Date of Award:

5-2010

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Chemistry and Biochemistry

Advisor/Chair:

Dr. Robert S. Brown

Abstract

Agricultural emissions are an important contributor to atmospheric aerosol. These emissions include nitrogen containing organic compounds, primarily as amines, which have not been well investigated to date. Although there have been several studies that have looked at the emission of gas phase amines, there are only a few studies that have focused on ambient amine-based aerosol. There have also only been a handful of smog chamber studies that have investigated amine aerosol chemistry. Kinetic studies have looked at the reactions of amines with OH and ozone. However, amine reactions with nitrate radical (NO3) are not well understood. Several years of measuring atmospheric particulate matter in Cache Valley, Utah, using an aerosol mass spectrometer (AMS), has shown the presence of amine aerosol in significant concentrations (0.5-6 μg/m3). Furthermore, the concentration of amine aerosol peaks at night when NO3 is the dominant oxidant. This thesis details experiments aimed at obtaining a better understanding of the underlying reactions that lead to aerosol formation in Cache Valley and is focused on amine reactivity studies, employing both field and laboratory experiments. There were two field studies performed near agricultural facilities in California. These studies provide a good comparison to the ambient chemistry observed in Utah. The detection of a small amount of amine aerosol was important in showing that amine aerosol is not unique to Utah. The results of these studies add to the previous knowledge base of ambient chemistry in California. This should help future researchers performing similar field studies in California and other locations. Smog chamber-based laboratory experiments included amine reactions with common oxidants, such as ozone and NO3. While small amounts of aerosol formation occurred with ozone (~10 μg/m3), reaction with NO3 produced the most aerosol (up to 135 μg/m3). The smog chamber studies show the importance of amine/NO3 chemistry in the formation of ambient aerosol. Researchers can use this work to aid in further understanding the ambient atmospheric chemistry occurring at various locations. The smog chamber studies also provide a knowledge base that should help guide future work into this area of research.

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