Theses and Dissertations at Montana State University (MSU)
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Item Interactive effects between lime, organic matter, and bacteria in the establishment of Leymus cinereus in mine tailings(Montana State University - Bozeman, College of Agriculture, 2015) Sanchez Espinoza, Deicy Noemi; Chairperson, Graduate Committee: Anthony HartshornThe landscape legacy of historical metal-mining activity can persist for decades. The most frequent strategies used for the remediation of contaminated soils include: the use of synthetic membranes to isolate contaminants (>$0.5 million/acre), direct revegetation (less expensive but difficult to sustain), or lime amendments ($5000/acre). Looking for more cost-effective bioremediation approaches, we performed a set of greenhouse studies to determine what combinations of soil amendments would lead to the best vegetative response, and potentially associated reductions in soil arsenic (As) levels, in "slickens" collected from the Lampert Ranch along the upper Clark Fork near Warm Springs, MT. In our first greenhouse experiment, we planted Leymus cinereus (basin wildrye) and compared (after 12 weeks) plant growth and foliar metal concentrations across treatments. Amendments included single or factorial additions of 5% lime, organic matter (+OM), and an arsenic-oxidizing (+oxbact) strain of Agrobacterium tumefaciens (Agtu). Surprisingly, the OM+oxbact treatment revealed among the best plant growth and arsenic uptake response. We then performed a second greenhouse experiment with two levels of OM (1.5% and 5%) and an additional treatment: a mutant (reducing strain) of Agtu. Basin wildrye grown in soils amended with 5% OM generally did better than those grown in soils amended with 1.5% OM. At the same time, foliar As uptake (biomass multiplied by As concentration) was unexpectedly high (0.020 mg pot-1) for plants grown in soils amended with 5% OM + oxbact, 3 times greater than foliar arsenic uptake in plants grown in soils amended with 5% OM+ lime and 4 times greater than foliar uptake by plants grown in soils amended with 5% OM and the reducing strain of Agtu. These results suggest the combination of OM and Agtu oxbact strain could provide a potentially cost- effective approach to remediating As-contaminated soils. Finally, our study results imply that soil restoration approaches could be improved through a greater consideration of microbial communities supported by these re-establishing vegetation communities, which could lead to more sustainable ecosystem successional trajectories.Item Hydrology of a waste rock repository capping system at the Zortman Mine(Montana State University - Bozeman, College of Agriculture, 1997) Warnemuende, E. A.Item Hydrologic evaluation of tailings covers at the Golden Sunlight Mine(Montana State University - Bozeman, College of Agriculture, 1994) Strong, Murray RandalItem Processes controlling arsenic solubility and mobility in soils(Montana State University - Bozeman, College of Agriculture, 1998) Jones, Clain A.Item Clean tailing reclamation : revegetation of mill tailings following removal of pyrite and heavy metals(Montana State University - Bozeman, College of Agriculture, 1997) Krueger, Jane MarieItem The impacts of trace metals on grass communities along the floodplains of Soda Butte Creek, Montana and Wyoming(Montana State University - Bozeman, College of Letters & Science, 1995) Stoughton, Julie AnnItem Revegetation of riparian mine tailings(Montana State University - Bozeman, College of Agriculture, 1996) Jackson, Don BrookeItem Alkaline industrial by-product effects on plant growth in acidic-contaminated soil systems(Montana State University - Bozeman, College of Agriculture, 2002) Mehlenbacher, Joel ThomasItem Control of acid rock drainage from mine tailings through the addition of dissolved organic carbon(Montana State University - Bozeman, College of Engineering, 2004) Sturman, Paul John; Chairperson, Graduate Committee: Alfred B. CunninghamAcid mine drainage detrimentally affects thousands of surface watercourses throughout the world and costs tens of millions of dollars annually in site remediation expenditures. This process is accelerated by the activity of iron- and sulfur-oxidizing bacteria which grow chemolithotrophically in mine tailings. Low cost, environmentally acceptable, and low maintenance treatment technologies are needed to both treat acid mine drainage and prevent its occurrence. The addition of dissolved organic carbon to mine tailings has the potential to stimulate beneficial heterotrophic populations of bacteria at the expense of iron and sulfur oxidizers. These experiments investigated the use of three organic carbon sources: molasses, cheese whey and methanol in controlling acid mine drainage from two tailings sources. All three organic carbon sources are easily dissolved in water, relatively inexpensive, and easily transported to remote locations. Mine tailings were acquired from the Fox Lake Mine (Manitoba) and the Mammoth Mine (Montana) and were packed into columns. Columns were watered on a weekly basis and dissolved organic carbon was periodically applied. The treatments increased pH up to 3 units over untreated controls, while simultaneously decreasing oxidation-reduction potential over 300 mV. Sulfate reducing bacteria were stimulated in columns treated with organic carbon, as were heterotrophic populations. Some iron- and sulfur-oxidizing organisms were found to be capable of heterotrophic growth, a condition which compromised treatment effectiveness. Individual organic carbon treatments were found to vary in pH/ORP effect from several months to over 2 years. Phylogenetic analysis of column samples suggests both a robust population of bacteria in untreated mine tailings and the growth of SRB resulting from treatment.Item Kinetics and community profiling of sulfate-reducing bacteria in organic carbon treated mine tailings(Montana State University - Bozeman, College of Engineering, 2005) McBroom, Mark David; Chairperson, Graduate Committee: Alfred Cunningham.Acid rock drainage (ARD) poses a significant health and environmental hazard worldwide via the discharge of highly acidic waters and potentially toxic levels of mobile metals. This is a result of weathering and microbial oxidation of pyretic minerals present in mine tailings. Sulfate reducing bacteria (SRB), which are often indigenous to mine tailings, have demonstrated promising potential in metabolically raising effluent pH and immobilizing metals through precipitation and biomineralization. The addition of an organic carbon source has the potential of stimulating the SRB and reducing ARD at its source. Often the success of a process based on implementing endemic microbial consortia for in situ bioremediation is highly dependent on an understanding of the community structure and potential activity of microbial community members when provided a specific substrate. The goal of this research was to identify viable methodologies that can be used to select and monitor successful bioremediation treatments. Differences in microbial community structure and activity of batch cultures inoculated with tailings were observed for independent treatments of whey and lactate as carbon sources. Community response to whey treatment of bench-scale columns was also observed. Development and optimization of DNA extraction and purification methods was required for the highly contaminated tailing samples. Microbial community structure and phylogeny were identified using denaturing gradient gel electrophoresis (DGGE) and automated sequencing. The methods used in this paper were successful at identifying pre- and posttreatment community structure of endemic microbial populations. Shifts in community structure were observed in treated columns and treated batch cultures. Sulfate reduction in treated batch cultures was highly variable between samples, suggesting microheterogeneities in community structure of sampled tailings. Selection for specific phylogenies was evident with respect to carbon source treatment, culturing conditions, and sampled inocula. Variability in community structure was roughly correlated to sulfate reduction in individual organic carbon treatments. Resulting community profiles were highly dependent on methods used in obtaining, amplifying, and isolating community DNA of phylogenetically distinct populations. The success of implementing molecular techniques to observe and optimize bioremediation is ultimately dependent on the methodology used.