TRANSPORT MECHANISMS OF METAL-BEARING HISTORIC MINE TAILINGS IN A SEMI-ARID ENVIRONMENT

Tellurium (Te) is an energy critical element that can be enriched in mine tailings residual from gold extraction (up to ~300 mg kg^-1). Under surficial conditions, Te in mine tailings undergoes oxidative weathering and is also susceptible to wind and water transport. Very little is known about the behavior of Te in the surficial environment, but some forms of Te are more toxic than arsenic and selenium. The potential toxicity combined with mass transport of Te-bearing particles by wind or water raises concerns regarding nearby ecosystem, environmental, and human health. Release of metal(loid)s to the environment from mine tailings has degraded ecosystem vitality and community health.

The goal of this project is to assess the mass transport of Te and other toxic metal(loid)s by wind and water from semi-arid mine tailings in the historic Delamar Mining District in Lincoln County, NV. Samples were collected along 8 transects (8 samples each) centered at the largest tailings pile to assess local wind transport. An additional 10 samples were collected along a dry streambed downstream of the site to assess surface water transport of the tailings toward a playa used for off-road recreational driving. The elemental composition of all samples was determined using wavelength dispersive-X-ray fluorescence (WD-XRF) to examine patterns of metal(loid) dispersion. Preliminary results of water transport demonstrate the enrichment of Te, Pb, Sb, Bi, Zn, and Cu downstream of the historic mill, but the highest concentrations of all elements occur ~4km from the mill, just downstream of a road, pointing to metal(loid) dispersion patterns complicated by other anthropogenic activities in the area. HYSPLIT modeling indicates that the predominant wind travels from southwest to northeast, but the dispersion pattern indicated by metal distribution suggests westward, down-valley transport. These data highlight that local topography complicates local wind patterns at the land surface and thus influences aeolian dispersion of metal(loid)s. Dust collected from filters were microwave acid digested and analyzed by ICP-MS to assess metal(loid) particulate transport on sampling days. Together, these results represent an important first step toward understanding the potential impacts of Te on the environment.