Deposition and Possible Sources of Organic Nitrogen in Rocky Mountain National Park

Katherine B. Beem, Suresh Raja, Florian M. Schwandner, Amy P. Sullivan,
Taehyoung Lee, Christian M. Carrico, Jeffrey L. Collett, Jr., Sonia M. Kreidenweis
Department of Atmospheric Science, Colorado State University, Atmospheric Science Dept, Fort Collins, CO 80523

William C. Malm
Cooperative Institute for Research in the Atmosphere, Colorado State University, CIRA, Fort Collins, CO 80523

Measurements of nitrogen deposition in and surrounding Rocky Mountain National Park took place during two campaigns of the Rocky Mountain Airborne Nitrogen and Sulfur (RoMANS) Study. Measurements were made in a spring campaign during five weeks in March and April 2006, and in a summer campaign during five weeks in July and August 2006. RoMANS measurements of deposited nitrogen a significant fraction of nitrogen is deposited as organic species. Organic nitrogen contributed 11-53% of the total wet nitrogen deposition. Atmospheric organic nitrogen can include contributions from biological sources, oxidation products of combustion emissions, and reduced forms of nitrogen including organic analogs of ammonia. Agricultural environments, including Confined Animal Feeding Operations, are possible sources of reduced organic nitrogen in the RoMANS study area. Northeastern Colorado is a known major source area of agricultural ammonia emissions and previous studies indicate a correlation between ammonia and amine emissions in livestock feeding operation environments. At the time of the RoMANS, speciation of the forms of organic nitrogen in wet deposition was not performed. Recent efforts have been initiated to determine whether significant quantities of amines are present in the atmosphere near likely sources and at locations downwind. Initial efforts are focusing on collection of gas phase amines using diffusion denuders followed by analysis using ion chromatography.