1. Chesapeake Biological Laboratory University of Maryland Solomons, Maryland 20688-0038
2. Department of Environmental Sciences Rutgers University New Brunswick, New Jersey 08903
3. JRC Institute for Environment and Sustainability I-21020 Ispra, Italy
4. Office of Oceanic and Atmospheric Research National Oceanic and Atmospheric Administration 1315 East−West Highway Silver Spring, Maryland 20910
5. Physical and Chemical Properties Division National Institute of Standards and Technology 100 Bureau Drive, Stop 8381 Gaithersburg, Maryland 20899-8381
6. Analytical Chemistry Division National Institute of Standards and Technology 100 Bureau Drive, Stop 8392 Gaithersburg, Maryland 20899-8393