1. Department of Chemistry, Gustavus Adolphus College, Saint Peter, Minnesota 56082, St. Croix Watershed Research Station, Science Museum of Minnesota, Marine on St. Croix, Minnesota 55047, Minnesota Pollution Control Agency, St. Paul, Minnesota, 55155, Department of Soil, Water, and Climate, University of Minnesota, St. Paul, Minnesota, 55108, Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, Minnesota, 55108, and North Central Forest Experiment Station, United States...