This award in the Chemistry Division supports research by Cynthia K. Larive of the Chemistry Department, University of Kansas, for the development of a new method for characterizing metal ion complexation and the aggregation of humic and fulvic acids isolated from ground and surface waters. The award is made in the Environmental Geochemistry and Biogeochemistry section of the Water and Watersheds activity of the 1995 NSF/EPA Partnership for Environmental Research. Collaborating on the project is W. Robert Carper of the Chemistry Department, Wichita State University. Pulsed field gradient nuclear magnetic resonance (NMR) spectroscopy will be used to determine the aggregation state of humic and fulvic acids and the degree of metal-ion induced aggregation. Potentiometric titration methods will be used to measure metal ion complexation, and NMR relaxation rates will indicate metal ion exchange rates and formation constants. This broad-based approach will enable investigators to construct a model of competitive metal ion binding and exchange rates in fulvic and humic acids. Samples from the Suwannee and Wakarusa Rivers will be used in initial tests of the generality of the new method. Humic and fulvic acids leach into ground and surface waters from soil and plant organic matter and are inherently heterogeneous in nautre. They are the major constituents of dissolved organic carbon and, as a group, interact with organic pollutants such as pesticides and herbicides, increasing their solubility. For this reason, they play an important role in the transport and bioavailability of anthropogenic organic contaminants. This research is focused on the participation of humic and fulvic acids in the complexation of metal ions and the development of new methods for analysis which will simultaneously determine metal ion concentration, complexation, and aggregation in samples from natural systems.
