Date of Award


Document Type

Open Access Thesis



First Advisor

April Hiscox


High concentrations of ammonium (NH4+) aerosols can lead to acidification of soils, forest decline, and eutrophication of water ways (Aneja et al. 2003). NH4+ along with its precursor ammonia (NH3) forms a complicated gas aerosol system that is poorly understood and requires further research. Rotating annular denuder systems actively sampled NH4+ from the northern corner of a sugarcane field at 2.89 m and 5.18 m above the northern corner of a sugarcane field in St. Gabriel, Louisiana over 31 days and 31 nights between May 25th and July 27th of 2011. These data were used to calculate the average NH4+ concentrations present at the two heights over the diurnal and nocturnal periods. An analytic concentration footprint model was used to identify the source areas of the sampled NH4+. Winds at the site were predominately southwesterly, and the NH4+ concentrations varied as the footprints cover various surfaces. Weak negative correlations with temperature and wind speed and positive correlations with humidity were observed. The largest portion of the NH4+ sampled over the period was sourced from the sugarcane. However, concentrations were higher when footprints extended into the surrounding pasture. A large portion of the NH4+ was also derived from non-local source areas as a result of the sampling method. Concentrations were highly variable and diurnal and nocturnal concentrations were weakly correlated. The heights were highly correlated but significantly different with 2.89 m averaging .0005 mg/m3 more NH4+. The results from this study have future applications to climate models and nutrient budgets.

Included in

Geography Commons