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Effects of physical and geochemical heterogeneities on mineral transformation and biomass accumulation during uranium bioremediation at Rifle, Colorado
Immunohistochemical evaluation of e-cadherin, Ki-67 and PCNA in canine mammary neoplasias: correlation of prognostic factors and clinical outcome
The method of monitoring the indicators of thermo-oxidative stability of mixtures of motor oils
Effects of physical and geochemical heterogeneities on mineral transformation and biomass accumulation during biostimulation experiments at
Abstract Electron donor amendment for bioremediation often results in precipitation of secondary minerals and the growth of biomass, which can potentially change flow paths and the efficacy of bioremediation. Quantitative estimation of precipitate and biomass distribution has remained challenging, partly due to the intrinsic heterogeneities of natural porous media and the scarcity of field data. In this work, we examine the effects of physical and geochemical heterogeneities on the spatial distributions of mineral precipitates and biomass accumulated during a uranium bioremediation experiment near Rifle, Colorado. Field bromide breakthrough data were used to infer a heterogeneous distribution of hydraulic conductivity through inverse transport modeling, while the solid phase Fe(III) content was determined by assuming a negative correlation with hydraulic conductivity. Validated by field aqueous geochemical data, reactive transport modeling was used to explicitly keep track of the microbial community dynamics and estimate the spatial distribution of precipitates and biomass. The results show that the maximum mineral precipitation and biomass accumulation occurs in the vicinity of the injection wells, occupying up to 5.4% volume of the pore space, and is dominated by reaction products of sulfate reduction. Accumulation near the injection wells is not strongly affected by heterogeneities present in the system due to the ubiquitous presence of sulfate in the groundwater. However, accumulation in the down-gradient regions is dominated by the iron-reducing reaction products, whose spatial patterns are strongly controlled by both physical and geochemical heterogeneities. Heterogeneities can lead to localized large accumulation of mineral precipitates and biomass, increasing the possibility of pore clogging. Although ignoring the heterogeneities of the system can lead to adequate prediction of the average behavior of sulfate-reducing related products, it can also lead to an overestimation of the overall accumulation of iron-reducing bacteria, as well as the rate and extent of iron reduction. These findings have important implications not only for uranium bioremediation at the Rifle site and for bioremediation of other redox sensitive contaminants at sites with similar characteristics, but also for development of optimal amendment delivery strategies
Study of the effect of the synthetic additive Monnol Elite 5W-40 SL/CF on the quality indicators of mineral motor oil M-10G2k
Graphoanalytical method for determining the indicators of thermal-oxidative stability of lubricating oils
Identification of qualitative regularities in the functioning of neural network models of a critical resource of lubricating oils
Prediction life of lubricants on the analysis of experimental data on their optical density
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