Saturated Experiments Research Articles

Transport characteristics of DNA-tagged silica colloids as a colloidal tracer in saturated sand columns; role of solution chemistry, flow velocity, and sand grain size

In recent years, DNA-tagged silica colloids have been used as an environmental tracer. A major advantage of this technique is that the DNA-coding provides an unlimited number of unique tracers without a background concentration. However, little is known about the effects of physio-chemical subsurface properties on the transport behavior of DNA-tagged silica tracers. We are the first to explore the deposition kinetics of this new DNA-tagged silica tracer for different pore water chemistries, flow rates, and sand grain size distributions in a series of saturated sand column experiments in order to predict environmental conditions for which the DNA-tagged silica tracer can best be employed. Our results indicated that the transport of DNA-tagged silica tracer can be well described by first order kinetic attachment and detachment. Because of massive re-entrainment under transient chemistry conditions, we inferred that attachment was primarily in the secondary energy minimum. Based on calculated sticking efficiencies of the DNA-tagged silica tracer to the sand grains, we concluded that a large fraction of the DNA-tagged silica tracer colliding with the sand grain surface did also stick to that surface, when the ionic strength of the system was higher. The experimental results revealed the sensitivity of DNA-tagged silica tracer to both physical and chemical factors. This reduces its applicability as a conservative hydrological tracer for studying subsurface flow paths. Based on our experiments, the DNA-tagged silica tracer is best applicable for studying flow routes and travel times in coarse grained aquifers, with a relatively high flow rate. DNA-tagged silica tracers may also be applied for simulating the transport of engineered or biological colloidal pollution, such as microplastics and pathogens.

Impact of heavy metal cations on deposition and release of clay colloids in saturated porous media

AbstractWhile the facilitated transport of heavy metals by colloids such as clay particles has been widely recognized, the influence of heavy metals on transport of the colloids has received much less attention. This study conducted saturated column experiments to systematically examine influence of multivalent heavy metal cations on transport of natural clay colloids and fullerene nC60 nanoparticles in glass bead porous media. Results showed that the presence of Cd2+ in the solution can cause more deposition of clay colloids in glass beads compared to Ca2+ at a given ionic strength (IS), and the subsequent release by IS reduction was less, demonstrating that the presence of Cd2+ increased the irreversibility of attachment. When the glass beads were initially adsorbed with Ca2+ and Cd2+, the release of clay colloids was significantly reduced due to strong cation bridge between the clay colloids and collector surfaces via the heavy metal cations. The release of clay colloids was significantly increased upon reduction of solution IS if the Na+ was used to exchange for the Ca2+ or Cd2+ before the IS reduction. Additional experiments showed that the nC60 nanoparticles that were deposited in the presence of Fe3+ and Cu2+ cannot be released by reduction of solution IS. However, the nanoparticle release occurred when the Ca2+ was used to exchange for the Fe3+ and Cu2+. Our work was the first to reveal the influence of heavy metal cations on the irreversibility of colloid attachment, and the findings have important implication to fabrication of functional nanomaterials for stabilization of heavy metals in soil and development of mathematic models for accurate prediction of cotransport of heavy metals and colloids in subsurface environments.

The Influence of Compost on Arsenic Removal from Contaminated Groundwater in Granitic Aquifers

Arsenic is classified as a group 1 human carcinogen according to the World Health Organization. Anthropogenic activities such as mining and wood preservation contribute to arsenic contamination of surface and sub-surface water. Most of the currently available remediation strategies to remove arsenic involve slow processes and produce residues that are difficult to treat or dispose. In this study, with an objective to develop alternative arsenic remediation strategies, we examined removal of arsenic using organic compost as a potential adsorbent. We ran saturated column experiments by injecting 10 mg/L arsenic-spiked synthetic groundwater to compare the arsenic removal between the presence and absence of compost in granitic aquifers. The water analysis showed the compost removed 14 percent (%) of arsenic from the contaminated water within 16 min, while there was no change in arsenic concentration in the experiment without compost. The results illustrated that arsenic treatment using compost is feasible for contaminated groundwater remediation. Different pH evolution was also observed in both experiments. The column with only decomposed granite showed a small decrease in pH, which we believed was caused by a dissolution of silicate minerals in the granite. The column with compost exhibited a more fluctuating pH. An abrupt drop in pH was observed at an early time period and thought to be caused by release of H+ from organic anions after water interacted with the compost. After the initial period, the change in pH was primarily driven by mixing of the water used for column saturation and the injected contaminated groundwater. The major factors identified for arsenic removal are the presence of iron (Fe) and a lower starting pH condition in the compost experiment, which provides more available sorption sites leading to higher arsenic sorption.

Role of nonspherical DLVO and capillary forces in the transport of 2D delaminated Ti3C2Tx MXene in saturated and unsaturated porous media

The transport and retention of two-dimensional (2D) nanomaterials, such as graphene oxide, in porous media have attracted lots of attention. However, previous studies often simplified these 2D colloids as equivalent spheres for numerical simulations, which ignored the influence of particle shape on colloid retention at multiple interfaces. In this study, a novel 2D nanomaterial delaminated Ti3C2Tx (d-Ti3C2Tx) was adopted to fill this knowledge gap. Comprehensive analyses of the 2D colloid retention mechanisms were conducted based on colloid characterization, saturated and unsaturated column experiments, reactive transport modeling, 2D-based DLVO and nonspherical capillary energy simulations. Results show that d-Ti3C2Tx mobility in both saturated and unsaturated conditions enhanced with the increase in pH and decrease in ionic strength. The DLVO interaction energy of d-Ti3C2Tx at the sand-water-interface (SWI) decreased with the orientation angle of the colloidal major axis to the sand surface from 0° to 90°. The primary mechanism under saturated flow conditions was the irreversible attachment in the deep secondary minimum at the SWI with the major axis of d-Ti3C2Tx parallel to the sand surface. The attachment in the primary minimum at 0° was impossible due to the extremely high energy barrier, and the attachment in the primary and secondary minimum at other orientation angles were negligible. d-Ti3C2Tx only experienced repulsive electrostatic force when approaching the air-water-interface (AWI) no matter the particle orientation. The detaching capillary potential energy was 3 orders of magnitude larger than the attractive DLVO interaction energy of the SWI in the secondary minimum at 0°, suggesting that the capillary force-induced irreversible attachment at the AWI was the primary mechanism under unsaturated flow conditions. This study shows that the DLVO and capillary potential energies were significantly dependent on the particle-interface orientation and colloidal shape. A simplification of 2D colloids as spheres is not recommended.

Effect of some heavy metals synergism on the longevity and bioaccumulation inside the muscles of frog ridibunda species under the laboratory conditions

Rana ridibunda frogs (Amphibians) are examined under laboratory conditions (10-18 C°) of the aquarium water (tap water), oxygen saturation, non-saturation and starvation. Body weight for two groups of frogs were (260-285 gr) and (58-115 gr). Two types of heavy metals effect were examined (single type and mixed types) of Cdcl2 and HgSo4 used. Longevity as LT50% and LT100% were determined by single heavy metals effect and synergism effect for both oxygen saturated and oxygen non-saturated waters experiments were conducted, then the bioaccumulation inside the legs muscles of the frog were examined for the heavy metals poisoning media (2PPT) concentration. Synergism effects were very clear and differences of O2 saturation were giving clear different results.

Modeling and experiment for effective diffusion coefficient of gas in water-saturated coal

The diffusion of gas in water-saturated porous media plays a significant role in CO2 geological sequestration and mine gas prevention and control. However, it is lack of an accurate model to calculate the effective diffusion coefficient of gas in a water-saturated coal core. In this work, an improved model was constructed to calculate the effective diffusion coefficient of gas in a water-saturated coal core by considering both the gas adsorption in residual pore and the gas dissolution in pore water. By using a PVT (Pressure-Volume-Temperature) test method, the calculation results of improved model are in the range of 1.03 × 10−12 ~ 30.40 × 10−12m2/s, which are 5 ~ 6 orders of magnitude lower than those calculated by traditional model, because the traditional model only considers the gas dissolution in pore water. Therefore, the results of improved model are more in line with the actual situation. Furthermore, the saturated moisture, equilibrium moisture and NMR experiments were carried out. Results shows that, the saturated moisture and equilibrium moisture decreases with the rising coal rank. The pore size changes from micropore/mesopore-dominated to micropores-dominated as the coal rank rise. In addition, the proportion of open porosity gradually reduces with the rising coal rank, while the closed porosity increases, indicating that the pore connectivity decreases with the growing coal rank. Finally, the influences of adsorbability, pore structure, pressure and liquid properties on the effective diffusion coefficient were analyzed.

Goethite effects on transport and activity of lysozyme with humic acid in quartz sand

Proteins play important roles in environmental processes and are essential to soil and ecosystem health. However, little is known about the transport of proteins, especially enzymes, in natural environments with significant heterogeneity. Here, we investigated the transport and retention of a model enzyme lysozyme (LSZ) with/without the presence of purified Aldrich humic acid (PAHA) by saturated transport experiments in heterogeneous sand columns containing mixtures of uncoated (QS) and goethite-coated quartz sand (GQS) with (GQS/(QS + GQS)) mass fractions w = 0, 0.1, 0.3 and 0.5. The impact of different PAHA/LSZ mass ratios (f = 0, 0.2 and 0.4) on LSZ mobility was also examined in a GQS/QS column (w = 0.3). The results revealed that the transport of pure LSZ and PAHA decreased with increasing w from 0 to 0.5, largely because of increased microscopic roughness and enhanced patch controlled electrostatic attraction between sand grains and LSZ or PAHA. Furthermore, an overall decline of the breakthrough curve plateau was observed when f was fixed as 0.2 at different w due to progressive PAHA-LSZ aggregation and physical straining. In these GQS/QS columns, positively charged LSZ broke through earlier because goethite of GQS tended to first capture negatively charged PAHA and PAHA-LSZ complexes/aggregations. At w = 0.3, LSZ retention was increased with increasing f and the retention profiles exhibited a hyper-exponential shape. Due to the preferential retention of overall negatively charged and larger-sized PAHA-LSZ aggregates in the GQS/QS column, the enzyme activity of retained LSZ was lower than that in the effluent and decreased with increasing w. The synergistic effect of humic acid and iron (hydr)oxide coating decreased LSZ mobility. These findings may facilitate a better understanding of the transport and retention of proteins in heterogeneous natural environment, and help to deal with the potential environmental risk posed by hazardous proteins.

Subsurface transport potential of perfluoroalkyl acids (PFAAs): Column experiments and modeling

Transport of ten perfluoroalkyl acids (PFAAs) was studied with one-dimensional (1-D) saturated column experiments using four soil types with an organic carbon fraction (foc) range of ~0–0.045. Columns were operated under conditions relevant to aqueous film-forming foam (AFFF)-impacted fire protection training areas to determine the ability of equilibrium transport parameters to describe 1-D PFAA transport, if rate-limited sorption influences PFAA transport, and if kinetic parameters can be used to evaluate factors causing rate-limited sorption. Results of initial screening of PFAA breakthrough found that over half of the breakthrough curves deviated from equilibrium transport and merited further investigation. Subsequent analysis showed that, in many cases, these deviations could be accounted for by considering the range of applicable equilibrium Kd values (i.e. based on standard deviation) applicable to the solid phase. Thus, transport of the majority of PFAAs in 3 soils with foc of 0–0.017 was not impacted by rate-limited sorption. Further, low sorption led to transport that was essentially simultaneous for the majority of PFAAs in these porous media. Exceptions were observed for long-chain PFAAs, and also in a fourth soil with foc of 0.045, which indicated the potential for rate-limited sorption to impact transport in some scenarios. Subsequent flow interruption experiments isolating kinetic behavior confirmed rate-limited sorption caused nonequilibrium transport. Linear free energy relationships (LFERs) developed in previous work to predict the inverse relationship between mass transfer coefficients (k) and sorption parameters (i.e., Kd) were used to estimate values of k for PFAAs in this study. Resulting k values were 10−3 to 10−8 h−1, consistent with previously measured kinetic parameters for other polar and anionic compounds. Models incorporating estimated k values resulted in improved predictions of breakthrough observed in nonequilibrium scenarios (R2 0.83–0.98), but k values will require further validation prior to broader application. This work illustrates rate-limited sorption considerations are needed to describe 1-D column saturated transport for some PFAAs and solid phases. At field scales, subsurface heterogeneity and PFAA precursor transformation may be equally or even more important in determining saturated PFAA transport, but kinetic parameters in this study may help to determine relative contributions of rate-limited sorption to overall transport.

Spectral Narrowing Accompanies Enhanced Spatial Resolution in Saturated Coherent Anti-Stokes Raman Scattering (CARS): Comparisons of Experiment and Theory.

We demonstrate theoretically and confirm experimentally the mechanism by which spectral narrowing accompanies enhanced spatial resolution in a saturated coherent anti-Stokes Raman scattering (CARS) signal that is demodulated at the third harmonic (3f) of the pump modulation frequency (f). Under these modulation conditions, theory predicts a narrowing of the full width at half-maximum (FWHM) of the CARS spectrum by a factor of 2.0 with respect to that of the spectrum obtained by demodulation at the fundamental frequency. Theory also predicts an improvement of spatial resolution by a factor of 1.7. Experimentally, narrowing of the FWHM of the CARS spectrum of 1,4-bis((E)-2-methylstyryl) benzene (MSB) crystals by a factor of 2.5 is observed upon saturation. Further experimental confirmation is provided from investigating diamond particles, for which spectral narrowing was enhanced by a factor of 2.8 and spatial resolution was enhanced by a factor of 2. Details of the mechanism and execution of the saturated CARS experiment are elucidated and limits to its applicability are suggested, one of which is the conclusion that the saturation approach is not suitable for extraction of harmonics beyond 3f. In this work, we have developed a more comprehensive understanding of the correlation between the observed experimental results and experimental factors than has been previously reported.

Mobility of Cellulose Nanocrystals in Porous Media: Effects of Ionic Strength, Iron Oxides, and Soil Colloids.

Understanding the dispersivity and migration of cellulose nanocrystals (CNCs) in porous media is important for exploring their potential for soil and water remediation. In this study, a series of saturated column experiments were conducted to investigate the coupled effects of ionic strength, iron oxides (hematite), and soil colloids on the transport of CNCs through quartz sand and natural soils (red earth and brown earth). Results showed that CNCs had high mobility in oxide-free sand and that iron oxide coating reduced the mobility of CNCs. An analysis of Derjaguin-Landau-Verwey-Overbeek interactions indicated that CNCs exhibited a deep primary minimum, nonexistent maximum repulsion and secondary minimum on hematite-coated sand, favorable for the attachment of CNCs. The maximum effluent percentage of CNCs was 96% in natural soils at 5 mM, but this value decreased to 4% at 50 mM. Soil colloids facilitated the transport of CNCs in brown earth with larger effect at higher ionic strength. The ionic strength effect was larger in natural soils than sand and in red earth than brown earth. The study showed that CNCs can travel 0.2 m to 72 m in porous media, depending on soil properties, solution chemistry, and soil colloids.

Silica colloids as non-carriers facilitate Pb2+ transport in saturated porous media under a weak adsorption condition: effects of Pb2+ concentrations.

Transport of environmental pollutants in groundwater systems can be greatly influenced by colloids. In this study, the cotransport of Pb2+ and silica (SiO2) colloids at different Pb2+ concentrations was systematically investigated by batch adsorption and saturated sand column experiments. Results showed that SiO2 colloids had low adsorption capacity for Pb2+ (less than 1% of the input) compared with sands. In saturated porous media, SiO2 colloids showed a high mobility; however, with the increase of Pb2+ concentration in the sand column, the mobility of SiO2 colloids gradually decreased. Notably, SiO2 colloids could facilitate Pb2+ transport, although they did not serve as effective carriers of Pb2+. Under the condition of low Pb2+ concentration, SiO2 colloids promoted the Pb2+ transport mainly through the way of "transport channel," while changing the porosity of the medium and masking medium adsorption sites were the main mechanisms of SiO2 colloid-facilitated Pb2+ transport under the condition of high Pb2+ concentration. The discovery of this non-adsorption effect of colloids would improve our understanding of colloid-facilitated Pb2+ transport in saturated porous media, which provided new insights into the role of colloids, especially colloids with weak Pb2+ adsorption capacity, in Pb2+ occurrence and transport in soil-groundwater systems.

Influence of humic substances on the transport of indium and gallium in porous media

Indium and gallium are used widely in modern industry, mostly for the production of semiconductors. They are considered as Technology-Critical Elements and have therefore received growing attention in the past few years. We investigated the influence of different types of humic substances on the transport of indium and gallium in laboratory-scale, saturated column experiments, to gain understanding of their mobility in natural environments. We evaluated the effect of different humic substances on the transport of indium and gallium in quartz sand: a commercial humic acid (Aldrich Humic Acid, AHA), a fulvic acid (Suwannee River Fulvic Acid, SRFA) and an aquatic natural organic matter (Suwannee River Natural Organic Matter, SRNOM). The impact of the flow rate and the influence of different concentrations of organic matter were also investigated. Indium was shown to be more mobile than gallium in the presence of humic substances. The mobility of indium in sand was highest for SRNOM, followed by SRFA and then AHA, while for gallium the order was SRFA > SRNOM > AHA. These results can be significant in understanding the mobility of indium and gallium in soils with various compositions of organic matter.

Influence of hydraulic gradient and temperature on the migration of E. coli in saturated porous media during bank filtration: a case study at the Second Songhua River, Songyuan, Northeastern China.

River bank filtration can effectively reduce the number of pathogenic microorganisms infiltrating into groundwater from surface water. Groundwater seepage velocity and temperature are considered to be important factors affecting the process, but the magnitude and mechanism of their impacts have not been clear for a long time. Based on the actual monitoring data of the Escherichia coli concentrations and soil samples of Second Songhua riverside source area, the migration of E. coli in saturated porous media under different velocities and different temperatures was studied using saturated soil column transport experiments. Concurrently, the migration characteristics of E. coli in the riverside source area were replicated by mathematical simulation. According to the field monitoring results, the concentration of E. coli decreased in the riverbank infiltration zone, and the removal rate was greater than 96%. The column experimental results showed that the lower the flow velocity was and the higher the temperature was, the greater the removal rate of E. coli was. And the flow velocity was the main factor affecting the removal of E. Coli. The mathematical simulation results showed that under the conditions of the largest hydraulic gradient (20%) and the highest concentration of E. coli (2500MPN/100mL) in river water, the safe exploitation distance of groundwater that did not cause a risk of E. coli pollution was more than 7m away from the river bank. These findings are expected to provide a scientific basis for the design of water intake schemes and the optimization of mining technology.

Influence of phosphate on deposition and detachment of TiO2 nanoparticles in soil

The widespread use of TiO2 nanoparticles (NPs) makes inevitable their release into the soil. Phosphate is also widespread within soil, and is likely copresent with TiO2 NPs. However, the influence of phosphate on deposition/release— and thereby on transport— of TiO2 NPs in soil is yet to be elucidated. In this study we conducted saturated column experiments to systematically examine the transport of TiO2 NPs in soil amended with phosphate at different ionic strengths (ISs) (1, 10, 100 mmol/L NaCl) and pHs (4 and 9). Results show that the deposition of TiO2 NPs decreased with decreasing IS, increasing pH, and when soil absorbed phosphate. These observations are qualitatively in agreement with Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energy calculations, because the repulsive energy barrier is larger and secondary minimum depth is smaller at a lower IS, higher pH, and in the presence of phosphate. Accordingly, both primary- and secondary-minimum deposition were inhibited. Interestingly, although the deposition was less at higher pH and in the presence of phosphate, the subsequent spontaneous detachment and detachment by reduction of solution IS in these cases were greater. In addition, the presence of phosphate in the solution can cause a small quantity of attached TiO2 NPs to detach, even without perturbations of physical and chemical conditions. Our study was the first to investigate the influence of phosphate on detachment of TiO2 NPs and the results have important implication for accurate prediction of fate and transport of TiO2 NPs in subsurface environments. Open image in new window

Characterization of the Pore Structure of Porous Media Using non‐Newtonian Fluids

AbstractWe demonstrate a simple, cheap method for pore size characterization of porous media that generates a distribution of pore radii for improved flow and transport modeling. The new method for pore structure characterization utilizes recent theoretical developments in non‐Newtonian fluids. Numerical evaluations and validations with synthetic porous media showed potential for obtaining a distribution of effective pore radii and their contribution to total flow only by complementing water with non‐Newtonian fluids in saturated infiltration experiments. To demonstrate this ability on real sands, a series of one‐dimensional column experiments was conducted with varying porous medium packings, including Accusands and a polydisperse sand/glass bead mixture. For each packing, distilled water and varying concentrations of guar and xanthan gum were injected over a range of flow rates and pressure gradients. The model‐generated pore radii were compared with pore radius distributions measured by X‐ray microcomputed tomography (μCT), with results demonstrating good agreement between the model and μCT data. Simulations of saturated water flow and drainage curves using model‐generated pore radii compared favorably to experimental data, with errors typically between 2% and 10% for single‐phase flow and approaching the error of the μCT measured radius distributions for the drainage curves.

The Analysis of the Evaporation Effect on Moisture Soil under Intermittent Operation of Ground-source Heat Pump

Abstract Based on the porous theory, a three-dimensional model is presented in this paper to study heat and mass transfer characteristics of moisture soil, which was considered as unsaturated porous media. Compared with saturated model and experiment results, the simulation is validated on the heating mode of the heat pump system. The distribution of the geo-temperature is predicted by using the model. Moreover, the evaporation especially surface evaporation is taken into account. The influencing factors such as soil saturated moisture content, soil actual moisture content and wind velocity are also studied in simulation. The results show that the evaporation has a great impact on the soil temperature field. Under the surface evaporation effect, the soil temperature decreases quickly in soil exothermic process and increases slowly in the recovery process. As the soil moisture rate and wind velocity increasing, the soil temperature falls quickly and recovers slowly under the intermittent operation of the heat pump system. The opposite results have been obtained with the effect of soil actual moisture content. Furthermore, all the results indicate that the effect attenuates with the depth of soil.

Physically Based Model for Extracting Dual‐Permeability Parameters Using Non‐Newtonian Fluids

Core Ideas We present a cost‐effective and simple method for dual‐permeability model parameterization. Physical characterization is done with only experimental results of saturated flow experiments. Model inputs require only saturated flow results with water and a non‐Newtonian fluid. Dual‐permeability models simulate flow and transport within soils characterized by preferential (macro) and matrix (micro) pore domains, with each exhibiting distinct hydraulic properties. The lack of suitable methods for determining appropriate and physically based model parameters remains a major challenge to applying these models. Here, we present a method that characterizes dual‐permeability model parameters using experimental results of saturated flows from water and a non‐Newtonian fluid. We present two submodels that solve for the effective pore sizes of micropores and macropores, with macropores represented either with cylindrical (for biological pores) or planar (for shrinkage cracks and fissures) pore geometries. The model also determines the percentage contribution (wi) of the representative macro‐ and micropores to water flow. We applied the model to experimental soil samples complemented with capillary tubes simulating the macropores and showed its ability to derive the bimodal pore size distributions in dual‐domain soils using only two fluids. As such, we present this method of characterization of dual structures for improved modeling of nonuniform preferential flow and transport in macroporous soils.

Mobility of silver nanoparticles (AgNPs) and oxidative degradation of endocrine disrupting chemicals by saturated column experiments

Mobility of silver nanoparticles (AgNPs) and oxidative degradation of endocrine disrupting chemicals by saturated column experiments

Characterization of synthetic porous media using non‐Newtonian fluids: experimental evidence

SummaryThe characterization of pore structures is required for a broad range of applications, from modelling flow dynamics to understanding petroleum reservoir performance. This research was based on a theoretical framework proposed by Abou Najm and Atallah for improved characterization of pore structures using Newtonian and non‐Newtonian fluids. Here, we report the first experimental evidence of the ability of non‐Newtonian shear‐thinning fluids to predict the pore structure of three synthetic porous media using only saturated infiltration experiments of water and guar gum solutions at different concentrations. The method predicted multiple distinct representative pore sizes, depending on the number of guar gum solutions used, optimized to mimic the functional behaviour of porous media in terms of flow and porosity. Statistical analysis revealed satisfactory agreement between the predicted and real pore structures in the three synthetic porous media.Highlights Experimental evidence of the ability of non‐Newtonian fluids to infer the pore structure of porous media Experiments enabled extraction of multi‐flow regimes mimicking functional flow and porosity behaviour Experiments with different guar gum concentrations on three synthetic porous media regenerated known pore structures Promising results for an inexpensive and safe new method for pore structure characterization

Changes in the chemistry of groundwater reacted with CO2: Comparison of results from laboratory experiments and the ZERT field site, Bozeman, Montana, USA

The Zero Emission Research and Technology (ZERT) field experiment at Bozeman, Montana, USA, was a multi-disciplinary field pilot designed to evaluate near-surface CO2 transport and monitoring technologies applicable to its potential leakage from deep storage reservoirs. As part of this program, sediment cores from two wells at the site were reacted with a solution having the approximate composition of groundwater from the site. A total of 50 water samples were collected from 7 containers, one with its sediments saturated with Na, placed for 15 days in a glove box with 1 atm of food-grade CO2. The objective of this laboratory study is to investigate the changes in the concentrations of major, minor and trace inorganic compounds, and to compare these changes with those observed in groundwater at the site following CO2 injection. The aim of the Na saturated experiment was to investigate the role of sorption/ion exchange on the observed chemical changes.Laboratory results showed rapid changes in pH (8.6–5.7), alkalinity (243–1295 mg/L as HCO3), and electrical conductance (539–1822 μS/cm) following CO2 exposure. Results showed an increase in concentrations of Ca (28–297 mg/L), Mg (18–63 mg/L) and Mn (2–837 μg/L) following CO2 injection. Results for the sodium saturated sample showed a significant role for sorption/ion exchange indicated by lower increases in the concentrations of Ca (32–189 mg/L), Mg (2–14 mg/L), Fe (7–28 μg/L) and Mn (3–465 μg/L) following CO2 exposure. These easily monitored chemical species could provide early detection of CO2-leakage into shallow groundwater. These experimental results, with the exception of Fe, are also in general agreement with those obtained from sampling the ZERT monitoring wells. The main geochemical processes responsible for the observed increases in the concentrations of solutes include: Dissolution of calcite and dolomite; dissolution/reduction of Mn-oxyhydroxides; and desorption-ion exchange from clays and Fe-oxyhydroxieds due to lowered pH values upon CO2 exposure. The trace metal concentrations in samples from both the laboratory experiments and ZERT wells are all significantly below the maximum contaminant levels (MCLs).