This is an award to support research on the interactions of chromium species in water solution with reducing substances. Principal focus of this project is on reducing effects of naturally occurring, organic compounds. The research will also consider effects of hydrogen-ion concentration, dissolved oxygen, iron, manganese and other naturally occurring reductive substances. The goal of this project is to understand and predict changes in chromium speciation and mobility in aquatic environments. Project objectives include determination of reaction rates and mechanisms for reduction of chromates by low-molecular weight reducing substances for guidance in subsequent work with natural organic compounds that may be found in soils and in surface water sediments that have been contaminated by chromium compounds. Chromium compounds are used industrially, for the tanning of leather, metal finishing, pulp and wood processing. A better understanding than now exists for the processes that affect transformations of chromium in the environment and which affect its mobility in groundwater are likely to be applied in engineering design of systems for management of chromium-containing wastes and to deal with the contamination of groundwater from existing deposits of chromium wastes.