Combined Gas and Particle Measurement System

Real-time measurements of particle species, including NO3-, NH4+, and SO4=, are needed at multiple locations in and beyond the NCORE network to understand pollutant fluxes and dynamics of PM2.5, and to constrain atmospheric models. Existing methods have proved problematic for widespread autonomous deployment creating, an opportunity for development of a reliable, autonomous approach. The innovation of the proposed project is use of a proven catalytic denuder difference method for measurement of the combined gas and particle abundance in combination with inertial separation of the particle species using an inert-surface cyclone to provide a measurement of the gaseous species alone. The difference between the two instrument modes measured with a single detector represents the abundance of the particle species. This method is applicable to NO3- and NH4+ using a standard NO chemiluminescence detector and for measurement of SO4= using a standard SO2 pulsed-fluorescence detector. The objective of the Phase I work is to characterize the response of the catalytic converter and inertial separation systems for the oxidized nitrogen species (HNO3 and NO3-) and the reduced nitrogen species (NH3 and NH4+) using laboratory-based standards. The Phase II work will extend the measurement system family to include measurement of SO2 and SO4=. Further work in Phase II will include field demonstrations of the systems in several different environments for complete characterization in anticipation of widespread deployment. The commercial application of the proposed technology is expected to be extensive, with the primary customers being local, state, and national air management agencies worldwide.