Source apportionment of atmospheric polycyclic aromatic hydrocarbons collected from an urban location in Birmingham, UK

Intensive seasonal sampling campaigns were undertaken at an urban location in Birmingham, U.K., in which high-volume samplers were used to collect particulate- and vapor-phase polycyclic aromatic hydrocarbons (PAHs) by means of filter papers and polyurethane foam plugs. Eighteen PAH species were determined by reversed-phase HPLC. Additionally, the suspended particle loading of the air was measured gravimetrically. Dichotomous stacked filter units (DSFUs) were run simultaneously with the high-volumes enabling the collection of particulate matter representative of fine (<2.1 mu m) and coarse sized (2.1-10 mu m) fractions. Filters from the DSFUs were analyzed for 19 metal species [by proton induced X-ray emission (PIXE)], ammonium, elemental carbon, and various anions. Metal and PAH concentrations were observed to be broadly in line with concentrations measured at other urban areas throughout the U.K. Chemical source apportionment studies took the form of principal component analysis (PCA) followed by multi-linear regression analysis (MLRA). This multivariate technique enabled major air pollution source categories to be identified along with the quantitative contributions of pollutant species to each source group. The results demonstrate that a combination of measurements of PAH and inorganic pollutants is a far more powerful tracer of emission sources than PAH data alone. PAH were found to be associated predominantly with emissions from road traffic, although other sources such as fuel oil, coal combustion, and incineration also contribute. Road traffic accounts for 88% of ambient benzo[a]pyrene at our site.