This award will support collaborative research between Dr. James Davis of the U.S. Geological Survey, Menlo Park, California and Dr. T. David Waite of the Australian Nuclear Science and Technology Organization, Menai, New South Wales, Australia. The researchers will use laboratory and field approaches to investigate the principal processes governing the transport of solutes that undergo significant chemical reactions in the groundwater environment. Primary objectives of the research include a better understanding of 1) the rates of sorption processes and their inclusion in coupled transport models, and 2) the importance of complexation and oxidation-reduction reactions in the transport of solutes. Both Drs. Davis and Waite are qualified aquatic chemists. This research has the potential of making significant contributions in the area of assessing risks which arise from industrial, nuclear and municipal pollution of groundwater aquifers.