1. U.S. Geological Survey, Water Resources Division, 345 Middlefield Road, Menlo Park, California 94025, University of Pittsburgh, Department of Geology and Planetary Science, 4107 O'Hara Street, Pittsburgh, Pennsylvania 15260-3332, U.S. Geological Survey, New York Water Science Center, 425 Jordan Road, Troy, New York 12180, Department of Environmental Science, Policy & Management, 137 Mulford Hall, University of California, Berkeley, California 94720, National Atmospheric Deposition Program Central...