The Characterisation of Airborne Particulate Matter by Automated Mineralogy: The Potential of the Mineral Liberation Analyser for the Monitoring of Mine-Derived Emissions. Michele Elmes BSc Honours 0000-0003-3194-3354 A thesis submitted for the degree of Doctor of Philosophy at the University of Queensland in 2020 School of Earth and Environmental Sciences Abstract With its links to adverse environmental and human health impacts, air pollution is an increasing and ubiquitous global concern. Air pollution, especially the particulate matter component, has been linked to cancer, pulmonary and cardiac disease, neurotoxicity and pernicious impacts on fertility and pregnancy. It has also been observed to affect climate by altering the radiation and chemical balance of the atmosphere. Unlike other pollution vectors, airborne particles are not constrained by topography, enabling them to be rapidly dispersed over vast distances. Although international air quality guidelines have been implemented, more than 90% of the global population are exposed to levels higher than those recommended by the World Health Organisation. Airborne particulate matter (APM) is a physically and chemically complex mix of organic and inorganic substance and, to accurately assess the potential environmental and human health implications, a detailed physical and compositional characterisation at the single particle level is required. The ultimate goal of an analytical technique for APM is to quantitatively identify all the chemical species within each individual particle to predict potential impacts and develop successful mitigation strategies. Micro-beam techniques, such as energy dispersive scanning electron microscopy (SEM-EDS) have been used extensively to generate information on the physical, morphological and chemical properties of single atmospheric particles down to a nominal diameter of 0.1µm. Traditional SEM-EDS methods, however, are prone to operator error and bias and the manual data processing is time consuming and costly and therefore impractical for regular monitoring purposes. As a result, computer-controlled SEM (CCSEM) is rapidly gaining predominance. Although the use of automated SEM-EDS analysis is well documented, few studies to date have used automated mineralogy systems, such as the Mineral Liberation Analyzer (MLA). The MLA was designed to improve the efficiency of mineral processing plants and, although the technique has been extensively used in the mining industry since its inception, it is only recently that this technique has been applied to other environmental fields. To our knowledge this is the first time the MLA has been used in the application of ambient APM analysis and has the potential to be a powerful tool in the APM analytical arsenal. 2 Prior to APM analysis, a suitable sampling and sample preparation technique was determined, a spectral reference library constructed and the accuracy and precision of the instrument tested by repeat analysis and comparison to certified reference materials (CRM), with mineral abundances (modal mineralogy) and repeat analysis showing relative standard deviations typically below 10%. Using the developed methodology, ambient APM was collected from four stations in the vicinity of a large iron-ore mining operation in Congonhas, Minas Gerais, Brazil, as well a control station lying outside the influence of the mine. To observe spatio-temporal variations, sampling was conducted over the dry, wet and transitional periods. The mineral phases observed strongly reflected the local geology, with clays and iron oxides contributing 70-80% of the particulates sampled. Particle size distributions reflected sources dominated by mechanical processes, with coarse particles (>2.5µm) accounting for 80-90%. A strong seasonality was observed with coarser particles more prevalent during the drier periods of May and August, with fine particles (<2.5µm) contributing to less than 10% of the total particulates sampled. Although the transport and ultimate fate of APM is largely controlled by particle size and shape, chemical species is critical in assessing the potential toxicity, as different species of the same elements can have different toxicological properties, bulk elemental concentrations may not be a true representation of bioaccessibility. As a result the ability to accurately identify potentially toxic elements in the atmosphere is essential to formulate a realistic risk assessment. Manganese bearing particles, predominantly Mn oxides and jacobsite, were detected in appreciable numbers, although only contributing to less than 1% of the total particulates sampled. The particle size distribution, however, indicated a geogenic, rather than anthropogenic, source. As deposition within the human lung is largely determined by size and density, the predominantly coarse particles and relatively insoluble mineral phases, suggested that the risk of inhalation toxicity for the exposed population is potentially relatively small. 3 Declaration by Author This thesis is composed of my original work, and contains no material previously published or written by another person except where due reference has been made in the text. I have clearly stated the contribution by others to jointly-authored works that I have included in my thesis. I have clearly stated the contribution of others to my thesis as a whole, including statistical assistance, survey design, data analysis, significant technical procedures, professional editorial advice, financial support and any other original research work used or reported in my thesis. The content of my thesis is the result of work I have carried out since the commencement of my higher degree by research candidature and does not include a substantial part of work that has been submitted to qualify for the award of any other degree or diploma in any university or other tertiary institution. I have clearly stated which parts of my thesis, if any, have been submitted to qualify for another award. I acknowledge that an electronic copy of my thesis must be lodged with the University Library and, subject to the policy and procedures of The University of Queensland, the thesis be made available for research and study in accordance with the Copyright Act 1968 unless a period of embargo has been approved by the Dean of the Graduate School. I acknowledge that copyright of all material contained in my thesis resides with the copyright holder(s) of that material. Where appropriate I have obtained copyright permission from the copyright holder to reproduce material in this thesis and have sought permission from co-authors for any jointly authored works included in the thesis. 4 Publications included in this thesis The following publication has been incorporated as Chapter 2. ELMES, M. & GASPARON, M. 2017. Sampling and single particle analysis for the chemical characterisation of fine atmospheric particulates: A review. J Environ Manage, 202, 137-150. Contributor Statement of contribution % Michele Elmes Drafting of Manuscript 100 Preparation of figures 100 Study Conception and Design 50 Massimo Gasparon Supervision, guidance 100 Study Conception and Design 50 The following publication has been incorporated as Chapter 4. ELMES, M., DELBEM, I., GASPARON, M. & CIMINELLI, V. 2020. Single-particle analysis of atmospheric particulate matter using automated mineralogy: the potential for monitoring mine-derived emissions. International Journal of Environmental Science and Technology. Contributor Statement of contribution % Michele Elmes Drafting of Manuscript 90 Acquisitio n of Data 10 Preparation of Figures 50 Interpretation of Data 60 Itamar Delbem Drafting of Manuscript 5 Acquisitio n of Data 90 Preparation of Figures 50 Massimo Gasparon Study conception and design 50 Supervision, guidance 50 Drafting of Manuscript 5 Interpretation of Data 20 Preparation of Figures 10 Critical Revisio n 50 Virginia Cimine lli Study conception and design 50 Supervision, guidance 50 Interpretation of Data 20 Critical Revisio n 50 5 Other publications during candidature GASPARON, M., DELBEM, I., ELMES, M. & CIMINELLI, V. Detection and analysis of arsenic-bearing particles in atmospheric dust using Mineral Liberation Analysis. Arsenic Research and Global Sustainability: Proceedings of the Sixth International Congress on Arsenic in the Environment (As2016), June 19-23, 2016, Stockholm, Sweden, 2016. CRC Press, 217. MOSTERT, M., GASPARON, M. & ELMES, M. 2017. Analysis of Iron Ores by Fusion and ICP-OES. AXT Application note, 1-9, http://www.axt.com.au/analysis-of-iron-ores-by-fusion-and-icp-oes/ Contributions by others to the thesis No contributions by others Statement of parts of the thesis submitted to qualify for the award of another degree No works submitted towards another degree have been included in this thesis. Research involving human or animal subjects No animal or human subjects were involved in this research. 6 Acknowledgments I would like to thank my supervisors Massimo Gasparon and Virginia Ciminelli, whose brainchild this project is, for their guidance, support and encouragement. I would like to thank my supervisor Carlos Spiers for helping me when everything seemed lost. I am grateful to Itamar Delbem at the Federal University of Minas Gerais (UFMG) for his patience training me on the MLA, his tireless work analysing the samples and his continued support throughout the project. I am also grateful to all the people at the UFMG Centre of Microscopy for providing the equipment and support for all MLA analyses and