Measurements, Modeling, and Analysis of Ammonia Flux from Hog Waste Treatment Technologies
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Date
2004-04-02
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Abstract
Gaseous ammonia has a relatively short residence time in the atmosphere, depositing quickly back to the earth's surface. Excessive ammonia deposition can enhance environmental processes such as eutrophication of aquatic ecosystems. Atmospheric ammonia that does not deposit quickly combines with acidic species, such as sulfuric acid, nitric acid, and hydrochloric acid, to form ammonium aerosols. Ammonium aerosol has a longer residence time in the atmosphere and therefore travels farther distances from the source than gaseous ammonia does. Eventually, ammonium aerosol undergoes deposition, also affecting the earth's ecosystems. Domestic animal waste comprises the largest global source of atmospheric ammonia.
Ammonia emissions from agricultural operations have recently attracted attention in the state of North Carolina due to the rapid expansion of the state's swine industry over the past decade. In order to assess the potential effects of enhanced ammonia emission due to the large hog population, quantitative measurements of ammonia emissions from commercial swine operations must be made. Traditionally, hog operations utilize waste treatment lagoon and spray field technology for waste management.
This study includes ammonia flux measurements from three farms with potential environmentally superior waste treatment technologies. These experimental technologies potentially produce lower ammonia emissions than the traditional waste management technology does. Field measurements are conducted over liquid waste surfaces, cropland soil surfaces, the surface of a covered waste treatment lagoon, and from a hog housing unit that contains a belt removal system for waste. The measured ammonia emissions from the liquid waste surfaces have been parameterized by a multivariate physical and chemical model.
A coupled mass transfer with chemical reactions model predicts ammonia flux across a gas-liquid interface, such as an air-waste lagoon interface. Ammonia flux measurements made from the liquid waste components of experimental waste management systems and from traditional hog waste treatment lagoons validate the mechanistic model. A comparison between modeled and measured ammonia emissions demonstrates the strengths and weaknesses of both the mechanistic model and the field measurement system. Analysis of the measured and modeled ammonia fluxes with respect to environmental parameters reveals discrepancies between the two methods of quantification. This study strives to quantify ammonia flux from experimental and traditional hog waste treatment technologies via a combination of modeling and measurements in order to develop agricultural ammonia emission factors and to assess the extent of enhanced atmospheric ammonia loading due to hog operations in North Carolina.
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Gaseous Ammonia Sources, Ammonia Emission Factors, Ammonia Aerosol, Ammonia, Atmospheric Ammonia, Atmospheric Nitrogen Budget
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Degree
MS
Discipline
Marine, Earth and Atmospheric Sciences
