We propose to design, develop, and test a comparatively inexpensive, robust, cavity attenuated phase shift (CAPS)-based monitor to measure total reactive nitrogen (NR) emission and deposition rates. The monitor will be capable of partitioning the emission/deposition rates between particle and gas allowing the monitor to adapt sampling modes to optimize the operation of the monitor. These monitors are intended for long term field use at ARM atmospheric observatories as well as in academic and government laboratories worldwide. One area of application is understanding how airborne nitrogen enters soil, and in what chemical form, which is critical to maintaining a healthy soil nitrogen balance. Excess nitrogen in an ecosystem can lead to diminished productivity, eutrophication, decreased resistance to disease, and loss of biodiversity. Because of these agricultural and ecological impacts, there is a clear need to quantify the magnitude of NR deposition and identify its chemical composition. The implementation of widespread monitoring has been hampered by the lack of easy-to-use and affordable instrumentation. The proposed monitor will comprise a Total Reactive Atmospheric Nitrogen Converter (TRANC) the output of which is coupled to a CAPS NOx monitor and a small weather station. The TRANC thermally decomposes both non-refractory atmospheric particles into their gas phase constituents, and any volatile nitrogen-containing gases to NOx. The output of the TRANC will be sent to a NOx monitor which employs the Cavity Attenuated Phase Shift (CAPS) technique to measure its concentration. The Phase I project will focus on a proof-of-principle demonstration using laboratory-generated gas and particle phase nitrogen containing species as well as a limited field measurement study. There are several monitoring networks comprising dozens of field sites, both in the United States and worldwide, which would purchase these monitors if available.
