The Development of US Ammonia Emission Factors for Use in Process Based Modeling

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Title: The Development of US Ammonia Emission Factors for Use in Process Based Modeling
Author: James, Kristen Marie
Advisors: Viney P. Aneja, Committee Chair
S. Pal Arya, Committee Member
Daniel Tong, Committee Member
Abstract: An increase in agricultural production to sustain a growing population across the world has resulted in more ammonia (NH3) to be released into the atmosphere. Effects of gaseous ammonia on human health and the environment include aerosol formation, soil acidification, eutrophication, loss of biodiversity, and the neutralization of acids produced by sulfur and nitrogen oxides. In the United States (US), agricultural production (crop + animal) accounts for ~81% of total ammonia emissions. Emissions from animal activities have been the focus of many recent studies as commercial operations continue to grow, dramatically increasing the number of animals in concentrated areas. Animal production facilities include dairy, beef, swine, poultry, sheep, goat, and horse operations. Past US ammonia emission factors for these animals are largely based on European studies and expressed as composite values. This study is in response to the need of an updated ammonia emission factor database for animal activities in the United States. All relevant ammonia emissions data from journal papers, conference papers, and reports published since 1998 is provided. Emissions data is organized into three sections including animal housing, manure storage, and land application. Emission factors are presented in mass units recommended by the United States Department of Agriculture (USDA) (g NH3-N kg-1 day-1 for housing and µg NH3-N m-2 day-1 for storage and land application) for use in process based modeling. Emission factors calculated for dairy cattle and swine are lower than those found in previous studies while the emission factor for beef cattle is significantly higher than previous estimates. Poultry emission factors were similar to those previously developed. In much of the literature information relating to these factors (i.e. average animal weight, minimum and maximum emissions, emissions from storage and land application) is inadequate or missing altogether. In order to develop a comprehensive emission factor database, more information (i.e. facility type, housing type, manure management system, average animal weight) should be presented in present and future observational studies. Due to the need for more observational studies in order to properly develop emission factor databases, this thesis includes continuous ammonia emissions collected at a swine finishing facility in Eastern North Carolina. Emissions, production, and meteorological data were collected for approximately one week in each season (i.e. summer 2007, fall 2007, winter 2008, and spring 2008) from a mechanically ventilated house and on-site storage lagoon in an effort to assess diurnal and seasonal variability in emissions. Barn emissions were calculated using measured gas concentrations and the sum of fan flow rates to be 2604.63±660.71 g NH3-N day-1, 1761.24±1087.26 g NH3-N day-1, 1657.01±1506.52 g NH3-N day-1, and 2659.34 g NH3-N day-1 in the summer, fall, winter, and spring respectively. Animal numbers and average weights were used to determine an emission factor for swine housing of 0.061±0.015 g NH3-N kg-1 day-1, 0.051±0.032 g NH3-N kg-1 day-1, 0.030±0.027 g NH3-N kg-1 day-1, and 0.060±0.027 g NH3-N kg-1 day-1 in summer, fall, winter, and spring seasons. A dynamic flow-through chamber system was used to make lagoon flux measurements. Average seasonal NH3-N fluxes off the surface of the lagoon were greatest in the summer at 3943±398 µg m-2 min-1 and lowest in the winter at 981±210 µg m-2 min-1. Fall and spring average NH3-N flux values were 1383±283 µg m-2 min-1 and 1641±362 µg m-2 min-1 respectively. Results of this study are generally in agreement with those found at similar finishing operations with the exception of ammonia emissions from housing measured in the winter which are lower than those presented in numerous previous studies.
Date: 2008-10-20
Degree: MS
Discipline: Marine, Earth and Atmospheric Sciences

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