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    Surface ozone exceedances in Melbourne, Australia are shown to be under NOx control, as demonstrated using formaldehyde:NO2 and glyoxal:formaldehyde ratios
    Ryan, RG ; Rhodes, S ; Tully, M ; Schofield, R (ELSEVIER, 2020-12-20)
    Two and a half years of multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements of nitrogen dioxide (NO2), formaldehyde (HCHO) and glyoxal (CHOCHO) are presented alongside in-situ ozone (O3) measurements in Melbourne, Australia. Seasonal and diurnal cycles, vertical profiles and relationships with key meteorological variables are provided. NO2 and CHOCHO were found at highest concentration for low wind speeds implying that their sources were predominantly localised and anthropogenic. HCHO showed an exponential relationship with temperature and a strong wind direction dependence from the northern and eastern sectors, and therefore most likely originated from oxidation of biogenic volatile organic compounds (VOCs) from surrounding forested and rural areas. The glyoxal:formaldehyde ratio (Rgf), reported for the first time in Australia, was consistently high compared to values elsewhere in the world with a mean of 0.105 ± 0.0503 and tended to increase with increasing anthropogenic influence. The HCHO:NO2 ratio (Rfn) was used to characterise tropospheric ozone formation conditions. A strong relationship was found between high temperature, low Rgf, high Rfn and high ozone surface concentrations. Therefore, we propose that both Rgf and Rfn may be useful indicators of tropospheric ozone production regimes and concentrations. The Rfn showed that the vast majority of high ozone production episodes occurred under NOx-limited conditions, suggesting that surface ozone pollution events in Melbourne could be curtailed using NOx emission controls.
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    Inquiry into the health impacts of air pollution in Victoria
    Walter, C ; Schofield, R ; Anderson, G ; Stone, J ; Wadlow, I ; Irving, L (Victorian Government, 2021-04-26)
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    Response to Issues Paper: Health arrangements in natural disasters of the Natural Disaster Royal Commission
    Schofield, R ; Silver, J ; Ryan, R ; Walter, C ; Rayner, P ; Murphy, C ; Deutscher, N ; Fisher, J ; Forehead, H ; Heyworth, J ; Ristovski, Z ; Morwaska, L ; Miljevic, B (National Disaster Royal Commission, 2020-06-30)
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    Use of portable air cleaners to reduce aerosol transmission on a hospital COVID-19 ward
    Buising, KL ; Schofield, R ; Irving, L ; Keywood, M ; Stevens, A ; Keogh, N ; Skidmore, G ; Wadlow, I ; Kevin, K ; Rismanchi, B ; Wheeler, AJ ; Humphries, RS ; Kainer, M ; Mcgain, F ; Monty, J ; Marshall, C (Cambridge University Press, 2021-01-01)
    Objective To study the airflow, transmission and clearance of aerosols in the clinical spaces of a hospital ward that had been used to care for patients with COVID-19, and to examine the impact of portable air cleaners on aerosol clearance. Design: Observational study. Setting: A single ward of a tertiary public hospital in Melbourne Australia. Intervention: Glycerine-based aerosol was used as a surrogate for respiratory aerosols. The transmission of aerosols from a single patient room into corridors and a nurses’ station in the ward was measured. The rate of clearance of aerosols was measured over time from the patient room, nurses’ station and ward corridors with and without air cleaners (also called portable HEPA filters). Results: Aerosols rapidly travelled from the patient room into other parts of the ward. Air cleaners were effective in increasing the clearance of aerosols from the air in clinical spaces and reducing their spread to other areas. With two small domestic air cleaners in a single patient room of a hospital ward, 99% of aerosols could be cleared within 5.5 minutes. Conclusion: Air cleaners may be useful in clinical spaces to help reduce the risk of healthcare acquired acquisition of respiratory viruses that are transmitted via aerosols. They are easy to deploy and are likely to be cost effective in a variety of healthcare settings.
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    Atmospheric Trace Metal Deposition from Natural and Anthropogenic Sources in Western Australia
    Strzelec, M ; Proemse, BC ; Barmuta, LA ; Gault-Ringold, M ; Desservettaz, M ; Boyd, PW ; Perron, MMG ; Schofield, R ; Bowie, AR (MDPI AG, 2020-05-07)
    Aerosols from Western Australia supply micronutrient trace elements including Fe into the western shelf of Australia and further afield into the Southern and Indian Oceans. However, regional observations of atmospheric trace metal deposition are limited. Here, we applied a series of leaching experiments followed by total analysis of bulk aerosol samples to a unique time-series of aerosol samples collected in Western Australia to determine atmospheric concentrations and solubilities of Fe and V, Mn, Co, Zn, and Pb. Positive matrix factorisation analysis indicated that mineral dust, biomass burning particulates, sea salt, and industrial emissions were the major types of aerosols. Overall, natural sources dominated Fe deposition. Higher atmospheric concentrations of mineral dust (sixfold) and biomass burning emissions were observed in warmer compared to cooler months. The fraction of labile Fe (0.6–6.0%) was lower than that reported for other regions of Australia. Bushfire emissions are a temporary source of labile Fe and may cause a peak in the delivery of its more easily available forms to the ocean. Increased labile Fe deposition may result in higher ocean productivity in regions where Fe is limiting, and the effect of aerosol deposition on ocean productivity in this region requires further study.
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    Atmospheric Trace Metal Deposition near the Great Barrier Reef, Australia
    Strzelec, M ; Proemse, BC ; Gault-Ringold, M ; Boyd, PW ; Perron, MMG ; Schofield, R ; Ryan, RG ; Ristovski, ZD ; Alroe, J ; Humphries, RS ; Keywood, MD ; Ward, J ; Bowie, AR (MDPI, 2020-04)
    Aerosols deposited into the Great Barrier Reef (GBR) contain iron (Fe) and other trace metals, which may act as micronutrients or as toxins to this sensitive marine ecosystem. In this paper, we quantified the atmospheric deposition of Fe and investigated aerosol sources in Mission Beach (Queensland) next to the GBR. Leaching experiments were applied to distinguish pools of Fe with regard to its solubility. The labile Fe concentration in aerosols was 2.3–10.6 ng m−3, which is equivalent to 4.9%–11.4% of total Fe and was linked to combustion and biomass burning processes, while total Fe was dominated by crustal sources. A one-day precipitation event provided more soluble iron than the average dry deposition flux, 0.165 and 0.143 μmol m−2 day−1, respectively. Scanning Electron Microscopy indicated that alumina-silicates were the main carriers of total Fe and samples affected by combustion emissions were accompanied by regular round-shaped carbonaceous particulates. Collected aerosols contained significant amounts of Cd, Co, Cu, Mo, Mn, Pb, V, and Zn, which were mostly (47.5%–96.7%) in the labile form. In this study, we provide the first field data on the atmospheric delivery of Fe and other trace metals to the GBR and propose that this is an important delivery mechanism to this region.
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    Characterization of aerosols over the Great Barrier Reef: The influence of transported continental sources
    Chen, Z ; Schofield, R ; Rayner, P ; Zhang, T ; Liu, C ; Vincent, C ; Fiddes, S ; Ryan, RG ; Alroe, J ; Ristovski, ZD ; Humphries, RS ; Keywood, MD ; Ward, J ; Paton-Walsh, C ; Naylor, T ; Shu, X (ELSEVIER, 2019-11-10)
    The rapid environmental changes in Australia prompt a more thorough investigation of the influence of transportation, local emissions, and optical-chemical properties on aerosol production across the region. A month-long intensive measurement campaign was conducted during spring 2016 at Mission Beach, a remote coastal site west of the Great Barrier Reef (GBR) on the north-east coast of Australia. One aerosol pollution episode was investigated in early October. This event was governed by meteorological conditions and characterized by the increase in black carbon (BC) mass concentration (averaged value of 0.35 ± 0.20 μg m-3). Under the influence of the continental transportation, a new layer of nucleation-mode aerosols with an initial size diameter of 20 nm was observed and aerosol number concentrations reached the peak of 6733 cm-3 at a diameter of 29 nm. The averaged aerosol extinction coefficient at the height of 2 km was 150 Mm-1, with a small depolarized ratio (3.5-5%). Simultaneously, the boundary layer height presented a fall-rise trend in the presence of these enhanced aerosol concentrations and became stable in a later stage of the episode. We did not observe clear boundary layer height diurnal variations from the LiDAR observations or from the Weather Research and Forecasting (WRF) model outputs, except in an earlier stage of the aerosol episode for the former. Although the sea breeze may have been responsible for these particles, on the balance of available data, we suggest that the aerosol properties at the GBR surface during this period are more likely influenced by regional transportation of continental sources, including biomass-burning aerosols.
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    Evaluating the Relationship between Interannual Variations in the Antarctic Ozone Hole and Southern Hemisphere Surface Climate in Chemistry-Climate Models
    Gillett, ZE ; Arblaster, JM ; Dittus, AJ ; Deushi, M ; Joeckel, P ; Kinnison, DE ; Morgenstern, O ; Plummer, DA ; Revell, LE ; Rozanov, E ; Schofield, R ; Stenke, A ; Stone, KA ; Tilmes, S (AMER METEOROLOGICAL SOC, 2019-06-01)
    Studies have recently reported statistically significant relationships between observed year-to-year spring Antarctic ozone variability and the Southern Hemisphere annular mode and surface temperatures in spring–summer. This study investigates whether current chemistry–climate models (CCMs) can capture these relationships, in particular, the connection between November total column ozone (TCO) and Australian summer surface temperatures, where years with anomalously high TCO over the Antarctic polar cap tend to be followed by warmer summers. The interannual ozone–temperature teleconnection is examined over the historical period in the observations and simulations from the Whole Atmosphere Community Climate Model (WACCM) and nine other models participating in the Chemistry–Climate Model Initiative (CCMI). There is a systematic difference between the WACCM experiments forced with prescribed observed sea surface temperatures (SSTs) and those with an interactive ocean. Strong correlations between TCO and Australian temperatures are only obtained for the uncoupled experiment, suggesting that the SSTs could be important for driving both variations in Australian temperatures and the ozone hole, with no causal link between the two. Other CCMI models also tend to capture this relationship with more fidelity when driven by observed SSTs, although additional research and targeted modeling experiments are required to determine causality and further explore the role of model biases and observational uncertainty. The results indicate that CCMs can reproduce the relationship between spring ozone and summer Australian climate reported in observational studies, suggesting that incorporating ozone variability could improve seasonal predictions; however, more work is required to understand the difference between the coupled and uncoupled simulations.
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    Submission to Victorian State Government in response to “Clean Air for All Victorians’ Victoria’s Air Quality Statement
    Fiddes, S ; Schofield, R ; Silver, J ; Rayner, P ; Murphy (Paton-Walsh), C ; Brear, M ; Manzie, C ; Walter, C ; Irving, L ; Johnston, F ; Abramson, M ; Heyworth, J ; Dharmage, S ( 2018)