James N. Galloway,^* Ellis B. Cowling<sup>**


*</sup>James N. Galloway is professor of environmental sciences at the University of Virginia, USA. His research on biogeochemistry includes the natural and anthropogenic controls on chemical cycles at the watershed, regional and global scales. His current research focuses on beneficial and detrimental effects of reactive nitrogen as it cascades among environmental reservoirs in the atmosphere and biosphere of the Earth. His address: Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22903, USA. jng@virginia.edu
^**Ellis Cowling is University Distinguished Professor At-Large at North Carolina State University. His interests in nitrogen began with his doctoral dissertation research on Nitrogen in Forest Trees and Its Role in Wood Deterioration at the University of Uppsala, Sweden and has continued in his leadership roles in the US National Acid Precipitation Assessment Program and the Southern Oxidants Study. His address: North Carolina State University, Raleigh, NC 27605, USA. ellis_cowling@ncsu.edu