UNIFIED PHYSICOCHEMICAL DESCRIPTION OF THE PROTONATION AND METAL ION COMPLEXATION EQUILIBRIA OF NATURAL ORGANIC ACIDS (HUMIC AND FULVIC ACIDS). 3. INFLUENCE OF POLYELECTROLYTE PROPERTIES AND FUNCTIONAL HETEROGENEITY ON THE COPPER ION BINDING EQUILIBRIA IN AN ARMADALE HORIZONS Bh FULVIC ACID SAMPLE.

The objective of this research, the development of a model that permits the interpretation of metal ion binding to a fulvic acid source in every conceivable experimental situation, has been reached. The model corrects, for deviations in the potentiometric properties that arise from two disruptive factors intrinsic to any fulvic acid source, a variable electric field, emanating from the surface of the fulvic acid molecule as a consequence of its increasing charge during nuetralization with standard alkali, and site heterogeneity. In the research conducted the complexation of Cu**2** plus by an Armadale Horizons Bh fulvic acid sample was studied to facilitate the program.