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Item Effects of saline-sodic water on EC, SAR, and water retention(Montana State University - Bozeman, College of Agriculture, 2003) Robinson, Kimberly MarieItem Water retention of soft sedimentary siltstone fragments(Montana State University - Bozeman, College of Agriculture, 1988) Ruddell, James PeterItem Evaluation of a constructed wetland : sediment characterization and laboratory simulation of wetland chemical processes(Montana State University - Bozeman, College of Agriculture, 1998) Lyons, Dale WellerItem Ecosystem dynamics and temporal variations in a microbially dominated, coastal antarctic lake(Montana State University - Bozeman, College of Agriculture, 2009) Dieser, Markus; Chairperson, Graduate Committee: John C. Priscu; Christine Foreman (co-chair)This study investigated the microbial ecology of Pony Lake, Antarctica. The main objectives of this research were to 1) characterize physicochemical parameters in Pony Lake during the transition from ice covered to ice free, 2) highlight seasonal and inter-seasonal alterations in lake parameters, 3) relate the physicochemical conditions in the ice and water column to microbial processes and community structure, 4) characterize the effects of phototransformation of dissolved organic matter (DOM) on its bioavailability to bacteria, and 5) demonstrate the role of carotenoid pigments in protecting cells against environmental stresses. Also included are results from three McMurdo Dry Valley lakes on the survivability of microbes encapsulated within the lake ice covers. The results of this study highlight the sensitivity of Antarctic environments and the close coupling of environmental conditions and biological processes. Inter-seasonal differences in weather conditions and snow accumulation strongly affected the physicochemistry of this lacustrine system. Biological processes were closely tied to the physicochemical lake conditions. As a consequence planktonic abundances, production rates, and community structure evolved distinctly in each year. Bacterial production was regulated by the quality of DOM. Whereas nutrient availability appeared to play a minor role in eutrophic Pony Lake water, it became more critical for microbial communities found within the ice column of Antarctic lakes. Especially in the ice cover of the McMurdo Dry Valley lakes, enhanced microbial diversity and survivability was associated with particles (nutrient enriched micro-zones) within an otherwise ultra-oligotrophic habitat. In Pony Lake ice, microbial activity and community structure differed with respect to different strata within the ice column, induced by freeze-concentration of solutes, bioavailability of DOM, and oxygen gradients. A comparison of carotenoid pigmented and non-pigmented heterotrophic bacteria indicated that pigmentation provides enhanced resistance to environmental stresses such as freeze-thaw cycles or solar radiation. Collectively, the Pony Lake data demonstrated that microorganisms that persist throughout the year were able to survive much more severe conditions while entrapped within the ice compared to those observed in the lake water during summer months. Further, this study contributes to a better understanding of the biogeochemical carbon cycle in a microbially dominated system.Item Assessing constructed wetlands for beneficial use of saline-sodic water(Montana State University - Bozeman, College of Agriculture, 2005) Kirkpatrick, Amber Denise; Chairperson, Graduate Committee: James W. Bauder.Changes in agricultural practices, and irrigation strategies combined with natural processes, have led to increased salinization of soil and water resources worldwide. Coal bed methane (CBM) development in the Powder River Basin of Montana and Wyoming results in the co-production of large volumes of sodic and moderately saline discharge water, and represents a potential source of salinization of soil and water resources. The objective of this study was to evaluate the potential of constructed wetlands as a tool for CBM product water management. This was accomplished by assessing seasonal water use, biomass production and water use efficiencies (WUE) of three plant communities. Native species establish hydrologically distinct communities in former ephemeral channels now running with CBM product water, and nine species of those cataloged were selected and segregated into three communities. Closed-system wetland cells were constructed and each community was assigned to four of these cells, i.e., lysimeters. Chemistry of the supply water was sodic and moderately saline (EC ~ 3.4 dS/m, SAR > 25), typical of northern portions of the Powder River Basin where low to moderate electrical conductivities (EC 2-3 dS/m) and high sodium adsorption ratios (SAR > 20) are common. All three communities had similar total water use but WUE's differed significantly among the communities. Evaporation from a Class A evaporation pan was observed to be higher than evapotranspiration from the planted lysimeters, but this is not definitive as there was only one replication of the pan. Species survival and colonization was very good for seven of the nine species selected. American bulrush (Scirpus americanus) had very sparse spring regrowth and Inland saltgrass (Distichlis stricta) was likely out-competed by Creeping spikerush (Eleocharis palustris). Results of this study indicate that constructed wetlands planted with native, salt tolerant species have potential to utilize substantial volumes of CBM product water while remaining robust and viable. Although results suggest evaporation from an open water surface to be greater than evapotranspiration from a constructed wetland, constructed wetlands have added benefits of providing wildlife habitat, recreation and viewshed enhancement.