Native Plants for Revegetation of Mercury- and Arsenic-Contaminated Historical Mining Waste—Can a Low-Dose Selenium Additive Improve Seedling Growth and Decrease Contaminant Bioaccumulation?

Highly contaminated exposed legacy gold mine tailings from the late 1800s are present in many locations throughout North America and other parts of the world that experienced gold rushes at that time. Those tailing fields can pose risks to human health and the environment. Revegetation of tailing fields can reduce dust generation and other risks associated with these sites. The objective of this study was to investigate if native rapid-growing plants could be successfully germinated in mercury (Hg) and arsenic (As) contaminated legacy mine tailings, both untreated and treated with a low dose of sodium selenite (Na₂SeO₃) to promote growth and decrease bioaccumulation of contaminants. After screening many candidates, four wide-spread North American native plant species were selected, Juncus tenuis, Anaphalis margaritacea, Symphotrichum novi-belgii, and Panicum virgatum for their tolerance, presence near legacy gold mine sites, and ability to germinate rapidly in harsh conditions. Three of these species germinated and grew well in untreated tailings except for S. novi-belgii. The selenite treatment increased biomass, emergence, shoot height, and root length in J. tenuis; emergence in A. margaritacea; and root lengths in P. virgatum. This treatment also decreased shoot [Hg] and [As] in P. virgatum by 36% and 40%. Low-dose selenite treatments hold promise for supporting germination and growth of native plants in Hg- and As-contaminated tailing fields.