PROJECT SUMMARY (Project 7; Betterton, Saez, Sorooshian, Arellano) Mining operations are potential sources of airborne metal and metalloid contaminants through both direct smelter emissions and wind erosion of mine tailings and other mineral deposits, especially in the semi-arid setting of the Southwestern US. The warmer, drier conditions predicted by climate models for this region may make contaminated atmospheric dust and aerosols increasingly important in the future due to their potential for exerting harmful effects on human and environmental health. The physicochemical characteristics and size distribution of atmospheric dust and aerosols will impact the distance of transport and the bioaccessibility of particulate-associated metal contaminants both in the environment and in the human respiratory tract. One of the field sites targeted by this project, the mine tailings impoundment at the Iron King Mine Humboldt Superfund Site (IKMHSS) is heavily contaminated (concentrations reaching up to thousands of parts-per- million) with lead, arsenic and other metals. The overall objective of the proposed work is to develop tools to predict metal transport by dust and by aerosol from mining operations at local, regional, and global scales. A computational fluid dynamics (CFD) model previously developed will be calibrated to be used as a forecast tool to predict airborne particulate matter, arsenic, and lead concentrations downwind of the IKMHSS tailings impoundment. In this work, we will measure and correlate dust generation from mine tailings and soils, using a portable wind tunnel that we have designed. Dust emission correlations and the local CFD model will be integrated into a regional model to predict long-range transport of dust and aerosols using large-scale weather forecasting tools. Physicochemical characterization of the dust and aerosol (e.g. particle size, the effect of humidity in lung environment on particle size) will be used to assess potential for transport and impact on human health. In addition, the effect of establishing a vegetative cover on the tailings impoundment on reducing dust generation and contaminant transport will be assessed. Results of this project will: (i) provide a quantitative assessment of dust and aerosol emissions from contaminated mining sites in semi-arid regions, with and without vegetation cover; (ii) provide a tool for forecasting dust and associated contaminant transport at the local (few km) and regional (hundreds of km) scales, including the link between regional weather forecasting and dust and aerosol transport (this is an important outcome since this information will be used by the mining industry to improve management of their tailings impoundments); and (iii) establish quantitative relations between physicochemical characteristics of dust and aerosol and their transport, including their potential effects in the respiratory system.