Project Summary (2015-2017)

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. The warmer, drier conditions predicted for the Southwestern US and other semi-arid regions by climate models may make contaminated atmospheric dust and aerosols increasingly important in the future, because of their potentially deleterious effects on human health and ecology. In particular, the size distribution and physicochemical characteristics of atmospheric dust and aerosol impacts not only the potential distance of transport and bioaccessibility, but also the distribution in the respiratory system after inhalation and subsequent toxicity. In particular, one of the field sites targeted by this project, the mine tailings impoundment at the Iron King Mine and Humboldt Superfund Site (IKMHSS), is heavily contaminated (concentrations reaching up to thousands of parts-per-million) with lead and arsenic.

The overall objective of the project is to develop tools to predict metal(loid) contaminant transport by dust and aerosols from mining operations at the local scale. A computational fluid dynamics (CFD) model previously developed is being calibrated to be used as a forecast tool to predict airborne particulate matter, arsenic, and lead concentrations downwind of the contaminated IKMHSS tailings impoundment. An important element of the prediction of contaminant transport from mining sites is the forecasting of dust emissions from the contaminant sources. The modeling effort is being validated with experimental work. Researchers are measuring and correlating dust generation from mine tailings and soils, using a portable wind tunnel that they have designed.

Dust emission correlations and the local CFD model are being coupled with weather forecasting to develop a tool to predict transport of contaminants at the local (i.e. few kilometer) scale. In addition, the effect of phytoremediation of the tailings impoundment on dust generation and contaminant transport is being assessed to confirm the hypothesis that vegetation cover reduces the movement of contaminated tailings into surrounding communities.

Results of this project will provide a quantitative assessment of dust and aerosol emissions from contaminated mining sites in semi-arid regions, with and without vegetation cover, and will provide a tool for forecasting dust and associated contaminant transport at the local scale, including the link between local weather forecasting and dust and aerosol transport.