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Development of a System to Evaluate Geochemical Gradients in Acid Mine Drainage Induced Sediments in a Column Format
- Publication Year :
- 2014
-
Abstract
- Acid mine drainage (AMD), a serious problem associated with coal mining, forms when sulfur-bearing minerals exposed during mining come into contact with oxygenated water, resulting in the production of sulfuric acid. AMD typically has a low pH (2.5-4.5) with high concentrations of sulfate, Fe(II), Mn(II), and Al. When AMD emerges at the terrestrial surface, acidophilic aerobic iron oxidizing bacteria (FeOB) oxidize Fe(II) to Fe(III), giving rise to massive Fe(III) hydroxide deposits referred to as iron mounds. The work described here is a contribution to a broader effort to examine the distributions of microbial activities in iron mound sediments. In order for future studies to be able to examine depth dependent activities of the microorganisms, the first goal of this work was to develop a reproducible, reusable column system to use for laboratory incubations of iron mound sediment. The columns were made of polycarbonate tubing with several sampling ports which were covered with extreme temperature silicone. The second goal of this work was to determine the diffusional characteristics within the columns. Bromide was tested first as a non-reactive tracer to establish a control for diffusion within the columns. The bromide followed a Fickian diffusion model in the columns. Fe(II) was tested next and found that instead of behaving in the same manner as bromide, Fe(II) was rapidly removed from solution, likely due to adsorption on iron mound sediments or by oxidative precipitation. Based on the results of the bromide test, the Fickian model was used to able to predict how H+, sulfate, glucose and acetate should diffuse within the iron mound sediment columns. These predictions will support future studies utilizing this column format to evaluate distributions of microbial activities with iron mound sediments.
Details
- Language :
- English
- Database :
- OpenDissertations
- Publication Type :
- Dissertation/ Thesis
- Accession number :
- ddu.oai.etd.ohiolink.edu.akron1397568296