The national atmospheric deposition program: an overview

The National Atmospheric Deposition Program (NADP) is the organization overseeing the long-term sampling and analysis of precipitation across the United States, Puerto Rico and the Virgin Islands. The three NADP networks that collectively involve routine operations at about 280 sites strive to develop a chemical climatology of atmospheric deposition for the benefit of scientists and agencies concerned with environmental effects. The papers included in the Special Section focused on the uses of NADP data offer some new perspectives on chemical wet deposition.