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DOE OSTI2020

Metal Bioavailability and Ecotoxicity of Bioremediated Oils and Tailings by BioTiger{sup TM}, a Microbial Consortium

Oil Sands and Mature Fine Tailings: Oil sand reserves are a major source of oil for the United States. Oil sands are a mixture of sand, clay, water, and bitumen. The refining process requires large volumes of water and generates hazardous Mature Fine Tailings (MFTs) that are stored in engineered settling ponds. They are of major environmental concern due to their persistence and difficulty to naturally biodegrade. MFT Contaminants of Concern: Naphthenic Acids (NAs), Polycyclic Aromatic Hydrocarbons (PAHs), Benzene, Toluene, Ethylbenzene and Xylene (BTEX), Metals, Residual Bitumen. BioTiger{sup TM} (BT{sup TM}), the SRNL patented 12 component microbial consortia was found to cometabolically degrade some NAs and PAHs. Previous studies performing short term exposure (48 hours and 7 days) to BT{sup TM} have resulted in increased toxicity due to the partial degradation of PAHs forming toxic intermediates. Objective: Evaluate the ecotoxicity of BT{sup TM} remediated MFTs exposed to a 2 week period w/ yeast (Y) extract. This work will determine BT{sup TM}'s remediation of MFTs from Fort McMurray, Alberta. Acute toxicity tests will be performed under section 9 of EPA's Method for Measuring Acute Toxicity using the freshwater organism, Ceriodaphnia dubia. Monitor BT{sup TM} growth through Most Probable Number (MPN) counts, pH, and metal bioavailability will also be evaluated. Preparing tailing solutions for biodegradation: BT{sup TM} components were grown in R2A media and combined. Mother BT{sup TM} was centrifuged at 7000 rpm for 20 minutes and resuspended in Bushnell Haus. 33 g of tailings were added to 1100 mL Bushnell Haus along with yeast extract (11 g) to create a 3% tailing solution. Treatments were performed in triplicate. Preparing solutions for toxicity tests using C. dubia: Supernatant was collected immediately after centrifuging at 7000 rpm for 20 min. Supernatant was filtered via a 0.22 μm sterile system. All treatments except MFT, Y peaked at T=4. This decrease in microbial growth could be associated with toxicity from intermediate byproducts. Treatments containing only MFTs decreased in the initial 11 days before growing significantly. Final solution for MFT, Y treatment had the highest pH. This could potentially be due to increased microbial activity linked with yeast consumption. All treatments except MFT, Y peaked at T=4. This decrease in microbial growth could be associated with toxicity from intermediate byproducts. Treatments containing only MFTs decreased in the initial 11 days before growing significantly. Future Direction: Await results from Acute Toxicity Tests and Metal Bioavailability Quantification of biosurfactant production. Evaluate hydrocarbon degradation byproducts using an analytical chemistry approach. More toxicity experiments with variations in time and conditions.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2012

Gas Production from Hydrate-Bearing Sediments - Emergent Phenomena -

Even a small fraction of fine particles can have a significant effect on gas production from hydrate-bearing sediments and sediment stability. Experiments were conducted to investigate the role of fine particles on gas production using a soil chamber that allows for the application of an effective stress to the sediment. This chamber was instrumented to monitor shear-wave velocity, temperature, pressure, and volume change during CO{sub 2} hydrate formation and gas production. The instrumented chamber was placed inside the Oak Ridge National Laboratory Seafloor Process Simulator (SPS), which was used to control the fluid pressure and temperature. Experiments were conducted with different sediment types and pressure-temperature histories. Fines migrated within the sediment in the direction of fluid flow. A vuggy structure formed in the sand; these small cavities or vuggs were precursors to the development of gas-driven fractures during depressurization under a constant effective stress boundary condition. We define the critical fines fraction as the clay-to-sand mass ratio when clays fill the pore space in the sand. Fines migration, clogging, vugs, and gas-driven fracture formation developed even when the fines content was significantly lower than the critical fines fraction. These results show the importance of fines in gas production from hydrate-bearing sediments, even when the fines content is relatively low.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2011

Effect of Grain Size on Uranium(VI) Surface Complexation Kinetics and Adsorption Additivity

Laboratory experiments were performed to investigate the contribution of variable grain sizes to uranium adsorption/desorption in a sediment collected from the US DOE Hanford site. The sediment was wet-sieved into four size fractions: coarse sand (1-2 mm), medium sand (0.2-1 mm), fine sand (0.05-0.2 mm), and clay/silt fraction (< 0.05mm). For each size fraction and their composite (sediment), batch experiments were performed to determine uranium adsorption isotherms, and stirred flow-cell experiments were conducted to derive kinetic data of uranium adsorption and subsequent desorption. The results showed that uranium adsorption isotherms and adsorption/desorption kinetics were size-specific, reflecting the effects of size-specific adsorption site concentration and kinetic rate constants. The larger-size fraction had a larger mass percentage in the sediment, but with a smaller adsorption site concentration and generally a slower uranium adsorption/desorption rate. The same equilibrium surface complexation reaction and reaction constant could describe uranium adsorption isotherms for all size fractions and the composite after accounting for the effect of adsorption site concentration. Mass-weighted, linear additivity was observed for both uranium adsorption isotherms and adsorption/desorption kinetics in the composite. Our analysis also showed that uranium adsorption site concentration estimated from the adsorption isotherms was 3 orders of magnitude less than a site concentration estimated from sediment surface area and generic site density. One important implication of this study is that grain size distribution may be used to estimate uranium adsorption site, and adsorption/desorption kinetic rates in heterogeneous sediments from a common location.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2011

Extraction of microbial proteome from soil: potential and limitations assessed through a model study

Proteomics is the study of functions and regulation of biological systems based on the analysis of the protein expression profile, and there is a general agreement that soil proteomics may be a tool for better soil management. Because of the ability of soils to stabilize extracellular proteins by various mechanisms, development of soil proteomics needs an assessment of the efficiency of protein extraction from various soil types. We evaluated the possibility of extraction of soil microbial proteome by inoculating Cupriavidus metallidurans CH34, which has a known proteome, into sterile sand, kaolinite, montmorillonite and a mixture of sand, kaolinite, montmorillonite, goethite and humic acids. One hour after inoculation, the viability of C. metallidurans was determined by the colony-forming units method (CFU), the amount of extracted proteins was determined by the Bradford method and the bacterial proteome was analysed by the two-dimensional gel electrophoresis technique (2D-GE). The bacterial number was 2.5 x 10{sup 6} CFU g{sup -1} of soil in all microcosms, whereas the total extracted protein content varied from 98.1 to 1268 {micro}g g{sup -1} in the various microcosms, but was undetectable in the inoculated montmorillonite. The number of protein spots from the bacterial culture and the inoculated microcosms varied between 317 and 591, with 54 variable spots among the pure culture and the microcosms. No protein spots were detected in the 2D-GE from the montmorillonite microcosm. The 2D-GE of artificial soil microcosms showed a protein pattern that was different from those of pure culture and sand and kaolinite microcosms. The results confirm the importance of clay-specific surface area and CEC in protein adsorption as montmorillonite alone had the largest sorptive capacity, and show that the artificial soil used also had a large sorptive capacity for microbial proteins. Globally, the results indicate that the extraction of proteins from soils is strongly influenced by the clay type and organic matter content, and that poor protein extraction efficiency may reduce the potential of soil proteomics.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2011

Flow Processes in the Dry Regime: The Effect on Capillary Barrier Performance

Engineered capillary barriers typically consist of two layers of granular materials designed so that the contrast in material hydraulic properties and sloping interface retains infiltrating water in the upper layer. We report here on the results of two bench-top capillary barrier experiments, interpretation, and numerical modeling. We measured hydraulic parameters for two coarse materials using standard methods and found that the materials had similar hydraulic properties despite being morphologically different (round vs. angular). The round sand provided a better functioning capillary barrier than the angular sand, but neither experiment could be characterized as a perfectly working capillary barrier. In both cases, more than 93% of the infiltrating water was successfully diverted from the lower layer, however, infiltration into the underlying layer was observed in both systems. Based on this work, we believe that non-continuum processes such as vapor diffusion and film flow contribute to the observed phenomena and are important aspects to consider with respect to capillary barrier design, as well as dry vadose zone processes in general. Using a theoretical film flow equation that incorporates the surface geometry of the porous material we found that infiltration into the coarse underlying sand layer appeared to be dominated by water film flow. The NUFT (Non-isothermal Unsaturated-saturated Flow and Transport) model was used for qualitative comparison simulations. We were able to reproduce the barrier breach observed in the experiments using targeted parameter adjustment, by which pseudo-film flow was successfully simulated.

36 MATERIALS SCIENCE↗

DOE OSTI2011

Novel Self-Thickening Chemicals for Improved Conformance Control

The objective of this project is to identify single chemical agents that exhibit a desirable rheological property whereby if such a chemical is dissolved in salt water it increases the solution viscosity significantly with time. We term that behavior as 'self-thickening' and have nicknamed this as 'T85 technology'. As detailed in the original project proposal, such single chemical products can be applied to advantage as agents for selectively slowing or blocking high flow water channels in subsurface oil reservoirs. The net effect is a decrease in water and an increase in oil flow and production. The initial testing has focused on five different synthetic co-polymers that have two or more chemical groups. These chemicals were dissolved at a concentration of 2500 ppm into different salt solutions (sodium chloride, potassium chloride, and calcium chloride) that encompass a range of dissolved salt concentrations. For the sodium chloride and potassium chloride solutions the salt concentration ranged from 1-5 wt%. The calcium chloride dihydrate sample concentrations ranged from 0.1-1 wt%. One set of samples being aged at 25 C and a second set at 50 C. Viscosity measurements versus aging time show two of these agents may exhibit apparent self-thickening behavior under certain salinity and temperature conditions. Generally the effect is greater in lower salinity NaCl brines and at 25 C. Preliminary flow experiments confirm that the aged fluids exhibit increased effective viscosity while flowing through a porous medium (sand pack). These flow tests include the case of the chemical fluid being aged on the bench before injection into a sand pack, and also a second series of sand packs where fresh chemical fluid is injected and allowed to age in-situ. Thus, the results of the static ageing tests together with the flow tests are a technical validation of the T85 concept.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2011

SLUDGE TREATMENT PROJECT ENGINEERED CONTAINER RETRIEVAL AND TRANSFER SYSTEM PRELMINARY DESIGN HAZARD AND OPERABILITY STUDY

This Hazard and Operability (HAZOP) study addresses the Sludge Treatment Project (STP) Engineered Container Retrieval and Transfer System (ECRTS) preliminary design for retrieving sludge from underwater engineered containers located in the 105-K West (KW) Basin, transferring the sludge as a sludge-water slurry (hereafter referred to as 'slurry') to a Sludge Transport and Storage Container (STSC) located in a Modified KW Basin Annex, and preparing the STSC for transport to T Plant using the Sludge Transport System (STS). There are six, underwater engineered containers located in the KW Basin that, at the time of sludge retrieval, will contain an estimated volume of 5.2 m{sup 3} of KW Basin floor and pit sludge, 18.4 m{sup 3} of 105-K East (KE) Basin floor, pit, and canister sludge, and 3.5 m{sup 3} of settler tank sludge. The KE and KW Basin sludge consists of fuel corrosion products (including metallic uranium, and fission and activation products), small fuel fragments, iron and aluminum oxide, sand, dirt, operational debris, and biological debris. The settler tank sludge consists of sludge generated by the washing of KE and KW Basin fuel in the Primary Clean Machine. A detailed description of the origin of sludge and its chemical and physical characteristics can be found in HNF-41051, Preliminary STP Container and Settler Sludge Process System Description and Material Balance. In summary, the ECRTS retrieves sludge from the engineered containers and hydraulically transfers it as a slurry into an STSC positioned within a trailer-mounted STS cask located in a Modified KW Basin Annex. The slurry is allowed to settle within the STSC to concentrate the solids and clarify the supernate. After a prescribed settling period the supernate is decanted. The decanted supernate is filtered through a sand filter and returned to the basin. Subsequent batches of slurry are added to the STSC, settled, and excess supernate removed until the prescribed quantity of sludge is collected. The sand filter is then backwashed into the STSC. The STSC and STS cask are then inerted and transported to T Plant.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2011

Land and Resource Management Issues Relevant to Deploying In-Situ Thermal Technologies

Utah is home to oil shale resources containing roughly 1.3 trillion barrels of oil equivalent and our nation’s richest oil sands resources. If economically feasible and environmentally responsible means of tapping these resources can be developed, these resources could provide a safe and stable domestic energy source for decades to come. In Utah, oil shale and oil sands resources underlay a patchwork of federal, state, private, and tribal lands that are subject to different regulatory schemes and conflicting management objectives. Evaluating the development potential of Utah’s oil shale and oil sands resources requires an understanding of jurisdictional issues and the challenges they present to deployment and efficient utilization of emerging technologies. The jurisdictional patchwork and divergent management requirements inhibit efficient, economic, and environmentally sustainable development. This report examines these barriers to resource development, methods of obtaining access to landlocked resources, and options for consolidating resource ownership. This report also examines recent legislative efforts to wrest control of western public lands from the federal government. If successful, these efforts could dramatically reshape resource control and access, though these efforts appear to fall far short of their stated goals. The unintended consequences of adversarial approaches to obtaining resource access may outweigh their benefits, hardening positions and increasing tensions to the detriment of overall coordination between resource managers. Federal land exchanges represent a more efficient and mutually beneficial means of consolidating management control and improving management efficiency. Independent of exchange proposals, resource managers must improve coordination, moving beyond mere consultation with neighboring landowners and sister agencies to coordinating actions with them.

04 OIL SHALES AND TAR SANDS↗

DOE OSTI2015

Treatment and Reuse of Wastewaters Discharged by Petroleum Industries (HMD/Algeria)

Industrial wastewaters discharged by petroleum industries contains: oil, heavy metals and chemicals used in the process of oil separation and treatment. These waters are a source of soil, water and air pollution, and lead a mortal danger to the ecosystem. Our aim in this work has an aspect that can contribute to the collective effort to address the enormous amount of water purges storage bins and reuse them to avoid any environmental damage. This was achieved by chemical treating of these wastewaters discharged from three different locations of Hassi Messaoud (HMD) petroleum field by flocculation with (C-5563) followed by coagulation with (C-2061) using two different acids as sequestering namely: Ascorbic and Citric acid. After experiments, the results showed that the wastewater can be treated without sequestering by adding 40 ppm of activated silicates. The best result was obtained by addition of 160 ppm of Ascorbic acid as sequestering agent and 20 ppm of activated silicates; resulting in removal of 92.81 % of suspended matter and 95.53 % of turbidity. Finally we concluded that this wastewater was satisfactorily treated and we recommend either inject it for enhanced oil recovery in industrial closest field (North field) to maintain the reservoir pressure and the improved rate recovery of oil reserves or reuse it in garden irrigation. In order to see the impact of the treated water on plants, irrigation tests have conducted on two types of plants (date palm and shaft apocalyptic) for one year. The tests showed that the thick layer of 5 cm and 0.08mm of particles diameter of dune sand removes most of remaining oil. The sand layer that fills the basin surrounding the shaft is removed and replaced every 06 months. So, Dune sand plays the role of natural filter. The garden plants appear and grow normally.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS2022

Keweenaw Bay Water Resources: Turbidity Data Decision Support for Shoreline Assessment and Management in Lake Superior'S Keweenaw Bay

The Keweenaw Bay Indian Community (KBIC) has shoreline along the south of Lake Superior that is contaminated with copper stamp sands from legacy mining. The stamp sands have been capped with sandy-loam soils and restored native species, but erosion and flooding threaten to re-deposit these stamp sands onto wetlands and into the bay. Erosion and flooding also threaten loss of beaches and shoreline, infrastructure, wetland restoration projects, and coastal highways, which has driven shoreline armoring. However, while shoreline armoring can be effective in protecting the intended areas, it can also exacerbate erosion in nearby unarmored areas, so its net impact on the shoreline is yet to be quantified. The DEVELOP team partnered with KBIC and the Environmental Protection Agency (EPA) to utilize imagery from Landsat 8 Operational Land Imager (OLI) and Sentinel-2 Multispectral Instrument (MSI) in order to analyze turbidity proxies. The results from these analyses showed that seasonal variation in study area was greatest during the season dominated by rain, but spatial variability across our study period did not show a clear trend. These results will be used to better inform future shoreline management efforts and support resilience in the face of more coastal erosion.

remote sensing↗

DOE OSTI2010

Formation of granular jets observed by high-speed x-ray radiography

When a heavy sphere is dropped onto a bed of loose, fine sand, a remarkable phenomenon occurs: a large, focused jet of sand shoots upwards. Although similar looking jets are observed on impact in fluid systems, they are held together by surface tension. Surprisingly, the granular jet exists in the absence of both surface tension and cohesion, thus fluid jet models are of limited use. Previous work proposed that the jet is created solely by the gravity-driven collapse of a void left by the sphere's descent through the pack. Here we present experimental evidence that granular jets are instead driven by a more complex process involving the interaction between the sand and interstitial air. Using high-speed X-ray radiography, and high-speed digital video, we observe the formation of the jet both inside and above the bed. We find that what previously was thought of as a single jet in fact consists of two components: a wispy, thin jet that varies little with pressure followed by a thick air-pressure-driven jet. This is further evidence that qualitatively new phenomena in granular systems can emerge as a function of air pressure. Our results highlight the importance of the dynamic coupling between gas and granule motion.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2018

Decontamination Experiments and Simulations Supporting Recovery After Widespread Contamination - 18685

Clean-up after an uncontrolled nuclear material release differs from common decontamination practices in the nuclear industry and military combat scenarios. Uncontrolled releases, particularly acts of terror, require specific protective actions guides (PAGs) to optimize short and long-term repercussions. Ideally, non-destructive decontamination methods would be employed. To help fulfill this need, the IWATERS (Integrated Wash Aid Treatment Emergency Reuse System) was proposed in 2014 for remediation outside the immediate blast area. 'Wash-Aid' is hosed onto affected areas, and the used wash solution is collected and recycled through sand/clay beds. To help characterize the IWATERS technology, the below was completed: - Decontamination experiments with a pressurized wash solution using Cs-137, Sr- 85, and Eu-152 contaminants on porous urban materials. - Sensitivity analyses on recycling bed variables using GoldSim{sup TM} CT. - A proposed framework that expands the recycling bed model to include probabilistic simulation of immediate recovery efforts. Removal efficacy of tap water and 0.5 M KCl were compared for Cs, Sr, and Eu across asphalt, brick, and concrete. The 0.5 M KCl solution significantly outperformed tap water in every case except for Eu on concrete and Cs on brick. Trends in the high-pressure decontamination with salt additive compared to low pressure decontamination show evidence of physical and chemical removal. Variations in cleaning rate yielded no significant trend. Pressure changes (by adjusting nozzle-to-coupon distance) were only significant for the highest pressure. Hypothetical Contamination Scenario: To tie the decontamination experiments and recycling bed model together, a small contamination scenario was created. Imagine the sides of a small concrete building uniformly contaminated with Cs-137. Power washing the building with 0.5 M KCl solution would result in 857 L of contaminated solution generated in 185 minutes. Two sand clay beds were designed to clean the used solution. With a sand mass fraction of 0.9, a 10 ft{sup 2} bed 4 ft tall could recycle the solution in 1.05 hrs. Changing the sand mass fraction to 0.5 yielded a 2.5 ft{sup 2} bed 4 ft tall (∼55-gallon drum) that recycled the solution in 7.43 hrs. This exercise showed how the sand/clay bed design can easily change to match the primary remediation goals. The second sand/clay bed would reduce the waste generation while the first bed reduces the remediation time. Conclusions: Variations on speed and nozzle distance (pressure) yielded insignificant differences in efficacy except for the closest distance. High-pressure washing showed increased decontamination efficacy with KCl additive in the majority of cases. Except for bed composition, key recycling bed parameters can be varied on-the-fly. This allows for optimization of, for example, time and waste generation. The hypothetical contamination scenario showed pairing decontamination experiment results with modeling tools can lead to increased preparedness for a large-scale contamination event. With collaboration and time, an expanded recovery/remediation model could aid in development of effective protective action guides.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2018

Depressurization-Induced Fines Migration in Sediments Containing Methane Hydrate: X-Ray Computed Tomography Imaging Experiments

Depressurization of hydrate-bearing sediments (HBS) can cause the movement of fine particles, and in turn, such fines migration affects fluid flow and mechanical behavior of sediments, ultimately affecting long-term hydrocarbon production and wellbore stability. In this work, we investigate how and to what extent depressurization of HBS causes fines migration using X-ray computed tomography (CT) imaging. Methane hydrate was synthesized in sediments with 10% fines content (FC), composed of sands with silt and/or clay, and the hydrate-bearing samples were stepwisely depressurized while acquiring CT images. The CT images were analyzed to quantify the spatial changes in FC in the host sediment and thus to capture the fines migration during depressurization. It was found that the FC changes began occurring from the hydrate dissociation regions. This confirms that the multiphase flow caused by depressurization accompanies fines migration. Depressurization of HBS with a hydrate saturation of ~20–40% caused FC reduction from ~10% to ~6–9%, and the extent of fines migration differed with the particle sizes of the host sands and the types of fines. It was found that fines migration was more pronounced with coarse sands and with silty fines. Such observed level of FC reduction is estimated to increase sediment permeability by several factors based on the Kozeny-type permeability model. In conclusion, our results support the notion that the extent of fines migration and its effect on fluid flow behavior need to be assessed in consideration of physical properties of host sediment and fine particles to identify optimum depressurization strategies.

42 ENGINEERING↗

DOE OSTI2018

Archie's Saturation Exponent for Natural Gas Hydrate in Coarse-Grained Reservoirs

Accurately quantifying the amount of naturally occurring gas hydrate in marine and permafrost environments is important for assessing its resource potential and understanding the role of gas hydrate in the global carbon cycle. Electrical resistivity well logs are often used to calculate gas hydrate saturations, S h , using Archie's equation. Archie's equation, in turn, relies on an empirical saturation parameter, n . Though n = 1.9 has been measured for ice–bearing sands and is widely used within the hydrate community, it is highly questionable if this n value is appropriate for hydrate–bearing sands. In this work, we calibrate n for hydrate–bearing sands from the Canadian permafrost gas hydrate research well, Mallik 5L–38, by establishing an independent downhole S h profile based on compressional–wave velocity log data. Using the independently determined S h profile and colocated electrical resistivity and bulk density logs, Archie's saturation equation is solved for n , and uncertainty is tracked throughout the iterative process. In addition to the Mallik 5L–38 well, we also apply this method to two marine, coarse–grained reservoirs from the northern Gulf of Mexico Gas Hydrate Joint Industry Project: Walker Ridge 313–H and Green Canyon 955–H. All locations yield similar results, each suggesting n ≈ 2.5 ± 0.5. Furthermore, for the coarse–grained hydrate bearing ( S h > 0.4) of greatest interest as potential energy resources, we suggest that n = 2.5 ± 0.5 should be applied in Archie's equation for either marine or permafrost gas hydrate settings if independent estimates of n are not available.

58 GEOSCIENCES↗

DOE OSTI2017

Application of the Aquifer Impact Model to support decisions at a CO 2 sequestration site

The National Risk Assessment Partnership (NRAP) has developed a suite of tools to assess and manage risk at CO 2 sequestration sites. The NRAP tool suite includes the Aquifer Impact Model (AIM), which evaluates the potential for groundwater impacts from leaks of CO 2 and brine through abandoned wellbores. There are two aquifer reduced-order models (ROMs) included with the AIM tool, a confined alluvium aquifer, and an unconfined carbonate aquifer. The models accept aquifer parameters as a range of variable inputs so they may have broad applicability. The generic aquifer models may be used at the early stages of site selection, when site-specific data is not available. Guidelines have been developed for determining when the generic ROMs might be applicable to a new site. This work considers the application of the AIM to predicting the impact of CO 2 or brine leakage were it to occur at the Illinois Basin Decatur Project (IBDP). Results of the model sensitivity analysis can help guide characterization efforts; the hydraulic parameters and leakage source term magnitude are more sensitive than clay fraction or cation exchange capacity. Sand permeability was the only hydraulic parameter measured at the IBDP site. More information on the other hydraulic parameters could reduce uncertainty in risk estimates. Some non-adjustable parameters are significantly different for the ROM than for the observations at the IBDP site. The generic ROMs could be made more useful to a wider range of sites if the initial conditions and no-impact threshold values were adjustable parameters.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

DOE OSTI2020

Soil properties and biochemical composition of ground-dwelling bee nests in agricultural settings

Soils deliver underrecognized ecosystem services by supplying habitat for ground-dwelling pollinators, such as wild bees and other organisms, that pollinate 80% of insect-pollinated plants and play a critical role in securing resilient pollination provisions. Our objective is to identify soil properties of ground nesting bee nests in agricultural settings of western Oregon, USA. We confirmed ground nesting bee and sand wasp activity in 7 agricultural sites and 1 recreational park. Soils from 17 bee and sand wasp nests were analyzed for pH, particle size distribution, and carbon and nitrogen content. We visually confirmed that 8 of the nesting bees were sweat bees from the Halictidae family and identified a captured bee specimen as Lasioglossum (Dialictus) (Hymenoptera: Halictidae). We located 2 sites with sand wasps where specimens were identified as Cerceris and Bembix (Hymenoptera: Crabronidae). The organic matter composition of three soil samples scraped from the linings of active nests were assessed using Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). The FTICR-MS results identified unknown lipid compounds in the nest soil samples, which we hypothesize are waterproofing lipids secreted to line cell walls. Bee nests occurred in slightly acidic, bare-ground soils with low rock/vegetation coverage, low organic carbon content (<1%), and exhibited significantly higher silt-plus-clay fractions (>75%) versus data published for bee nests in prior work. Our findings present important implications for textural controls on nest site selection in wet, cool environments and demonstrate the importance of integrating soil properties to improve our understanding of ground-dwelling organisms and associated soil habitats.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2024

Pore confinement enhances but surface adhesion reduces bacterial cell-to-cell conjugation

As the habitats of bacteria, soil pore network and surface properties control the distribution, adhesion, and motility of bacteria in soils. These physical processes in turn influence bacterial accesses to nutrients and bacterial interactions. Our understanding on the pore- and surface-mediated bacterial interactions is currently limited. In this research, we evaluated the effects of soil pore confinement and surface adhesion on conjugation-based bacterial interactions. The interaction was measured by plasmid transfer between donor and recipient cells within the population of soil bacterium Pseudomonas putida. We found that the presence of porous sand media led to a net increase in conjugation frequency compared to sand-free liquid control. The increase is attributed to the facilitated effect of pore confinement on the collision of bacteria within pores. In contrast, bacterial adhesion to sand surfaces under elevated ionic strength conditions decreased the conjugation frequency as a result of mobility reduction on the surface. Such collision and adhesion mechanisms jointly drive the conjugation as a function of pore and surface properties of porous media. Finally, these results provide valuable insights into the roles of soil pores and surfaces in regulating horizontal gene transfer, an essential cell-to-cell interaction sustaining key processes of soil ecology and health.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2015

Bench-scale electrokinetic remediation for cesium-contaminated sediment at the Hanford Site, USA

Electrokinetic (EK) remediation has been applied to extract various contaminants such as radionuclides, heavy metals, and organic compounds from contaminated sediment and soil using electric currents. We conducted a laboratory experiment to investigate the efficiency of EK remediation method for Hanford sediment (76% sand and 24% silt-clay) after artificial contamination with nonradioactive 133Cs (0.01 M CsNO3) as a surrogate for radioactive 137Cs. The initial 133Cs concentration in the bulk sediment was 668 mg kg-1, with a higher 133Cs concentration for the silt-clay fraction (867 mg kg-1) than for the sand fraction (83 mg kg-1). A significant removal of cationic 133Cs from the sediment occurred from the cathode side (-), whereas the removal was negligible from the anode side (+) during the EK remediation process for 68 days. Based on microwave-assisted total digestion, 312 mg kg-1 of 133Cs was removed from the bulk sediment, which corresponds to the removal efficiency of 47%. The EK method was significantly more efficient for the silt-clay fraction than for the sand fraction. X-ray diffraction (XRD) and scanning electron microscopy-electron dispersive spectroscopy (SEM-EDS) analyses indicate that change in major crystalline mineral phases was insignificant during the EK remediation and the removal of 133Cs from the Hanford sediment by the EK method is attributed mainly to cation exchange with K in clay minerals. The experimental results suggest that the EK method can effectively remove radioactive Cs from the surface or subsurface sediment contaminated by radioactive materials in the Hanford Site, Washington, USA.

Cation exchange↗