Polycyclic aromatic hydrocarbons were measured near Interstate 40, just east of Research Triangle Park, North Carolina. One hundred seven 8-h integrated samples were collected on 20 sampling days over a 2 month period in Fall 2014. The 8-h samples were collected by low flow (16.7 L/min) fine particulate samplers. The samples were analyzed using gas chromatography-mass spectrometry. Temporal distribution of the PAHs (0.1–21.6 ng/m3 ± 9.0 std) were compared to meteorological and pollutant data collected at the near roadway station. There is a weak but significant correlation between the sum of the measured PAHs with ozone, nitrogen dioxide and nitric oxide, with the R2 values being 0.0049, 0.0187 and 0.0788 respectively. However the p-values (α = 0.05) were 0.044, 0.002 and 0.044, which are significant. Wind rose analysis illustrated the morning hours which were predominantly southern winds, while the afternoon hours illustrated southerly and easterly winds, which suggests that the automobile traffic as the main source of PAHs. The nighttime hours wind rose shows winds from northerly and easterly direction, which are predominantly from the RDU International Airport. PAH concentration found in this study compare favorably to other research studies (0.1 to 193.6 ng/m3) both nationally and internationally.
Gaseous ammonia plays a crucial role in the earth’s atmosphere. Major sources of atmospheric ammonia include agriculture and fires. As the climate continues to change, the pattern of fires across the US will also change, leading to changes in ammonia emissions. This study examines four major science questions using satellite and in-situ data from 2010–2014: (1) How have concentrations of ammonia changed across the US? (2) How have the strength and frequency of fires changed? (3) How has this change in fires impacted ammonia emissions? (4) How does the US EPA NEI compare with the calculated emissions? Satellite and in-situ data were used to evaluate the annual concentrations of ammonia and to calculate the total ammonia emissions across the continental US. The results of this study showed that ammonia concentrations have slightly increased over the five-year period. The total fire number and the average fire radiative power have decreased, while the total yearly burn area has increased. The calculated ammonia emissions from fires on a national scale show an increasing trend and when compared with the US EPA NEI for ammonia emissions from fires, annual ammonia emissions are, on average, a factor of 0.49 higher than the NEI.