1. Department of Civil and Environmental Engineering, University of Illinois, Urbana-Champaign, 205 N. Mathews Avenue, Urbana, Illinois 61801-2352, Requimte/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal, and Illinois State Geological Survey, 615 E. Peabody Drive, Champaign, Illinois 61820