Browsing by Author "Viney Aneja, Committee Chair"

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Examination of Inter-relationships among Meteorological Transport Patterns, Ozone Concentrations, and Human Health Endpoints in New York State.
(2010-10-15) Garcia, Valerie Cover; Heather Cheshire, Committee Chair; Viney Aneja, Committee Chair; Stacy Arnold Nelson, Committee Member; S. Rao, Committee Member; Viney Aneja, Committee Member
Measurement, Analysis, and Modeling of Fine Particulate Matter in Eastern North Carolina
(2007-02-28) Goetz, Stephen; Viney Aneja, Committee Chair; Yang Zhang, Committee Member; Pal Arya, Committee Member
An analysis of fine particulate mass concentrations in eastern North Carolina was conducted in order to investigate the impact of the hog industry and its emissions of ammonia into the atmosphere. This analysis included collecting acidic gas and inorganic fine particulate concentrations at a hog facility and at a site ˜10 miles away, while the regional impact of hog industry was studied with data, which was obtained from the North Carolina Division of Air Quality, for multiple regional sites (Fayetteville, Goldsboro, Jacksonville, Kenansville, Kinston, Raleigh, Wilmington). This regional fine particulate data was then simulated using ISORROPIA, a thermodynamic model that simulates the gas and aerosol equilibrium of inorganic atmospheric species. The local analysis showed the dominance of the ammonium sulfate aerosol, and the seasonal observations showed the impact of both urban areas and marine areas on this region. While no meteorological trends were seen in the local data, the time series plots showed an environment where regional sulfate plays a large part. While nitrate is present in this environment, it is present 1 order of magnitude less then the sulfate aerosol. The ammonium and sulfate values are highly correlated, and the molar ratio is consistent with the relative values of ammonium, sulfate, and nitrate present. The regional observational data analyses show that the major constituents of fine particulate matter are organic carbon, sulfate, nitrate, ammonium and elemental carbon. The observed PM2.5 concentration is positively correlated with temperature but negatively-correlated with wind speed. The correlation between PM2.5 mass and wind direction at some locations indicates the impact of the emissions from hog facilities on PM2.5 formation. The modeled results overpredict the observed results in each case, where the nitrate concentrations had the largest percentage overprediction. The predicted total inorganic PM concentrations are overpredicted by 40-45% of the observed values under conditions with median initial total PM species concentrations, median RH and median temperature. The ambient conditions with high PM precursor concentrations, low temperature and high relative humidity favor the formation of the secondary PM. The model runs of the individual days at the three speciated sites showed overprediction for all species, where some predicted values of ammonium were within a factor of 2 of the observed concentrations.
Nitrate Isotopic Composition in Rainfall and Fine Particulate Matter: Back Trajectory, Meteorology, and Source - Receptor Relationship Analysis
(2006-08-22) Occhipinti, Christopher Olovson; William Showers, Committee Member; Dev Niyogi, Committee Co-Chair; Viney Aneja, Committee Chair
The southeastern portion of North Carolina is a dense crop and animal (swine) agricultural region which previous research suggests emits a significant portion of the state's nitrogen emissions. These findings indicated that transporting air over this region can effect nitrogen concentrations in precipitation at sites at least 50 miles away. The present study was able to combine isotope compositional information with the concept of back trajectory analysis to examine the relationship between this regional nitrogen emission source and receptors independent of pollutant concentration information. The Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model was used to determine potential sources of nitrogen in rainwater collected at an urban receptor site in Raleigh, North Carolina, during the first three quarters of 2004. The delta 15N isotope ratio signatures of each sample were used to further differentiate between sources of the rainwater nitrogen. This study examined the importance of pollutant sources such as animal agricultural activity and meteorology on rainfall chemistry as well as their implications on fine particulate matter formation. Additionally, meteorological conditions associated with anomalous springtime fine particulate matter concentrations found in coastal New Hanover County, North Carolina were investigated. Samples that transited the dense crop and animal (swine) agricultural region of east-southeastern North Carolina (i.e. the source region) had lower delta 15N isotope ratios in the nitrate ion (average = -2.1 ± 1.7 per mil) than those from a counterpart nonagricultural region (average = 0.1 ± 3.0 per mil.) However, the limited data set does not offer any conclusive evidence of similar patterns in ammonium ions. An increase in PM fine mass concentrations in the urban receptor site (yearly average = 15.1 ± 5.8 μg/m3) was also found to correspond to air transport over the dense agricultural region relative to air which was not (yearly average = 11.7 ± 5.8 μg/m3). Fine particulate matter concentrations over the course of four years in four counties around the state were examined, and peak levels of PM2.5 were found in the summer at 3 of the 4 sites. The fourth site, located in costal New Hanover County had a fine particulate matter peak in the spring, which appeared to be unusual as most literature indicates that conditions for high PM2.5 levels are generally found in the summer. Investigation of the phenomenon revealed that historically, meteorological conditions including relative humidity, temperature, and wind direction allow for a peak to exist much earlier in the year at such a location. Transport of pollutants from the dense swine region to the Northwest of New Hanover County is more common in the springtime, along with relative humidity that is in a range witch allows an increase in particulate matter to occur.