The mobility and bioavailability of metal ions in natural waters depend on their chemical speciation, which involves a distribution of the metal ions between different complex (metal-ligand) species, colloid-adsorbed species and insoluble phases, each of which may be kinetically labile or inert. For example, in fresh water the metal ions are distributed among organic complexes (e.g., humates), colloids (e.g., as surface-adsorbed species on colloidal phases such as FeOOH), solid phases (e.g., hydroxide, oxide, carbonate mineral phases), and labile complexes with the simple inorganic anionic ligands commonly present in natural waters (e.g., for ZnII, the aqueous species, Zn2+, ZnOH+, Zn(OH)2(aq), Zn2OH3+, ZnSO4(aq), ZnCO3(aq)…).
Walter de Gruyter, 2015. Vol. 37, no 1, 15-19 p.