SPECIATION OF IRON AND MANGANESE IN DAM WATER PARTICLES USING ELECTRON-SPECTROSCOPY FOR CHEMICAL-ANALYSIS (ESCA)

The speciation of iron and manganese compounds retained by membrane fi ltration of dam water samples was studied by use of electron spectrosc opy for chemical analysis (ESCA). Samples were taken at various depths and times of year from North Pine Dam near Brisbane, Australia. Both surface and bulk properties of samples representative of the water col umn profile were investigated. ESCA results showed that iron(III) comp ounds were found to predominate in the whole water column in any seaso n of the year while the significance of iron(II) species varied in the hypolimnion (the bottom layer). In summer, although various ratios of manganese(II), manganese(III) and manganese(IV) compounds were found to occur down the water column, manganese(IV) compounds were predomina nt in the epilimnion (the top layer), while both manganese(II) and (IV ) compounds predominated in the metalimnion (the middle layer) and the hypolimnion. The majority of Mn(IV) compounds were found throughout t he water column after heavy rain and winter season. The ratios of atom ic concentrations of iron and manganese as determined by atomic absorp tion spectrophotometry and ESCA are also discussed.