Browsing by Author "Gulson, B"

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    Comparison of lead isotopes with source apportionment models, including SOM, for air particulates
    (Elsevier, 2007-08-01) Gulson, B; Korsch, K; Dickson, B; Cohen, DD; Mizon, K; Davis, JM
    We have measured high precision lead isotopes in PM2.5 particulates from a high ly-trafficked site (Mascot) and rural site (Richmond) in the Sydney Basin, New South Wales, Australia to compare with isotopic data from total suspended particulates (TSP) from other sites in the Sydney Basin and evaluate relationships with source fingerprints obtained from multi-element PM2.5 data. The isotopic data for the period 1998 to 2004 show seasonal peaks and troughs that are more pronounced in the rural site for the PM(2.5)samples but are consistent with the TSP. The Self Organising Map (SOM) method has been applied to the multi-element PM2.5 data to evaluate its use in obtaining fingerprints for comparison with standard statistical procedures (ANSTO model). As seasonal effects are also significant for the multi-element data, the SOM modelling is reported as site and season dependent. At the Mascot site, the ANSTO model exhibits decreasing Pb-206/(204) Pb ratios with increasing contributions of fingerprints for "secondary smoke" (industry), "soil", "smoke" and "seaspray". Similar patterns were shown by SOM winter fingerprints for both sites. At the rural site, there are large isotopic variations but for the majority of samples these are not associated with increased contributions from the main sources with the ANSTO model. For two winter sampling times, there are increased contributions from "secondary industry", "smoke", "soil" and seaspray with one time having a source or sources of Pb similar to that of Mascot. The only positive relationship between increasing Pb-206/(204) Pb ratio and source contributions is found at the rural site using the SOM summer fingerprints, both of which show a significant contribution from sulphur. Several of the fingerprints using either model have significant contributions from black carbon (BC) and/or sulphur (S) that probably derive from diesel fuels and industrial sources. increased contributions from sources with the SOM summer fingerprints could explain the summer-time peaks in isotopic ratio at both sites and, at the rural site, be associated with meteorological influences. Nevertheless, the SOM results indicate that there are multiple overlapping 'weak' sources. © 2007, Elsevier Ltd.
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    Fine-particle Mn and other metals linked to the introduction of MMT into gasoline in Sydney, Australia: results of a natural experiment.
    (Elsevier, 2005-11-01) Cohen, DD; Gulson, B; Davis, JM; Stelcer, E; Garton, D; Hawas, O; Taylor, A
    Using a combination of accelerator-based ion beam methods we have analysed PM2.5 particulates for a suite of 21 species (H, C, Na, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Pb) to evaluate the contribution to Sydney (New South Wales, Australia) air associated with the introduction of MMT as a replacement for lead. MMT was discontinued in 2004. Teflon filters representing continuous sampling for a 7 year period from 1998 to 2004 were analysed from two sites: one from Mascot, a suburb close to the Central Business District [CBD (n=718)] and a high trafficked area, and the other, a relatively rural (background) setting at Richmond, 20 km west of the CBD (n=730). Manganese concentrations in air at the background site increased from a mean of 1.5–1.6 ng m−3 to less than 2 ng m−3 at the time of greatest MMT use whereas those at Mascot increased from about 2 to 5 ng m−3. From the maximum values, the Mn showed a steady decrease at both sites concomitant with the decreasing use of MMT. Lead concentrations in air at both sites decreased from 1998 onwards, concomitant with the phase out of leaded gasoline, attained in 2002. Employing previously determined elemental signatures it was possible to adjust effects from season along with auto emissions and soil. A high correlation was obtained for the relationship between Mn in air and lead replacement gasoline use (R2 0.83) and an improved correlation for Mn/ Al+Si+K and lead replacement gasoline use (R2 0.93). In addition, using Mn concentrations normalized to background values of Al+Si+K or Ti to account for the lithogenically derived Mn, the proportion of anthropogenic Mn was approximately 70%. The changes for Mn and Pb detected in the particulates are attributed to the before-during-after use of MMT and decreasing use of lead in gasoline. The values measured in Sydney air are well below the reference concentration of 50 ng Mn m−3. The incremental increases in air, however, are larger than expected given the limited use of MMT only in lead replacement gasoline and high quality monitoring should be undertaken in countries where MMT is used in all gasoline. © 2005, Elsevier Ltd.