Land Resources & Environmental Sciences Thesis Defense
- Monday, May 18, 2015 from 10:00am to 11:00am
- Plant Biosciences Building - view map
Diecy Sanchez, M.S. Candidate in Land Resources & Environmental Sciences, will present her defense titled "Interactive Effects of Bacteria, Lime and Organic Matter in the Establishment of Leymus Cinereus in Mine Tailings - Montana" at 10:00 a.m. in Room 108, Plant Bioscience Building. Diecy is advised by Dr. Tony Hartshorn.
The landscape legacy of historical mining activity can persist for decades. The most frequent strategies used for the remediation of mining soils include: the use of layers to isolate the toxicants (highly expensive) and the direct revegetation (cheaper but hard to establish). Looking for new bioremediation approaches, we performed a greenhouse study to determine what combinations of soil amendments would lead to the best vegetative response, and potentially associated reductions in soil arsenic levels in tailings collected from along the Clark Fork River. In our first greenhouse experiment we planted Leymus cinereus and after 12 weeks, we compared plant growth responses and foliar as well as root metal concentrations across treatments. Amendments included single or factorial additions of lime, organic matter (+OM), and arsenic oxidizing (+oxbact) strain of Agrobacterium tumefaciens. The full combination of treatments and OM+ oxidizing bacteria showed the best plant growth and arsenic uptake response. Since the combination of OM and bacteria looked so critical to promote plant growth we designed a second greenhouse experiment were we evaluate responses of plant growth and arsenic uptake having two levels of OM (1.5% and 5% respectively) and reducing strain of Agrobacterium tumefaciens. In the second experiment we observed that treatments with 5% OM generally did better than those ones with 1.5%. At the same time, foliar As concentration and arsenic uptake was greatest in +OM oxbact, and the full combination of treatments with oxbact. With these results, we suggest that the use of OM and Agrobacterium tumefaciens oxbact strain could imply a potential new and cost savings-approach in the remediation of mine tailing soils. Finally, our study results also suggest that restoration approaches might be improved through a greater consideration of microbial communities supported by these re-establishing vegetation communities, which could lead to a more natural and cost effective ecosystem successional trajectories.
- Department of Land Resources and Environmental Sciences