Enhancing the application of field portable x-ray fluorescence technology for the measurement of metal-contaminated soils

Field portable X-ray Fluorescence (pXRF) is utilised widely for a variety of environmental applications due to its rapid and inexpensive estimation of metal(loid) concentrations. The use of pXRF for metal-contaminated soil screening is an emerging measurement approach,however, its use for final quantitative assessments is less common, largely due to data quality concerns. This thesis evaluates the application of pXRF for the measurement of metal contaminated soils and in turn, assesses data quality, reliability and application benefits. The thesis research applies an evidence-based approach across five inter-related papers that examinea broad spectrum of pXRF-related misconceptions. These studies cover user safety, ex-situ and in-situ analytical performance for assessment of metal-contaminated sites and related environmental investigations. The thesis is comprised of a technical assessment of pXRF and its application to investigate and understand environmental contamination problems.The technical assessment component of the thesis is comprised of: the measurement of radiation dose rates from four different pXRF spectrometers to determine user pXRF-related radiation exposure an analytical evaluation of ex-situ pXRF to assess the accuracy, precision and detection limits of pXRF during the measurement of metal-contaminated soils an assessment of in-situ pXRF application for metal-contaminated site assessments to evaluate the benefits of lower cost and high volume sampling using pXRF compared to the current approach of less sampling and ex-situ wet chemistry analysis.The use of pXRF for the investigation of urban metal contamination is executed using two cases studies from Sydney and Newcastle in New South Wales: analysis of domestic garden soils collected as part of Macquarie University's free soil metal analysis program (VegeSafe) assessment of inorganic and organic contaminants collected from public and private soils in a former industrial city. The outcomes of the evaluation and application of pXRF demonstrates that it is safe for users and is capable of generating accurate and inexpensive geochemical measurements of soils for a range of metal-contaminants. In addition to the five papers on pXRF, this thesis presents three additional case studies examining contemporary and legacy metal contamination hazards in other mining and urban centres across Australia. Collectively, these research studies demonstrate that both legacy and contemporary environmental contamination by toxic metal(loid)s remains a hazard and a potential risk of harm to Australian residents.