Chemical characterization of urban air pollutants in precipitation, aerosols and gas-phases in northeast New Jersey in the US east coast

To chemically characterize urban air pollution in the US east coast, precipitation for water-soluble inorganic/organic ions and trace metals, aerosols for trace metals, and gas-phase samples for NOx, O3 and NO3 were studied in northeast New Jerseymetropolitan areas from 2006 to 2008. Precipitation and aerosols were collected by automatic wet-only precipitation collector and MOUDI (Multi-Orifice Uniform Deposit Impactor), respectively, while gaseous pollutants were measured by O3/NOx analyzers. Results showed that sulfate (SO4 2-) and ammonium (NH4 +) are the most dominant ions controlling the precipitation acidity (pH 3.8 ~ 6.4). Acetate (CH3COO−) and formate (HCOO−) are the major water-soluble organic acid species in the region. The elements Al,Zn and Fe are dominant in the mass of the trace metals measured. Major sources for pollutants in precipitation were identified as: (1) nitrogen-enriched soil, (2) secondary pollution processes, (3) marine sources, (4) incineration, (5) oil combustion, and (6) malonate-vanadium-enriched sources. About half of the precipitation events were characterized by mixed sources. For the size distributions of aerosol particles collected during this study, the total aerosol mass showed a typical bimodal distribution with two peaks around 0.32-0.56μm and 3.2-5.6μm. Typical crustal trace metals (Fe, Cu, Mn and Sc) had coarse particulateaccumulation mode and their enrichment factors showed tilted normal distributions pattern peaking at 1.0-1.8μm, while the other trace metals had fine particulate accumulation mode and their enrichment factor showed monotonic decline patterns withoverwhelmingly high peaks in the size range of 0.18-0.32μm. Three major traffic relatedsources for trace metals were identified: (1) brake wear and fuel combustion, (2) primary fuel combustion, and (3) tire abrasion and fuel combustion. Results from the gas-phase measurements showed significant diurnal and weekday/weekend variations in the O3 concentrations, with higher concentrations beingfound during the daytime and on weekends. The 24-h diurnal variations of O3 and NOx showed a typical four-periods pattern: (1) morning NOx peak, (2) mid-day O3 formation, (3) afternoon NOx accumulation, and (4) nighttime balancing. NOx and O3 showed negative correlations indicating possible VOC-sensitive characteristics while no obvious influence of HNO3 on O3 was observed.Ph.D.Includes bibliographical referencesIncludes vitaby Fei Son