Mine tailings pose a health risk for populations and ecosystems in the Southwest; this is why effective, and low-cost solutions for the long term are needed. This work is groundbreaking since little information is available with regards to applying greenhouse studies of phytostabilization to the field for mine tailing remediation. Mine tailings from Iron King Mine and Humboldt Smelter Superfund (IKMHSS) site can be considered one of the worst scenarios due to the extreme conditions which prevent the growth of a vegetation cap. The high concentration of metals, such as arsenic and lead, highly acidic, lack of the nutrients carbon and nitrogen in the soil structure, and low microbial communities are factors that negatively affect plant growth. This project provides practical field-scale applications for the use of phytostabilization, which uses plants to create a vegetation cap that stabilizes metals in the root zone while preventing wind and water erosion in mine tailings. The project is divided into three main studies: (1) the assessment of the translation of successful greenhouse results to the field of phytostabilization using compost-assisted direct planting. This includes the use of different rates of compost as an amendment and different desert native plant species in addition to some potential parameters that could be used as indicators of a successful modification of biochemical and physical environment from a disturbed soil towards a more healthy soil when compost assisted direct planting phytostabilization is used; (2) the second study aims to evaluate the effect of the phytostabilization strategy on reducing windborne transport of particle and metal(loids) following the establishment of the vegetation cap. The results indicate that the vegetation resulted from direct planting decreases dust emissions from IKMHSS mine tailings; and (3) the third study focuses on one of the most important requirements for phytostabilization application in the field, the performance of the different plant species selected from the greenhouse studies. This performance was evaluated as the metal accumulation in aerial plant tissue based on metal concentration guidelines from the National Research Council as well as changes in the composition of plant species and canopy cover with time. The results derived from the translation of compost–assisted direct plating based on successful greenhouse results are showing the capacity of this technology on a field scale by maintaining a canopy cover over time that decreases mobilization by not hyper-accumulating metals in the aerial tissue and by preventing windborne particle dispersion with the potential of disrupting contamination pathways.

The frequency of dust storms is increasing globally yet it is often difficult to determine dust sources in mixed events. Dust events may negatively impact human health, but the composition of major dust sources is not well characterized in arid regions globally. In the western US, the National Wind Erosion Research Network (NWERN) has various sites evaluating seasonal dust emissions to quantify dust fluxes. We used existing dust samples to characterize the isotopic, chemical, and mineralogical composition of dust over multiple seasons from ten representative NWERN sites and compared with land use, vegetation, and surficial geology. Our results show variability in dust chemistry across the ten sites primarily related to differences in surficial geology (local bedrock and sediment) with other factors playing a minor role. In some cases, seasonal vegetation and wind direction played a role in controlling dust composition. For example, the El Reno site showed seasonal differences in mineralogy related to carbonate precipitation and dissolution in the soil during wet summers and dry winters. The Holloman Air Force Base (HAFB) site had distinct seasonal changes in dust chemistry with spikes in Na, Mg, Ca, Ni, and Sr during the spring months possibly related to changes in wind direction and inputs from neighboring White Sands National Park. The Lordsburg Playa site had distinct chemistry relative to other sites with high concentrations of Li, Na, Ca, and Sr due to the prevalence of evaporite minerals. Mineralogy results show the presence of quartz, phyllosilicates, and feldspar minerals at each of the NWERN sites with HAFB also containing calcium sulfate and iron oxide minerals. The 87Sr/86Sr results showed lower ratios correlating with younger bedrock (e.g., ~0.7075 at the Red Hills site surrounded by Miocene volcanic rocks), but some of the sites with recent surficial sediments had higher ratios (e.g., ~0.714 at the CPER site with Tertiary sediments). By creating a library of isotopic, chemical, and mineralogical data for dust sources across the western US, our dataset has implications for identifying characteristics that may be used for tracking dust sources.