Active and abandoned mines may present health risks, especially to children, from environmental exposure to airborne chemical elements, such as Pb, As, and Mn. X-ray fluorescence analysis of tailings at the Three Kids Mine show they contain high levels of: Pb (15,300 mg/kg), As (3690 mg/kg), and Mn (153,000 mg/kg). Soil was sampled along eight transects, radiating from the dried tailings ponds. Concentrations of Mn and Pb to the NE are at background concentrations at 4.8 km, and, As and Sr at 3.2 km from the mine. Going SW to the City of Henderson, all elements are at background at 1.6 cm, with the closest houses at 1.8 km. The United States Environmental Protection Agency (USEPA) Regional Screening Levels (RSLs) are exceeded for Pb, As and Mn at 0.8 km on all transects except one. The RSLs are exceeded for Pb, As and Mn on the NE transects at 1.6 km. Future home sites are on a NE transect between 0.4 km and 2.3 km downwind from the tailings ponds, in an area highly impacted by tailings which exceed the USEPA RSLs. This research demonstrates that there has been the farthest transport of tailings offsite by the prevailing winds to the NE; the closest currently-built homes have not received measurable tailings dust because they are upwind; and that precautions must be taken during the proposed remediation of the mine to restrict dust-transport of Pb, As, and Mn to avoid human exposure and ecological damage.

Differential pulse polarography (DPP) was used to assess the interaction of Pb²⁺ with various humic acid analogs and several humic acids. DPP analysis demonstrated that the reduction peak maximum (E_p) for Pb²⁺ shifted to more negative values in the presence of humic acids and humic acid analogs. The observed E_p for Pb²⁺ in the presence of humic acids and humic acid analogs is influenced by ligand concentration, solution pH and Pb²⁺ concentration. Shifts in the E_p for Pb²⁺ are related to the reduction potential and can be rationalized using the Lingane equation.

Hazardous substances (e.g., toxic elements, oxides of nitrogen, carbon and sulfur) are discharged to the environment by a number of natural and anthropogenic activities. Anthropogenic air pollution commonly contains trace elements derived from contaminants and additives released into the atmosphere during fossil fuel combustion (automobiles, power generation, etc.) as well as physical processes (e.g., metal refining, vehicle brake wear, and tire and pavement wear). Analysis of pollutant chemical concentrations in lichens collected across the Las Vegas Valley allows documentation of the distribution of air pollution in the Valley. Analyses of lichen biomass (Buellia dispersa), when compared to windrose diagrams, shows pathways of airborne pollutant transport across the Las Vegas Valley. The west and north sectors of the Las Vegas Valley contained the lowest target contaminates (e.g., Cr, Cu, Co, Pb, Ni) and the highest NO₃⁻ while the east and south sectors contained the highest levels of target contaminates and lowest NO₃⁻. Additionally, metals and NO₃⁻ detected in the east and south sectors of the valley indicate that air pollution generated in the valley is moving from the south to the north-northeast and across the valley, exiting on the north and south side of Frenchman Mountain.

Gd³⁺ forms a strongly colored complex with 4-(2-pyridylazo)-resorcinol (PAR) in aqueous solutions. We characterized the Gd³⁺-PAR complex in order to use it as a probe of Gd³⁺ speciation in the presence of environmentally relevant ligands. The formation of the Gd³⁺-PAR complex was investigated from pH 5 to 8 in the presence of excess PAR. The absorbance of the Gd³⁺-PAR complex dramatically increased from pH 5 to 8 and application of the method of continuous variation indicates that the complex was primarily 1:2 Gd(PAR)₂ at pH 8. Stability constants for Gd³⁺ with other ligands can be quantified by competitive displacement of the PAR ligand. To establish the viability of this approach, we measured the stability constants between Gd³⁺ and several organic acids and carbonate. Our measurements show reasonable agreement with the literature values. We used the competitive displacement approach to establish that humic acids can competitively displace PAR from the Gd(PAR)₂ complex.