Non-Technical Summary

AMMONIA EMISSION FACTORS AND POTENTIALS FOR OPEN LOT DAIRIES Teresa Cassel, Deanne Meyer, Lowell Ashbaugh, Robert Flocchini University of California, Davis

The San Joaquin Valley air basin exceeds the federal standard for PM10 (suspended particles with aerodynamic diameter less than 10 micrometers). Measurement periods for which PM10 concentrations exceed the federal standard occur almost entirely in the winter months, a time when ammonium nitrate has been shown to comprise 27% of the total PM10 concentration in the San Joaquin Valley air basin (Chow, et al. “PM10 source apportionment in California’s San Joaquin Valley”, Atmos. Enviro. 1992, 26A, 3335). Particulate ammonium nitrate is formed through a chemical reaction between ammonia and nitrous oxide gases in the air. Knowledge of the sources of both gases is necessary for determining which is limiting the rate of particle formation in a specific geographical region. The decomposition of animal manure is the largest source of ammonia in many air basins, including the San Joaquin. In regions where reducing ammonia emissions can be expected to reduce PM10 concentrations animal feeding operations, such as dairies, will be expected to adopt reasonable control measures. In order to develop controls, the mechanisms determining ammonia emission rates on the dairy must be understood. Steps in this direction include discovering which areas of the facility produce the majority of the ammonia, determining how weather patterns influence emissions, and investigating the differences in emission rates from different facilities. The described research was conducted to measure ammonia emissions from commercial dairies in the San Joaquin Valley. The project incorporated a technique for estimating the potential of a facility to produce ammonia to verify that the measured values did not exceed the total amount of nitrogen in the manure that might volatilize as ammonia. The measurements, which agree well with the estimates of potential, will provide a tool for assessing the contribution of ammonia from dairies to PM10 concentrations in the San Joaquin Valley. This research has demonstrated that some regions of the dairy produce much less ammonia than was previously assumed, while other regions were found to produce more. These trends were consistent at three different dairies. This knowledge should direct the development of control efforts away from those areas with lower emission and towards those that are more significant contributors. Teresa Cassel Crocker Nuclear Laboratory One Shields Ave. Davis, CA 95616 voice: (530) 752-0199 fax: (530) 752-0952 [email protected]