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Sediment Contamination along Desert Wash Systems from Historic Mining Sites in a Hyperarid Region of Southern Nevada, USA

Sims, Douglas B., Hooda, Peter S., Gillmore, Gavin K.
Soil & sediment contamination 2013 v.22 no.7 pp. 737-752
arsenic, barium, cadmium, chromium, cyanides, drought, lead, mercury, mining, risk, sediment contamination, sediments, selenium, Nevada
Abandoned mining sites in hyperarid environments are generally assumed to present an insignificant risk to water availability. This study investigated the impact abandoned mine sites in Southern Nevada can have on the wider environment. Southern Nevada is characterized with little precipitation and prolonged droughts. Precipitation in Southern Nevada is often in the form of short and intense events with the potential to mobilize and transport contaminated sediments down gradient. This work evaluated the movement of trace elements (Ag, As, Ba, Cd, Cr, Hg, Pb, and Se) and cyanide in surface sediments of three desert washes near the historic mining town of Nelson, a hyperarid region of Southern Nevada. Results indicate trace elements have been mobilized and transported down gradient from sources to areas not directly impacted by mining. Contaminants used in mining operations (Hg and CN⁻) as well as those of geogenic nature migrated as far as 6000 m, providing evidence of their transport in hyperarid environments, contrary to the generally held belief. Although contaminants in this study are below levels that are environmentally significant, the findings show that transport is possible. This study demonstrates that large amounts of contaminant-laden sediments might be a significant threat in hyperarid environment and to areas down gradient from source materials.