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Lauchnor E.,Montana State UniversityBozeman | Phillips A.,Montana State UniversityBozeman | Gerlach R.,Montana State UniversityBozeman | Cunningham A.B.,Montana State UniversityBozeman
Water Resources Research | Year: 2015

The model for microbially induced calcite precipitation (MICP) published by Ebigbo et al. (2012) has been improved based on new insights obtained from experiments and model calibration. The challenge in constructing a predictive model for permeability reduction in the underground with MICP is the quantification of the complex interaction between flow, transport, biofilm growth, and reaction kinetics. New data from Lauchnor et al. (2015) on whole-cell ureolysis kinetics from batch experiments were incorporated into the model, which has allowed for a more precise quantification of the relevant parameters as well as a simplification of the reaction kinetics in the equations of the model. Further, the model has been calibrated objectively by inverse modeling using quasi-1D column experiments and a radial flow experiment. From the postprocessing of the inverse modeling, a comprehensive sensitivity analysis has been performed with focus on the model input parameters that were fitted in the course of the model calibration. It reveals that calcite precipitation and concentrations of NH4+ and Ca2+ are particularly sensitive to parameters associated with the ureolysis rate and the attachment behavior of biomass. Based on the determined sensitivities and the ranges of values for the estimated parameters in the inversion, it is possible to identify focal areas where further research can have a high impact toward improving the understanding and engineering of MICP. © 2015. American Geophysical Union. All Rights Reserved.


PubMed | Montana State University and Montana State UniversityBozeman
Type: | Journal: Frontiers in microbiology | Year: 2016

Biomineralized ferric oxide microbial mats are ubiquitous features on Earth, are common in hot springs of Yellowstone National Park (YNP, WY, USA), and form due to direct interaction between microbial and physicochemical processes. The overall goal of this study was to determine the contribution of different community members to the assembly and succession of acidic high-temperature Fe(III)-oxide mat ecosystems. Spatial and temporal changes in Fe(III)-oxide accretion and the abundance of relevant community members were monitored over 70 days using sterile glass microscope slides incubated in the outflow channels of two acidic geothermal springs (pH = 3-3.5; temperature = 68-75C) in YNP. Hydrogenobaculum spp. were the most abundant taxon identified during early successional stages (4-40 days), and have been shown to oxidize arsenite, sulfide, and hydrogen coupled to oxygen reduction. Iron-oxidizing populations of Metallosphaera yellowstonensis were detected within 4 days, and reached steady-state levels within 14-30 days, corresponding to visible Fe(III)-oxide accretion. Heterotrophic archaea colonized near 30 days, and emerged as the dominant functional guild after 70 days and in mature Fe(III)-oxide mats (1-2 cm thick). First-order rate constants of Fe(III)-oxide accretion ranged from 0.046 to 0.05 day(-1), and in situ microelectrode measurements showed that the oxidation of Fe(II) is limited by the diffusion of O2 into the Fe(III)-oxide mat. The formation of microterracettes also implicated O2 as a major variable controlling microbial growth and subsequent mat morphology. The assembly and succession of Fe(III)-oxide mat communities follows a repeatable pattern of colonization by lithoautotrophic organisms, and the subsequent growth of diverse organoheterotrophs. The unique geochemical signatures and micromorphology of extant biomineralized Fe(III)-oxide mats are also useful for understanding other Fe(II)-oxidizing systems.


Reeves W.K.,1000 East University Avenue | Reeves W.K.,Apo Box Inc. | Lloyd J.E.,1000 East University Avenue | Stobart R.,1000 East University Avenue | And 4 more authors.
Journal of the American Mosquito Control Association | Year: 2010

Culicoides sonorensis is the primary vector of bluetongue and epizootic hemorrhagic disease viruses in North America. Bluetongue disease is one of the most economically important arthropod-borne diseases of sheep in North America, because it causes significant morbidity and mortality and can lead to local quarantines and international trade restrictions. Long-lasting repellent pesticides could be applied to sheep as they are moved down from mountain pastures to protect them from biting midges until the 1st frost. We tested long-lasting pesticides on sheep as repellents against C. sonorensis. Both PYthon ear tags with 10 zeta-cypermethrin (9.8 g/tag) synergized with 20 piperonyl butoxide (PBO) and a 12-ml low-volume spray application of ready-to-use sheep insecticide (Y-TEX) with 2.5 permethrin and 2.5 PBO in an oil-based formulation were repellent to C. sonorensis for at least 35 wk after a single application. © 2010 by The American Mosquito Control Association, Inc.

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