Date of Report: March 31, 2003 (Mid-year Report)

EPA Agreement Number: R829515C003 Center Name and Institution of Center Director: Rocky Mountain Regional Hazardous Substance Research Center, Colorado State University, Fort Collins, Colorado Identifier used by Center for Project: Project 1 Title of Project: Redox Transformations, Complexation and Soil/Sediment Interactions of Inorganic Forms of As and Se in Aquatic Environments: Effects of Natural Organic Matter (NOM) Investigator(s) and Institution(s):Donald L. Macalady, P.I.: Department of Chemistry and Geochemistry, Colorado School of Mines (CSM), Golden, CO 80401, Dianne Ahmann, Co-P.I.: Division of Environ. Sci. and Engr., CSM, Golden, CO 80401, Dr. John Garbarino, United States Geological Survey (USGS), Denver, CO 80225 Type of Research: Basic Project Period: November 1, 2001 to October 31, 2003