Spatial modeling for radon concentrations in subway stations in Seoul, Korea.

This study examined the environmental and geological determinants of radon concentration in subway stations by applying a spatial statistical model to the integrated GIS database. The data were collected for 237 underground subway stations located inside the city of Seoul, South Korea and used for mapping to illustrate the spatial distribution of airborne radon exposure and analysis of potential contribution of station-specific and geological determinants. A Bayesian conditional autoregressive regression (CAR) model was developed to explain the radon concentrations, and the predicted radon surface was generated and visualized to identify hotspot regions where elevated radon exposure is likely to be present in underground settings. The findings include: (1) subway stations located within granite bedrock maintained relatively higher radon concentrations; (2) underground radon emanation is not only controlled by lithology and the associated uranium content of the rocks and soil, but also by structural factors which facilitate easy migration of radon from deeper parts of the earth's crust; (3) radon risks would be elevated if the underground facility is constructed too deep without any control measure; and (4) not only the foundation of an underground facility but also the nature of the soil and rocks in the vicinity helps determine whether or not dangerous levels of radon gas are likely to accumulate inside. This modeling effort is expected to provide guidelines regarding the identification of future station locations with a lower radon risk and the mandatory installation of adequate radon reduction systems for the underground space where people stay or commute for long periods of time.

Effective cesium removal from Cs-containing water using chemically activated opaline mudstone mainly composed of opal-cristobalite/tridymite (opal-CT).

Opaline mudstone (OM) composed of opal-CT (SiO2·nH2O) has high potential use as a cesium (Cs) adsorbent, due to its high specific surface area (SSA). The objective of this study was to investigate the Cs adsorption capacity of chemically activated OM and the adsorption mechanism based on its physico-chemical properties. We used acid- and base-activation methods for the surface modification of OM. Both acid- and base- activations highly increased the specific surface area (SSA) of OM, however, the base-activation decreased the zeta potential value more (- 16.67 mV), compared to the effects of acid-activation (- 6.60 mV) or non-activation method (- 6.66 mV). Base-activated OM showed higher Cs adsorption capacity (32.14 mg/g) than the others (acid: 12.22 mg/g, non: 15.47 mg/g). These results indicate that base-activation generates pH-dependent negative charge, which facilitates Cs adsorption via electrostatic attraction. In terms of the dynamic atomic behavior, Cs cation adsorbed on the OM mainly exist in the form of inner-sphere complexes (IS) containing minor amounts of water molecules. Consequently, the OM can be used as an effective Cs adsorbent via base-activation as an economical and simple modification method.

Corrigendum: Effect of Divalent Cations (Cu, Zn, Pb, Cd, and Sr) on Microbially Induced Calcium Carbonate Precipitation and Mineralogical Properties.

[This corrects the article DOI: 10.3389/fmicb.2021.646748.].

Effect of Divalent Cations (Cu, Zn, Pb, Cd, and Sr) on Microbially Induced Calcium Carbonate Precipitation and Mineralogical Properties.

Microbially induced calcium carbonate precipitation (MICP) is a bio-geochemical process involving calcium carbonate precipitation and possible co-precipitation of other metals. The study investigated the extent to which a urease-positive bacterium, Sporosarcina pasteurii, can tolerate a range of metals (e.g., Cu, Zn, Pb, Cd, and Sr), and analyzed the role of calcium carbonate bioprecipitation in eliminating these divalent toxicants from aqueous solutions. The experiments using S. pasteurii were performed aerobically in growth media including urea, CaCl2 (30 mM) and different metals such Cu, Zn, Pb, and Cd (0.01 ∼ 1 mM), and Sr (1 ∼ 30 mM). Microbial growth and urea degradation led to an increase in pH and OD600, facilitating the precipitation of calcium carbonate. The metal types and concentrations contributed to the mineralogy of various calcium carbonates precipitated and differences in metal removal rates. Pb and Sr showed more than 99% removal efficiency, whereas Cu, Zn, and Cd showed a low removal efficiency of 30∼60% at a low concentration of 0.05 mM or less. Thus the removal efficiency of metal ions during MICP varied with the types and concentrations of divalent cations. The MICP in the presence of divalent metals also affected the mineralogical properties such as carbonate mineralogy, shape, and crystallinity.

Cesium removal using acid- and base-activated biotite and illite.

Biotite and illite have excellent cesium (Cs) adsorption capacity due to their negative charges in addition to adsorption sites of the planar, interlayer, and frayed edge sites (FES). The aim of this study is to investigate the Cs adsorption capacity using acid- and base-activated biotite and illite based on their mineralogical characteristics. The acid-activated biotite and base-activated illite exhibited high Cs removal efficiency from the low-level Cs-containing DI water (97.5 % and 97.3 %, respectively). The acid-activation of biotite increased the specific surface area (SSA, 12.08 → 43.04 m2/g), Fe(III)/Fe(II) ratio (0.56 → 0.76), and wedge zone d-spacing (1.017 → 1.065 nm), while the zeta potential (-4.06 → -4.82 mV) decreased. The base-activation of illite resulted to a decrease in the SSA (22.14 → 18.49 m2/g), zeta potential (-7.68 → -31.64 mV), and Fe(III)/Fe(II) ratio (0.92 → 0.79). However, only acid-activated biotite appeared to have a high capacity of Cs removal from Cs-containing seawater (73.9 %; base-activated illite: 26.1 %). These results indicate that the FES of biotite owing to acid-activation showed better results in regards to Cs adsorption as compared to the pH-dependent negative charges of the base-activated illite.

Biogenesis of Magnetite Nanoparticles Using Shewanella Species Isolated from Diverse Regions.

The objective of this study was to synthesize magnetite (Fe3O4) nanoparticles using diverse Shewanella species isolated from different environments. Magnetite formation experiments were performed with 11 species of Shewanella using akaganeite (ß-FeOOH) as an electron acceptor and lactate (C3H6O3) as an electron donor under a N2 atmosphere at room temperature. Magnetites and other products formed by the bacteria were characterized by XRD and TEM-EDS analyses. In this study, all the strains of Shewanella species produced magnetite nanoparticles with 2.5 to 20 nm in size. However, the size of the magnetite varied with the species of Shewanella, and a few species formed Fe(III) oxide as secondary minerals such as goethite and lepidocrocite. These results indicate that different species of iron-reducing bacteria belonging to the genus Shewanella exhibit different rates of Fe(III) reduction resulting in magnetite nanocrystals of varying size and formation of secondary mineral species.

Mixed Contaminants Removal Efficiency Using Bio-FeS Nanoparticles.

Advances in nanotechnology has provided diverse industrial applications including an environmental remediation field. In particular, bio-nanotechnology gives extended eco-friendly remediation practice. Among diverse bio-nanoparticles synthesized by microorganisms, the iron based nanoparticles (NPs) are of great interest because of their availability, low cost and toxicity to human health and the environment. In this study, iron based nanoparticles were biologically synthesized and mineralogically identified. Also, the removal efficiency of mixed contaminants, high As(III)-low Cr(VI) and high As(V)-low Cr(VI), using these bio-nanoparticles were conducted. As a result, biologically synthesized NPs were identified as FeS complex and their catalytic capacity showed highly effective to immobilize more than 97% of mixed contaminants by adsorption/mineralization.

Microbially Induced Formation of Fe Carbonates by Metal-Reducing Bacteria Enriched from a CO2 Repository Candidate Site.

The objectives of this research were to study the microbial diversity of metal-reducing bacteria enriched from sedimentary rock collected from a CO2 repository candidate site and to examine the effect that the bicarbonate concentration had on the iron reduction and biomineralization by the cultures. The enriched metal-reducing bacteria (i.e., JG-3) consisted mostly of Exiguobacterium sp. and Shewanella sp., and the microbial reduction of akaganeite (ß-FeOOH), an Fe(III) oxyhydroxide, was examined over 7 days of bacterial cultivation at 30 °C under different concentrations of bicarbonate (0~210 mM). The akaganeite (ß-FeOOH) transformed into goethite (α-FeOOH) and magnetite (Fe3O4) in low HCO-3 buffered medium (<70 mM) and was transformed to magnetite and siderite (FeCO3) in high HCO-3 buffered medium (>140 mM). These results indicate that metal- reducing bacteria from a deep subsurface environment reduce and transform an iron oxyhydroxide to siderite (FeCO3) in HCO-3 buffered medium and that microbial iron reduction may accelerate the mineral trapping of CO2 for deep geologic sequestration.

Effects of Aging on Transformation of Biogenic Magnetite Nanoparticles.

This study examined the microbial synthesis of magnetite and Pd/Zn-substituted magnetite using metal-reducing bacteria (Clostridium sp.), and the mineralogical characteristics of various types of magnetite formed initially and transformed minerals aged for 5 years. XRD, SXRD, and TEM-EDS analyses were used to characterize the mineralogy, crystal structure, chemistry, shape, and size distribution of the magnetites and transformed minerals. The metal-reducing bacteria reduced akaganeite and Pd/Zn-akaganeite to magnetite and Pd/Zn-substituted magnetite using glucose as an electron donor, respectively. Metal substitution of Pd and Zn within the magnetite structure resulted in a decrease in the unit-cell parameter of the magnetite crystals. After 5 years, the biogenic magnetite showed changes in unit-cell parameters and transformation to siderite during prolonged cultivation under anaerobic conditions. These results indicate that long-term aging may affect the mineralogical transformation and alter the nano-sized crystal structure.

Microbial Precipitation of Cr(III)-Hydroxide and Se(0) Nanoparticles During Anoxic Bioreduction of Cr(VI)- and Se(VI)-Contaminated Water.

This study examined the microbial precipitations of Cr(III)-hydroxide and Se(0) nanoparticles during anoxic bioreductions of Cr(VI) and Se(VI) using metal-reducing bacteria enriched from groundwater. Metal-reducing bacteria enriched from groundwater at the Korea Atomic Energy Research Institute (KAERI) Underground Research Tunnel (KURT), Daejeon, S. Korea were used. Metal reduction and precipitation experiments with the metal-reducing bacteria were conducted using Cr(VI)- and Se(VI)-contaminated water and glucose as a carbon source under an anaerobic environment at room temperature. XRD, SEM-EDX, and TEM-EDX analyses were used to characterize the mineralogy, crystal structure, chemistry, shape, and size distribution of the precipitates. The metal-reducing bacteria reduced Cr(VI) of potassium chromate (K2CrO4) to Cr(III) of chromium hydroxide [Cr(OH)3], and Se(VI) of sodium selenate (Na2SeO4) to selenium Se(0), with changes of color and turbidity. XRD, SEM-EDX, and TEM-EDX analyses revealed that the chromium hydroxide [Cr(OH)3] was formed extracellularly with nanoparticles of 20­30 nm in size, and elemental selenium Se(0) nanoparticles had a sphere shape of 50­250 nm in size. These results show that metal-reducing bacteria in groundwater can aid or accelerate precipitation of heavy metals such as Cr(VI) and Se(VI) via bioreduction processes under anoxic environments. These results may also be useful for the recovery of Cr and Se nanoparticles in natural environments.

Biomineralization of Mg-Enriched Calcium Carbonates by Aerobic Microorganisms Enriched from Rhodoliths.

The objective of this study was to investigate the effect of Mg:Ca ratio in the medium on the formation of low- and high-Mg calcite by aerobic microorganisms enriched from rhodoliths (mainly Proteus mirabilis, Wu Do-1). XRD analyses showed that both low- and high-Mg calcites were formed depending on the Mg:Ca ratio in the medium. Calcite was formed at Ca:Mg ratios of 6:0 and 3:1 and high-Mg calcite was formed at Ca:Mg ratios of 1:1 and 1:3 in the medium. Huntite was formed with a Ca:Mg ratio of 0:6. SEM-EDS analyses showed that the low- and high-Mg calcite crystals had a rhombohedron shape and consisted of Ca, Si and Mg with extracellular polymeric substances (EPS). These results indicate that Wu Do-1 induced precipitation of low- and high-Mg calcite crystals depending on the Ca:Mg ratio in the medium. The carbonate minerals were precipitated on the cell walls and EPS via the accumulation of Ca and/or Mg ions. Therefore, microbial formation of carbonate minerals may play an important role in Ca, Mg, and carbon biogeochemistry as well as CO2 fixation in the natural environments.

Synthesis of Nano-Sized Silicon Oxide, Iron Oxide and Carbonates from Chrysotile Asbestos.

The objectives of this study were to investigate the physicochemical dissolution of chrysotile asbestos and to synthesize nano-sized materials and carbonate minerals from the asbestos via acid dissolution and pH changes. Chrysotile asbestos powder was dissolved in 3 different acids, HCl, HThe objectives of this study were to investigate the physicochemical dissolution of chrysotile asbestos and to synthesize nano-sized materials and carbonate minerals from the asbestos via acid dissolution and pH changes. Chrysotile asbestos powder was dissolved in 3 different acids, HCl, H2SO4, and HNO3, and the solutions were then titrated using NH4OH and reacted with CO2. The residual material and precipitates were examined with XRD and TEM-EDS. ICP-AES analysis was also used to investigate the chemical makeup of the solution. The concentration of Mg in the solution was about 1,280 mg/L. The chrysotile became noncrystalline silica after acid treatment (pH = 0). At pH 8.6 and 9.5, the precipitates were amorphous iron oxide and nesquehonite [Mg(HCO3)(OH)·2(H2O)] after reaction with CO2. The particle size of the precipitates ranged from 2 to 500 nm. These results indicate that dissolution of chrysotile asbestos using HCl, H2SO4, and HNO3 can chemically alter chrysotile fibers. Also, the dissolved materials can be used as precursors for other materials such as silica, iron oxide, and carbonates. This process may be useful for the synthesis of silica and iron oxides and for mineral carbonation for carbon sequestration. SO4, and HNO3, and the solutions were then titrated using NH4OH and reacted with CO2. The residual material and precipitates were examined with XRD and TEM-EDS. ICP-AES analysis was also used to investigate the chemical makeup of the solution. The concentration of Mg in the solution was about 1,280 mg/L. The chrysotile became noncrystalline silica after acid treatment (pH = 0). At pH 8.6 and 9.5, the precipitates were amorphous iron oxide and nesquehonite [Mg(HCO3)(OH)·2(H2O)] after reaction with CO2. The particle size of the precipitates ranged from 2 to 500 nm. These results indicate that dissolution of chrysotile asbestos using HCl, H2SO4, and HNO3 can chemically alter chrysotile fibers. Also, the dissolved materials can be used as precursors for other materials such as silica, iron oxide, and carbonates. This process may be useful for the synthesis of silica and iron oxides and for mineral carbonation for carbon sequestration.

Iron Oxyhydroxide Nanoparticle-Coated Carbon Cloth Electrode for Remediation of Cr(VI)-Contaminated Wastewater.

Among in situ and ex situ groundwater technologies, electrochemical treatment has been successfully employed to remediate water heavily contaminated with metals. Electrochemical treatment of Cr(VI)-contaminated wastewater has been attempted using various factors such as electrode materials, surfactants, and electrolytes. In this study, inexpensive carbon cloth was selected and coated with iron oxyhydroxide nanoparticles to enhance electrochemical remediation of Cr(VI)-contaminated wastewater. Iron oxyhydroxide nanoparticles (INP) synthesized by chemical precipitation were coated on carbon cloth electrodes by immersion to examine Cr(VI) removal. The efficiency of Cr(VI) reduction/immobilization was compared between carbon cloth (CC) and carbon cloth coated with iron oxyhydroxide nanoparticles (INP-CC) with/without DC application at a constant potential of 5.0 V to treat water contaminated with 100 mg/L Cr(VI) for 48 h. The removal rate of Cr(VI) was as follows: 10% for CC electrodes and 32% for INP-CC electrodes, compared to >90% for both CC and INP-CC electrodes with DC application for 48 h. In the INP-CC + EC group the pH-Eh condition tended to acidic oxidizing condition due to oxidative substances, O2(g) and hydrogen ions generated on anodic reaction during 12~24 h when Cr(VI) removal reached at 80%, but the CC + EC group remained with minor change for 36 h resulting less reduction efficiency of Cr(VI), despite a successful removal efficiency after 48 h which is similar to the INP-CC + EC group. These results indicated that multiple interactions (C/Cr6+­Cr3+/Fe3+­Fe2+/H+­OH−) on the surface of CC and INP-CC enhanced by EC might contribute to reduction of Cr(VI) and adsorption/precipitation of chromate ions. In particular, INP-CC+ EC might perform dual roles as an electron donor for Fe2+ and/or as an absorbent with DC application in Cr(VI) immobilization. INP-CC enhanced-EC technology could be an economic and efficient approach to remediation of wastewater heavily contaminated with Cr(VI).

Microbially-Mediated Precipitation of Calcium Carbonate Nanoparticles.

The objective of this study was to investigate the biomineralization of carbonate minerals using microorganisms (Wu Do-1) enriched from rhodoliths. A 16S rRNA sequence analysis showed that Wu Do-1 mainly contained Proteus mirabilis. The pH decreased from 6.5 to 5.3 over the first 4 days of incubation due to microbial oxidation of organic acids, after which it increased to 7.8 over the remaining incubation period. XRD analysis showed that the precipitates were Mg-rich cal- cite (MgxCa(1-x)CO3), whereas no precipitates were formed without the addition of Wu Do-1 in D-1 medium. SEM-EDS analyses showed that the Mg-rich calcite had a rhombohedron shape and consisted of Ca, Si and Mg with an extracelluar polymeric substance (EPS). In addition, TEM-EDS analyses revealed they were hexagon in shape, 500-700 nm in size, and composed of Ca, Mg, C, and O. These results indicated that Wu Do-1 induced precipitation of Mg-rich calcite on the cell walls and EPS via the accumulation of Ca and/or Mg ions. Therefore, microbial precipitation of carbonate nanoparticles may play an important role in metal and carbon biogeochemistry, as well as in carbon sequestration in natural environments.

Optimizing Calcium Phosphates by the Control of pH and Temperature via Wet Precipitation.

A series of calcium phosphates synthesized through a wet precipitation route of hydroxylapatite (HAP) was investigated over a wide range of temperature and pH (25-80 degrees C, and pH 6.5-10.0) using a combination of microscopic and spectroscopic analyses. XRD and FTIR show that monetite and brushite are formed as a single phase at non-ideal conditions of HAP, respectively. From TGA results, it is found that brushite is converted to monetite at a range 175-200 degrees C when heated at the heating rate, 10 degrees C/min. This phase transformation is also observed when brushite is aged at pH 8.5 and 60 degrees C for 24 hr in solution. Morphology of brushite is sensitive to pH variation. At pH 6.5, tabular and platy crystals of brushite are observed whereas needle-like ones are predominant at pH 8.5. For HAP formed at pH 10.0, their shapes tend toward needle-like particles as temperature increases. HAP particles at pH 8.5 are very similar in morphology to HAP at pH 10.0, but their lengths are two or three times as great as those at pH 10.0. These observations demonstrate that desired phase and properties of calcium phosphates can be controlled by pH, temperature, and aging time through a wet precipitation method.

Biotransformation and Its Application: Biogenic Nano-Catalyst and Metal-Reducing-Bacteria for Remediation of Cr(VI)-Contaminated Water.

The use of ubiquitous metal-reducing bacteria (MRB) and the synthesis and transforming capability of nano-sized catalysts (BNC) provide enormous potential for the transformation of environmental waste to environmental catalysts, such as abandoned mine precipitates that are transformed into nontoxic and inexpensive catalysts for remediating contaminated groundwater. In this study, BNC from acid mine drainage (AMD) precipitates are transformed to nm-sized siderite after a fermenting process under anaerobic conditions, and MRB enriched from inter-tidal flat sediments were examined for efficiency in the Cr(VI) reduction and immobilization in upward flow-through sand column tests. As a result, BNC and MRB proved to have excellent Cr(VI) reducing/immobilizing capacity independently and when used in conjunction. In addition the combination of BNC+MRB showed to have a capacity enhanced with 20% more capability of Cr(VI) reduction and immobilization in flow-through column test for 168 h.

Microbial Synthesis of Iron Sulfide (FeS) and Iron Carbonate (FeCO3) Nanoparticles.

This study examined mineral transformations during anoxic bioreduction of iron hydroxide and iron oxyhydroxysulfate found in acid mine drainage (AMD) into iron sulfide (FeS) and siderite (FeCO3) nanoparticles. Glucose (10 mM) was inoculated into AMD to stimulate indigenous bacterial growth for bioreduction of Fe(III)-containing minerals. Changes in microbial, geochemical, and mineralogical characteristics were monitored via 16S rRNA, XRD, SEM-EDX, TEM-EDX, ICP-AES, and IC analyses. The AMD was found to be rich in elements, including Fe, Al, Mn, Na, and S (SO4), and had a pH of 5.2. The mineral contents mainly consisted of Fe(III)-containing minerals, such as schwertmannite [Fe8O8 (OH)8-2x(SO4)x · nH2O] and akaganeite [ß-FeO(OH)]. During anoxic bioreduction of AMD, the Fe(III)-containing minerals were transformed by indigenous iron-reducing bacteria (e.g., Geobactersp.) into Fe(II)-containing minerals, such as iron sulfide (FeS) and iron carbonate, siderite (FeCO3), within 3-4 days. The microbially-formed iron sulfide (FeS) and siderite (FeCO3) were of 40-60 nm and 10 nm-3 µm in size, respectively. These results not only show that indigenous iron-reducing bacteria in AMD can aid or accelerate formation of Fe(II)-containing minerals when under anoxic environments, but can also offer a simple method for microbial synthesis of nano-sized Fe(II)-containing minerals that can be used as catalysts for environmental remediation by recycling AMD.

Microbial Synthesis and Characterization of Superparamagnetic Zn-Substituted Magnetite Nanoparticles.

The objective of this study is to examine microbial synthesis of magnetite and Zn-substituted magnetite nanoparticles by iron-reducing bacteria (Clostridium sp.) enriched from intertidal flat sediments. The magnetite nanoparticles were synthesized by the bacteria under anaerobic conditions at room temperature using akaganeite (ß-FeOOH) or Zn-substituted akaganeite (ß-ZnxFe1-xOOH) as a magnetite precursor during glucose fermentation. This research indicates that fermentation processes can establish the microbial synthesis of magnetite and Zn-substituted magnetite when conditions are at room temperature, ambient pressure, and pH values near neutral to slightly basic (pH < 8).

Microbially Induced Precipitation of Strontianite Nanoparticles.

The objectives of this study were to investigate the microbially mediated precipitation of strontium by microorganisms, and to examine the mineralogical characteristics of the precipitates. Wu Do-1 (Proteus mirabilis) enriched from rhodoliths was used to precipitate strontium at room temperature under aerobic environment. The growth of Wu Do-1 gradually increased over 16 days (OD600 = 2.6) and then decreased until 22 days (OD600 = 2.0) during microbial incubation for strontium precipitation. Also, the pH decreased from 6.5 to 5.3 over 4 days of incubation due to microbial oxidation of organic acids, and then the pH increased up to 8.6 at 25 days of incubation due to NH3+ generation. The Sr2+ concentration in the biotic group sharply decreased from 2,953 mg/L to 5.7 mg/L over 29 days of incubation. XRD, SEM-/TEM-EDS analyses revealed that the precipitates formed by Wu Do-1 (Proteus mirabilis) were identified as 20-70 nm sized strontianite (SrCO3). Therefore, these results suggested that formation of sparingly soluble Sr precipitates mediated by Wu Do-1 (Proteus mirabilis) sequesters strontium and carbon dioxide into a more stable and less toxic form such as strontianite (SrCO3). These results also suggest that bioremediation of metal-contaminated water and biominealization of carbonate minerals may be feasible in the marine environment.

Fate and transport of uranium (VI) in weathered saprolite.

Batch and column experiments were conducted to investigate sorption and transport of uranium (U) in the presence of saprolite derived from interbedded shale, limestone, and sandstone sequences. Sorption kinetics were measured at two initial concentrations (C0; 1, 10 µM) and three soil:solution ratios (Rs/w; 0.005, 0.25, 2 kg/L) at pH 4.5 (pH of the saprolite). The rate of U loss from solution (µmole/L/h) increased with increasing Rs/w. Uranium sorption exhibited a fast phase with 80% sorption in the first eight hours for all C0 and Rs/w values and a slow phase during which the reaction slowly approached (pseudo)equilibrium over the next seven days. The pH-dependency of U sorption was apparent in pH sorption edges. U(VI) sorption increased over the pH range 4-6, then decreased sharply at pH > 7.5. U(VI) sorption edges were well described by a surface complexation model using calibrated parameters and the reaction network proposed by Waite et al. (1994). Sorption isotherms measured using the same Rs/w and pH values showed a solids concentration effect where U(VI) sorption capacity and affinity decreased with increasing solids concentration. This effect may have been due to either particle aggregation or competition between U(VI) and exchangeable cations for sorption sites. The surface complexation model with calibrated parameters was able to predict the general sorption behavior relatively well, but failed to reproduce solid concentration effects, implying the importance of appropriate design if batch experiments are to be utilized for dynamic systems. Transport of U(VI) through the packed column was significantly retarded. Transport simulations were conducted using the reactive transport model HydroGeoChem (HGC) v5.0 that incorporated the surface complexation reaction network used to model the batch data. Model parameters reported by Waite et al. (1994) provided a better prediction of U transport than optimized parameters derived from our sorption edges. The results presented in this study highlight the challenges in defining appropriate conditions for batch-type experiments used to extrapolate parameters for transport models, and also underline a gap in our ability to transfer batch results to transport simulations.