Document Type

Honors Thesis

Publication Date

Spring 5-6-2026

Abstract

Phytoextraction is a method for removal and recovery of heavy metals from contaminated substrates using plants. There is a growing need to test, identify, and further understand species effective for phytoextraction to feasibly remove and recover heavy metals. In this study, the phytoextraction capacity of Willow (Salix) species was tested for metal contaminated soils and waters from legacy mining in Butte, Montana. The willows were grown in a hydroponic system in two 8-week long growth trials, employing a 2x2 factorial design of contaminated soil, clay beads, contaminated mine water and uncontaminated water as the media. Heavy metal concentrations (Mn, Zn, As, Cu and Cr) within willow root, leaf, and shoot tissues were measured separately to examine the phytoextraction potential of willows from 4 different treatments. The metal concentrations of the influent and effluent water and soil in the 4 treatments were tested to examine the effectiveness of metal removal from substrates. The willows effectively stored Mn and Zn in their tissues and partially removed those metals from the growth media, depending on the treatment and substrate. However, only root tissues displayed substantial storage of the metals limiting the “above-ground” phytoextraction efficiency of willows for metal removal and recovery in a short period. As resource recovery from waste and contaminated sites continues to gain global interest, developing technologies like phytoextraction, have promising potential for recovering valuable products and reducing contamination.

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