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University of California – Merced

1. Leven, Alexander. Fate of redox-active manganese oxide minerals as an in-situ treatment for mercury-contaminated sediments.

Degree: Environmental Systems, 2018, University of California – Merced

Addition of Mn(IV)-oxide phases pyrolusite or birnessite was investigated as remedial amendment for Hg-contaminated sediments. Because inorganic Hg methylation is a byproduct of bacterial iron and sulfate reduction, reaction of Mn(IV) oxides with pore water should poise sediment oxidation potential at a level higher than favorable for Hg methylation. Changes in Mn(IV)-oxide mineralogy and oxidation state over time were investigated in sediment tank mesocosm experiments in which Mn(IV)-oxide amendment was either mixed into Hg-contaminated sediment or applied as thin-layer sand cap on top of sediment. Mesocosms were sampled between 4 and 15 months of operation and solid phases were characterized by X-ray absorption spectroscopy (XAS). For pyrolusite-amended sediments, Mn(IV)-oxide was altered to a mixture of Mn(III)-oxyhydroxide and Mn,Fe(II,III)-oxide phases, with a progressive increase in the Mn(II)-carbonate fraction over time as mesocosm sediments became more reduced. For birnessite-amended sediments, both Mn(III) oxyhydroxide and Mn(II) carbonate were identified at 4 months, indicating a faster rate of Mn reduction compared to pyrolusite. After 15 months of reaction, birnessite was converted completely to Mn(II) carbonate, whereas residual Mn,Fe(II,III)-oxide phases were still present in addition to Mn(II) carbonate in the pyrolusite mesocosm. Mn(IV)-oxides in the thin layer sand cap showed no changes in XAS spectra after 10 months of reaction. Equilibrium phase relationships support the interpretation of mineral redox buffering by mixed-valent (Mn,Fe)(II,III) oxide phases. Results suggest that longevity of the amendment treatment for redox buffering can be controlled by adjustment of the mass and type of Mn(IV)-oxide applied, mineral crystallinity, surface area, and particle size.

Subjects/Keywords: Geochemistry; Geochemistry; Manganese; Mercury; Redox; Remediation

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Leven, A. (2018). Fate of redox-active manganese oxide minerals as an in-situ treatment for mercury-contaminated sediments. (Thesis). University of California – Merced. Retrieved from http://www.escholarship.org/uc/item/0ts9w73s

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Leven, Alexander. “Fate of redox-active manganese oxide minerals as an in-situ treatment for mercury-contaminated sediments.” 2018. Thesis, University of California – Merced. Accessed September 23, 2018. http://www.escholarship.org/uc/item/0ts9w73s.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Leven, Alexander. “Fate of redox-active manganese oxide minerals as an in-situ treatment for mercury-contaminated sediments.” 2018. Web. 23 Sep 2018.

Vancouver:

Leven A. Fate of redox-active manganese oxide minerals as an in-situ treatment for mercury-contaminated sediments. [Internet] [Thesis]. University of California – Merced; 2018. [cited 2018 Sep 23]. Available from: http://www.escholarship.org/uc/item/0ts9w73s.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Leven A. Fate of redox-active manganese oxide minerals as an in-situ treatment for mercury-contaminated sediments. [Thesis]. University of California – Merced; 2018. Available from: http://www.escholarship.org/uc/item/0ts9w73s

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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