Date of Award

Spring 2021

Degree Type

Thesis

Committee Chair

Alysia Cox

First Advisor

Katie Hailer

Second Advisor

Beverly Hartline

Third Advisor

Robert Pal

Abstract

Butte, MT has extensive environmental damage due to 120 years of mining, milling, and smelting starting in the late 1800’s with no control or forethought on waste management. The area is now one of the largest superfund complexes in the United States and has been extensively remediated with restoration continuing. A growing number of studies are investigating native plants’ ability to aid in metal removal after reclamation efforts. Basin wildrye, Leymus cinereus, grows in each of the restored and contaminated areas sampled. This study investigated the Mn, Fe, Cu, Zn, As, Cd, and Pb content of aerial plants and roots, as well as surrounding soil, on a transect to 25 meters from the creek bank. Aerial plants averaged a content (all values ppm) of Mn 20.0 ± 0.6, Fe 260 ± 67, Cu 4.0 ± 0.2, Zn 30 ± 1, As 0.30 ± 0.01, and Pb 0.200 ± 0.002; roots averaged a content of Mn 104 ± 3, Fe 6,000 ± 2,875, Cu 22.0 ± 0.9, Zn 132 ± 5, As 3.0 ± 0.2, and Pb 4.00 ± 0.04; soils averaged a content of Mn 210 ± 27, Cu 101 ± 4, and Zn 220 ± 16; and cores averaged a content of Mn 270 ± 41, Cu 310 ± 19, Zn 410 ± 39, As 260 ± 56, and Pb 193 ± 6. The soil showed higher metal contents than the roots, which showed higher concentrations than the areal plants. Element content increased with increased distance from the bank. Soil contents increased by factors of 4, 12, and 0.2 for Mn, Cu, and Zn respectively; aerial plant content increased by factors of 0.2, 3, 7, 0.4, and 3 for Mn, Fe, Cu, Zn, and Pb respectively; and root contents increased by factors of 0.2, 58, 10, 0.13, and 9 for Mn, Fe, Cu, Zn, and Pb respectively. In addition, a potential Mn and Fe deficiency below the Warm Springs Settling Ponds could indicate the ponds settle out Mn as well as other metals. Overall, the Warm Springs (contaminated) location had the highest elemental contents followed by Miles Crossing (restored, suspected groundwater upwelling), Santa (twice restored), and Hay Canyon (control). Potentially toxic elements exist in the plants and soil along Silver Bow Creek and the Upper Clark Fork River. Keywords:

Comments

A thesis submitted in partial fulfillment of the requirements for the degree of Masters of Geoscience: Geochemistry

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