Persistence of uranium groundwater plumes: Contrasting mechanisms at two DOE sites in the groundwater–river interaction zone

Zachara, John M.; Long, Philip E.; Bargar, John R.; Davis, James A.; Fox, Patricia; Fredrickson, Jim K.; Freshley, Mark D.; Konopka, Allan; Liu, Chongxuan; McKinley, James P.; Rockhold, Mark; Williams, Kenneth H.; Yabusaki, Steven B.

doi:10.1016/j.jconhyd.2013.02.001

Cited by 141 publications

(147 citation statements)

References 93 publications

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“…This study was conducted in Hanford Reach of the Columbia River adjacent to the Hanford 300A (approximately 46°22′ 15.80′′N, 119° 16′ 31.52′′W) in eastern Washington, as described elsewhere (Slater et al, 2010; Zachara et al, 2013; Stegen et al, 2016), from March to November 2014. The hyporheic zone of the Columbia River experiences geographic variation in groundwater-surface water mixing, porewater geochemistry, and microbial community composition on sub-hourly to annual timescales (Peterson and Connelly, 2004; Arntzen et al, 2006; Slater et al, 2010; Lin et al, 2012; Stegen et al, 2012, 2016; Zachara et al, 2013).…”

Section: Methodsmentioning

confidence: 99%

Coupling Spatiotemporal Community Assembly Processes to Changes in Microbial Metabolism

et al. 2016

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Community assembly processes generate shifts in species abundances that influence ecosystem cycling of carbon and nutrients, yet our understanding of assembly remains largely separate from ecosystem-level functioning. Here, we investigate relationships between assembly and changes in microbial metabolism across space and time in hyporheic microbial communities. We pair sampling of two habitat types (i.e., attached and planktonic) through seasonal and sub-hourly hydrologic fluctuation with null modeling and temporally explicit multivariate statistics. We demonstrate that multiple selective pressures—imposed by sediment and porewater physicochemistry—integrate to generate changes in microbial community composition at distinct timescales among habitat types. These changes in composition are reflective of contrasting associations of Betaproteobacteria and Thaumarchaeota with ecological selection and with seasonal changes in microbial metabolism. We present a conceptual model based on our results in which metabolism increases when oscillating selective pressures oppose temporally stable selective pressures. Our conceptual model is pertinent to both macrobial and microbial systems experiencing multiple selective pressures and presents an avenue for assimilating community assembly processes into predictions of ecosystem-level functioning.

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Section: Methodsmentioning

confidence: 99%

Coupling Spatiotemporal Community Assembly Processes to Changes in Microbial Metabolism

et al. 2016

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“…Uranium concentrations in the water table of the Rifle aquifer are 2-8 times higher than the drinking water contamination limit (0.126 µM) established by the uranium mill tailings remedial action (UMTRA). A detailed review of geochemical characteristics of the site has already been published (Zachara et al, 2013) and in situ bioremediation of U 6+ has been intensely studied at this site (Anderson et al, 2003;Williams et al, 2011;Williams et al, 2013). Similar to previous years, acetate was injected into the subsurface at a concentration of ~15 mM between August and October, 2011 and monitored from 6 different wells (Giloteaux et al, 2013).…”

Section: Description Of Sampling Sitementioning

confidence: 96%

Potential forMethanosarcinato contribute to uranium reduction during acetate-promoted groundwater bioremediation

Holmes

Orellana

Giloteaux

et al. 2017

Preprint

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“…We believe our model is an important first step based on the experimental data, which could critically contribute toward this long-term goal. Our model is sufficiently robust and flexible that it can be modified to include the multiple species or metabolisms that may exist under bioremediation or natural scenarios such as that at DOE's Rifle and Hanford Sites, respectively (Zachara et al, 2013). However, in order to use it, the researchers need to determine what parameters and respective values need to be used for the field site to make accurate predictions of U fate and transport.…”

Section: Practical Implicationsmentioning

confidence: 99%

Modeling Substrate Utilization, Metabolite Production, and Uranium Immobilization in Shewanella oneidensis Biofilms

Renslow

Ahmed

Nuñez

et al. 2017

Front. Environ. Sci.

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In this study, we developed a two-dimensional mathematical model to predict substrate utilization and metabolite production rates in Shewanella oneidensis MR-1 biofilm in the presence and absence of uranium (U). In our model, lactate and fumarate are used as the electron donor and the electron acceptor, respectively. The model includes the production of extracellular polymeric substances (EPS). The EPS bound to the cell surface and distributed in the biofilm were considered bound EPS (bEPS) and loosely associated EPS (laEPS), respectively. COMSOL ® Multiphysics finite element analysis software was used to solve the model numerically (model file provided in the Supplementary Material). The input variables of the model were the lactate, fumarate, cell, and EPS concentrations, half saturation constant for fumarate, and diffusion coefficients of the substrates and metabolites. To estimate unknown parameters and calibrate the model, we used a custom designed biofilm reactor placed inside a nuclear magnetic resonance (NMR) microimaging and spectroscopy system and measured substrate utilization and metabolite production rates. From these data we estimated the yield coefficients, maximum substrate utilization rate, half saturation constant for lactate, stoichiometric ratio of fumarate and acetate to lactate and stoichiometric ratio of succinate to fumarate. These parameters are critical to predicting the activity of biofilms and are not available in the literature. Lastly, the model was used to predict uranium immobilization in S. oneidensis MR-1 biofilms by considering reduction and adsorption processes in the cells and in the EPS. We found that the majority of immobilization was due to cells, and that EPS was less efficient at immobilizing U. Furthermore, most of the immobilization occurred within the top 10 µm of the biofilm. To the best of our knowledge, this research is one of the first biofilm immobilization mathematical models based on experimental observation. It has the ability to predict the relative contributions to U immobilization of laEPS, bEPS, and cells.

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Persistence of uranium groundwater plumes: Contrasting mechanisms at two DOE sites in the groundwater–river interaction zone

Cited by 141 publications

References 93 publications

Coupling Spatiotemporal Community Assembly Processes to Changes in Microbial Metabolism

Coupling Spatiotemporal Community Assembly Processes to Changes in Microbial Metabolism

Potential forMethanosarcinato contribute to uranium reduction during acetate-promoted groundwater bioremediation

Modeling Substrate Utilization, Metabolite Production, and Uranium Immobilization in Shewanella oneidensis Biofilms

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