title: Changes in atmospheric concentrations of polycyclic aromatic hydrocarbons and polychlorinated biphenyls between the 1990s and 2010s in an Australian city and the role of bushfires as a source.
abstract: Over recent decades, efforts have been made to reduce human exposure to atmospheric pollutants including polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) through emission control and abatement. Along with the potential changes in their concentrations resulting from these efforts, profiles of emission sources may have also changed over such extended timeframes. However relevant data are quite limited in the Southern Hemisphere. We revisited two sampling sites in an Australian city, where the concentration data in 1994/5 for atmospheric PAHs and PCBs were available. Monthly air samples from July 2013 to June 2014 at the two sites were collected and analysed for these compounds, using similar protocols to the original study. A prominent seasonal pattern was observed for PAHs with elevated concentrations in cooler months whereas PCB levels showed little seasonal variation. Compared to two decades ago, atmospheric concentrations of ∑13 PAHs (gaseous + particle-associated) in this city have decreased by approximately one order of magnitude and the apparent halving time (t1/2) was estimated as 6.2 ± 0.56 years. ∑6iPCBs concentrations (median value; gaseous + particle-associated) have decreased by 80% with an estimated t1/2 of 11 ± 2.9 years. These trends and values are similar to those reported for comparable sites in the Northern Hemisphere. To characterise emission source profiles, samples were also collected from a bushfire event and within a vehicular tunnel. Emissions from bushfires are suggested to be an important contributor to the current atmospheric concentrations of PAHs in this city. This contribution is more important in cooler months, i.e. June, July and August, and its importance may have increased over the last two decades.
authors.affiliation: National Research Centre for Environmental Toxicology, The University of Queensland, 39 Kessels Road, Coopers Plains, QLD 4108, Australia. Electronic address: x.wang18@uq.edu.au.
authors.forename: Xianyu
authors.initials: X
authors.lastname: Wang
authors.affiliation: National Research Centre for Environmental Toxicology, The University of Queensland, 39 Kessels Road, Coopers Plains, QLD 4108, Australia.
authors.forename: Phong K
authors.initials: PK
authors.lastname: Thai
authors.affiliation: National Research Centre for Environmental Toxicology, The University of Queensland, 39 Kessels Road, Coopers Plains, QLD 4108, Australia.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: College of Environmental Science and Engineering, Dalian Maritime University, Dalian 116026, China.
authors.forename: Qingbo
authors.initials: Q
authors.lastname: Li
authors.affiliation: Department of Science, Information Technology and Innovation, Ecosciences Precinct, 41 Boggo Road, Dutton Park, QLD 4102, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Wainwright
authors.affiliation: Griffith School of Environment, Griffith University, 170 Kessels Road, Nathan, QLD 4111, Australia.
authors.forename: Darryl W
authors.initials: DW
authors.lastname: Hawker
authors.affiliation: National Research Centre for Environmental Toxicology, The University of Queensland, 39 Kessels Road, Coopers Plains, QLD 4108, Australia.
authors.forename: Jochen F
authors.initials: JF
authors.lastname: Mueller
mesh_terms: D001315:Australia; D002947:Cities; D004784:Environmental Monitoring / Q000379:methods*; D005390:Fires; D005740:Gases / Q000032:analysis; D006801:Humans; D011078:Polychlorinated Biphenyls / Q000737:chemistry*; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry*; D013997:Time Factors
chemical_list: D005740:Gases; D011084:Polycyclic Aromatic Hydrocarbons; D011078:Polychlorinated Biphenyls
keywords: Emission source profile; Polychlorinated biphenyls; Polycyclic aromatic hydrocarbons; Seasonal variation; Temporal change