A majority of the oxides of nitrogen which are produced in the atmosphere by anthropogenic and natural processes is converted to nitric acid. Nitric acid is ultimately removed from the atmosphere by both wet and dry deposition processes. This surface loss of nitric acid and nitrate in aerosols is the major sink of the oxides of nitrogen in the atmosphere. Nitric acid is not only an important species in the atmospheric nitrogen cycle, but it can also contribute significantly to the acidity of precipitation. An understanding of the cycle of nitric acid in the troposphere, and especially the processes and rates of removal of this compounds from the atmosphere, is a current critical issue in atmospheric chemistry. This project is the continuation aimed at obtaining an improved understanding of the removal from the atmosphere of nitric acid by land, water and plant surfaces. Sampling and analytical procedures have been developed to permit direct field measurements of the dry deposition of nitric acid. In the continuation of this research, field studies will be performed at different locations to better define surface sinks of nitric acid and the cycle of this compound through the continental or marine atmosphere.
