The National Atmospheric Deposition Program (NADP) provides this report (.pdf format) entitled "Nitrogen in the Nation's Rain." The report describes the nitrogen cycle (atmospheric nitrogen pathways), human activities that contribute to nitrogen levels, the role of agriculture (through fertilizers), effects on aquatic systems, and measurements of nitrogen deposition. In addition, the report highlights the Chesapeake Bay region (as a case study), and provides information on NADP and ways of reducing nitrogen deposition. The report may be browsed online or downloaded as a .pdf document.