1. Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6038
2. Oak Ridge Associated Universities, P.O. Box 117, Oak Ridge, Tennessee 37831-0117
3. Department of Civil Engineering, P. O. Box 10024, Lamar University, Beaumont, Texas 77710
4. Department of Microbiology, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
5. U.S. EPA, 79 TW Alexander Drive, Human Exposure Analysis Branch, MD-56, Research Triangle Park, North Carolina 27711
6. Florida Department of Environmental Protection, 2600 Blair Stone Road, Tallahassee, Florida 32399
7. National Environmental Research Institute of Denmark, Copenhagen, Denmark
8. Institute of Environmental Physics, University of Bremen, D-28359 Bremen, Germany