Brendan Halliburton

Differential injurious effects of ambient and traffic-derived particulate matter on airway epithelial cells

Exposure to airborne particulate matter (PM) may promote development of childhood asthma and trigger acute exacerbations of existing asthma via injury to airway epithelial cells (AEC).

Characterization and ecological risk assessment of nanoparticulate CeO2 as a diesel fuel catalyst.

Nanoparticulate cerium dioxide (nano-CeO2 ), when combusted as an additive to diesel fuel, was transformed from 6 nm to 14 nm sizes into particles near 43 nm, with no obvious change in the unit cell dimensions or crystalline form. Cerium sulfate, if formed during combustion, was below detection limits. Ceria nanoparticles were agglomerated within the soot matrix, with a mean aerodynamic diameter near 100 nm. The dissolution of cerium from the dried ceria catalyst in synthetic soft water was extremely small (<0.0006% or <0.2 µg Ce/L), with particles being highly agglomerated (<450 nm). Agglomeration was reduced in the presence of humic acid. In the combusted samples, soot was dominant, and the solubility of cerium in soft water showed an almost 100-fold increase in the <1 nm fraction compared to that before combustion. It appeared that the nano-CeO2 remained agglomerated within the soot matrix and would not be present as dispersed nanoparticles in aquatic or soil environments. Despite the increased dissolution, the solubility was not sufficient for the combusted ceria to represent a risk in aquatic ecosystems. The predicted environmental concentrations were still orders of magnitude below the predicted no effects concentration of near 1 mg/L. In the soil environment, any cerium released from soot materials would interact with natural colloids, decreasing cerium concentrations in soil solutions and further minimizing the potential risk to soil organisms.

Techniques for Repeatable Measurement of PM Emissions from Light Duty Gasoline Vehicles

Concern over exhaust fine particles (sub-2.5 µm) emissions from the transport sector due to their adverse health effects, has spread to include those from gasoline powered vehicles which are believed to dominate the fine particle size spectrum in urban centres. The measurement of fine particle emissions from gasoline light duty engines poses many technical challenges [1][2]. This paper discusses the methodology, testing and analysis protocols developed to allow the accurate quantification of PM from light duty gasoline vehicles. The developed methodology was used as part of an Australian Government funded study into the assessment of the health impacts of ethanol blend fuels [3].

Development of a new smog chamber for studying the impact of different UV lamps on SAPRC chemical mechanism predictions and aerosol formation

Environmental context Chemical mechanisms are an important component of predictive air quality models that are developed using smog chambers. In smog chamber experiments, UV lamps are often used to simulate sunlight, and the choice of lamp can influence the obtained data, leading to differences in model predictions. We investigate the effect of various UV lamps on the prediction accuracy of a key mechanism in atmospheric chemistry. Abstract A new smog chamber was constructed at CSIRO following the decommissioning of the previous facility. The new chamber has updated instrumentation, is 35 % larger, and has been designed for chemical mechanism and aerosol formation studies. To validate its performance, characterisation experiments were conducted to determine wall loss and radical formation under irradiation by UV lamps. Two different types of blacklights commonly used in indoor chambers are used as light sources, and the results using these different lamps are investigated. Gas-phase results were compared against predictions from the latest version of the SAPRC chemical mechanism. The SAPRC mechanism gave accurate results for hydrocarbon reaction and oxidation formation for propene and o-xylene experiments, regardless of the light source used, with variations in ozone concentrations between experiment and modelled results typically less than 10 % over 6-h irradiation. The SAPRC predictions for p-xylene photooxidation showed overprediction in the rate of oxidation, although no major variations were determined in mechanism results for different blacklight sources. Additionally, no significant differences in the yields of aerosol arising from new particle formation were discernible regardless of the light source used under these conditions.

Fugitive greenhouse gas emissions in ventilation air from Australian underground coal mines

Seam gas released during coal mining is a substantial source of fugitive greenhouse gas emissions worldwide. Most of these emissions originate from underground mining; however, lack of robust global data means that the scale of emissions remains uncertain. Some coal-producing countries are attempting to improve the quality of emission estimates by using ventilation data to calculate emissions from individual mines. Legislation recently introduced in Australia now requires coal mine operators to estimate and report annual fugitive emissions. This article examines the methodology currently used at most Australian mines to meet these requirements. To assess the performance of this methodology, we compared the results of routine measurements of ventilation air flow rate and gas composition to those made with reference methods. The primary sources of uncertainty in the techniques are identified and their contributions to the uncertainty of the reported fugitive emission fluxes are estimated.

Synthetic aerosols from fine carbon nanotubes of 10 nanometres diameter

Aerosol generation, sampling and analysis for fine carbon nanotubes (CNT) of 10nm diameter is demonstrated and compared to structures formed by coarse CNT. Aggregate structures formed in an aerosol are coil-shaped for fine CNT and bundles for coarse CNT. These structures could be an expression of differences in their physical properties, such as the bending stiffness.