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Moisture content of rock/coal can change its mechanical properties and absorption capacities, which can directly affect gas diffusivity, change the stress distribution and hence cause significant impacts on the overall gas or coal extraction process. Observation of the water penetration process and water distribution in the coal matrix will be beneficial for the understanding of the fluid-solid coupling mechanism in hydraulic fracturing, aquifer cracking and coal seam infusion. However, the observation of water penetration process and the determination of water distribution mode were hard to be non-destructively achieved as coal is a non-uniform, inhomogeneous and un-transparent material. µ-CT imaging, which is based on variation of X-ray attenuation related to the density and atomic composition of the scanned objects, enables a four-dimensional (spatial-temporal) visualise of the heterogeneous and anisotropic coal samples. The primary aim of this paper is extending the application of µ-CT imaging to explore the moisture penetration and distribution within coal samples during water infusion process, which has been reported by very little literature. The working principle and procedures of CT imaging was firstly introduced. Then, the determination equation of moisture distribution based on density profile was established. The CT determined moisture content has been compared with weighting method for verification. The paper has demonstrated that µ-CT can be used for non-destructively imaging the moisture distribution within coal samples. [ABSTRACT FROM AUTHOR]

Nowadays, some fracking fluids can enable resourceful extraction of coalbed methane and reduce greenhouse gas emissions. However, their toxicity or corrosiveness will cause harm to downhole workers and pollute groundwater resources. Thus, five kinds of clean composite fracturing fluids were developed in this paper by using starch solution as the matrix and adding various preparations. The change rule of methane adsorption capacity by microstructure changes of coal samples was investigated systematically, and the optimal composite fracturing fluid was determined. The results showed that the new fracturing fluid increased the degree of aromatic ring condensation by 43.3% and the average pore size by 52.1%. Also, the adsorption constants of a value decreased by 11.6% and b value decreased by 23.9%, which can remarkably reduce the methane adsorption. The experimental results provide theoretical support for the clean production of coalbed methane. [ABSTRACT FROM AUTHOR]

In this paper, the aluminum gel with polymeric aluminum chloride (PAC) as the gelling agent and carbamide as a catalyst were investigated. The gelling regularities were studied, and its gelling performance was evaluated under high temperature and high salinity. The results showed that the basicity, mass fraction of PAC and carbamide, temperature, and salinity significantly influenced the formation of the gel. The gel exhibited exceptional thermal stability and gel strength under high temperature and salinity conditions. The results indicated that when the aluminum gel was prepared with 8 wt% PAC and 1 wt% carbamide and dissolved in brine with a salinity of 110,000 mg/L, the dehydration rate was less than 1 wt% after being aged for 180 days at 130 °C. Furthermore, the gel strength, elasticity, and yield stress increased with the rise in salinity. The experimental results showed that the aluminum gel is highly significant in plugging reservoirs with high temperature, high salinity, and low permeability. [ABSTRACT FROM AUTHOR]

In the CCUS project, CO2 utilization had achieved remarkable results in oil displacement. But, at present, one of the main reasons that seriously affected the large-scale application of CCUS projects was that the corrosion behavior of underground environment on pipe string or wellbore was not fully evaluated. It was revealed that the wellbore corrosion behavior in the harsh environment in the process of CO2 flooding was the key to ensure the safe production of oil fields. Therefore, this paper took the corrosion environment with temperature of 81.7°C, pressure of 52.3 MPa and high salinity in the well depth of 4517 m as the research object, to study the corrosion behavior of oil casing N80 steel through corrosion rate, corrosion morphology and electrochemical experiments. The results showed that the corrosion rate increased with the increase of experimental time, behaved by the charge transfer resistance decreased. However, when the experiment increased from 800 h to 1000 h, the pitting corrosion rate increased from 1.47 mm/a to 1.782 mm/a, which was consistent with the ratio of anode/cathode Tafel constants and corrosion density. This was mainly because the relatively dense FeCO3 corrosion product layer generated on the N80 steel surface gradually brook down due to synergistic effect of amorphous CrO3, Fe2+/Ca2+ complex salt and Cl– during the experiment, which promoted the initiation and development of the corrosion pits. Compared with the bare N80 steel, the incomplete corrosion product layer aggravated the rapid development of pitting corrosion. [ABSTRACT FROM AUTHOR]

Both natural and anthropogenic processes can lead to the increasing salinity of surface waters. The knowledge about the ecological consequences of salinization on the biota is limited especially in case of microbiota, like diatoms. We collected the existing knowledge about the relationship between salinity and diatoms in fresh and saline waters. Based on the available papers, conductivity and ion composition are the most important variables shaping diatom communities. Secondary salinization can mask regional differences in diatom assemblages. Trait-based analyses highlight the competitive advantages of motile guild and the extreme trait categories in these environments. The increasing conductivity along a wide conductivity scale decreases the alpha-diversity. Salinization induces the spread and invasion of marine and brackish species into inland freshwaters as well as that of freshwater species tolerating elevated conductivity and/or need specific ions. Concerning food webs, salinity can directly change diatom communities and the subsequent upper trophic levels but most likely this effect manifests as a top-down regulation. Applicable diatom indices are available to assess the level of salinization. Furthermore, diatom-inferred salinity reconstructions are widely applied to assess the past changes of salinity. However, future models predicting ecological consequences of salinization are scarce and sometimes contradictory. [ABSTRACT FROM AUTHOR]

In the process of natural gas production using foam to lift liquid, there exists obvious difference in the requirements of foam stability between wellbores and gathering & transportation systems. To ensure the effect foam dewatering of gas wells and highly efficient defoaming and gas-water separation on surface, it is meaningful to investigate the influencing factors of foam stability comprehensively. In this paper, a tight gas block in China which adopted foam for liquid lifting was taken as an example. It was researched that the key influencing factors and changing rules of foam stability through static and dynamic experiments on foam stability, chemical defoaming experimets and field tests. The results showed that the concentration of foaming agent used in the field, namely UT-11C, had the most significant effect on the foam stability followed by the salinity, temperature and PH value. Foam stability was also can be improved with higher pressure. Results of chemical defoaming experiments showed that even under the optimal defoaming concentration, mamely 1%, it also took about 20 minutes to completely eliminate the foam. Combined with the laboratory results and the statistical analysis of the water production in field, the optimal injection amount of foaming agent was calculated, which makes the dosage reducing by 40%. And the effective was validated by field test. This work not only ensures the high production of gas wells, but also takes the economy into account, having a strong guidance for the production of natural gas fields. [ABSTRACT FROM AUTHOR]

A heat storage tank (HST), described in this paper, may be applied to numerous systems used for thermal energy generation and storage. Working principle and heat-flow processes of the HST remain the same and are independent of the systems in which the HST is being used. This paper presents a thermal-flow analysis of a heat storage tank (HST) operating in an air compressor heat pump (ACHP) and a dry cooler (DC) combined cycle. The HST is operated under transient conditions for four different ACHP steady states. The HST was analysed using lumped capacitance method. The heating power of a single coil varied from 2.2 to 3.2 kW. 50% increase in mass flow rate of heating water in the coils increased the HST water mean temperature by 5.6 °C. A differential equation for the HST water temperature variation was solved analytically and it was presented with the use of dimensionless numbers. The presented solution is of a general form. An important parameter such as number of the coils may be varied easily. Additionally, a Mathcad computational program was proposed for the estimation of HST-ACHP-DC system thermodynamic and thermal-flow parameters. System dynamics was studied using MATLAB/Simulink. An optimal operating parameters of the HST were found and are presented in the paper. The aforementioned parameters are as follows: mass flow rates of heating and cooling media in all three coils, mass flow rate of freshwater supplying the HST, number of loops in coils and resulting heat transfer area, diameter of the loops of the coils, diameter of the coils, time after which water in the HST reaches a steady value, time period within which the HST may fulfil demand for central heating and domestic hot water (DHW) preparation without being charged simultaneously. The presented analytical model was validated based on the available data in the field literature and a high compliance was reached. For this purpose theoretical model results were compared to results of HST computational fluid dynamics (CFD) simulations. The temperature calculated using the presented model differed from the one obtained by the CFD analysis by 2.96 K. [ABSTRACT FROM AUTHOR]

The paper is devoted to comparative analysis of detailed gas-geochemical studies carried out in the Alekseev Bay (Peter the Great Gulf, Japan Sea) in 1989 and 2022. The distribution of methane and carbon dioxide in water is given in details. CTD measurements were made to determine water temperature and salinity. The main regularities in the distribution of gas geochemical fields in the Alekseev Bay (Peter the Great Gulf) are shown basing on the available geological information, taking into account the materials of the predecessors. The results obtained are in demand both in theoretical studies of the gas geochemical fields distribution on the Earth's surface in connection with the seismotectonic and geological features of the region, and in the practice of developing methods and technologies for measuring the balance flows of the main greenhouse gases, emission and absorption. The results are also relevant for the implementation of research programs within the "climate agenda." [ABSTRACT FROM AUTHOR]

The exploration of unconventional hydrocarbons may be very effective in promoting economic development and confronting energy crisis around the world. However, the environmental risks associated with this practice might be an impediment if not adequately dimensioned. In this context, naturally occurring radioactive materials and ionizing radiation are sensitive aspects in the unconventional gas industry that may compromise the environmental sustainability of gas production and they should be properly monitored. This paper provides a radioecological assessment of the São Francisco Basin (Brazil) as part of an environmental baseline evaluation regarding the Brazilian potential for exploring its unconventional gas reserves. Eleven and thirteen samples of surface waters and groundwater were analyzed for gross alpha and beta using a gas flow proportional counter. A radiological background range was proposed using the ± 2 Median Absolute Deviation method. Using geoprocessing tools, the annual equivalent doses and lifetime cancer risk indexes were spatialized. Gross alpha and beta background thresholds in surface water ranged from 0.04–0.40 Bq L−1 to 0.17–0.46 Bq L−, respectively. Groundwater radiological background varies from 0.006–0.81 Bq L−1 to 0.06–0.72 Bq L−1 for gross alpha and beta, respectively. All environmental indexes are relatively higher in the south of the basin, probably a direct response to the local volcanic formations. Traçadal fault and local gas seepages might also influence the gross alpha and beta distribution. All samples have radiological indexes below the environmental thresholds, and should remain at acceptable levels with the development of the unconventional gas industry in Brazil. [ABSTRACT FROM AUTHOR]

Microplastics are a widespread contaminant found not only in various natural habitats but also in drinking waters. With spectroscopic methods, the polymer type, number, size, and size distribution as well as the shape of microplastic particles in waters can be determined, which is of great relevance to toxicological studies. Methods used in studies so far show a huge diversity regarding experimental setups and often a lack of certain quality assurance aspects. To overcome these problems, this critical review and consensus paper of 12 European analytical laboratories and institutions, dealing with microplastic particle identification and quantification with spectroscopic methods, gives guidance toward harmonized microplastic particle analysis in clean waters. The aims of this paper are to (i) improve the reliability of microplastic analysis, (ii) facilitate and improve the planning of sample preparation and microplastic detection, and (iii) provide a better understanding regarding the evaluation of already existing studies. With these aims, we hope to make an important step toward harmonization of microplastic particle analysis in clean water samples and, thus, allow the comparability of results obtained in different studies by using similar or harmonized methods. Clean water samples, for the purpose of this paper, are considered to comprise all water samples with low matrix content, in particular drinking, tap, and bottled water, but also other water types such as clean freshwater. [ABSTRACT FROM AUTHOR]

Brackish water is usually consumed by almost all population in southern Algeria as fresh water despite its high salinity. This region has a significant potential of solar energy and enormous reserves of brackish groundwater which can be exploited by solar desalination systems to supply small communities by potable water. In the current paper, we propose a new contribution to improve the performance of the conventional solar distiller using abundant local dune sand as heat storage medium and photo-catalytic additive within the absorber plate. Experimental results carried out at Ouargla's University show that — The yield is proportional to some extent certain value with the sand surface density. — For a particle's diameter ≤0.08 mm, the optimal value of the sand surface density is (sand 2.815 kg/m2 of absorber area); this leads to a daytime improvement of 61.46% on the yield compared to the baseline case. — Moreover, adding (charcoal 0.563 kg/m2 of absorber area) to the brackish water within each unit increases the output by a mean of 13.82%. After sunset, the distillation process continues for significant time. — Finally, after an economical and physical analysis, the distillate is produced with low cost and high quality. [ABSTRACT FROM AUTHOR]

Inorganic chlorine is susceptible to water and soil salinization due to its non-degradability and high mobility. To clarify the environmental risks associated with the active inorganic chlorine in municipal solid waste (MSW), the specific characteristics and contributions of inorganic chlorine in different MSW categories were investigated in this study. MSW samples were collected from eight representative waste classification residential areas in Hangzhou, China. It was found that the inorganic chlorine content in different MSW categories varied significantly (0–113 mg/g). Perishable waste, paper, and plastic were found to be the main sources of inorganic chlorine in MSW. A four-category classification system was used to quantify the contribution of inorganic chlorine from each waste category. It was found that the misclassification of inorganic chlorine contributions from perishable waste and other waste accounted for 51.96% and 48.04%, respectively. However, when correctly classified into the four-category system, their contributions were reduced to 67.14% and 30.65%, respectively. Therefore, MSW classification showed a significant reduction in the overall contribution of inorganic chlorine. The misclassification reduces the contribution of inorganic chlorine to 48.04%, while correct classification increases the reduction to 69.35%. [ABSTRACT FROM AUTHOR]

Bare, non-pretreated platinum wires and screen-printed platinum electrodes were used as both working and counter electrodes in the measurement of dissolved oxygen using a chronoamperometric method. The oxygen reduction current response in the diffusion state was used for a linear determination of air saturation. We evaluated the two different materials in general for their sensing performance such as conditioning time, accuracy, resolution and stability over 13 h of continuous mid-term measurement. A good performance was found for the wire electrodes in terms of accuracy with a current slope of 1.0–1.6 µA (% as)-1 and a resolution of 10–15 nA (Lowest Level of Detection = 0.1% as), but with an unstable current response result over the course of the measurement. The screen-printed electrodes have a resolution of 10–18 nA (Lowest Level of Detection = 0.6–0.8% as) and an accuracy of 620–660 nA (% as)-1 but they showed promising reproducibility and stability. Both materials require several hours of conditioning in the chronoamperometric method before a stable current response is achieved. For biotechnological applications, the platinum screen printed electrodes were evaluated in typical parameter settings (pH 4.0 and 7.4, salinity 0.1 to 10x phosphate buffered saline and temperature 12 to 42 °C) and showed correlations between the response time and stability and the temperature. No correlations were found between salinity, pH and the current response. In this paper, we present inexpensive electrode materials and a simple to implement chronoamperometric method for reliable direct measurement of dissolved oxygen in aqueous media. [ABSTRACT FROM AUTHOR]

Salinity in deltaic systems is expected to increase in the near future due to sea level rise. This will cause severe environmental consequences because salinity can be detrimental to agriculture, aquaculture and human consumption. Tidal dynamics are important in regulating salinity in river deltas. However, there is still uncertainty about the influence of different tidal amplitudes on deltas' salinity. This paper investigates the impact of various tidal amplitudes on the spatiotemporal salinity distribution in deltas through three-dimensional idealized modelling. Numerical simulations are carried out with a common hydrograph and different tidal ranges. Both tide-influenced and river-dominated cases were considered. Results suggest that small increases in the tidal amplitude in river-dominated or low tidal regimes cases can have positive effects against salinization. Tide-induced mixing helps to increase freshwater areas and volumes. The water in the delta remains fresh for longer periods in scenarios representative of microtidal regimes. Further increases in the tidal amplitude to meso- and macrotidal levels reverse these effects and reduce freshwater areas and volumes. Results were used to test how salinity correlates with channel orders and river discharge in the presence of tides. These correlations are controlled more by bathymetry than tidal forcing. This study provides important insights into how changes in tidal range could impact spatiotemporal salinity distributions in deltas. [ABSTRACT FROM AUTHOR]

Aristino-Traianoupolis area hosts one of the most significant water-dominated low-temperature geothermal fields in Greece. It is located on the southwestern uplifted margin of the Tertiary Evros Delta molassic basin, 10 km east of the town of Alexandroupolis (Thrace, NE Greece). The upper hydrothermal system of the Aristino Geothermal Field (AGF), one of the most promising in continental Greece, contains fluids with temperatures ranging from 51 to 99 °C, within a series of overlapping aquifers at very low depths (100–430 m). The main geothermal anomaly for temperatures higher than 90 °C covers an area of 6 km2, to a maximum prospected depth of 500 m below ground surface. The scattered regional anomaly exceeds 50 km2 and is characterized by excessively high and abruptly changing thermal gradient (42 to 450 °C/km) and heat flow (80–800 mW/m2), that are both typical of a fault-controlled hydrothermal system. Since 1993, the AGF has undergone non-systematic geothermal investigation, with emphasis on low-depth (100–500 m) drilling. This paper provides, for the first time, a synthetic and detailed evaluation of all available temperature data gathered in the last 25 years. The steady-state temperature logs reveal the dominant role of conduction for the upper geothermal system, accompanied, in most cases, by rapidly changing and abnormally high thermal gradients (100–450 °C/km), triggered, most probably, by a deeper system of higher temperature. This hypothesis is also supported by the applied chemical geothermometers, which suggest initial fluid temperatures at 140–150 °C, the hydrochemical characteristics of the fluids hosted in the deeper and most promising investigated reservoir (ignimbrite) of the upper system, and the extrapolated temperatures from the conductive temperature–depth profiles. The lower widespread medium enthalpy hydrothermal system should extend at depths 500–1000 m within volcanics and the expected Eocene limestones and basal clastic series of the Tertiary sequence that have filled the basin. Nevertheless, these assumptions need to be verified by appropriate investigations and new drillings at depths greater than 600–700 m, which would confirm the presence of a productive medium enthalpy reservoir. [ABSTRACT FROM AUTHOR]

Swelling elastomers swell when in contact with certain fluids and are used in different applications in oil drilling and bioengineering. Flory–Huggins polymer-fluid interaction parameter is an important factor that controls swelling. It is conventionally determined by chemical dissociation of the polymer, a difficult and time-consuming method. Current paper focuses on a novel and easier method of estimating this parameter through swelling and mechanical testing. Two different elastomers were kept in saline water of 0.6% and 12% concentration at 50 °C for a period of one month. Changes in mass, volume, density, and elastic and bulk moduli were recorded at different intervals. Shear modulus was used to determine chain density. Density, volume swelling ratio, molar volume, shear modulus, and average chain molecular weight values were used to determine. Both materials showed a decreasing trend in values as swelling progresses, as expected. Value of was higher in high-salinity brine, and larger decrease in value was observed in lower-salinity solution. For instance, in high salinity brine, a drop in χ value from 0.87 to 0.7 was observed for material-A, and a drop from 1.0 to 0.75 for material-B over the 30-day swelling period. In low salinity brine, chi-value decreased from 0.79 to 0.63 for material-A, and from 0.84 to 0.64 for material-B. This work is beneficial for engineers and scientists working on swellable elastomers in particular (petroleum drilling and development), and rubbers and polymers in general. [ABSTRACT FROM AUTHOR]

Growing freshwater scarcity in arid and remote areas usually is caused by the growth of population, urbanization and industrialization and the rather limited natural resources of potable water. In coastal belt of southwest region of Bangladesh, groundwater contains high salinity as well as excessive arsenic contamination. Though pond sand filter and rainwater harvesting system are usually used to meet the freshwater demand throughout the year in this area, along with these, household-based solar desalination could be a good source of drinking water in this region. In this study, a low-cost Tubular Solar Still (TSS) was designed using locally available materials to meet such demand. It was consisted of a tubular frame (0.00275 m thick helical GI wire, 1.0 m long and 0.2 m in diameter) and a rectangular tray (1.0 m × 0.16 m × 0.05 m) covered with black polythene paper. The collection bottle was kept in an insulation box. The field experiment on the constructed TSS was carried out on the rooftop of Civil Engineering Department building from June 25, 2011, to June 20, 2012. Daily distilled output from the TSS was collected approximately 2 h after sunset. The maximum daily production rate was found as 3.83 l/m2 in May 2012. The production cost of distilled water is estimated as 0.39 BDT/L or 0.0046 USD/L. The application of this process can fulfill the demand of freshwater for drinking purpose for single household in coastal areas. [ABSTRACT FROM AUTHOR]

With the development of underground space and the continuous development of subways, the emergence of artificial freezing method has solved the problem of how to ensure the safety of excavation and damage the environment during subway construction. This paper relies on the horizontal freezing method of the connecting passage between Zhengzhou Airport and Xuchang City Railway Yingbin Avenue Station~Xinzheng Airport Station. The flow rate and direction of the seepage field, the influence of phase change and heat transfer boundary conditions are controlled based on the heat transfer of porous media. And seepage theory and practical engineering use COMSOL Multiphysics to establish a numerical model of the coupling of the seepage field and the temperature field in the connecting channel. The model is used to simulate the influence of groundwater velocity, freezing pipe diameter, and initial ground temperature freezing pipe spacing on the temperature field development under single-row freezing, and the sensitivity formulas of the above factors on the freezing wall thickness and freezing time are given. Through the sensitivity analysis and comparison of various factors, the results show that the influence of the four factors on the freezing temperature field in descending order is groundwater flow rate, freezing pipe spacing, freezing pipe diameter, and initial ground temperature. In this case, it can effectively offset the influence of groundwater velocity on the freezing temperature field. [ABSTRACT FROM AUTHOR]

During service in sea water, the steel used in the construction of ships experiences deterioration caused by corrosion and fatigue. The degradation of the material is a complex phenomenon that is affected by many parameters such as the manufacturing procedure, the chemical composition, the time of service, the mechanical properties of the steel. In this paper, an experimental study is conducted on the high-strength low-alloy steel known as grade NV EH32 aiming to highlight the effect of the real conditions of service on its mechanical properties. For that, the results of experiments conducted in both the laboratory and sea water are discussed. Accelerated corrosion tests were performed in the laboratory. The mechanical properties and microscopic behaviour are compared to specimens obtained from hulls of ships encountered: a long period of service about 35900 hours of navigation in the Mediterranean Sea and 8544 hours of immersion in calm sea water (harbour). In both real and simulated marine atmosphere, the yield and tensile strength decreased considerably. It is found that the ductility decreases considerably with the increase in the salinity, time of exposure to corrosion and after a long period of service of the steel in marine atmosphere. Aspect of microbial corrosion is discovered when the steel is held in calm sea water and caused the decrease in the mechanical properties. [ABSTRACT FROM AUTHOR]

This study evaluates the quality of drinking water samples (sample size = 52) taken from various locations of Pithoragarh district, Uttarakhand. The parameters include physiochemical properties viz. total dissolved solids (TDS in mg/L), electrical conductivity/salinity (µS/cm), pH and radiological dose attributable to radon in water (µSv/y). TDS values for the tested samples varied within the range of 18–434 mg/L with average value of 148 mg/L. Electrical conductivity and pH for these samples was measured as 36–868 µS/cm (average: 296 µS/cm) and 6.8–8.2 (average: 7.2), respectively. Radon activity concentration for these water samples was measured using scintillation-based radon monitor, immediately after sampling at the location site. Radon activity concentration was measured as 0.6–81.9 Bq/L with an average value of 17.8 Bq/L. The paper also estimates the annual effective ingestion dose (µSv/y), annual effective inhalation dose (µSv/y) and total effective dose (µSv/y) attributable to radon in drinking water samples. [ABSTRACT FROM AUTHOR]

We consider methods for calculating the distribution of the temperature and rheological parameters (differential stresses) in the lithosphere using results of deep electromagnetic sounding in the Russian Arctic zone on the territory of the Kola–Karelian region. Temperature modeling is carried out under the assumption that, within the upper part of section (at depths less than 20–30 km), changes in resistivity with depth are due to the influence of porosity, permeability, moisture and salinity of pore solutions. For depths of more than 20–30 km, it is assumed that the resistivity of the lower part of the Earth's crust and upper mantle is determined, first and foremost, by the mineral composition of "dry" rocks, temperature, and pressure. Estimates of temperature at depth based on geoelectric sections are made by calculating the heat balance equation taking into account the assumptions about the distribution of energy sources in the Earth, the thermophysical properties of its individual layers, and their petrographic composition. The change in the mineral composition of the lithosphere with depth was taken on the basis of a priori geological estimates and superdeep drilling data. The dependence of temperature on depth is calculated by minimizing the discrepancy between the conductivity profile obtained on the basis of theoretical calculations and the conductivity profile based on a priori data from petrophysical studies. Taking into account the developed foundations of geothermal interpretation, the modeling of geoelectric sections obtained in the FENICS experiment on deep sounding of the lithosphere using industrial power lines is carried out. Rheological studies are aimed at studying the possible existence of the boundary of the transition of matter from a brittle to ductile state in the Earth's crust of the Baltic Shield in accordance with the theoretical concepts of Nikolaevsky. This hypothetical boundary is known as the brittle–ductile transition (BDT) zone. Theoretical calculations of the rheological parameters of the lithosphere are performed using nonlinear equations connecting the components of the stress tensor and the strain rate tensor with the components of stress tensors and their time derivatives. The calculation results showed that the boundaries of uncertainty in the estimated position of the BDT boundary are in the range from 5–10 to 3–40 km. More reliable estimates are obtained using soundings with controlled sources. For this purpose, this paper presents the results of the Murman-2018 experiment on deep remote sounding in the Murmansk block with a linear (uniform) step of changing the separation between the source and receiver up to 56 km. A three-layer gradient-stepped section of the A type is revealed. The upper layer with a resistivity of 2 × 104 Ohm m and a thickness of 10 km is characterized by increased fragility due to the existence of subvertical flattening with depth zones of fractures and faults. Deeper than 10 km, there is a border of a sharp increase in resistivity to 106–107 Ohm m. It is conventionally defined as the impenetrability boundary. On the basis of this result and taking into account a large number of indirect geophysical factors, we concluded that the impermeability boundary corresponds to the BDT boundary, and the results of this work show that the use of electrical sounding allows one to obtain quantitative estimates of the temperature and rheological parameters of the lithosphere. [ABSTRACT FROM AUTHOR]

In this paper, a Tamm plasmon resonance-based sensor is theoretically studied to calculate the salinity of seawater as well as a temperature sensor based on photonic crystals. The transfer matrix method (TMM) is used to systematically study and analyze the reflected s-polarized electromagnetic waves from the sensing structure. The proposed structure composes of prism/Au/water/ (S i / S i O 2) N /Si. The sensitivity, figure-of-merit, quality factor, and detection limit of the sensors are improved by optimizing the thickness of the seawater layer, incident angle, salinity concentration, and temperature. The proposed salinity sensor records a very high sensitivity of 8.5 × 10 4 nm/RIU and quality factor of 3 × 10 3 , and a very low detection limit of 10 - 7 nm. Besides, the suggested temperature sensor achieves high sensitivity (from 2.8 to 10.8 nm/°C), high-quality factor of 3.5 × 10 3 , and a very low detection limit of 3 × 10 - 7 nm. These results indicate that the proposed sensor is a strong candidate for salinity and temperature measurements. [ABSTRACT FROM AUTHOR]

Freshly excavated overburden (spoils) dumped during open-cut coal mining generate saline leachate that can lead to environmental impacts. Predictions of leachate salinity remain uncertain, largely due to incomplete knowledge of responses of spoils to varying moisture conditions. This study carried out column leaching experiments on four spoil types, originating from Queensland, Australia. Following characterisation of the fresh spoil material, four moisture regimes were tested: three wetting-drying conditions with leaching occurring biweekly, weekly, and fortnightly and one completely saturated regime with leaching occurring weekly. Thirty-four leaching cycles were conducted except for one spoil type for which only 12 cycles were completed. Results showed higher EC and leachate ion concentrations from the saturated regime, while among the wetting-drying regimes, the spoil leached on a fortnightly basis resulted in higher salt release for two geochemically similar spoil types. Overall, lower and steady pH was recorded for spoils leached under saturated conditions. Irrespective of spoil type, sodium was the dominating cation contributing to the overall leachate salinity. The paper provides new insights into parameterising leaching models and in the role of water-rock interactions which informs experimental design and conceptualisation of full-scale models. [ABSTRACT FROM AUTHOR]

Deep geological disposal is the preferred solution for long-term storage of radioactive waste in many countries. In a deep repository, cementitious materials are widely used in the structure and buffer/backfill of the repository for the stabilisation of the hazardous materials. The cement acts as a physical barrier and also contributes chemically to waste containment by buffering the groundwater to a high pH, limiting the solubility of many radionuclides. This paper describes an experimental and modelling study which evaluates the geochemical interaction between young cement leachate (YCL, pH = 13) and a generic hard rock (in this case Hollington sandstone, representing a 'hard' host rock) during permeation with the leachate, as it drives mineralogical changes in the system. One-dimensional reactive transport was modelled using a mixing cell approach within the PHREEQC geochemical code to identify the essential parameters and understand and scale up the effect of variations in these parameters on the observed geochemical processes. This study also focused on the effects of variable porosity, reactive surface area and pore volume on improving the modelling of rock alteration in the system compared to conventional models that assume constant values for these properties. The numerical results showed that the interaction between the injected hyper-alkaline leachate and the sandstone sample results in a series of mineralogical reactions. The main processes were the dissolution of quartz, kaolinite and k-feldspar which was coupled with the precipitation of calcium silicate hydrate gel and tobermorite-14A (C–S–H), prehnite (hydrated silicate), saponite-Mg (smectite clay) and mesolite (Na–Ca zeolite). The simulation showed that the overall porosity of the system increased as primary minerals dissolve and no stable precipitation of the secondary C–S–H /C–A–S–H phases was predicted. The variable porosity scenario provides a better fitting to experimental data and more detailed trends of chemistry change within the column. The time and the number of moles of precipitated secondary phases were also improved which was related to greater exposure surface area of the minerals in the sandstone sample to the YCL. Article Highlights: The drop in calcium, aluminium and silicate concentrations is mainly due to the formation of calcium silicate hydrate and zeolite minerals as secondary phases. The simulation showed that the overall porosity of the system increased as primary minerals dissolve and no stable precipitation of the secondary C–S–H /C–A–S–H phases was predicted. The dissolution of primary minerals and the precipitation of secondary C–S–H phases had a minimal effect on the pH values, and this was controlled mainly by the initial fluid chemistry. The variable porosity scenario provides a better fitting to experimental data and more detailed trends of chemistry change within the column. [ABSTRACT FROM AUTHOR]

This paper presents the effects of silane coupling agent, which includes interfacial adhesive strength, water treatment, polymer composites and coatings that make it valuable for multi-materialization. The methoxy-type silane coupling agent composites-based modification is discussed using different methods exhibiting higher reactivity towards hydrolysis. The characteristics of developed vulcanization, in particular the dimethoxy-type silane-coupling agents than the trimethoxy-type have improved properties such as environment friendly fabrication process, mechanical, physical, swelling and dynamic viscoelastic properties of composites. The modification of aggregated surface along with asphalt binder excel their properties. Specifically, the silane coupling agent (SCA) Glycidoxypropyl trimethoxysilane (KH-560) utilization realizes the modification purpose. This review focuses on synthetic approaches, surface modification, surface thermodynamic properties, techniques, salinization reaction and recent development in use of silane modifiers in various applications. [ABSTRACT FROM AUTHOR]

The discharge of untreated high-salinity mine water will cause harm to the environment, such as the increase of salt content in river water. Capacitive deionization technology has the advantages of low cost, high efficiency, and no pollution. It is an effective means to treat highly mineralized water in the oil field. This paper establishes a simplified mathematical model based on the Nernst Planck equation, combined with porous media flow theory and Langmuir isotherm theory. The capacitive deionization process of NaCl solution by finite element method is simulated. The results show that the convection mass transfer effect of ions in the activated carbon electrodes is weak. When the initial solution ion concentration is equal, the activated carbon cathode can absorb more Cl−. In the solution with an initial concentration of 1.7 mol/m3, when the electrode adsorption reaches saturation, the concentration of Cl− is 0.1 mm lower than that of Na+. In the capacitive deionization process using activated carbon electrodes, the desalting efficiency of ions is almost proportional to the voltage and inversely proportional to the liquid flow rate. In a relatively low concentration solution, the desalination effect of using activated carbon as electrodes is better. [ABSTRACT FROM AUTHOR]

Repeated mining of upper and lower coal seams causes roof sandstone to be repeatedly disturbed and results in the continuous deterioration of its permeability and damage properties, causing water leakage in the overlying aquifer, which significantly affects the surface environment and mine safety. This paper employed monotonous triaxial compression (MTC) tests and axial stress cycle loading and unloading (ACLU) tests to investigate the mechanical behavior of Jurassic sandstones. The acoustic emission (AE) data and permeability coefficient of the sandstones were simultaneously measured during mechanical testing. Results indicate that increased confining pressure enhances mechanical strength of the sandstones and reduces sandstone permeability, while increased permeation pressure reduces mechanical strength of the sandstones and enhances sandstone permeability under the MTC and the ACLU. The peak volumetric strain of the sandstones decreases and the volume expansion advances with decreasing confining pressure or increasing permeation pressure. The overall variation of permeability coefficient is closely related to the volumetric strain of the sandstones under the MTC and the ACLU. The AE characteristics exhibit a certain correspondence with different deformation stages and permeability variations of the sandstones under the MTC and the ACLU. In addition, the confining pressure and stress loading path can effectively change the damage evolution characteristic of the sandstones. [ABSTRACT FROM AUTHOR]

The paper presents brief results of integrated studies of the northern part of the Sea of Okhotsk close to of the Kuril arc, obtained on cruise 92 of the R/V Akademik M.A. Lavrentiev in April–May 2021. The relief was refined and the distribution of geophysical and gas-geochemical fields was obtained. Volcanic edifices hidden in the sedimentary layer were discovered. A large array of data was obtained on the distribution of temperature and salinity of surface waters, as well as the concentrations of methane, carbon dioxide, and atomic mercury in the near-water atmosphere along the route of the vessel. [ABSTRACT FROM AUTHOR]

Artificial waste dumps with ore debris are widely distributed in mines and lead to complex groundwater compositions, which affect slope stability. Soil salinization with calcium sulfate is prominent in a gypsum waste dump in southwestern Sichuan, China. To identify the interaction between the soil and calcium sulfate at this site, this paper aims to study the shear strength of saturated soil, investigate the soil micropore structure, and discuss their contributions to slope stability. The shear test results of the six groups showed that cohesion increased and then decreased with increasing calcium sulfate concentration, while the internal friction angle showed the opposite pattern. Correspondingly, micropore content in the 500–1000 μm range decreased sharply when the concentration was greater than 500 mg/L, accompanied by a uniform size and complex morphology. Because the water film absorbed on the clay minerals was compressed slightly at low calcium sulfate concentrations, soil cohesion was enhanced due to the combination of intergranular attraction and viscosity. In contrast, particles were compacted tightly at high calcium concentrations, which decreased the soil swelling capacity and amplified the effect of the internal friction angle in the shear process. Long-term rainfall infiltration and water discharge repeatedly deteriorated the soil shear strength due to the variation in groundwater ion concentration, which ultimately induced cracks and failure of the waste dump slope. Therefore, the mechanism of water-soil interaction and its contribution to slope stability were revealed. [ABSTRACT FROM AUTHOR]

In Panama City, the water supply sources for the population come mainly from surface waters, but in times of drought and extreme natural phenomena, the need to resort to underground sources is explored. This paper concerns an exploratory investigation with the aim of assessing the quality of groundwater in the southeastern part of the Province of Panama and to determine its possible use as drinking water during extreme natural phenomena. Monthly monitoring over a period of 15 months was carried out. The study included the sampling and analysis of groundwater by different physic-chemical, hydrochemical and biological parameters. The results showed that most of the parameters in the analysed groundwater conformed to the Panamanian drinking water norm and the water potability diagram, this is a convenient source of raw water for purification. As for other uses for this water source, it should be used with caution since it represents a medium risk of soil salinization for irrigation water; and it is a moderately hard water for industrial uses. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, we have investigated minimization of total cost to pump a given flow rate from any number (n) of wells up to a water tank, under steady-state flow conditions. Regarding groundwater flow, we have considered infinite or semi-infinite aquifers, to which the method of images applies. Additional regional groundwater flow can be taken into account, too. The pipe network connecting the wells to the tank can include junctions at the locations of the wells only. Moreover, all pumps have equal efficiency. We have derived a new analytical formula, which holds at the critical points of the total cost function. Based on this formula, we derived a system of n equations and n unknowns, to calculate the well flow rate combinations which correspond to the critical points of the total cost function. The n-1 equations are 2nd degree polynomials, while the remaining one is linear, expressing the constraint that the sum of well flow rates must be equal the required total flow rate. The solution of the system can be achieved using commercial solvers. Moreover, we have concluded that there is one feasible solution that minimizes the total cost. Finally, we present a tabulation process to facilitate the use of solvers and we provide and discuss two illustrative examples. [ABSTRACT FROM AUTHOR]

Water injection in the aquifer induces deformations in the soil. These mechanical deformations give rise to a change in porosity and permeability, which results in non-linearity of the mathematical problem. Assuming that the deformations are very small, the model provided by Biot's theory of linear poroelasticity is used to determine the local displacement of the skeleton of a porous medium, as well as the fluid flow through the pores. In this continuum scale model, the Kozeny–Carman equation is commonly used to determine the permeability of the porous medium from the porosity. The Kozeny–Carman relation states that flow through the pores is possible at a certain location as long as the porosity is larger than zero at this location in the aquifer. However, from network models it is known that percolation thresholds exist, indicating that the permeability will be equal to zero if the porosity becomes smaller than these thresholds. In this paper, the relationship between permeability and porosity is investigated. A new permeability-porosity relation, based on the percolation theory, is derived and compared with the Kozeny–Carman relation. The strongest feature of the new approach is related to its capability to give a good description of the permeability in case of low porosities. However, with this network-inspired approach small values of the permeability are more likely to occur. Since we show that the solution of Biot's model converges to the solution of a saddle point problem for small time steps and low permeability, we need stabilisation in the finite element approximation. [ABSTRACT FROM AUTHOR]

Endemic fluorosis is widespread in China, especially in the arid and semi-arid areas of northwest China, where endemic fluorosis caused by consumption of drinking water high in fluorine content is very common. We analyzed data on endemic fluorosis collected in Ningxia, a typical high-fluorine area in the north of China. Fluorosis cases were identified in 539 villages in 1981, in 4449 villages in 2010, and in 3269 villages in 2017. These were located in 19 administrative counties. In 2017, a total of 1.07 million individuals suffered from fluorosis in Ningxia, with more children suffering from dental fluorosis and skeletal fluorosis. Among Qingshuihe River basin disease areas, the high incidence of endemic fluorosis is in Yuanzhou District and Xiji County of Guyuan City. The paper holds that the genesis of the high incidence of endemic fluorosis in Qingshui River basin is mainly caused by chemical weathering, evaporation and concentration, and dissolution of fluorine-containing rocks around the basin, which is also closely related to the semi-arid geographical region background, basin structure, groundwater chemical characteristics, and climatic conditions of the basin. The process of mutual recharge and transformation between Qingshui River and shallow groundwater in the basin is intense. There is a close coupling relationship between the power of central and southern Ningxia disease areas and Qingshui River watershed of excess fluorine water. Because the traditional drinking water source of the residents in the basin is shallow groundwater, the underground water is the main cause of the high incidence of endemic fluorosis. The results show that Xiji County and Yuanzhou District were the areas of high incidence of endemic fluorosis which gradually decreased to the middle and lower reaches of Qingshui River. In space, distribution characteristics are Qingshui River source area > Qingshui River valley basin area, tributary area > trunk stream area, upstream area > middle reaches area> downstream area of Qingshui River. This is relatively consistent with the spatial distribution of fluoride ion content in Qingshui River groundwater. [ABSTRACT FROM AUTHOR]

Many shallow foundations are constructed within the soil layer above the groundwater table, where the soil remains unsaturated, and the failure of shallow foundation is mostly related to shear failure. The shear strength of the unsaturated soil is one of the main engineering properties required in geotechnical designs. Previous researchers suggested that the shear strength of the unsaturated soil depends on matric suction in the soil. The shape of the soil–water characteristic curve (SWCC) has a significant effect on the characteristics of unsaturated shear strength with respect to matric suction. In this paper, a new model was proposed for the estimation of the unsaturated shear strength from SWCC. In this new model, meniscus was considered to transfer soil suction into both additional net normal stress and additional cohesion. Based on the categorization from soil science, water in soil can be categorized into three groups: (1) gravity water, (2) capillary water and (3) hygroscopic water. The elemental analysis on the contractile skin indicated that only the capillary water in the soil can transfer stress into soil skeleton. Consequently, the SWCC is modified by considering capillary water only for the estimation of unsaturated shear strength. In the derivation, unsaturated soil is considered as four-phase material. Finally, a new mathematical equation for the estimation of the unsaturated shear strength was proposed and verified with the experimental data from the published literature. In addition, the proposed equation does not consist of any empirical parameter and can be used to predict the shear strength of unsaturated soil. [ABSTRACT FROM AUTHOR]

Purpose: Salinisation is a threat not only to arable land but also to freshwater resources. Nevertheless, salinisation impacts have been rarely and only partially included in life cycle assessment (LCA) so far. The objectives of this review paper were to give a comprehensive overview of salinisation mechanisms due to human interventions, analyse the completeness, relevance and scientific robustness of existing published methods addressing salinisation in LCA and provide recommendations towards a comprehensive integration of salinisation within the impact modelling frameworks in LCA. Methods: First, with the support of salinisation experts and related literature, we highlighted multiple causes of soil and water salinisation and presented induced effects on human health, ecosystems and resources. Second, existing life cycle impact assessment (LCIA) methods addressing salinisation were analysed against the International Reference Life Cycle Data System analysis grid of the European Commission. Third, adopting a holistic approach, the modelling options for salinisation impacts were analysed in agreement with up-to-date LCIA frameworks and models. Results and discussion: We proposed a categorisation of salinisation processes in four main types based on salinisation determinism: land use change, irrigation, brine disposal and overuse of a water body. For each salinisation type, key human management and biophysical factors involved were identified. Although the existing methods addressing salinisation in LCA are important and relevant contributions, they are often incomplete with regards to both the salinisation pathways they address and their geographical validity. Thus, there is a lack of a consistent framework for salinisation impact assessment in LCA. In analysing existing LCIA models, we discussed the inventory and impact assessment boundary options. The land use/land use change framework represents a good basis for the integration of salinisation impacts due to a land use change but should be completed to account for off-site impacts. Conversely, the land use/land use change framework is not appropriate to model salinisation due to irrigation, overuse of a water body and brine disposal. For all salinisation pathways, a bottom-up approach describing the environmental mechanisms (fate, exposure and effect) is recommended rather than an empirical or top-down approach because (i) salts and water are mobile and theirs effects are interconnected; (ii) water and soil characteristics vary greatly spatially; (iii) this approach allows the evaluation of both on- and off-site impacts and (iv) it is the best way to discriminate systems and support a reliable eco-design. Conclusions: This paper highlights the importance of including salinisation impacts in LCA. Much research effort is still required to include salinisation impacts in a global, consistent and operational manner in LCA, and this paper provides the basis for future methodological developments. [ABSTRACT FROM AUTHOR]

The Tarim area, characterized by deep reservoirs, high temperatures, and limited fresh water resources, necessitates a fracturing fluid system that exhibits excellent temperature shear resistance, low friction, and salinity tolerance. This study presents the development of a zwitterionic hydrophobic polymer, HPC-5, as an effective thickener using five types of polymeric monomers, including AM, AA, DMC, AMPS, and a non-ionic hydrophobic monomer. The method employed for synthesis was free-radical polymerization in solution. A series of experiments including viscosity measurement with variation of salinity, solubility and drag reduction test, crosslinking test, thermal and shear resistance, sand-carrying test, gel breaking evaluation, and core damage test were conduct under the simulated reservoir conditions. The zwitterionic design imparts great salt tolerance to HPC-5, and the apparent viscosities of HPC-5 solutions can maintain comparably high values with 10×104 ppm NaCl and CaCl2 concentration. Meanwhile, the molecules of HPC-5 associate with each other to form tight net structures, resulting in an excellent viscoelasticity of the solution. To achieve high pump rate during hydraulic fracturing operation in ultra-deep reservoirs, the delayed crosslinking agent ZDC-L was prepared for forming a delayed crosslinking gel fracturing fluid system using reservoir brine, and the drag reduction rate can reach over 70% before crossing link within 4 min. Under pH = 4 conditions, the crosslinking time can be significantly delayed to over 4 min while maintaining exceptional temperature resistance up to 160 ℃ for the gel. These properties make it highly suitable for hydraulic fracturing operations in ultra-deep wells with temperatures reaching up to 7000 m depth at pump rates of 4~5m3/min. [ABSTRACT FROM AUTHOR]

The Quaternary deposit in the Shanghai region is composed of a layered multi-aquifer-aquitard system (MAAS). The MAAS was formed mainly during the warm geological era over 2.6 million years ago. There is one artesian aquifer and five confined aquifer layers (AqI to AqV) in the MAAS with a very high groundwater pressure head. The groundwater in the aquifers of Shanghai is composed of both fresh and saline water due to it originating in different environmental conditions. AqI is the uppermost shallow confined aquifer, and it contains highly mineralised formation water with a wide variety of naturally occurring inorganic compounds. AqII and AqIII have slightly lower salinity and different hydrochemicals from those in AqI. The deeper aquifers, AqIV and AqV, have much lower levels of hydrochemicals. With the urbanisation of the Shanghai region, a large amount of underground infrastructure has been constructed in the shallow aquifers (AqI and AqII). As a result, the hydrochemicals in the groundwater present a potential hazard to this infrastructure. This paper reviews the hydrogeochemical compositions of aquifers in Shanghai and then discusses possible hazards to infrastructure construction within aquifers. In addition, this paper assesses the hydrogeochemical environment of the groundwater and the possibility of such environment-induced hazards arising in Shanghai. [ABSTRACT FROM AUTHOR]

The regular hydrochemical monitoring of groundwater in the Mila basin over an extended period has provided valuable insights into the origin of dissolved salts and the hydrogeochemical processes controlling water salinization. The data reveals that the shallow Karst aquifer shows an increase in TDS of 162 mg L−1 while the thermal carbonate aquifer that is also used for drinking water supply exhibits an increase of 178 mg L−1. Additionally, significant temperature variations are recorded at the surface in the shallow aquifers and the waters are carbogaseous. Analysis of dissolved major and minor elements has identified several processes influencing the chemical composition namely: dissolution of evaporitic minerals, reduction of sulphates, congruent and incongruent carbonates' dissolution, dedolomitization and silicates' weathering. The hydrogeochemical and geothermometric results show a mixing of saline thermal water with recharge water of meteoric origin. Two main geothermal fields have been identified, a partially evolved water reservoir and a water reservoir whose fluid interacts with sulphuric acid (H2S) of magmatic origin. These hot waters that are characterized by a strong hydrothermal alteration do ascend through faults and fractures and contribute to the contamination of shallower aquifers. Understanding the geothermometry and the hydrogeochemistry of waters is crucial for managing and protecting the quality of groundwater resources in the Mila basin, in order to ensure sustainable water supply for the region. A conceptual model for groundwater circulation and mineralization acquisition has been established to further enhance understanding in this regard. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents a vapor compression heat pump-driven humidification–dehumidification process with energy recovery option. Two systems with different applications of recovered energy are proposed. System A recovers energy for preheating inlet feed water to the heat pump condenser, while system B recovers energy for preheating the humidifier inlet air. The system performance metrics such as gained output ratio (GOR), recovery ratio (RR), productivity, specific electrical energy consumption (SEEC) and the cost of freshwater production are investigated based on variations in mass flowrate ratios, humidifier effectiveness, seawater temperature, brine heat exchanger effectiveness, unit cost of electricity and expected plant life. The thermo-economic performance of the proposed system is compared with system "C" without energy recovery option. Findings reveal the need to recover thermal energy associated with the discharged brine for humidification and dehumidification desalination system having ineffective/poor component effectiveness, especially the humidifier. The proposed system shows that the cost of freshwater for system C can be reduced by about 15.23% with energy recovery in system A. The GOR of system C is improved by about 23.1%, whereas the RR, productivity and SEEC of system C are improved by about 23.3% each. The conditions at which the energy recover is effective are also shown in the results. [ABSTRACT FROM AUTHOR]

Sub-mesoscale and mesoscale (i.e., 1–10 km and 10–200 km, respectively) ocean processes are highly relevant for the understanding of global circulation, mixing of water masses and energy exchange between ocean layers. However, the processes happening at these scales are hard to be characterized using direct measurements of temperature and salinity. Direct measurements are obtained from vertical probes and/or autonomous vehicles, which, despite their high vertical resolution, are sparsely located in space and therefore unable to capture spatial details at these scales. Seismic oceanography (SO) data have been successfully used to imaging and characterize the ocean at these spatial scales. These data represent indirect measurements of the ocean temperature and salinity along kilometric transects with high horizontal resolution (i.e., a near-synaptic view of the system under investigation), but lower vertical resolution when compared with direct observations. Despite its complex oceanographic setting, the Madeira Abyssal Plain is still largely uncharacterized due to the lack of direct observations. We show for the first time a comprehensive processing, modelling and interpretation of three 2-D seismic oceanography sections from this region. The data show coherent seismic reflection in space, depth and time and shed light into this oceanographic setting with an unprecedent horizontal resolution. The SO modelling and interpretation are combined with existing direct measurements and a quantitative method to correlate thermohaline staircases interpreted from conductivity-temperature-depth casts and seismic reflections is proposed. The results show the relatively stable presence of thermohaline staircases in simultaneously time and space between 1200 and 2000 m of water depth and their spatial variability and contribute to the generalization of SO in physical oceanography. [ABSTRACT FROM AUTHOR]

This review comprehensively summarizes potential applications of SiO2–polymer composites especially in oil industries: enhanced oil recovery (EOR), loss circulation (LC), and relative permeability modification (RPM). The significance of these materials has been widely recognized as high-performance functional materials as they combine the flexural properties of the polymer and enhanced thermo-mechanical characteristics of SiO2 nanoparticles (NPs). The composite exhibits increased impact resistance and tensile strength without decreasing the flexibility of the polymer. The addition of SiO2 into the polymer matrices can further extend the possibility of creating hierarchically structured materials, and therefore, SiO2–polymer composites have attracted great interest in various industries. Compared to other materials, suspended NPs/polymer composites offer various advantages, such as high thermal stability, long-term stability, salinity tolerance, and viscosity increment which are very crucial criteria for increased oil production. [ABSTRACT FROM AUTHOR]

Selective ion transport underpins fundamental biological processes for efficient energy conversion and signal propagation. Mimicking these 'ionics' in synthetic nanofluidic channels has been increasingly promising for realizing self-sustained systems by harvesting clean energy from diverse environments, such as light, moisture, salinity gradient, etc. Here, we report a spatially nanoconfined ion separation strategy that enables harvesting electricity from CO2 adsorption. This breakthrough relies on the development of Nanosheet-Agarose Hydrogel (NAH) composite-based generators, wherein the oppositely charged ions are released in water-filled hydrogel channels upon adsorbing CO2. By tuning the ion size and ion-channel interactions, the released cations at the hundred-nanometer scale are spatially confined within the hydrogel network, while ångström-scale anions pass through unhindered. This leads to near-perfect anion/cation separation across the generator with a selectivity (D-/D+) of up to 1.8 × 106, allowing conversion into external electricity. With amplification by connecting multiple as-designed generators, the ion separation-induced electricity reaching 5 V is used to power electronic devices. This study introduces an effective spatial nanoconfinement strategy for widely demanded high-precision ion separation, encouraging a carbon-negative technique with simultaneous CO2 adsorption and energy generation. Nanogenerators have promising applications in energy and environment-related fields. Here, the authors developed Nanosheet-Agarose Hydrogel generators to enable near-perfect anion/cation separation, leading to simultaneously CO2 adsorption and energy generation. [ABSTRACT FROM AUTHOR]

The bioturbation potential of three freshwater operculate snails, Filopaludina bengalensis, Gabbia orcula and Melanoides tuberculata, was compared, using water column depth and sediment surface area as the explanatory variables. Assessment of nutrient fluxes from sediment to overlying water was estimated in glass microcosms, that varied in height (tall, medium, short) and base (narrow, wide), resulting in six habitat conditions. In course of movement and grazing, all the three snail species modified surface architecture of the sediment. Besides, the snails modulated NOXˉ (NO2ˉ-N + NO3ˉ-N), NH4+-N and PO43−-P concentrations and other parameters (TDS, conductivity) of the water column in significantly varying proportions. Snail-induced changes in the rate of nutrient flux were highest for F. bengalensis. Periphytic chlorophyll-a concentration was reduced in all snail-treated microcosms compared to the control. Grazing, scraping and movement of snails on sediment facilitated the release of the nutrients in a species-specific manner depending on sediment surface area and water column depth of the microcosm. Apparently, snails may be useful in mobilizing the sediment content in freshwater lakes and ponds, facilitating ecosystem processes. [ABSTRACT FROM AUTHOR]

Drinking water in much of Asia, particularly in coastal and rural settings, is provided by a variety of sources, which are widely distributed and frequently managed at an individual or local community level. Coastal and near-inland drinking water sources in South and South East (SSE) Asia are vulnerable to contamination by seawater, most dramatically from tropical cyclone induced storm surges. This paper assesses spatial vulnerabilities to salinisation of drinking water sources due to meteorological variability and climate change along the (ca. 6000 km) coastline of SSE Asia. The risks of increasing climatic stresses are first considered, and then maps of relative vulnerability along the entire coastline are developed, using data from global scale land surface models, along with an overall vulnerability index. The results show that surface and near-surface drinking water in the coastal areas of the mega-deltas in Vietnam and Bangladesh-India are most vulnerable, putting more than 25 million people at risk of drinking 'saline' water. Climate change is likely to exacerbate this problem, with adverse consequences for health, such as prevalence of hypertension and cardiovascular diseases. There is a need for identifying locations that are most at risk of salinisation in order for policy makers and local officials to implement strategies for reducing these health impacts. To counter the risks associated with these vulnerabilities, possible adaptation measures are also outlined. We conclude that detailed and fine scale vulnerability assessments may become crucial for planning targeted adaptation programmes along these coasts. [ABSTRACT FROM AUTHOR]

In closed-loop geothermal systems, the operation of a Borehole Heat Exchanger (BHE) affects the thermal equilibrium of the surrounding subsoil. This study was part of a large laboratory program undertaken to understand how the cyclic thermal stress induced by a BHE in the subsoil can change sediments' mechanical properties, if the BHE works in extreme running conditions which induce both freeze-thaw cycles and heating processes in the ground. This paper presents the results from an experimental laboratory investigation on the effects of different pore water salinity concentrations on the vertical strain induced in a thermally loaded silty clay. The considered study case is the historical center of Venice (Italy), which provides an example of typical conditions of densely urbanized areas inserted in coastal or transitional environments, with abundance of cohesive layers and brackish conditions in the subsoil. Results show that the irreversible compaction effect induced on sediments increases with higher salinity concentration, despite the fact that increasing salt content lowers the sediment freezing point, thereby protecting the soil from freezing processes. [ABSTRACT FROM AUTHOR]

Salinization threatens the viability of water resources and is common in many important inland freshwater lakes worldwide, especially in arid and semi-arid areas. Bosten Lake is a typical inland freshwater lake that has evolved into a subsaline lake and is located in the arid region of Northwest China. The water resources of Bosten Lake are important for supplying regional drinking water and agricultural irrigation and for economic development. In this study, changes in salinity with time and space were analyzed in Bosten Lake. Overall, the salinity increased from 0.39 g/L in 1958 to 1.87 g/L in 1987, reaching its highest value in 1987. After 1987, the salinity decreased to 1.17 g/L in 2003 and increased to 1.45 g/L in 2010. Increased salinity adversely affects aquatic lake systems, regional eco-environments and water resource use, and has become a serious environmental problem in Bosten Lake. Thus, the causes of increasing salinity are discussed in this paper. Overall, the influences of climate variations and human activities resulted in the salinization of the lake. Understanding the salinization processes in Bosten Lake can be useful for implementing actions that improve water quality and water resource use in the lake. [ABSTRACT FROM AUTHOR]

The present study has analyzed the origin of recharge and groundwater salinity in the Haouz alluvial plain, located in Central Morocco. Stable isotopic data (O, H) indicate that the recharge of the alluvial aquifer is dominated by high-altitude meteoric water originating from the High-Atlas Mountains that border the plain to the south. Tritium globally indicates the presence of recent groundwater, as well as mixing between old and recent groundwater. Alluvial groundwater salinity varies from east to west. This variability is mainly induced by enrichment in chloride and sulfate salt contents. Strontium content reveals that sulfate could be related, respectively, to the influence of the Senonian carbonate deposits containing gypsum. Dissolution of halite is revealed by the plot of O vs Cl, where the most saline samples do not show any changes in O. Br/Cl ratio varies in a wide range, probably due to an orographic effect. The nitrate distribution was analyzed using indicator-geostatistical techniques resulting in probability maps. Nitrate contamination is shown to occur particularly in the eastern part of the Haouz plain. In this paper, some aspects of groundwater resources management are addressed. Different management actions are identified with regard to the current water resources status and to the land and water uses. In this framework controlling groundwater abstraction, optimizing irrigation and enhancing mountain-front recharge constitute the major key management actions that should be carried out. [ABSTRACT FROM AUTHOR]

This article describes LIMPACS, a research initiative designed by the International Geosphere-Biosphere Program. The LIMPACS programme is designed to assess how and why lakes have changed, are changing and might change in the future as a result of human activity. The article outlines the program's major set of foci, such as: climate forcing, climate variability, land/ocean dynamics, and human-environment interactions. Other papers in this volume are based on a meeting of scientists to develop research priorities.