Study Of Water Interaction Research Articles

Study of Water Interaction with UO2, U2O5, and UO3: Tracking the Unexpected Reduction of Uranium Cations and Characterization of Surface-Bound Hydroxyls

Study of Water Interaction with UO₂, U₂O₅, and UO₃: Tracking the Unexpected Reduction of Uranium Cations and Characterization of Surface-Bound Hydroxyls

The use of Radon (Rn222) isotopes to detect groundwater discharge in streams draining Table Mountain Group (TMG) aquifers

Environmental isotopes have been used for decades as natural tracers in studies aimed at understanding complex hydrogeological processes such as groundwater and surface water interactions. Radon (Rn222) is a naturally occurring, radioactive isotope which is produced from radium (Ra226) during the radioactive decay series of uranium (U238). Since U238 is present in most geological substrates, Rn222 is produced in various lithological structures and subsequently transported with groundwater through fractures and pore spaces in an aquifer towards surface water discharge points in rivers and springs. This study aimed to determine (i) the concentration of Rn222 within both surface water and groundwater in Table Mountain Group (TMG) aquifer systems, and (ii) the feasibility of using Rn222 isotopes as a natural tracer in groundwater-surface water interaction studies. This study was conducted in a highly fractured TMG aquifer system near Rawsonville, South Africa. Surface water from two perennial rivers (i.e. Gevonden and Molenaars), together with groundwater from a nearby borehole, were sampled and their corresponding Rn222 concentrations measured. Our study found median Rn222 concentrations in the Gevonden River of 76.4 Bq∙L-1 and 67.2 Bq∙L-1 in the dry and wet seasons, respectively. Nearly 12% of surface water samples exceeded 100 Bq∙L-1. These abnormally high Rn222 concentrations can only be attributed to the influx of groundwater with extremely high Rn222 concentrations. Under ambient (no pumping) conditions, Rn222 concentrations in groundwater range between 130–270 Bq∙L-1. However, when the borehole was pumped, and inflowing water from the surrounding aquifer was sampled, even higher Rn222 concentrations (391–593 Bq∙L-1) were measured. These extremely high Rn222 concentrations in groundwater are believed to be attributed to the underlying granitic geology and the prevalence of faults. The use of Rn222 isotopes as an environmental tracer in groundwater–surface water interaction studies is therefore regarded as a feasible option in similar highly fractured aquifer systems.

Earth Stewardship Science—Transdisciplinary Contributions to Quantifying Natural and Cultural Heritage of Southernmost Africa

Evaluating anthropogenic changes to natural systems demand greater quantification through innovative transdisciplinary research focused on adaptation and mitigation across a wide range of thematic sciences. Southernmost Africa is a unique field laboratory to conduct such research linked to earth stewardship, with ‘earth’ as in our Commons. One main focus of the AEON’s Earth Stewardship Science Research Institute (ESSRI) is to quantify the region’s natural and cultural heritage at various scales across land and its flanking oceans, as well as its time-scales ranging from the early Phanerozoic (some 540 million years) to the evolution of the Anthropocene (changes) following the emergence of the first human-culture on the planet some 200 thousand years ago. Here we illustrate the value of this linked research through a number of examples, including: (i) geological field mapping with the aid of drone, satellite and geophysical methods, and geochemical fingerprinting; (ii) regional ground and surface water interaction studies; (iii) monitoring soil erosion, mine tailing dam stability and farming practices linked to food security and development; (iv) ecosystem services through specific biodiversity changes based on spatial logging of marine (oysters and whales) and terrestrial (termites, frogs and monkeys) animals. We find that the history of this margin is highly episodic and complex by, for example, the successful application of ambient noise and groundwater monitoring to assess human-impacted ecosystems. This is also being explored with local Khoisan representatives and rural communities through Citizen Science. Our goal is to publicly share and disseminate the scientific and cultural data, through initiatives like the Africa Alive Corridor 10: ‘Homo Sapiens’ that embraces storytelling along the entire southern coast. It is envisioned that this approach will begin to develop the requisite integrated technological and societal practices that can contribute toward the needs of an ever-evolving and changing global ‘village’.

Analysis of the effect of fish oil on wind waves and implications for air–water interaction studies

Abstract. Surfactant layers with viscoelastic properties floating on the water surface dampen short gravity-capillary waves. Taking advantage of the known virtue of fish oil to still angry seas, a laboratory study has been made to analyse wind-wave generation and the interaction between wind waves, paddle waves, and airflow. This was done in a tank containing a thin fish-oil film uniformly spread on the water surface. The research was aimed, on the one hand, at quantifying for the first time the effectiveness of this surfactant at impeding the generation of wind waves and, on the other, at using the derived conditions to disentangle relevant mechanisms involved in the air–sea interaction. In particular, our main interest concerned the processes acting on the wind stress and on the wave growth. With oil on the water surface, we have found that in the wind-only condition (no paddle waves) the wave field does not grow from the rest condition. This equilibrium is altered by irregular paddle (long) waves, the generation and evolution of short waves (in clean water and with oil) being modified by their interaction with the orbital velocity of the long waves and their effect on the airflow. Paddle waves do grow under the action of wind, the amount being similar in clean and oily water conditions, a fact we ascribe to the similar distortion of the wind vertical profile in the two cases. We have also verified that the wind-supported stress on the oily water surface was able to generate a surface current, whose magnitude turns out to be comparable to the one in clean water. We stress the benefits of experiments with surfactants to explore in detail the physics at, and the exchanges across, the wavy and non-wavy air–water interface.

Hydropedological Interpretation of Regional Soil Information to Conceptualize Groundwater–Surface Water Interactions

Core Ideas Hydropedology can serve as an indicator of the hydrological behavior of catchments. Hydropedological interpretations are applicable at regional scales. Internal catchment properties are often more important than environmental factors. Understanding and quantifying groundwater–surface water interactions is important for effective water resource management. Characterization of these interactions is difficult due to heterogeneities in landscapes and difficulties in measuring hydrological processes at different scales. Although soils play an integral role in the hydrological functioning of landscapes, very few groundwater–surface water interaction studies consider soils as key components of hydrologic variation. We studied 21 catchments in South Africa with available stream attributes, such as baseflow index (BFI) and hydrological variability (CVB). The soils of the catchments were interpreted and grouped into four classes based on dominant hydropedological response: Recharge, Interflow, Responsive (shallow), and Responsive (wet). The dominant soil distribution patterns in the catchments were then determined. Significant positive Spearman correlation coefficients exist between BFI and soil attributes such as depth (0.72), clay content (0.54), and the area covered by Recharge soils (0.81). The occurrence of Interflow and shallow soils is inversely correlated to BFI (−0.86 and −0.67, respectively), whereas CVB was positively correlated to the area of Interflow soils (0.81) and negatively to the area of Recharge soils (−0.75). Based on the hydropedological soil distribution pattern, three conceptual models of groundwater–surface water interactions were constructed: (i) those where vertical drainage and recharge of groundwater in the upper slopes are dominant, with return flow to soil layers in lower‐lying positions, and soil and groundwater contribute to streamflow; (ii) those where vertical drainage through soils and recharge of groundwater is dominant in upper and lower lying landscape positions, there is no return flow to soils, and only groundwater contributes to streamflow; and (iii) those where lateral flow at the soil–bedrock interface is dominant throughout the catchment, limited recharge occurs, and the stream is fed through lateral flow from soils with limited contribution from groundwater.

Radon, CO2 and CH4 as environmental tracers in groundwater/surface water interaction studies − comparative theoretical evaluation of the gas specific water/air phase transfer kinetics

The applicability of radon as environmental tracer in groundwater/surface water interaction studies has been documented in a considerable number of publications. In some of these reports it has also been suggested to validate the radon based results by using CO2 and CH4 as supplementary tracers. The on-site measurement of the three gaseous parameters relies on their extraction from the water followed by the measurement of their concentration by means of mobile gas-in-air detectors. Since most related practical applications require the recording of time series, a continuous extraction of the gases from (e.g.) a permanently pumped water stream is necessary. A precondition for the sound combined interpretation of the resulting time series is that the individual temporal responses of the extracted gas-in-air concentrations to instantaneously changing gas-in-water concentrations are either identical or in reproducible relation to each other. The aim of our theoretical study was the comparison of the extraction behavior of the three gaseous solutes with focus on the individual temporal responses to changing gas-in-water concentrations considering in particular the gas specific water/air phase transfer kinetics. We could show that the overall mass transfer coefficients of radon, CO2 and CH4 result in a virtually similar temporal response to aqueous concentration changes, thus confirming the straightforward combined measurement/utilization of the dissolved gases as environmental tracers in groundwater/surface water interaction studies.

Hyporheic zone exchange fluxes and residence times inferred from riverbed temperature and radon data

Summary Vertical profiles of temperature, radon and electrical conductivity are used to characterise downwelling, neutral and upwelling hyporheic zones along a pool–riffle sequence in the Haughton River in north-eastern Australia. Water residence times and vertical fluxes are derived from temperature and radon data and then directly compared for downwelling profiles. Temperature and radon-derived fluxes in downwelling zones ranged from 0.02 to 24 m day −1 with a mean of 1.69 m day −1 while residence times across the study site ranged from tens of minutes to greater than 15 days. The radon approach has the lowest uncertainty for residence times between 0.1 and 15 days while the uncertainty of the temperature approach (using a diel river signal) is lowest for residence times that are less than a few days. For 83% of depths in downwelling profiles, radon-derived residence times were greater (some up to two orders of magnitude greater) than temperature-derived residence times. When the error bounds of the residence time estimates were accounted for, 57% of radon-derived residence times were considerably greater than temperature-derived residence times in downwelling profiles. We suggest that this disparity is due to the different influence of small scale heterogeneity on temperature and radon transport. These field based results indicate that small scale heterogeneity may play a far more important role than has been previously considered in groundwater–surface water interaction studies.

Density functional theory study of water interactions on Mn-doped CeO2(111) surface

Spin-polarized density functional theory (DFT + U) periodic calculations have been performed to study water adsorption and dissociation on the 12.5% Mn-doped CeO2(1 1 1) surface. Our results indicated that Mn cation is the surface active site for water adsorption and dissociation reactions. The H2O molecule preferably adsorbs on a Mn cation, causing some relaxation of the surface O-layer and, thus, facilitating the bonding of one of the HH2O with the nearest oxygen atom. After overcoming an energy barrier of 0.46 eV, the water molecule could dissociate into OH and H species. The latter configuration is about 50% more exothermic than the molecular one, suggesting the Ce0.875Mn0.125O1.9375(1 1 1) surface would be easily hydroxylated under reaction conditions. In addition, the calculations showed that water adsorption on the Mn-doped CeO2(1 1 1) surface did not favor the creation of surface oxygen vacancies as it has been reported for pure CeO2(1 1 1). On the other hand, we created a surface oxygen defect in the slab with structural oxygen vacancies and computed water interactions on the reduced surface. Although, the adsorption of OH species in the O-hole caused many surface and subsurface atomic displacements, no changes in the oxidation state of Mn and Ce cations were detected.

Water Adsorption at the Tetrahedral Titania Surface Layer of SrTiO3(110)-(4 × 1).

The interaction of water with oxide surfaces is of great interest for both fundamental science and applications. We present a combined theoretical (density functional theory (DFT)) and experimental (scanning tunneling microscopy (STM) and photoemission spectroscopy (PES)) study of water interaction with the two-dimensional titania overlayer that terminates the SrTiO3(110)-(4 × 1) surface and consists of TiO4 tetrahedra. STM and core-level and valence band PES show that H2O neither adsorbs nor dissociates on the stoichiometric surface at room temperature, whereas it does dissociate at oxygen vacancies. This is in agreement with DFT calculations, which show that the energy barriers for water dissociation on the stoichiometric and reduced surfaces are 1.7 and 0.9 eV, respectively. We propose that water weakly adsorbs on two-dimensional, tetrahedrally coordinated overlayers.

A review of the numerical modelling of salt mobilization from groundwater-surface water interactions

Salinization of land and water is a significant challenge in most continents and particularly in arid and semi-arid regions. The need to accurately forecast surface and groundwater interactions has promoted the use of physically-based numerical modelling approaches in many studies. In this regard, two issues can be considered as the main research challenges. First, in contrast with surface water, there is generally less observed level and salinity data available for groundwater systems. These data are critical in the validation and verification of numerical models. The second challenge is to develop an integrated surface-groundwater numerical model that is capable of salt mobilization modelling but which can be validated and verified against accurate observed data. This paper reviews the current state of understanding of groundwater and surface water interactions with particular respect to the numerical modelling of salt mobilization. 3D physically-based fully coupled surface-subsurface numerical model with the capability of modelling density-dependent, saturated-unsaturated solute transport is an ideal tool for groundwater-surface water interaction studies. It is concluded that there is a clear need to develop modelling capabilities for the movement of salt to, from, and within wetlands to provide temporal predictions of wetland salinity which can be used to assess ecosystem outcomes.

Fourier transform infrared spectroscopic and theoretical study of water interactions with glycine and its N-methylated derivatives

In this study we attempt to explain the molecular aspects of amino acids' hydration. Glycine and its N-methylated derivatives: N-methylglycine, N,N-dimethylglycine, and N,N,N-trimethylglycine were used as model solutes in aqueous solution, applying FT-IR spectroscopy as the experimental method. The quantitative version of the difference spectra method enabled us to obtain the solute-affected HDO spectra as probes of influenced water. The spectral results were confronted with density functional theory calculated structures of small hydration complexes of the solutes using the polarizable continuum model. It appears that the hydration of amino acids in the zwitterionic form can be understood allowing a synchronized fluctuation of hydrogen bonding between the solute and the water molecules. This effect is caused by a noncooperative interaction of water molecules with electrophilic groups of amino acid and by intramolecular hydrogen bond, allowing proton transfer from the carboxylic to the amine group, accomplishing by the chain of two to four water molecules. As a result, an instantaneous water-induced asymmetry of the carboxylate and the amino group of amino acid molecule is observed and recorded as HDO band splitting. Water molecules interacting with the carboxylate group give component bands at 2543 ± 11 and 2467 ± 15 cm(-1), whereas water molecules interacting with protons of the amine group give rise to the bands at 2611 ± 15 and 2413 ± 12 cm(-1). These hydration effects have not been recognized before and there are reasons to expect their validity for other amino acids.

Ab Initio Study of Water Interaction with a Cu Surface

We have performed a first principles investigation of water interaction with a Cu surface. The calculated surface energy of a Cu(100) slab is in reasonable agreement with experimental data. The energy of water dissociation is in agreement with experiment. The results of the ab initio calculations are compared to experimental data on hydrogen partial pressure. It is concluded that Cu(OH)(ads) is formed due to a reaction between Cu and anoxic water. The energy of the Cu(100) slab with OH and H adsorbed is lower than the energy of the same slab with an adsorbed water molecule.

Thermodynamics of Water Interaction with Human Stratum Corneum I: Measurement by Isothermal Calorimetry

A thermodynamic study of water interaction with human stratum corneum (SC) is presented. The procedure consisted of conjoint water vapor sorption and heat flow measurements. Heat of sorption of water in excised human SC at various relative humidities was measured in an isothermal calorimeter at 32°C using back and thigh skin from three different donors. These measurements, combined with the gravimetric sorption isotherm, were used to calculate the integral and differential enthalpies and entropies associated with binding of water to SC. Differential enthalpy values suggest hydrogen‐bonding interactions similar to those for water in wool keratin. The changes in differential enthalpy and entropy with increasing water content followed a pattern similar to that seen in wool and other hydrophilic polymers. The results are partially interpreted in terms of a BET isotherm with monolayer volume vm = 0.022g H2O/g dry SC and binding parameter C = 6.5 × 108.

Infrared reflection absorption study of water interaction with H-terminated Si(100) surfaces

Water adsorption on clean and hydrogenated Si(100) surfaces was studied under ultra high vacuum conditions using surface infrared spectroscopy. The study shows that H-Si-Si-OH and SiH2 species are formed on Si(100)-(2 × 1) and Si(100)-(2 × 1)-H surfaces, respectively. The reactivity behaviour of Si(100)-(3 × 1)-H and Si(100)-(1 × 1)-H is similar, both stabilizing oxygen inserted silicon dihydrides.

Molecular simulation study of water interactions with oligo (ethylene glycol)-terminated alkanethiol self-assembled monolayers.

Molecular simulations were performed to study a system consisting of protein (e.g., lysozyme) and self-assembled monolayers (SAMs) terminating with different chemical groups in the presence of explicit water molecules and ions. Mixed SAMs of oligo (ethylene glycol) [S(CH2)4(OCH2CH2)4OH, (OEG)] and hydroxyl-terminated SAMs [S(CH2)4OH] with a mole fraction of OEG at chiOEG = 0.2, 0.5, 0.8, and 1.0 were used in this study. In addition, methyl-terminated SAMs [S(CH2)11CH3] were also studied for comparison. The structural and dynamic behavior of hydration water, the flexibility and conformation state of SAMs, and the orientation and conformation of protein were examined. Simulation results were compared with those of experiments. It appears that there is a correlation between OEG surface resistance to protein adsorption and the surface density of OEG chains, which leads to a large number of tightly bound water molecules around OEG chains and the rapid mobility of hydrated SAM chains.

A Study of Water Interaction with γ-Al2O3Surface by Adsorption Calorimetry

The steps at 70, 62, and 56 kJ/mol were specified on the dependences of differential heats \(\overline Q _a\) of adsorption on the values of adsorption aon the hydroxylated γ-Al2O3surface resulted from the interaction of adsorbed water molecules with the surface-coordinated water molecules, acid and basic hydroxyl groups, respectively; effective charges qwere estimated for the protons of coordinated water molecules and acid and basic OH groups. The hydration numbers were calculated in the region of monolayer coverage for the three aforementioned adsorption sites. The texture changes discovered in γ-Al2O3particles were attributed to the interlamellar swelling of the secondary sorbent packets formed from its primary particles.

A comparative study of water interaction with alkali–metal cation-exchanged X-type zeolites by pulsed field gradient NMR and temperature-programmed desorption

1H pulsed field gradient (PFG) NMR is applied to study water self-diffusion in LiX, NaX and CsNaX under the regimes of restricted intracrystalline diffusion and long-range diffusion. The dependence of the long-range diffusivities on temperature, loading and type of cation may be easily rationalised on the basis of a simple microkinetic approach. The apparent activation energies, determined from the Arrhenius plots of the long-range diffusivities, are compared with the effective desorption energies determined in previous temperature-programmed desorption (TPD) studies. Though there are coinciding trends, the absolute values of the desorption energies are smaller by 10…20 kJ mol −1 than the maximum values of the apparent activation energies of long-range diffusion. This difference is most likely to be attributed to a remaining influence of molecular diffusion in the TPD measurements.

10] Nuclear magnetic resonance study of water interactions with proteins, biomolecules, membranes, and tissues

Nuclear magnetic resonance (NMR) is a powerful tool in studying the structure and dynamics of chemical and biochemical systems. This chapter reviews some basic aspects of the application of NMR to the study of water interactions with proteins, biomolecules, membranes, and tissues. A basic characteristic of biological membranes is their permeability to water and ions. The transport of water through cell membranes and the diffusion of water inside the cell are investigated by NMR along with other methods such as isotope diffusion. The self-diffusion coefficient of water inside a cell is also obtained by NMR. An important application of the study of magnetic relaxation in tissues is magnetic resonance imaging (MRI). This technique is based upon the detection of in vivo NMR signals, often in the presence of magnetic field gradients. The NMR intensity of liquid water is used to determine the amount of nonfreezable water. In an NMR study of water in a biological system, the most comprehensive work should include temperature and frequency dependence of the relaxation times of proton, deuterium, and oxygen-17 in the same system.