RELEASED FROM SE-EXPOSED ALGAE

We have assessed a fractionation scheme for selenium species that sepa rates Se-containing amino acids and other organoselenium compounds in aqueous samples. We investigated the retention of standard solutions o f selenate (Se+6), selenite (Se+4), and selenomethionine (Se-2) by fra ctionation media (Sephadex A-25 ion-exchange resin, copper-treated Che lex-100 ligand-exchange resin, and activated charcoal) and by several types of membrane filters. The fractionation method successfully isola ted Se from the standard solutions into appropriate fractions for radi ometric quantitation of Se-75. However, some filter media retained una cceptably large amounts of selenate and selenite. Mass balance microco sms were inoculated with green algae (Chlamydomonas reinhardtii) previ ously exposed to inorganic Se-75, and the fractionation scheme was use d to examine the release of Se-75 species into water and air. The resu lts of the microcosm exposure indicate that seasonal blooms and crashe s of phytoplankton populations may produce increased concentrations of organoselenium species.