The Complexing of Copper by Humified Organic Matter From Laboratory Preparations, Soil and Peat

Summary The metal complexing properties of the colloidal and non‐colloidal fractions of water extracts of peat and aerobically composted lucerne, and of chelating resin and alkali extracts of peat and soil organic matter were compared. The contributions of the non‐colloidal fractions to the complexing properties of the whole extracts are considerable, and on a weight‐for‐weight basis are somewhat greater than that of the corresponding colloidal material. No one compound is preponderantly responsible for the complexing action. The complexing activity of the non‐colloidal fractions is confined almost entirely to the acidic constituents. On the basis of the enhancement of the visible range of optical absorbance of the various preparations, Cu 2+ is more extensively complexed than Mg 2+ , Mn 2+ , Cd 2+ , Zn 2+ , Co 2+ , Ni 2+ , and Pb 2+ .