1. Dep. of Civil & Environmental Engineering Michigan State Univ. East Lansing MI 48824 USA
2. Mekong River Commission Vientiane Lao PDR
3. Office of Research and Development, National Exposure Research Lab. U.S. Environmental Protection Agency Athens GA 30605 USA
4. USDA‐ARS Environmental Microbial and Food Safety Lab. Beltsville MD 20705 USA