Date of Thesis

Spring 2017

Thesis Type

Honors Thesis (Bucknell Access Only)

Degree Type

Bachelor of Science

Major

Geology & Environmental Geosciences

Second Major

Languages, Cultures & Linguistics

First Advisor

Molly M. McGuire

Second Advisor

Ellen K. Herman

Keywords

annular flume, AMD, mine drainage, laboratory, geochemistry

Abstract

Precipitate formation and deposition play an important role in the transportation of contaminants in abandoned mine drainage systems (AMD). AMD streams contain a multitude of chemical and hydrological factors whose influence on precipitate formation and deposition is difficult to determine with field studies. An annular flume offers the ability to control chemical and hydrological variables in a laboratory setting while more closely simulating AMD stream conditions than traditional benchtop studies. This thesis describes the work conducted using an annular flume to investigate the effects of flow rate and bed material on the oxidation of Fe2+ and deposition of iron to the bed. Initial hypotheses for this research were threefold. First, increasing flow rate would increase Fe2+ oxidation through faster incorporation of dissolved oxygen. Second, the presence of a bed would increase Fe2+ oxidation through increased turbulence and heterogeneous catalysis of Fe2+. Third, the presence of a bed would increase iron deposition via precipitate filtration through bed grains and attraction to bed grain nucleation sites. The results of this work show that while bed material seems to have no effect on Fe2+ oxidation, it does seem to increase deposition of iron precipitates. This work additionally presents adjustments made to the methods of flume operation during these experiments to be able to more accurately compare results; it thus serves as a record of method refinement for future annular flume simulations of AMD. The decision to control for initial dissolved oxygen in the system part-way through experimentation resulted in the identification of carbon dioxide as a potentially significant variable for Fe2+oxidation in these simulated AMD systems. The effect of flow rate on Fe2+oxidation remains inconclusive after conducting these experiments; however future work with the annular flume may elucidate the effect by measuring carbon dioxide during these simulations.

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