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Abstract

This study examines contamination from abandoned mine mill waste in the sediments of the Carnation Wash system, Nelson, NV. The Carnation Wash was chosen because only one milling site is located near the head of the wash system. This is the only mill facility located within the wash or surrounding area of the wash and therefore, this mill is the primary source for processed mine tailings in the Carnation Wash system. Contaminants from the precious metal extraction process (such as CN- and Hg) are mobile in the aqueous phase, however, geogenic trace elements have been shown to be mobilized as sorbed species on sediment transported by storm-water flow according to enrichment ratio modeling. The geogenic metals Pb, Ag, Cd, and Se, and the metalloid As, are released from native ores by the intensive use of CN- and Hg in the extraction of precious metals. This has resulted in a concentration of geogenic trace elements (Pb, Ag, Cd, Se, and As) in mine wastes that have been transported down gradient as much as 6000m from source areas. Trace elements (Pb, Ag, Cd, Se, and As) in sediments exceeded a threshold enrichment value of 1.5, which differentiates between natural erosion and release of these trace elements, and anthropogenically influenced trace element mobilization and transport in wash sediments.