Perspectives in Designing and Operating A Regional Ammonia Monitoring

Ammonia emissions are increasingly recognized as a major contributor to nitrogen deposition and aerosol formation. Some research indicating that ammonia gas contributes up to 30 percent of total nitrogen deposition in regions with high ammonia concentrations. However, the magnitude and geographic extent of elevated ammonia concentrations are currently unknown, with most estimates based on measurements of relatively limited geographic extent and duration. Accurate determinations of the magnitude and extent of pollutants require a uniform network of monitoring locations with sufficient density to detect trends and gradients in pollutant concentrations. However, the behavior of ammonia gas in the atmosphere may be sufficiently different from other gaseous pollutants like sulfur dioxide and nitric acid to preclude it from the traditional characterization methods of existing regional monitoring networks. For example, the removal rates of ammonia gas are orders of magnitude greater than those of sulfur dioxide and nitric acid, which may result in extremely steep concentration gradients of the gas. In addition, the bidirectional nature of ammonia gas flux and the ammonia-ammonium equilibrium may require covariant measurements and inferential models to estimate net flux. This presentation will examine these and other design considerations for an ammonia gas monitoring network.

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