Aspects of humic and fulvic acid chemistry

Humic and fulvic acids are present in all environmental waters and are known to combine with environmental contaminants and pollutants producing water soluble complexes. These complexes may be much more mobile than the unassociated contaminant through the environment because of groundwater and surface water movement. Therefore, of considerable interest, is to determine the characteristics and contaminant complexing ability of these materials. Most investigations of the complexing abilities of humics have been conducted on material which has been extracted from natural waters. The resulting solid humic material is then redissolved in an aqueous solution of known chemical composition. Part one of this thesis describes work designed to ascertain whether the extraction procedure alters the properties of the material, thus invalidating the results obtained from e.g. stability constant measurements. Experiments showed that the material was not altered and that measurements of stability constants using extracted material were valid. Part Two describes the development of an ion-exchange resin technique for measuring stability constants. Stability constants for the reaction of humic with nickel and europium were measured by this technique. The thesis also contains an account of the investigation and development of a method for investigating metal-humic interactions by fluorescence spectrophotometry. Competition reactions with calcium have also been investigated.