Browsing by Author "Hawas, O"

Now showing 1 - 6 of 6
  • Thumbnail Image
    Item
    Apiezon L-type grease coating of 8-µm Nuclepore Polycarbonate coarse filters used in GENT aerosol sampling units
    (Australian Nuclear Science and Technology Organisation, 2006-04) Stelcer, E; Noorman, J; Button, D; Hawas, O; Cohen, DD
    Coarse stage Nuclepore filters used in GENT aerosol sampling units were coated with a thin film of Apiezon L-type grease in order to minimise the loss of particles on the filters due to 'bounce off'. Originally Freon was used as the solvent to dissolve the Apiezon grease in the coating process. Because of the environmental impact, Freon was discontinued and replaced with Fluorinert. Apiezon grease did not dissolve freely in the Fluorinert and it was replaced by Fomblin grease in 1995. This increased production costs and coated Nuclepore coarse filters ceased production in 2004. Users were concerned that their stocks of coated Nuclepore filters were diminishing and as no alternative supply was available the feasibility of coating the coarse filters in house needed to be investigated. This report describes experiments conducted at ANSTO and the results obtained during the investigation of the coating process under laboratory conditions. Apiezon grease and Toluene were used in this process. Experiments were based on the procedure proposed by Prof P. Hopke and Dr A. Markwitz [1] with modification to this technique to increase the uniformity of the grease layer across the filter surface and to achieve approximately 100 µg of Apiezon grease per filter.
  • No Thumbnail Available
    Item
    Apportionment of sources of fine and coarse particles in four major Australian cities by positive matrix factorisation
    (Elsevier, 2008-01) Chan, YC; Cohen, DD; Hawas, O; Stelcer, E; Simpson, R; Denison, L; Wong, N; Hodge, M; Comino, E; Carswell, S
    In this study, 437 days of 6-daily, 24-h samples Of PM2.5, PM2.5-10 and PM10 were collected over a 12-month period during 2003-2004 in Melbourne, Sydney, Brisbane and Adelaide. The elemental, ionic and polycyclic aromatic hydrocarbon composition of the particles were determined. Source apportionment was carried out by using the positive matrix factorisation software (PMF2). Eight factors were identified for the fine particle samples including 'motor vehicles', 'industry', 'other combustion sources', 'ammonium sulphates', 'nitrates', 'marine aerosols', 'chloride depleted marine aerosols' and 'crustal/soil dust'. On average combustion sources, secondary nitrates/sulphates and natural origin dust contributed about 46%, 25% and 26% of the mass of the fine particle samples, respectively. 'Crustal/soil dust', 'marine aerosols', 'nitrates' and 'road side dust' were the four factors identified for the coarse particle samples. On average natural origin dust contributed about 76% of the mass of the coarse particle samples. The contributions of the sources to the sample mass basically reflect the emission source characteristics of the sites. Secondary sulphates and nitrates were found to spread out evenly within each city. The average contribution of secondary nitrates to fine particles was found to be rather uniform in different seasons, rather than higher in winter as found in other studies. This could be due to the low humidity conditions in winter in most of the Australian cities which made the partitioning of the particle phase less favourable in the NH4NO3 equilibrium system. A linear relationship was found between the average contribution of marine aerosols and the distance of the site from the bay side. Wind erosion was found associated with higher contribution of crustal dust on average and episodes of elevated concentration of coarse particles in spring and summer. © 2007, Elsevier Ltd.
  • No Thumbnail Available
    Item
    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.
  • No Thumbnail Available
    Item
    IBA methods for characterisation of fine particulate atmospheric pollution: a local, regional and global research problem
    (Elsevier B. V., 2004-06) Cohen, DD; Stelcer, E; Hawas, O; Garton, D
    The IBA techniques of PIXE, PIGE, RBS and PESA have been used simultaneously to analyse fine particle pollution collected on Teflon filters. This provided a suite of 23 elements from hydrogen to lead which can be used to characterisation and fingerprint pollution sources and estimate their contributions to the total mass loading. These methods have been demonstrated to be applicable for aerosol pollution studies on a local, regional and even globe scale on time frames from a few days to decades. © 2020 Elsevier B.V
  • Thumbnail Image
    Item
    Source apportionment of ambient volatile organic compounds in major cities in Australia by positive matrix factorisation
    (Clean Air Society of Australia and New Zealand, 2008-05) Chan, AYC; Christensen, E; Golding, G; King, GF; Gore, W; Cohen, DD; Hawas, O; Stelcer, E; Simpson, R; Denison, L; Wong, N
    Source apportionment of the 6-daily, 24 h volatile organic compound (VOC) samples collected during 2003–2004 in Melbourne, Sydney and Brisbane was carried out using the Positive Matrix Factorisation software (PMF2). Fourteen C4-C10 VOCs were chosen for source apportionment. Biogenic emissions were not covered in this study because tracer VOCs such as isoprene were not measured. Five VOC source factors were identified, including the ‘evaporative / fuel distribution’ factor (contribute to 37% of the total mass of the 14 VOCs on average), the ‘vehicle exhaust / petrochemical industry’ factor (24%), the ‘biomass burning’ factor (13%), the ‘architectural surface coatings’ factor (5%) and the ‘other sources’ factor (14%). The relative contributions of the source factors to the ambient VOC concentration at the sampling sites were comparable to the relative emission loads of the local sources in Australian air emission inventories. The high contribution from evaporative emissions indicates that introduction of reduction measures for evaporative emissions could substantially reduce the VOC emissions in Australian cities. The total VOC mass and the contributions from vehicle related sources and biomass burning were higher in winter and autumn, while the contributions from surface coatings were higher in summer. © 2008, Clean Air Society of Australia and New Zealand
  • No Thumbnail Available
    Item
    Using multiple type composition data and wind data in PMF analysis to apportion and locate sources of air pollutants.
    (Elsevier, 2011-01) Chan, YC; Hawas, O; Hawker, D; Vowles, P; Cohen, DD; Stelcer, E; Simpson, R; Golding, G; Christensen, E
    In this study a small but comprehensive data set from a 24-hourly sampling program carried out during June 2001 in an industrial area in Brisbane was chosen to investigate the effect of inclusion of multiple type composition data and wind data on source apportionment of air pollutants using the Positive Matrix Factorisation model, EPA PMF 3.0. The combined use of aerosol, VOC, main gaseous pollutants composition data and wind data resulted in better values of statistical indicators and diagnostic plots, and source factors which could be more easily related to known sources. The number of source factors resolved was similar to those reported in the literature where larger data sets were used. Three source factors were identified for the coarse particle samples, including ‘crustal matter’, ‘vehicle emissions’ and ‘sea spray’. Seven source factors were identified for the fine particle and VOC samples, including ‘secondary and biogenic’, ‘petroleum refining’, ‘vehicle emissions’, ‘petroleum product wholesaling’, ‘evaporative emissions’, ‘sea spray’ and ‘crustal matter’. The factor loadings of the 16 wind sectors and the calm wind sector from the PMF analysis were also used to quantify the directional contribution of the source factors. While the contributions were higher in the prevailing wind directions as expected, calm winds were also found to contribute up to 17% of the pollutant mass on average. The factor loadings, normalised by the overall abundance of the wind sectors, were also used to assess the directional dependences of the source factors. The results matched well with the location of known sources in the area. There was also a higher contribution potential from calm winds for local sources compared to that for distant sources. The results of directional effect using the PMF factor loading approach were similar to those by using the other approaches. This approach, however, also provides estimates of the mass contribution of source factors by wind sector and also the uncertainty of the results. © 2011, Elsevier Ltd.