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.
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