1. Environmental Chemistry and Technology Program, University of Wisconsin—Madison, 660 North Park Street, Madison, Wisconsin 53706, United States
2. Department of Soil, Water, and Climate, University of Minnesota Twin Cities, 1991 Upper Buford Circle, St. Paul, Minnesota 55108, United States
3. Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
4. Research Division, California Air Resources Board, P.O. Box 2815, Sacramento, California 95812, United States