Gonzalez, Isbel. Characteristics of organic and elemental carbon in particulate matter on the US East Coast: a case study at metropolitan Newark in New Jersey. Retrieved from https://doi.org/doi:10.7282/t3-w5f0-pe93
DescriptionTo investigate the day- and night-time variability of carbonaceous aerosols in the ambient air in metropolitan Newark in New Jersey on the US east coast, particulate air samples of PM2.5 (particles with diameter ≤2.5 µm) and PM2.5-10 (particles with diameter 2.5-10 µm) were collected from downtown Newark. Air samples were analyzed by thermal-optical analysis methods for elemental carbon (EC) and organic carbon (OC). The results show that the total carbonaceous particulate matter (PM) in the air was dominated by coarse-mode particles. The OC/EC ratios varied from 5.3 to 50.9, with an average of 19.2 ± 11.7 for PM2.5, and from 5.1 to 13.7, averaging 7.5 ± 2.1 for PM2.5-10. Higher concentrations of OC in PM2.5 particles occurred at night with a moderate correlation with Relative Humidity (RH) (R²=0.52), suggesting the possible formation of secondary organic aerosols (SOC) via aqueous-phase oxidation of low volatility organic compounds. Fine-mode OC had moderate correlations with PM2.5 sodium (R2=0.59) and PM2.5-10 sodium (R2=0.37), suggesting a mixed influence of anthropogenic and marine sources. Fine mode EC had a strong relationship with PM2.5 nitrate (R² = 0.75), suggesting an anthropogenic source for PM2.5 EC, as nitrate is a secondary aerosol formed from nitrogen oxides (NOx) emitted mainly by traffic sources. The concentrations of coarse mode EC (PM2.5-10) were higher during the daytime than at night, suggesting a major contribution from mobile sources. The PM10/PM2.5 ratios observed during this study were 4.6 for OC and 7.8 for EC, higher than those from selected previous studies. The highest concentrations of carbonaceous aerosols were associated with east-southeast winds; busy highways were also in that direction, while the concentrations of them were the lowest under west winds. This suggests that winds played an important role in the variations of carbonaceous aerosols in the air in this region.