Humic and other negatively charged colloids of iron and copper in river water

Iron and copper present as humic and other negatively charged colloids are studied by sorption on indium-treated XAD-2 resin and DEAE-Sephadex A-25 anion exchanger and by filtration. The iron species include colloidal particles consisting of hydrated iron(III) oxide, clay and humic substances and smaller amounts of hydrated iron(III) oxide-clay or -silica aggregates, whereas most of the copper exists as humic complexes.