METAL-METAL INTERACTIONS IN BIOLOGICAL-SYSTEMS .4. FRESH-WATER SNAIL BULINUS-GLOBOSUS

The toxicity against title snails of all Al, Cd, Co(Il), Cr(III), Cu(I I), Fe (III), Mg, Mn(II), Mo(VI), Ni(II), Pb(II), Se(VI), V(V) and Zn ions was checked in 96 h tests in the water of Kariba Lake. Based on t he mortality - concentration relationship the toxicity order of the ab ove ions against Bulinus globosus is Cu(II) > Ni(II) > Cd > Pb(II) > Z n > Al > V(V)> Cr(III) > Se(VI) > Fe(III) = Co(II) > Mn(II) > Mg > Mo( VI). Only Mg, Pb(II), Cu(II), Cd, Zn and Ni(II) ions are harmful to th ese snails as their mortality is observed at the naturally occuring co ncentrations. Other metal ions cause lethality at naturally unrealisti c concentrations. The following pairs of metal ions were also checked for mutual interactions: Cd-Al, Cd-Co, Cd-Cr, Cd-Cu, Cd-Fe, Cd-Mg, Cd- Mn, Cd-Mo, Cd-Ni, Cd-Pb, Cd-Se, Cd-V, Cd-Zn, Cu-Al, Cu-Co, Cu-Cr, Cu-F e, Cu-Mg, Cu-Mn, Cu-Mo, Cu-Ni, Cu-Pb,, Cu-Se, Cu-V, Cu-Zn, Ni-Al, Ni-C o, Ni-Cr, Ni-Fe, Ni-Mg, Ni-Mn, Ni-Mo, Ni-Pb, Ni-Se, Ni-V, Ni-Zn, Pb-Al , Ph-Co, Pb-Cr, Pb-Fe, Ph-Mg, Ph-Mn, Pb-Mo, Ph-Se, Pb-V, Pb-Zn, Zn-Al, Zn-Co, Zn-Cr, Zn-Fe, Zn-Mg, Zn-Mn, Zn-Mo, Zn-Se, Zn-V. Synergism and antagonism were several times observed in various combinations of ions . The effect of metal-metal interactions on an accumulation of those m etals in the flesh and shells of snails was also observed and measured .