Speciation of Metal Ions Associated with Fine Fe(III)-oxyhydroxide Particles in Cement Creek Basin, Colorado after the 2015 Gold King Mine Spill
Abstract/Contents
- Abstract
- The Gold King Mine Spill on August 5th, 2015 released 3,000,000 gallons of acid mine waters and 880,000 pounds of metals to the Animas River Watershed. The initial impacts of the spill appear to have been naturally mitigated, in part, by the presence of iron-oxyhydroxide particles, which are known to sorb metals from aqueous solutions. Hydrated metal ions can form inner- and outer-sphere sorption complexes on Fe(III)-oxyhydroxide particles, and their sorption is dependent on several factors, including pH, aqueous silica content, and the presence of Fe(II) and As(III)-oxidizing bacteria. We apply laboratory-based x-ray diffraction (XRD), x-ray fluorescence (XRF), inductively coupled plasma-mass spectrometry (ICP-MS), and synchrotron-based micro x-ray fluorescence mapping (µXRF) and x-ray absorption spectroscopy (XAS) on water, sediment (upper 6 cm), and fine particle samples from 15 sites in Cement Creek Basin to determine the effect of pH on the association of Pb(II), Cu(II), and Zn(II) with Fe(III)-oxyhydroxide particles. Solid phase analyses show pH-dependent partitioning of Cu, Pb, and Zn occurs between sediment and fine particle phases. Goethite (Fe3+O(OH)) and ferrihydrite (Fe3+2O3 •.5(H2O)), two Fe(III)-oxyhydroxides that sorb metals from solution as a function of pH, comprise 31-66 percent of the iron species identified in extended x-ray absorption fine structure (EXAFS) fitting of the fine particle samples. The pH-dependent partitioning of metal ions suggests that changes in pH could have a major impact on the speciation of metal cations, including the mobilization of Pb(II) if the pH decreased to ~2.7 in Cement Creek Basin, and mobilization of Zn(II) and Cu(II) if pH decreased to 5.6 or 4.5, respectively, at the Animas River confluence. Such changes could pose significant environmental hazards to aquatic organisms and the human population in the Animas River Watershed, which is used by six states and twelve Native American tribes for water, recreation, and agriculture.
Description
| Type of resource | text |
|---|---|
| Date created | May 2018 |
Creators/Contributors
| Author | Ledingham, Gregory |
|---|---|
| Primary advisor | Brown, Gordon |
| Advisor | Jew, Adam |
| Degree granting institution | Stanford University, Department of Geological Sciences |
Subjects
| Subject | Stanford School of Earth Energy & Environmental Sciences |
|---|---|
| Subject | acid mine drainage |
| Subject | Gold King Mine Spill |
| Subject | Geological Sciences |
| Genre | Thesis |
Bibliographic information
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- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
Preferred citation
- Preferred Citation
- Ledingham, Gregory (2018). Speciation of Metal Ions Associated with Fine Fe(III)-oxyhydroxide Particles in Cement Creek Basin, Colorado after the 2015 Gold King Mine Spill. Stanford Digital Repository. Available at: https://purl.stanford.edu/xd380sp2227
Collection
Undergraduate Honors Theses, Doerr School of Sustainability
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- Contact
- greg.ledingham7@gmail.com
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