Browsing by Author "Hallal, T"

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    Size-resolved elemental composition of aerosol particles in greater Sydney in 2002–2003
    (CSIRO Publishing, 2013-08-02) Hallal, T; Box, GP; Cohen, DD; Stelcer, E
    Between November 2002 and December 2003 samples of PM2.5 and PM10 (particulate matter less than 2.5- and 10-μm aerodynamic diameter) aerosols were collected at four sites in the Sydney Basin in order to determine the spatial and seasonal variation of size-resolved aerosol chemical composition in the Sydney region and relate this to aerosol optical properties. Accelerator-based ion beam analysis was used to determine the elemental composition and black carbon (BC) was determined using the laser integrating plate method. Aerosol species were determined by multiplying a marker element by a factor based on molecular weight ratios. Mass concentrations at the rural sites were lower than at the urban sites with an average PM2.5/PM10 mass ratio of 0.5–0.6 for all sites although at the urban sites it was 0.2–0.25 in summer. For all sites BC was the dominant element, followed by Na. For the urban sites this was followed by Cl suggesting sea salt and then the soil elements Al and Si. For the rural sites the soil elements Al, Si and Ca were more important than Cl, which was found to decrease away from the coast. Analysis of aerosol species shows that BC accounts for a larger portion of PM2.5 than PM10 and sea salt and sulfate levels are higher in summer than in winter. © 2013, CSRIO Publishing.
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    Size-resolved properties of atmospheric aerosols in Sydney and Regional NSW
    (Department of the Environment and Water Resources, 2007-09-13) Hallal, T; Box, GP; Radhi, M; Box, MA; Cohen, DD; Stelcer, E
    In recent years it has become evident that size-resolved chemical composition of atmospheric aerosols is important in determining optical properties such as refractive index, scattering and absorption coefficients, extinction and hygroscopicity. These properties affect the way radiation is scattered and absorbed as it passes through the atmosphere, and thus are important for the calculation of aerosol radiative forcing and "atmospheric correction" of satellite images, as well as local air quality and visibility. We report results from a study of the size-resolved chemistry of atmospheric aerosols in Sydney and regional NSW, and their relationship to optical properties. PM2.5 and PM10 samples were collected at four sites during the summer, autumn, winter and spring of 2003. These were analysed using Ion Beam Analysis (IBA) and selected samples have also been analysed by Scanning Electron Microscopy (SEM). The elemental chemistry, in combination with meteorological parameters and a chemical thermodynamic model, was then used to determine the aerosol refractive index for each of the sites and size fractions. IBA results show seasonal differences within sites and between sites, as well as differences between PM2.5 and PM10 composition at particular sites. Refractive index values also show seasonal and spatial differences. Further PM2.5 and PM10 measurements were made during winter 2006 in Sydney, and Wagga Wagga in regional NSW. A second set of measurements, including using a 10-stage MOUDI sampler for better size-resolution of the chemistry is planned and similarly analysed.