S1 Biogeochemical controls of uranium bioavailability from the dissolved phase in natural freshwaters Marie-Noële Croteau 1 *, Christopher C. Fuller 1 , Daniel J. Cain 1 , Kate M. Campbell 2 and George Aiken 2 1 U.S. Geological Survey, 345 Middlefield Rd, Menlo Park, CA94025, United States 2 U.S. Geological Survey, 3215 Marine St Suite E-127, Boulder, CO80303, United States ASSOCIATED CONTENT Supporting Information: 14 pages, 7 tables, 5 figures, 6 equations and text