Research Projects

Project at a Glance

Title: Flux measurements of ammonia to estimate emission factors for area sources.

Principal Investigator / Author(s): Dennis Fitz

Contractor: UC Riverside

Contract Number: 98-340

Research Program Area: Emissions Monitoring & Control, Atmospheric Processes

Topic Areas: Modeling, Stationary Sources


Emission rates from fugitive sources can be estimated by integrating the net downwind flux rate of pollutant over the height of the pollutant plume. Fluxes are measured by fast measurements at a general location of deposition in coordination with vertical wind speed measurements. Researchers from the University of California, Riverside, College of Engineering-Center for Environmental Research and Technology (CE-CERT) recently proposed using a fabric diffusion denuder to directly measure ammonia flux. Such a direct flux measurement approach would provide an inexpensive alternative to active sampling. The objective of this research was to evaluate the feasibility of determining emission factors for fugitive sources of ammonia using this passive flux sampler. The use of a fabric denuder (rather than a tubular denuder, used previously) allowed short-term sample collection periods for the measurement of ammonia flux, thus making it possible to sample during periods of prevailing daytime winds. Emissions from five distinct sources were characterized to demonstrate that the approach is a viable method for measuring emission factors. Flux measurement obtained directly from the passive flux denuder and those calculated from an active filter-pack sampler combined with wind velocity were compared. The results show significant correlation between the two methods and invite further investigation into characterization of the passive flux denuder response. Estimation of the emission factors for the five sources were undertaken although samples were not taken at high enough elevations to determine the top of the plume. With further development and evaluation of this technique, it is possible that a larger inventory base for ambient ammonia emissions can be developed more economically than by using active samplers.


For questions regarding this research project, including available data and progress status, contact: Heather Choi at (916) 322-3893

Stay involved, sign up with ARB's Research Email Listserver