Salt Accumulation Research Articles

Quantifying the spatial water salinity threshold of saline water irrigation by applying distributed WAVES model

CONTEXTSaline water irrigation presents a viable solution to alleviate freshwater scarcity. However, it's crucial to consider the threshold of salinity, as excessive levels can adversely affect crop yield, crop productivity and soil sustainability. Additionally, due to varying surface conditions and management practices at the regional level, a distributed approach to saline water irrigation management is necessary. OBJECTIVEThe primary goal of this research was to develop a regional agro-hydrological crop model. The validated regional model was then employed to identify the spatial water salinity threshold for saline water irrigation. METHODSIn this research, we utilized the WAVES (WAter Vegetation Energy and Solute model), which was adapted for mulching environment and validated in severely arid and saline fields. To account for spatial variations, we applied a distributed method to upscale the WAVES to the regional level. Multisource and multiscale data were used for regional model validation. Different scenarios of salinity levels for saline water irrigation were simulated, and a comprehensive criterion to determine water salinity threshold was proposed considering cotton yield, water productivity and soil salt accumulation. RESULTS AND CONCLUSIONSModel evaluation indicated a high level of accuracy for the developed regional model. The comparison between simulated and measured values for soil salt content, soil water content, cotton leaf area index, measured lint yield, and statistical yield resulted in indices of agreement of 0.90, 0.71, 0.93, 0.58, and 0.70, respectively. The validated regional model was employed to simulate various saline water irrigation scenarios. The findings revealed that under identical irrigation water salinity, cotton cultivation on sandy loam soil is more productive but has a larger yield reduction percentage compared to silty loam soil. Moreover, the research indicates a groundwater depth of 1.5 m is associated with higher cotton production. Additionally, a spatial pattern of the irrigation water salinity threshold for saline water irrigation was determined, suggesting that the water salinity in most areas of the Tarim Irrigation District should not exceed 6 g L−1. Notably, in the current practice of pumping groundwater in situ for irrigation, approximately 46% of the areas are at risk, indicating that it's not suitable for saline water irrigation. SIGNIFICANCEThis study developed a distributed model under a typical irrigation district characterized by mulching, severe drought and salinization and defined the distributed spatial threshold for saline water irrigation. These research results hold significant implications for guiding regional-scale saline water irrigation and groundwater extraction.

Biomass derived evaporator with highly interconnected structure for eliminating salt accumulation in high-salinity brine

Solar-driven evaporator is regarded as an energy-saving and eco-friendly desalination technology. However, available unfriendly synthetic materials and salt crystallization problems limit the evaporator's performance and development, especially in high-salinity condition. Hence, inspired by the highly interconnected microchannels, a carbonized white gourd (CWG) derived self-desalting evaporator was developed to evaporate and desalinate seawater. To evaluate the efficacy of the porous features, the effect of different porosity configurations on water evaporation and anti-salt abilities of CWG was discussed. High and stable evaporation rates of 1.76 and 1.44 kg·m−2·h−1 were reached for 3.5 wt% and 20 wt% NaCl solutions, respectively, which were attributed to the highly efficient water transport and self-desalting capabilities, and it further increased to 2.19 kg·m−2·h−1 by adding an extra convective air (2 m/s) located at the evaporation interface. Moderate airflow effectively enhanced the evaporation efficiency and delayed re-crystallization of salt, promoting a long-term stable desalination process. Conversely, excessive convective flow (4 m/s) may directly impair evaporative stability and salt resistance. This research is expected to provide a new insight into the design of high performance, low cost, eco-friendly and salt-resistant evaporator applied to solar desalination.

Soil Quality Index for Different Cropping Systems in Northwestern Himalaya Region of India

Background: A study was conducted to examine the impact of soil quality under different cropping systems in Mid hill conditions of Himachal Pradesh”. The study was carried out to ascertain the physical, chemical and biological properties of soils under prevalent cropping systems maize- wheat, rice- wheat and vegetable based in different in mid hill conditions of northwestern Himachal Pradesh.
 Methods: On the basis of representative 90 soil samples from two depths i.e. 0-0.15 m and 0.15-0.30 m were collected. Soil samples were analyzed for their physical, chemical and biological properties and key indicators were identified using multivariate statistical analysis for computing the soil quality index.
 Results: Soil reaction across various sites under present study was 5.30-6.70. Higher salt accumulation (EC) was observed under vegetable based cropping systems as compared to those of cereal based. Organic carbon was medium to high and available N, P and K contents were in low to medium range. DTPA Fe, Mn, Zn and Cu were observed sufficient, whereas total Fe, Mn, Zn and Cu were recorded higher in cereal and vegetable based cropping system. Microbial biomass carbon, microbial biomass nitrogen, potentially mineralizable nitrogen and soil respiration were low to medium in all cropping systems.
 Conclusion: Soil quality index was 1.00 under vegetable based cropping system as compared to the cereal based cropping systems.

Carbon foam directly synthesized from industrial lignin powder as featured material for high efficiency solar evaporation

Interfacial solar evaporation has emerged as a promising method for clean water production. Among the various types of evaporators, biomass-based carbon evaporators have garnered significant attention due to their renewability and low cost. However, biomass-based carbon materials still face certain challenges, including limitations in terms of their morphology, size adjustability, light absorption capability, and mechanical strength. To overcome these issues, a novel carbon foam evaporator has been developed and extensively optimized. The carbon foam can be directly synthesized from industrial lignin powder without the need for any additives, using a simple and environmentally friendly methodology that involves foaming, carbonization, and activation processes. The evaporator demonstrates remarkable attributes, encompassing swift water transport capacity, broad-spectrum sunlight absorption, expeditious photo-thermal conversion capability, low density (0.281 g cm−3), low thermal conductivity (0.0473 W m−1 K−1), and a profusion of micro-pores (1430.49 m2/g of SBET). The developed lignin-based solar evaporator achieves a high water evaporation rate of 2.11 kg m−2h−1, coupled with an impressive evaporation efficiency of 93.37 % under 1 sun. Furthermore, the evaporator demonstrates exceptional resistance to salt accumulation and exhibits efficient recycling capabilities. Notably, the evaporator's flexible and plastic nature enhances its versatility and holds great promise for its application in the field of solar-powered seawater desalination.

State of the Art and New Technologies to Recycle the Fertigation Effluents in Closed Soilless Cropping Systems Aiming to Maximise Water and Nutrient Use Efficiency in Greenhouse Crops

Inappropriate fertilisation results in the pollution of groundwater with nitrates and phosphates, eutrophication in surface water, emission of greenhouse gasses, and unwanted N deposition in natural environments, thereby harming the whole ecosystem. In greenhouses, the cultivation in closed-loop soilless culture systems (CLSs) allows for the collection and recycling of the drainage solution, thus minimising contamination of water resources by nutrient emissions originating from the fertigation effluents. Recycling of the DS represents an ecologically sound technology as it can reduce water consumption by 20–35% and fertiliser use by 40–50% in greenhouse crops, while minimising or even eliminating losses of nutrients, thereby preventing environmental pollution by NO3− and P. The nutrient supply in CLSs is largely based on the anticipated ratio between the mass of a nutrient absorbed by the crop and the volume of water, expressed as mmol L−1, commonly referenced to as “uptake concentration” (UC). However, although the UCs exhibit stability over time under optimal climatic conditions, some deviations at different locations and different cropping stages can occur, leading to the accumulation or depletion of nutrients in the root zone. Although these may be small in the short term, they can reach harmful levels when summed up over longer periods, resulting in serious nutrient imbalances and crop damage. To prevent large nutrient imbalances in the root zone, the composition of the supplied nutrient solution must be frequently readjusted, taking into consideration the current nutrient status in the root zone of the crop. The standard practice to estimate the current nutrient status in the root zone is to regularly collect samples of drainage solution and determine the nutrient concentrations through chemical analyses. However, as results from a chemical laboratory are available several days after sample selection, there is currently intensive research activity aiming to develop ion-selective electrodes (ISEs) for online measurement of the DS composition in real-time. Furthermore, innovative decision support systems (DSSs) fed with the analytical results transmitted either offline or online can substantially contribute to timely and appropriate readjustments of the nutrient supply using as feedback information the current nutrient status in the root zone. The purpose of the present paper is to review the currently applied technologies for nutrient and water recycling in CLSs, as well as the new trends based on ISEs and novel DSSs. Furthermore, a specialised DSS named NUTRISENSE, which can contribute to more efficient management of nutrient supply and salt accumulation in closed-loop soilless cultivations, is presented.

Lithium salts cytotoxicity and accumulation in melanoma cells in vitro.

Boron neutron capture therapy is a perspective selective technology for the destruction of cancer cells, while the use of lithium instead of boron may represent a new and promising vector for the development of neutron capture therapy (NCT). The aim of the study was a comparative assessment of the cytotoxicity of various lithium salts, as well as an analysis of the accumulation of lithium in tumor cells in vitro to determine the possibility of using lithium in NCT. The cytotoxicity of lithium salts was determined using MTT-test and colony forming assay on human fibroblasts BJ-5ta, human skin melanoma SK-Mel-28, and mouse skin melanoma B16 cell lines. An assessment of lithium concentration in cells was performed using inductively coupled plasma atomic emission spectrometry. Our results showed that three different lithium salts at a concentration of 40 μg/ml are not toxic for both tumor and normal cells. The highest uptake values were obtained on murine melanoma B16 cells when exposed to lithium carbonate (0.8 μg/106 cells); however, human melanoma SK-Mel-28 cells effectively accumulated both lithium carbonate and lithium citrate (about 0.46 μg/106 cells for two salts). Thus, our results demonstrate a range of non-toxic doses of lithium salts and a high uptake of lithium by tumor cells, which indicates the possibility to use the lithium in NCT.

MODERN ASSESSMENT OF FERTILITY OF DARK CHESTNUT SOILS OF KAMYSTINSKY DISTRICT OF KOSTANAY REGION

The article presents the results of a study on the morphological, nutritional characteristics of arable dark chestnut soils in the Kamystinsky district of the Kostanay region. According to the structure of the morphological profile, dark chestnut soils belonged to medium and low thickness types, where the thickness of the humus horizon A + B1 is noted within the range of 29 - 45 cm in depth. The accumulation of carbonates and ready soluble salts depends on the parent rocks and the grain-size distribution of dark chestnut soils. In dark chestnut immature soil, there are no carbonates along the soil profile, but gypsum is found at a depth of 36 cm. The line of bubbling from hydrochloric acid is different in ordinary and carbonate genus of dark chestnut soil. The humus content is low, in the plough-layer of soils it ranges 1.10 - 3.05%, the supply of nitrate nitrogen is very low, moving forms of phosphorus are medium and low, while potassium content is very high and elevated.

Experimental investigation of salt precipitation behavior and its impact on injectivity under variable injection operating conditions

During the CO2 geological sequestration in saline aquifers, salt precipitation issues can diminish reservoir injectivity and significantly escalate injection costs. Variations in the gas supply during injection can lead to fluctuations in CO2 injection rates. These abrupt changes in injection parameters can affect the distribution of reservoir pressures and brine migration behavior, subsequently influencing salt precipitation dynamics. This study employs a designed micromodel with representative geological boundary conditions to investigate salt precipitation behavior under variable injection conditions, and the experimental conditions are at atmospheric pressure and 50 °C. The flow rates of the CO2 injection flow rates range from 0.5 mL/min to 4 mL/min. The findings reveal that under variable injection conditions, changes in gas injection rates can induce fluctuations in the reservoir solution, leading to the formation of “wet salt barriers” characterized by clustered salt growth near the inlet. This phenomenon significantly impairs injectivity. When sufficient supplemental solution is introduced, most of the previously precipitated salt is initially dissolved, eventually reaching a dynamic equilibrium that restricts further salt growth. However, under conditions of limited supplemental solution, salt precipitation predominates, and salt can proliferate, further impacting injectivity. This paper proposes a variable injection strategy to mitigate the impact of salt precipitation on injectivity. It recommends transitioning from low to high flow injection rates as early as possible to prevent the reflow of the solution near the injection interface, thereby minimizing salt accumulation and its adverse effects on injectivity.

Omniphobic melamine sponge for interfacial solar desalination of saturated water with anti-fouling performance

Interfacial solar desalination has shown great potential to address the global freshwater scarcity attributing to the advantages of high energy conversion efficiency, environmental friendly, cost effective and so on. However, accompanied by rapid vapor generation in the interfacial region, salt simultaneously crystallizes on the surface of photothermal materials, especially in highly concentrated brine, which would seriously affect the efficiency and long-term stability due to the blocking of vapor escaping channels as well as decreasing of solar absorption. In addition, organic substances in seawater may also pollute the absorbers during evaporation. Here, we demonstrate an omniphobic-hydrophilic melamine sponge based janus photothermal absorber by taking advantage of the 1H,1H,2H,2H-perfluorooctyltrichlorosilane modification, providing the upper layer both hydrophobic and oleophobic features, resulting in salt resistance and anti-fouling performance, respectively. Even with saturated NaCl solution as input, no salt accumulation was observed on the light absorbing surface during 8 h continuous evaporation. Moreover, the absorber exhibits excellent anti-fouling properties in oily water. Our strategy provides an avenue for the development of multifunctional solar absorbers aiming to sustainable treatment of highly concentrated brine and oil-bearing water.

Water Transport and Salt Precipitation in Anion-Exchange Membrane Electrolyzers

The hydrophilic nature of hydrocarbon ionomers and membranes presents a major challenge in anion-exchange membrane (AEM) electrolysis, despite improved stability from reinforcements and modified polymer chemistry. Durability and performance are still highly influenced by the operation mode and water management within the membrane-electrode-assembly (MEA).Dry cathode operation in AEM water electrolysis, where only the anode is supplied with liquid electrolyte (KOH), offers increased hydrogen purity but poses challenges for non-fluorinated anion-exchange polymers that are sensitive to water content. In-situ neutron imaging with high resolution (~6 µm effective resolution) revealed that adjusting the anion-exchange capacity of the cathode binder ionomer can retain membrane humidification (Fig. 1)1.In the electrochemical reduction of CO2 using AEM, water management and salt precipitation are significant challenges. High-resolution neutron imaging of a zero-gap CO2 electrolyzer operating at 200 mA cm-² and 2.8 V showed salt precipitates penetrating the cathode gas diffusion layer, leading to blocked CO2 gas transport and a decay in Faraday efficiency. Salt accumulation was higher under the cathode channel of the flow field than the land2.Both studies demonstrate the substantial impact of water management and salt precipitation on the operation of AEM-based electrolyzers and how neutron imaging can assist in addressing these challenges. References (1) Koch, S.; Disch, J.; Kilian, S. K.; Han, Y.; Metzler, L.; Tengattini, A.; Helfen, L.; Schulz, M.; Breitwieser, M.; Vierrath, S. Water management in anion-exchange membrane water electrolyzers under dry cathode operation. RSC Adv 2022, 12, 20778–20784.(2) Disch, J.; Bohn, L.; Koch, S.; Schulz, M.; Han, Y.; Tengattini, A.; Helfen, L.; Breitwieser, M.; Vierrath, S.; High-resolution neutron imaging of salt precipitation and water transport in zero-gap CO2 electrolysis. Nat Commun 2022, 13, 6099. Figure 1

Early Failure Detection for CO2 Reduction Electrolyzers Via in-Line Electrochemical Impedance Spectroscopy

The electrochemical CO2 reduction reaction (CO2RR) presents the opportunity to produce chemical feedstocks and fuels directly from CO2. Recent achievements in energy efficiency and current density are approaching the targets required for commercial viability; however, stability remains more than two orders of magnitude below the required 80,000 h. In CO2RR there is a challenge to distinguish the cause of failure among many possibilities. Failure can result from initial setup (e.g. over or under compression of the membrane and electrodes), gradual degradation of components (e.g. cathode and anode catalyst restructuring and dissolution), accumulation of products or byproducts (e.g. alcohols or salt accumulation), or immediate failures (e.g. a hole in the membrane or a short circuit). These failure modes must be addressed to reach the targeted stability needed for the wide-scale adoption of this technology. Early identification and mitigation of these failures would increase the electrolyzer lifetime and the commercial viability of CO2RR electrolyzers.Current techniques to characterize failures of the electrolyzer rely on post-mortem analysis of cell components. The analysis of individual components after operation may not accurately reflect their state in operando. There are techniques that are capable of analyzing the cell in operation (e.g. XAS, Raman, and TEM), but these typically require modified cell architectures and are operated at lower reaction rates. To effectively diagnose failure, the analysis technique should be applied to electrolyzers operating under realistic conditions.Here we implement an in-line real-time electrochemical impedance spectroscopy (EIS) technique to monitor CO2RR electrolyzers during operation. EIS is a non-destructive technique that can provide continuous information on the performance of specific components within the electrolyzer. We characterize common failure modes, such as poor compression, salt formation, catalyst degradation, and short circuits, and their identifying changes to the EIS response. We extract key electrochemical parameters from the EIS response and use them to develop a framework to identify and prevent the most common failure modes. Among other applications, this framework allowed for the detection of anode catalyst degradation 11 h before other indicators, such as cell voltage or product selectivity. This technique and framework can be applied to monitor CO2 electrolyzers as they are scaled and stacked.

Fabrication and Model-Guided Design of Thick-Format Lithium Ion Electrodes

To enable the use of renewable energy in place of fossil fuels for grid-scale electricity generation, low-cost, long-duration (3 hr charge, 12 hr discharge) energy storage systems must be developed to bridge the intermittency of these resources. This present work explores the adoption of thick-format lithium-ion electrodes to minimize inactive material cost and achieve <$100/kWh of storage. Thick lithium iron phosphate (LFP) pellets were fabricated using a dry pressing process, and the effects of composition, thickness/porosity balance, and electrolyte choice on the performance of the LFP half cells were explored. LFP electrodes with thicknesses up to 1 mm and capacities up to ~15 mAh/cm2 exhibited good rate performance (~90% utilization at a C/10 rate) and stable cycling over 100 cycles. A physics-based model was used to study transport within these thick electrodes. As thickness increases, large concentration gradients form across the electrode, with salt depletion at the current collector and salt accumulation at the separator exceeding the solubility limit of conventional electrolytes. Unlike fast-charging thin electrodes where kinetic overpotentials dominate inefficiencies, thick electrode performance is diffusion-limited, suggesting that methods for minimizing tortuosity and increasing ionic conductivity will be key in enabling low-cost thick electrodes. Figure 1

Interface Instability Analysis in Solid-State Lithium Batteries Using Advanced in Situ Methods

Solid-state lithium batteries are steadily gaining research interest due to their inherently safe design, high energy density and long life cycle. A polymer electrolyte is a key component of current battery technology and can enable the development of next-generation ultra-efficient solid-state lithium batteries. Despite the promise of high energy density, the development of polymer-based solid-state lithium batteries is hindered by interfacial challenges such as passivating layer formation and lithium dendrite infiltration [1-3]. Therefore, a deeper understanding of the interface chemistry and possible failure scenarios is essential for ensuring ideal battery performance. Advanced and in situ characterization methods are crucial for comprehending how these interfaces work with cell cycling and identifying responsible factors for cell failure [4].Here, by using in situ X-ray tomography, combined with XPS, SEM, and AES, we present the structural and chemical evolution of a lithium/PVDF-HFP-based polymer electrolyte interface over prolonged cell cycling at a higher temperature, from the pristine state up to cell failure. The electrolyte membrane, stacked between strips of metallic lithium under pressure, is scanned with this imaging technique while galvanostatic cycling. The in situ X-ray computed tomography provides in-depth 3D interface images and, non-invasively with accuracy and resolution, displays lithium penetration inside the electrolyte. A 3D reconstruction shows the structure of the electrolyte after cycling as a result of the lithium infiltration (Figure 1). Post-mortem XPS provides chemical information and shows an accumulation of lithium salts and organic compounds resulting from the degradation of membrane constituents during cycling. Impedance data reveal the degradation is followed by an increase in interfacial resistance. The higher-resolution SEM images and AES provide complementary data to the X-ray data. Together, these techniques contribute to a deeper comprehension of interfacial changes and provide the suggestions needed to overcome failure mechanisms and enhance the electrochemical performance.

Visualizing the Effect of Temperature on Carbonate Salt Production in CO2 Electrolysis

Carbon dioxide (CO2) electrolysis is a novel and promising technology to tackle anthropogenic climate change by reducing our dependency on fossil fuels and creating a sustainable carbon cycle. However, current CO2 electrolysis suffers from low CO2 reduction reaction (CO2RR) selectivity and rapid gas diffusion electrode (GDE) degradation and flooding due to carbonate precipitation. As the hydrophilic precipitate accumulates in the porous structure of the cathode GDE, the liquid anolyte invades the pores, blocking the catholyte from reaching the catalyst layer. This effect promotes the adverse hydrogen evolution reaction and thus decreases the CO2RR selectivity (1). Current literature focuses on limiting carbonate precipitate formation as opposed to understanding the factors affecting its growth (2). While carbonate precipitation is dependent on the specific electrolyte in a flow cell, the impact of parameters, such as operating temperature and GDE porosity, on the nature of carbonate precipitation still need to be investigated (3).In this study, we examine the relationship between cell temperature with carbonate precipitate accumulation. A zero-gap alkaline membrane electrode assembly (MEA) was used with potassium carbonate as the anolyte and humidified CO2 as the catholyte. Electrochemical impedance spectroscopy was used to calculate the activation, ohmic, and mass transport losses of the cell before and after a constant current density phase where faradaic efficiency was measured to quantify the CO2RR selectivity degradation due to salt accumulation. Furthermore, to characterize precipitate growth, the cathode GDEs were imaged before and after electrochemical testing using scanning electron microscopy (SEM) and wavelength dispersive spectroscopy (WDS). To quantify precipitate-driven flooding over operation time, identical MEAs were imaged using operando X-ray synchrotron radiography over a range of temperatures. Through-plane images of the operating cell were processed to find the electrolyte thickness in the cathode GDE as a function of time. Radiography results revealed progressive, cyclical flooding as well as preferential gas pathways. Moreover, after four hours of constant current operation and at a cell temperature of 60℃, the catalyst layer exhibited large amounts of uniformly distributed precipitates, while the GDE contained large, localized precipitate crystals. This indicates that at high temperatures, carbonate precipitates significantly block the catalyst layer and cause flooding into the substrate layer. This work provides new insight into the effect of temperature on carbonate precipitate buildup, deepening the understanding of the mechanism responsible for precipitate degradation. M. E. Leonard, L. E. Clarke, A. Forner-Cuenca, S. M. Brown, and F. R. Brushett, ChemSusChem, 13 (2020).Y. Xu et al., ACS Energy Lett, 6, 809–815 (2021).E. R. Cofell, U. O. Nwabara, S. S. Bhargava, D. E. Henckel, and P. J. A. Kenis, ACS Appl Mater Interfaces, 13, 15132–15142 (2021).

Flexible hierarchical polypyrrole-coated Cu-BTC MOFs photothermal textile for efficiently solar water evaporation and wastewater purification

Solar-driven interfacial water evaporation (SDIWE) endures a significant potential for producing clean water from seawater and wastewater because it requires no additional energy source. Photothermal materials with efficient solar absorption and pollutant removal capabilities are critical for SDIWE. However, an efficient and facile strategy to prepare a high-performance and flexible photothermal material and simultaneously prevent the salt accumulation for efficient and long-term steady evaporation to produce potable water from seawater and wastewater is still a challenge. Herein, based on the MS and ALD processes, two novel flexible photothermal materials are synthesized using the flexible polyester fabric substrate, hierarchical metal–organic framework Cu-BTC MOFs, and polypyrrole (PPy) as a light-absorption layer. In particular, under the synergistic effect of the hierarchical porous Cu-BTC MOFs and PPy with excellent solar absorption, the flexible photothermal material possesses excellent light absorption (92.58 % ∼ 93.98 %), super hydrophilicity, low thermal conductivity, high evaporation rate (1.53 ∼ 1.56 kg m-2h−1 for 15 days), outstanding salt resistance (1.42 kg m-2h−1 at a salinity of 15 wt%), and excellent metal ions and organic pollutants removal capacity after solar evaporation. These multifunctional properties ensure its great application prospect for future freshwater production while also providing a new reference for other applications.

Highly Salt-tolerant hydrogen evolution reaction based on dendritic urchin-like MoC/MoS2 heterojunction in seawater

The direct electrolysis of abundant near-neutral seawater resources for hydrogen production faces significant challenges due to insufficient catalyst activity and salt toxicity. Herein, we demonstrate a novel dendritic urchin-like MoC/MoS2 heterojunction in-situ formed on carbon cloth (CC@MoC/MoS2-H) through a combination of hydrothermal and high-temperature annealing processes. This unique dendritic urchin-like structure consists of numerous nanorods on carbon cloth, which enhances the catalytic active sites and provides space for efficient bubble release. The resulting CC@MoC/MoS2-H exhibits superior catalytic performance, with an overpotential of 91 mV and 136 mV at the current density of 10 mA cm−2 in the 1 M PBS electrolyte and natural seawater, respectively, surpassesing that of most non-noble metal compounds reported previously. Finite element simulations reveal that the urchin-like structure has significantly higher bubble release capacity compared to the randomly stacked structure. Additionally, the urchin-like structure demonstrates substantially greater current density retention under electrolytic conditions designed to simulate salt accumulation, in comparison to the small-size structure. Furthermore, the average H2 production efficiency of 78,493 μmol h−1 g−1 was evaluated for three consecutive hours using commercial solar panels rated at 2 V on a large-scale electrode assembly from seawater, which is comparable to the present photocatalytic hydrogen production efficiency. This work opens new avenues for the development of catalytic structures compatible with seawater.

Soil Salinity Mapping of Croplands in Arid Areas Based on the Soil–Land Inference Model

Soil salinization can decrease soil productivity and is a significant factor in causing land degradation. Precision mapping of salinization in agricultural fields would improve farmland management. This study focuses on the cropland in the Manas River Basin, located in the arid region of northwest China. It explores the potential of a soil mapping method, the Soil–Land Inference Model (SoLIM), which only requires a small number of soil samples to infer soil salinization of farmlands in arid areas. The model was utilized to create spatial distribution maps of soil salinity for the years 2009 and 2017, and changes in the distribution were analyzed. The research results indicate: (1) Through the analysis of sample point data, it was observed that soil salinity in the study area tends to accumulate in the surface layer (0–30 cm) in spring and in the subsoil layer (60–90 cm) during the crop growing season, with significant spatial variability. Therefore, it is necessary to conduct detailed salinity mapping. (2) Using field measurements as validation data, the simulation results of the SoLIM were compared with spatial interpolation methods and regression models. The SoLIM showed higher inference accuracy, with R2 values for the simulation results of the three soil layers all exceeding 0.5. (3) The SoLIM spatial inference showed salt accumulation in the northern part and desalination in the southern part. The findings of this study suggest that the SoLIM has the potential to effectively map soil salinization of croplands in arid areas, offering an efficient solution for monitoring soil salinity in arid oasis croplands.

Salt-tolerance mechanisms in quinoa: Is glycinebetaine the missing piece of the puzzle?

Salinization of arable land has been progressively increasing, which, along with the effects of climate change, poses a serious risk to food production. Quinoa is a halophyte species that grows and is productive in highly saline soils. This study addresses the mechanisms of response and adaptation to high salinity. We show that the differential distribution of sodium in plants depends on the variety, observing that varieties such as Pandela Rosada limit the passage transit of sodium to the aerial part of the plant, a mechanism that seems to be regulated by sodium transporters such as HKT1s or SOS1. Like other halophytes of the Amaranthaceae family, quinoa plants have salt glands (bladder cells), which have been reported to play an important role in salt tolerance. However, our study shows that the contribution of bladder glands to salt accumulation is rather low. The 1H-NMR metabolome study of quinoa subjected to salt stress showed important modifications in the contents of amino acids, sugars, organic acids, and quaternary ammonium compounds (glycinebetaine). The compound with a higher presence was glycinebetaine, which makes up 6% of the leaf dry matter under saline conditions. Our findings suggest that glycinebetaine can act as an osmolyte and/or osmoprotectant, facilitating plant development under high saline ambient.

Synergistic dual-mechanism raised structure and vertically aligned porous 3D hydrogel fabric for ultra-high salt-resistant water desalination

A solar evaporator with simple fabrication process, exceptional photothermal conversion efficiency and dependable continuous water evaporation holds significant potential for seawater desalination and wastewater treatment. Despite the substantial research dedicated to developing high-efficiency solar evaporators, there remains a need for additional exploration to tackle concerns such as salt crystallization, low evaporation efficiency, poor durability and stability. Here, an efficient water transport PVA hydrogel (water transport layer) and polydopamine/carbon black modified 3D raised-fabric (photothermal layer) are innovatively designed as solar evaporators. The synergistic effect between the periodic raised structure and polydopamine/carbon black results in outstanding photothermal conversion capabilities of PDA/CB@RF. Meanwhile, the porous structure of PVA hydrogel and its vertically aligned channels facilitate ion exchange and ensure a consistent water supply to the photothermal layer. This phenomenon serves to prevent the accumulation of salt in the photothermal layer, thereby markedly enhance the water evaporation capability of the PDA/CB@RF evaporator. The results demonstrate that the PDA/CB@RF evaporator system exhibits excellent photothermal conversion performance with its surface temperature rapidly ascending to 73.3 ℃ under 1 sun light intensity, and effectively boost the water evaporation rate (1.73 kg m-2h−1, 1 sun). Furthermore, the PDA/CB@RF evaporator exhibits excellent conversion efficiency (91.9 %) and self-desalting capability. Overall, this solar evaporator system with a 3D raised fabric design integrates light and thermal energy, consistent water evaporation and self-desalting functionalities, which makes it hold the potential to solve the pressing challenge of water shortage.

Reusable Floating Spherical Hydrogel Evaporator for Solar Desalination with Salt Mitigation and Contaminant Elimination.

The generation of clean and drinkable fresh water from seawater and contaminated water holds great potential to mitigate water scarcity. Herein, a floating spherical hydrogel evaporator (SHE) is designed to achieve sunlight-driven desalination, self-salt cleaning, and removal of environmental contaminants. The spherical lightweight polystyrene is coated with a porous carbon-embedded sodium alginate/PVA/CMC photothermal hydrogel to generate a spherical hydrogel evaporator (SHE) that floats naturally. The SHE is very sensitive to the weight imbalance (500 mg) and can respond quickly to the accumulation of salt by rotation to the fresh evaporation surface, realizing excellent antisalt fouling performance. Remarkably, with energy localization by porous carbon, the spherical floating evaporator achieved a high evaporation rate of 2.65 kg m-2 h-1 with an evaporation efficiency of 98%. At the same time, SHE is also capable of adsorbing both organic contaminants and heavy metal ions through functional groups of the hydrogel, attaining 99% removal efficiency. Overall, this low-cost spherical floating evaporator may offer solution for eco-friendly and sustainable production of fresh water on a large scale.