Browsing by Author "Bandy, Brian J."

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    Chemical characterisation of water-soluble ions in atmospheric particulate matter on the East Coast of Peninsular Malaysia
    (European Geosciences Union (EGU) / Copernicus Publications, 2019-02-06) Farren, Naomi J.; Dunmore, Rachel E.; Mead, Mohammed Iqbal; Mohd Nadzir, Mohd Shahrul; Abu Samah, Azizan; Phang, Siew-Moi; Bandy, Brian J.; Sturges, William T.; Hamilton, Jacqueline F.
    Air quality on the east coast of Peninsular Malaysia is influenced by local anthropogenic and biogenic emissions as well as marine air masses from the South China Sea and aged emissions transported from highly polluted East Asian regions during the winter monsoon season. An atmospheric observation tower has been constructed on this coastline at the Bachok Marine Research Station. Daily PM2.5 samples were collected from the top of the observation tower over a 3-week period, and ion chromatography was used to make time-resolved measurements of major atmospheric ions present in aerosol. SO 2− 4 was found to be the most dominant ion present and on average made up 66 % of the total ion content. Predictions of aerosol pH were made using the ISORROPIA II thermodynamic model, and it was estimated that the aerosol was highly acidic, with pH values ranging from −0.97 to 1.12. A clear difference in aerosol composition was found between continental air masses originating from industrialised regions of East Asia and marine air masses predominantly influenced by the South China Sea. For example, elevated SO 2− 4 concentrations and increased Cl− depletion were observed when continental air masses that had passed over highly industrialised regions of East Asia arrived at the measurement site. Correlation analyses of the ionic species and assessment of ratios between different ions provided an insight into common sources and formation pathways of key atmospheric ions, such as SO 2− 4 , NH + 4 and C 2 O 2− 4 . To our knowledge, time-resolved measurements of water-soluble ions in PM2.5 are virtually non-existent in rural locations on the east coast of Peninsular Malaysia. Overall this dataset contributes towards a better understanding of atmospheric composition in the Maritime Continent, a region of the tropics that is vulnerable to the effects of poor air quality, largely as a result of rapid industrialisation in East Asia.
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    Development of a combined heart-cut and comprehensive two-dimensional gas chromatography system to extend the carbon range of volatile organic compounds analysis in a single instrument
    (MDPI, 2016-07-20) Dunmore, Rachel E.; Hopkins, James R.; Lidster, Richard T.; Mead, Mohammed Iqbal; Bandy, Brian J.; Forster, Grant; Oram, David E.; Sturges, William T.; Phang, Siew-Moi; Samah, Azizan Abu; Hamilton, Jacqueline F.
    The majority of atmospheric measurements of volatile organic compounds (VOCs) are usually limited to a small range, either in volatility or time resolution. A combined heart-cut gas chromatography (GC) with comprehensive two-dimensional GC (GC×GC) instrument was developed, specifically to increase the number of VOCs analysed using a single instrument. The system uses valve based modulation and was fully automated, making it suitable for use in the field. A laboratory comparison to an existing dual-channel GC (DC-GC) instrument demonstrated that this new GC-GC×GC can accurately measure atmospheric mixing ratios of C 5 -C 13 VOC species with a wide range of functionalities. Approximately hourly field measurements were conducted at a remote marine atmospheric research station in Bachok, Malaysia. This region was shown to be influenced by clean marine air masses, local anthropogenic and biogenic emission sources and aged emissions transported from highly polluted South East Asian regions. A dramatic shift in air mass direction was observed each day associated with the development of a sea breeze, which influenced the diurnal profiles of species measured at the Bachok site. A proton-transfer-reaction mass spectrometer (PTR-MS) was also deployed at Bachok and compared to the new GC-GC×GC instrument. Overall, the GC-GC×GC instrument has been shown to perform well in lab comparisons and during field observations. This represents a good compromise between volatility and high complexity online measurements of VOCs.