Source apportionment and dispersion mapping of fugitive dust using directional passive monitors
Student thesis: Doctoral Thesis
This study combines passive directional dust monitoring methods with ICP-MS analysis, binary mixing modelling and geostatistical modelling to generate dust dispersion maps, enabling a record of Air Pollution Control residue (APC) dust dispersion on and around a hazardous waste landfill site for a complete calendar year. This is therefore, the first study of nuisance dust dispersion on such a scale, using these methods, and the first time these methods have been used in conjunction to accurately visualise dust dispersion data over time. The proportion of APC in fugitive dust at and around the Wingmoor Farm hazardous waste landfill site near Bishop’s Cleeve, Gloucestershire, UK, was quantified and mapped using passive directional samplers, which were deployed both on the site and in farmland to the north and north-east. Samples from 19 monitors, collected fortnightly over the year, were analysed for Absolute Area Coverage (AAC) and Effective Area Coverage (EAC) prior to HF and HNO3 digestion and analysis by ICP-MS. Following geochemical characterisation of the two key “end-members”, background soils (sand and gravel, and clay) and APC, Ca/Fe and Mn/Pb mixing models were developed providing a means of determining the proportion of APC in each sample. Sample proportions derived from each mixing model were mapped using both variograms and kriging, supported through ISATISTM, to build a model of both general dust and APC dispersion over a square kilometre for the year. Meteorological conditions and movements on site were also recorded and their relationships with dust levels in the surrounding area analysed. APC was found at off-site monitoring locations throughout the year, however at far lower levels than previously assumed by prior modelling exercises. The maps presented a visualisation of dust dispersion on- and off-site, demonstrating the viability of this methodology for modelling both fugitive general dust, and, in this case, APC. In combination with the other data collected on-site, factors affecting the dispersion of both general dust and APC were identified. The development of this modelling and mapping method provides a novel, robust and cost-effective technique for both representing and understanding the dispersion of APC, delivering a useful tool for practical application by industry, local government and in the field of Environmental Forensics.
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