THE DETERMINATION OF NATIVE IONIC COPPER CONCENTRATIONS AND COPPER COMPLEXATION IN PEAT SOIL EXTRACTS

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Abstract
In acid peaty soils most of the Cu in the soil solution is present as organic complexes. Methods are described for measuring total soil solution Cu by flameless atomic absorption spectroscopy and estimating the proportion of this Cu that is complexed using Cu titration and a Cu ion selective electrode. With these acidic peats of diverse origin, total Cu in solution at natural pH values (3.4-3.5) ranged 0.14-0.2 .mu.M. Of this, 90% was complexed. Raising the pH of aqueous extracts to about 6.0 increased the degree of complexation of soluble Cu in extracts of all 3 peats to > 98%. The results are discussed in relation to current thinking about the nature of Cu complexation by humic and fulvic acids.