ARL News

Ammonia Intercomparison at Beltsville


November 30, 2001

NOAA scientists are participating in an experimental comparison of chemical methods to measure ammonia in the atmosphere. Ammonia is the most abundant basic gas in the troposphere, and is responsible for new particle formation (in reaction with sulfur oxidation products) and ecosystem eutrophication. Despite its importance to tropospheric and ecosystem chemistry, few adequate methods exist to quantify its concentration in the atmosphere. ARL scientists are collaborating with researchers from USDA Agricultural Research Service, Howard University, the niversity of Maryland Chesapeake Biological Laboratory, and the University of Delaware to intercompare results from a variety of batch (integrated) and real-time techniques. The experimental site is located within 500m of dairy barns on the USDA campus; depending upon wind direction, ammonia concentrations are expected to range from less than 1 to over 50 micrograms per cubic meter. Techniques being compared include annular and honeycomb denuders, bulk filter packs, acid impingers, passive samplers, a liquid fluorescence technique, and a conversion-difference/ozone chemiluminescence method. The experiment was scheduled to run through Dec. 10.

Contact information: Winston T Luke
Phone: (301) 713-0684