SURFACE COMPLEXATION OF ALUMINUM ON ISOLATED FISH GILL CELLS

Cells from the gills of largemouth bass (Micropterus salmoides) were isolated and exposed to dilute solutions of Al, Al in the presence of fluoride, or Al plus dissolved organic matter (DOM) to determine the cells' metal binding potential in an acidic medium. Microelectrophoresis was employed to monitor the extent of aluminum sorption to cells in the presence of added ligand. In the absence of Al, the gill cells exhibit an appreciable negative charge; Al binding to the cell surface increases the electric potential at the shear plane and leads to a reduction in the cell's (negative) electrophoretic mobility. In the presence of both Al and F, aluminum complexation at the gill surface is only marginally reduced; the formation of a mixed ligand complex, {F-Al-L-cell}, is proposed to account for the observed results. The presence of such ternary complexes was subsequently verified by F-19 nuclear magnetic resonance spectroscopy and by potentiometry. Addition of DOM increased the negative electrophoretic mobility of the isolated gill cells both in the presence and absence of aluminum (7.4 muM).