title: Molecular composition of organic aerosols at urban background and road tunnel sites using ultra-high resolution mass spectrometry.
abstract: Organic aerosol composition in the urban atmosphere is highly complex and strongly influenced by vehicular emissions which vary according to the make-up of the vehicle fleet. Normalized test measurements do not necessarily reflect real-world emission profiles and road tunnels are therefore ideal locations to characterise realistic traffic particle emissions with minimal interference from other particle sources and from atmospheric aging processes affecting their composition. In the current study, the composition of fine particles (diameter ≤2.5 μm) at an urban background site (Elms Road Observatory Site) and a road tunnel (Queensway) in Birmingham, UK, were analysed with direct infusion, nano-electrospray ionisation ultrahigh resolution mass spectrometry (UHRMS). The overall particle composition at these two sites is compared with an industrial harbour site in Cork, Ireland, with special emphasis on oxidised mono-aromatics, polycyclic aromatic hydrocarbons (PAHs) and nitro-aromatics. Different classification criteria, such as double bond equivalents, aromaticity index and aromaticity equivalent are used and compared to assess the fraction of aromatic components in the approximately one thousand oxidized organic compounds at the different sampling locations.
authors.affiliation: Centre for Atmospheric Science, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK. markus.kalberer@atm.ch.cam.ac.uk.
authors.forename: Haijie
authors.initials: H
authors.lastname: Tong
authors.affiliation: Centre for Atmospheric Science, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK. markus.kalberer@atm.ch.cam.ac.uk.
authors.forename: Ivan
authors.initials: I
authors.lastname: Kourtchev
authors.affiliation: School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: Pallavi
authors.initials: P
authors.lastname: Pant
authors.affiliation: School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Keyte
authors.affiliation: Department of Chemistry and Environmental Research Institute, University College Cork, Cork, Ireland.
authors.forename: Ian P
authors.initials: IP
authors.lastname: O'Connor
authors.affiliation: Department of Chemistry and Environmental Research Institute, University College Cork, Cork, Ireland.
authors.forename: John C
authors.initials: JC
authors.lastname: Wenger
authors.affiliation: School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: Francis D
authors.initials: FD
authors.lastname: Pope
authors.affiliation: School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: Roy M
authors.initials: RM
authors.lastname: Harrison
authors.affiliation: Centre for Atmospheric Science, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK. markus.kalberer@atm.ch.cam.ac.uk.
authors.forename: Markus
authors.initials: M
authors.lastname: Kalberer