1. Research Assistant, Univ. of Illinois, Urbana, IL 61801; presently, NRC Post-Doctoral Research Associate, EPA Cincinnati, 26 W Martin Luther King Dr., Cincinnati, OH 45264 (corresponding author).
2. Associate Professor, Dept. of Civil and Environmental Engineering, 3230D NCEL, MC-250, 205 North Mathews Ave., Univ. of Illinois, Urbana, IL 61801.