Salt Precipitation Research Articles

The 288.2 K Isothermal Evaporation Experiment of Potassium Precipitation Brine in West Taijinair Salt Lake

Rubidium and cesium are important strategic resources, and West Taijinar Salt Lake is rich in rubidium and cesium reserves, while the concentration is low and the relationship with coexisting potassium and magnesium ions is complex. In order to understand the evaporative enrichment and salt precipitation patterns of rare elements such as lithium, rubidium, cesium, and boron of the brine after potassium precipitation in West Taijinar Salt Lake, the 288.2 K isothermal evaporation experiment was carried out. The experimental results show that during the evaporation process at 288.2 K, the following salts precipitate from the brine after potassium crystallization: halite (NaCl), bischofite (MgCl2·6H2O), carnallite (KCl·MgCl2·6H2O), hexahydrite (MgSO4·6H2O), epsomite (MgSO4·7H2O), boric acid (H3BO3), and lithium sulfate monohydrate (Li2SO4·H2O). The concentrations of lithium and boron are significantly enriched, the content of Li+ was enriched from 1.7 g/L to 5.63 g/L, and the B2O3 content was enriched from 6.72 g/L to 50.78 g/L. The isomorphism phenomenon of Rb+, Cs+, and K+ makes Rb+ and Cs+ enter potassium ore to form solid solution-type carnallite ((K, Rb)MgCl3·6H2O, (K, Cs)MgCl3·6H2O)) and reduce the content of brine. This study provides data support for the development and comprehensive utilization of lithium, boron, rubidium, and cesium resources in West Taijinar Salt Lake.

Synergistic photothermal enhancement of the antibacterial activity of fibroin hydrogel by dual-directional crosslink strategy for efficient solar steam generation

Silk fibroin (SF) has attracted wide attention due to its excellent biocompatibility and versatile adjustability. The regeneration and reutilization of silk fibroin can efficiently utilize waste cocoons and silk. However, the regenerated SF hydrogels suffer from inadequate mechanical properties and lack inherent antibacterial capabilities, limiting their application in seawater desalination. This study achieved a novel hydrogel (STS@Fe) with photothermal antimicrobial activity, good mechanical property, and excellent durability using a green dual-directional crosslink and meso-reconstruction strategy. The metal-phenolic networks (MPN) were synthesized utilizing the natural plant polyphenol tannic acid (TA) and Fe3O4 nanoparticles. This research incorporated MPN into dissolved and regenerated silk fibroin and sodium alginate solution, enhanced mechanical properties through cryogenic salt precipitation, and prepared STS@Fe hydrogel. The inherent photothermal properties of Fe3O4 nanoparticles and TA complex, coupled with their synergistic effect under near-infrared radiation, can confer excellent photothermal-enhanced antibacterial activity to the fibroin hydrogel. The tensile strength of STS@Fe hydrogel is enhanced 31 times than that of traditional fibroin hydrogel, and its evaporation rate is 4.77 times higher than that of pure water evaporation. The hydrogel has an efficient seawater desalination rate and outstanding antibacterial properties in real seawater conditions. Moreover, The STS@Fe shows effective treatment capabilities for dyeing wastewater and oily saline water.

Experimental investigation and predictive modeling of dry-out and salt precipitation effects during underground gas storage operations

Formation damage poses the greatest threat to underground gas storage (UGS) operations, with permeability reduction being a key cause of injectivity and productivity losses. To better understand the mechanisms behind dry-out and salt precipitation (DSP) and predict the resulting near-wellbore damage, this study experimentally and quantitatively evaluates key factors affecting rock properties before and after salt precipitation. We conducted long-term gas-brine core flooding experiments, obtained salt-contaminated samples, and supplemented them with core permeability-porosity parameter tests, high-pressure mercury intrusion porosimetry (MIP), and scanning electron microscopy (SEM) experiments to better evaluate the salt clogging behavior of the samples. In addition, we discussed the applicability of the key parameter prediction model in modeling the DSP effects, including the water content of natural gas (WCNG), the porosity-permeability clogging model (PPC), and relative permeability (RP) function, providing usage recommendations. Based on our findings, we introduced a model to predict water saturation, salt saturation, and the salt-induced skin factor near the wellbore, particularly after viscous displacement ends, when liquid becomes immobile and evaporation dominates.The results show that salt precipitation has a significant impact on core porosity and permeability. Notably, lower flow rates subtly promote salt precipitation by enhancing the role of evaporation, resulting in greater salt accumulation. In addition, elevated salinity and higher initial water saturation are key contributors to the precipitation process, further exacerbating salt buildup within the reservoir. MIP experiments further confirm the aforementioned impacts. SEM observations reveal NaCl crystals, either clustered or isolated, extensively distributed within the pores and filling the pore spaces from micro to nanometer scale, highlighting their substantial role in altering pore structure and impacting porosity and permeability due to DSP effects. Our developed model confirms that high temperature, low pressure, high flow rates, low initial porosity and permeability, and strong near-well inertia effects lead to DSP effects manifesting sooner near the wellbore during the post-viscous displacement stage. Model validation with core-scale predictions closely matches experimental data in terms of trend.By laying the groundwork for analyzing the mechanisms of flow-through drying and salt precipitation, our findings can be directly applied to identifying the key controlling factors influencing DSP effects, mitigating formation damage, improving injectivity and productivity, and enhancing the efficiency of UGS operations under various operational conditions.

Purification and Characterization of γ-Glutamyl Transpeptidase from Toona sinensisand Its Function on Formation of Sulfur-Containing Volatiles.

γ-Glutamyl transpeptidase (GGT) in Toona sinensis shoot (TS) was extracted and purified through salt precipitation, ion-exchange column, and gel filtration chromatography methods. The GGT had two peptides with M.W. 35 and 50 kDa. Its function in the formation of TS sulfur-containing volatiles (SCVs) was evaluated. The highest GGT hydrolytic activity was at pH 7.0 and 50 °C. Its activity was enhanced by Ca2+, Mg2+, K+, Na+, and Ba2+ and reduced by Cu2+, Fe3+, Mn2+, and Zn2+. The SCVs reached the highest level at GGT to TS sulfur-containing precursors extract 1:20. The aroma produced by GGT from the extract was similar to that of raw TS, especially for the cooked onion-like/TS-like flavor. These results revealed the characteristics and function of GGT in TS on sulfurous aroma formation. It could be applied to retrieve the production of sulfur-containing aroma from thermally preserved TS or similar vegetables, which lost GGT activity irreversibly during heat drying.

Micro‐nanobubbles assisted fouling reduction in membrane distillation for desalination

AbstractThe present study describes the use of micro‐nanobubbles (MNBs) as an easy‐to‐use method for delaying scaling in membrane distillation (MD) while treating highly concentrated saline feed (10 wt.%). The hydrodynamic flow conditions with MNBs are enhanced compared to the traditional gas bubbling in MD. Specifically, an air cushion is formed between the membrane surface and bulk, limiting the deposition of solid particles on the surface. Also, turbulence created by the MNBs reduces the membrane fouling. The findings of the MD performance analysis showed that, in the absence of nanobubbles, considerable membrane scaling occurred during the treatment of high‐salinity feed, which significantly decreased the distillate flux to 70% after 20 h. The one‐time incorporation of air NBs into the saline feed significantly reduced salt precipitation or fouling on the polyvinylidene fluoride (PVDF) membrane surface by delaying the start of flux drop and preventing membrane wetting, thus improving MD performance. For nanobubble‐assisted MD, the only measured flux drop after 20 h of operation was 57% under similar input concentration and operating parameters.

Proton Pool for the Mitigation of Salt Precipitate Enhancing CO2 Electroreduction in a Flow Cell

Flow cells featuring a gas diffusion electrode (GDE) have emerged as an attractive platform for electrochemical CO2 reduction, offering high current densities (~300 mA·cm−2) and low energy consumption. However, the formation of salt precipitates, particularly carbonate and bicarbonate, poses a significant deficiency by reducing the cell’s operational longevity. In this study, we present a novel approach to mitigate salt precipitates in real-time through acid–base interaction. Recovery efficiency and partial current density of the cell were used to evaluate the capability of removing salt precipitates and the maintenance of CO2 reduction reactions (CO2RRs). It was suggested that the direct treatment of intermittent acid rinse recovers the performance of CO2RRs to a large extent (>97%), and the modification of the proton exchange resin reduces the reduction rate of partial current densities to 1/15 than that of the unmodified. This improvement enhances the cell’s catalytic performance, enabling the stability test for catalysts within the GDE-based flow cell.

Turning mine-tailing streams into sources of water and mineral salts in a membrane-sustained circular scenario

The discharge of wastewater from the mining industry has a critical ecological impact, potentially endangering both soil and marine ecosystems. Alternatively, recovering pure water and valuable materials from these hypersaline streams through a technologically efficient process, would help reduce the ecological impact of the waste, while providing a viable supply chain for raw materials such as magnesium, potassium and others, considered critical to the economy. In this context, this work aimed to simultaneously recover pure water and mineral salts from mine wastewater by membrane-assisted crystallization (MAC). A prior theoretical study based on thermodynamic parameters attempted to predict salts precipitation at different temperatures. MAC tests were then performed at specific thermal gradients and feed pretreatment conditions, achieving preferential precipitation of solids products of different composition containing large quantities of Ca or Mg/K minerals from the real mine tailing wastewater. The experiments also demonstrated the central impact of heterogeneous nucleation effects.

Photothermal evaporation of pure, saline, muddy, and dye-contaminated waters using carbon black@PDMS sponges with superhydrophilic surface

This study aimed to develop a carbon black (CB)@ polydimethylsiloxane (PDMS) sponge capable of highly efficient photothermal water evaporation. The sponge was fabricated through a straightforward method that did not entail a high-temperature carbonization process, utilizing a sugar cube as a sacrificial template to create a porous structure, followed by CB incorporation into the PDMS matrix. A polyvinyl alcohol (PVA) coating was used to enhance the hydrophilicity of the sponge, resulting in improved water absorption and distribution. The photothermal performance of the PVA-coated CB@PDMS sponge was evaluated using various contaminated water types, including seawater, muddy water, and Rhodamine-B-contaminated water. The sponge demonstrated water-evaporation rates ranging from 3.28–4.38 kg/m²·h, significantly reducing the water-evaporation enthalpy and effectively preventing salt precipitation during seawater desalination. Additionally, it maintained its performance over repeated experiments and demonstrated efficiency improvement over multiple cycles, indicating that its effectiveness increased with repeated use, likely because of surface conditioning and structural stabilization. Moreover, the water recovered from seawater, muddy water, and dye-contaminated water was free of trace contaminants, thereby yielding clean water and demonstrating the suitability of the sponge for water purification and desalination applications.

Enhanced lipase production and characterization from Aeromonas media VBC8: Applications in biodegradation of lubricating oil waste

This study aimed to explore the potential of a novel indigenous strain for the improved production of lipase from castor oil-contaminated soil. Among the various isolates, Aeromonas media VBC8 was found to be the most effective for lipase production. The effect of different inducer oils (olive, peanut, soybean, rice bran, sunflower, coconut, sesame, and fish liver oil) on the biomass of A. media VBC8 and its lipase activity was determined. Among the various oils assessed, fish liver oil exhibited highest lipase activity, with 89 U/mL with 9.1 g/L of biomass. Furthermore, Box-Behnken Design was used to optimize the cultural conditions resulting in an enhanced lipase activity of 1156 U/mL. The lipase was purified through ammonium salt (60 w/v %) precipitation, desalting and ion exchange column, achieving a yield of 16 % and specific activity of 98.4 U/mL. The purified lipase remained active over a wide range of pH 4.0–11.0 and temperature of 10–80 °C with maximum activity at pH 8.0 and 40 °C. SDS-PAGE analysis revealed the lipase's molecular weight to be 94 kDa. The study also evaluated the role of crude and purified lipase in the biodegradability of lubricating oil waste, achieving a maximum fatty acid conversion of 39 and 76 %, respectively, after 7 h incubation at room temperature.

Potential for 50% Mechanical Strength Decline in Sandstone Reservoirs Due to Salt Precipitation and CO2–Brine Interactions During Carbon Sequestration

AbstractPredictive modeling of CO2 storage sites requires a detailed understanding of physico-chemical processes and scale-up challenges. Dramatic injectivity decline may occur due to salt precipitation pore clogging in high-salinity aquifers during subsurface CO2 injection. This study aims to elucidate the impact of CO2-induced salt crystallization in the porous medium on the geomechanical properties of reservoir sandstones. As the impact of salt precipitation cannot be isolated from the precursor interactions with CO2 and acidified brine, we present a comprehensive review and discuss CO2 chemo-mechanical interactions with sandstones. Laboratory geochemical CO2–brine–rock interactions at elevated pressures and temperatures were conducted on two sandstone sets with contrasting petrophysical qualities. Interaction paths comprised treatment with (a) CO2-acidified brine and (b) supercritical injection until brine dry-out, salt crystallization, and growth. Afterward, the core samples were tested in a triaxial apparatus at varying stresses and temperatures. The elastic moduli of intact, CO2-acidified brine treated, and salt-affected sandstones were juxtaposed to elucidate the geochemical–geomechanical-coupled impacts and identify the extent of crystallization damages. The salt-affected sandstones showed a maximum of 50% reduction in Young’s and shear moduli and twice an increase in Poisson’s ratio compared to intact condition. The deterioration was notably higher for the tighter reservoir sandstones, with higher initial stiffness and lower porosity–permeability. We propose two pore- and grain-scale mechanisms to explain how salt crystallization contributes to stress localization and mechanical damage. The results highlight the potential integrity risk imposed by salt crystallization in (hyper)saline aquifers besides injectivity, signaling mechanical failure exacerbated by pressure buildup.

Polyelectrolyte Additive-Modulated Interfacial Microenvironment Boosting CO2 Electrolysis in Acid.

Acidic CO2 electrolysis offers a promising strategy to achieve high carbon utilization and high energy efficiency. However, challenges still remain in suppressing the competitive hydrogen evolution reaction (HER) and improving product selectivity. Although high concentrations of potassium ions (K+) can suppress HER and accelerate CO2 reduction, they still inevitably suffer from salt precipitation problems. In this study, we demonstrate that the sulfonate-based polyelectrolyte, polystyrene sulfonate (PSS), enables to reconstruct the electrode-electrolyte interface to significantly enhance the acidic CO2 electrolysis. Mechanistic studies reveal that PSS induces high local K+ concentrations through the electrostatic interaction between PSS anions and K+. In situ spectroscopy reveals that PSS reshapes the interfacial hydrogen-bond (H-bond) network, which is attributed to the H-bonds between PSS anions and hydrated proton, as well as the steric hindrance of the additive molecules. This greatly weakens proton transfer kinetics and leads to the suppression of undesirable HER. As a result, a Faradaic efficiency of 93.9 % for CO can be achieved at 250 mA cm-2, simultaneous with a high single-pass carbon efficiency of 72.2 % on commercial Ag catalysts in acid. This study highlights the important role of the electrode-electrolyte interface induced by polyelectrolyte additives in promoting electrocatalytic reactions.

A parallel compositional reservoir simulator for large-scale CO2 geological storage modeling and assessment

Storing CO2 in deep aquifers and depleted gas reservoirs is an effective way to achieve carbon neutrality. However, the numerical simulation of CO2 storage in these formations is challenging due to the complexity of gases-brine systems. The number of gas species included in the gases-brine fluid models of existing simulators cannot meet the rapidly evolving CO2 sequestration scenarios. To address this intricate issue, we developed a three-dimensional fully implicit parallel CO2 geological storage simulator (PRSI-CGCS) on distributed-memory computers based on our in-house parallel platform. This simulator uses a compositional fluid model with a diverse range of gas species, including CO2, C1 ~ C3, N2, H2S, as well as newly added gases H2 and O2, which may be encountered in geological CO2 storages. Besides, we provide more suitable scaling factors for different gases in the stability analysis bypassing (SAB) method to accelerate the gases-brine phase equilibrium calculations. PRSI-CGCS does not incorporate energy conservation equations, and salt precipitation or dissolution is also not considered. Numerical experiments show that our simulator is scalable, robust and validated to simulate large-scale CO2 storage problems with hundreds of millions of grid blocks on a parallel supercomputer cluster. Besides, after our modification on scaling factors, the SAB method can reduce the number of stability analyses by 61.39 % to 88.71 %, thereby reducing simulation time. Furthermore, case studies indicate that injecting O2 and H2 along with CO2 reduces the stability or capacity of CO2 storage and increases the pressure required for injection. However, this impact is not significant when the impurity content is less than 10 %.

Silk-based polyelectrolyte evaporator with excellent salt resistance for high-rate and stable solar desalination

Solar-driven interfacial evaporation technology is a promising solution to solve global freshwater shortages through desalination. However, salt accumulation in the evaporator affects light absorption and reduces evaporation efficiency, thereby significantly reducing the service life and operating efficiency of the evaporator. Herein, we propose a strategy for sustainable salt resistance that enables strong salt resistance and rapid water delivery by in situ polymerization of sodium acrylate (PAAS) on the directional channel. As a result, the as-prepared SF/rGO@PAAS can achieve a high evaporation rate of up to 2.31 kg m−2 h−1 and high evaporation efficiency of up to 98% under one sun, benefiting from the inherent hydrophilicity of silk fibroin (SF), the directional channel design of water transport layer, and the efficient solar light absorption in full spectrum of reduced graphene oxide (rGO). More importantly, due to the electrostatic effect of PAAS, the evaporator showed excellent salt resistance, with no salt precipitation for 5 days of continuous evaporation in simulated seawater (3.5 wt%) while maintaining the high evaporation rate. This salt resistant evaporator provides an effective solution to the salt accumulation and addresses a key challenge in sustainable desalination.

Microenvironment Manipulation Strategies for Acidic CO2 Electrolysis

AbstractThe electrochemical reduction of CO2 (CO2RR) has gained significant attention due to its potential to reduce carbon emissions and produce valuable fuels and chemicals. CO2RR is typically carried out in neutral or alkaline conditions, while challenges such as the carbon crossover and salt precipitate can hinder the practical application. Conducting CO2RR in acidic media presents a promising method to address these issues, although it faces the problem of low efficiency and poor catalysis stability. Regulating the interface/surface microenvironment near the catalysts is crucial to minimize the competitive hydrogen evolution reaction and enhance CO2RR activity and long‐term stability. This review outlines recent advancements in acidic CO2RR, emphasizing various microenvironment engineering strategies for optimizing the CO2RR kinetics including electrolyte composition manipulation, catalyst design, electrode modification and cell configuration optimization. Additionally, the review addresses challenges into developing practical and cost‐effective CO2RR systems.

Temperature-responsive solvation enabled by dipole-dipole interactions towards wide-temperature sodium-ion batteries

Rechargeable batteries with high durability over wide temperature is needed in aerospace and submarine fields. Unfortunately, Current battery technologies suffer from limited operating temperatures due to the rapid performance decay at extreme temperatures. A major challenge for wide-temperature electrolyte design lies in restricting the parasitic reactions at elevated temperatures while improving the reaction kinetics at low temperatures. Here, we demonstrate a temperature-adaptive electrolyte design by regulating the dipole-dipole interactions at various temperatures to simultaneously address the issues at both elevated and subzero temperatures. This approach prevents electrolyte degradation while endowing it with the ability to undergo adaptive changes as temperature varies. Such electrolyte favors to form solvation structure with high thermal stability with rising temperatures and transits to one that prevents salt precipitation at lower temperatures. This ensures stably within a wide temperature range of ‒60 −55 °C. This temperature-adaptive electrolyte opens an avenue for wide-temperature electrolyte design, highlighting the significance of dipole-dipole interactions in regulating solvation structures.

Investigation of Different Throat Concepts for Precipitation Processes in Saturated Pore-Network Models

The development of reliable mathematical models and numerical discretization methods is important for the understanding of salt precipitation in porous media, which is relevant for environmental problems like soil salinization. Models on the pore scale are necessary to represent local heterogeneities in precipitation and to include the influence of solution-air-solid interfaces. A pore-network model for saturated flow, which includes the precipitation reaction of salt, is presented. It is implemented in the open-source simulator DuMuX\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{\ extrm{X}}$$\\end{document}. In this paper, we restrict ourselves to one-phase flow as a first step. Since the throat transmissibilities determine the flow behaviour in the pore network, different concepts for the decreasing throat transmissibility due to precipitation are investigated. We consider four concepts for the amount of precipitation in the throats. Three concepts use information from the adjacent pore bodies, and one employs a pore-throat model obtained by averaging the resolved pore-scale model in a thin-tube. They lead to different permeability developments, which are caused by the different distribution of the precipitate between the pore bodies and throats. We additionally apply two different concepts for the calculation of the transmissibility. One obtains the precipitate distribution from analytical assumptions, the other from a geometric minimization principle using a phase-field evolution equation. The two concepts do not show substantial differences for the permeability development as long as simple pore-throat geometries are used. Finally, advantages and disadvantages of the concepts are discussed in the context of the considered physical problem and a reasonable effort for the implementation and computational costs.

Rising temperatures and sinking hopes: An in-depth analysis of the interplay between climate change, land use patterns, and the desiccation of a global biosphere reserve

Global ecosystems and communities are significantly impacted by climate change and extreme events. The rapid desiccation of massive wetlands, which are essential for controlling water cycles, and biodiversity, preventing floods, and supplying essential ecosystem services, is one of the most upsetting effects. The once-largest lake in the Middle East, Lake Urmia, had a significant impact on ecology, economy, and human life contributing to climate regulation, species preservation, habitat conservation, tourism and recreation, and a wide range of other ecosystem services. The Ramsar Convention classified the lake as a Wetland of International Importance, and UNESCO designated it as a Biosphere Reserve. The ecological, agricultural, and societal challenges caused by rising temperatures, improper water resource management and overuse, enhanced salinity, and declining water levels have made Lake Urmia an acute symbol of environmental vulnerability. Using Landsat imagery, this study begins a thorough analysis of changes in the Lake Urmia basin from 1990 to 2020. The endeavor aims to develop effective conservation and restoration strategies by identifying the multiple reasons that led to its vulnerable situation. The study attempts to identify the role of precipitation, temperature trends, agricultural development, population growth, water consumption, evapotranspiration, and atmospheric salt and aerosol concentrations in the desiccation of the lake. This study presents a comprehensive knowledge of the complex interplay between climate change, human activity, and water management and may have implications for the holistic recovery of the lake. The findings have the potential to improve prognostic models and inform targeted mitigation strategies for not only Lake Urmia but also for other globally threatened wetlands.

Deciphering Permian wetland deposits of the Parnaíba Basin through an integrated study of lithofacies and palynofacies in Western Gondwana

During the Permian, the northwestern portion of the supercontinent Gondwana experienced significant climate changes, among which the increasing aridity in the Parnaíba Basin, located between Brazil's northern and northeastern regions. The marine influence associated with the Panthalassa Ocean, evident in the Silurian and Devonian deposits, was progressively attenuated in the late Carboniferous, culminating in extensive continental deposits during the Permian and the Early Triassic in this region. In this paper, we present the first palynofacies analysis of the Permian Pedra de Fogo Formation, conducted concurrently with the description and association of sedimentary facies from outcrops located in the state of Maranhão, southwest of the Parnaíba Basin. A total of 15 m of sedimentary succession was described, and 28 samples were selected for palynofacies analysis. As a result, we identified six sedimentary facies, which were grouped into two distinct facies associations: Fa1 – Central Lake and Fa2 – Playa Lake. The palynofacies analysis considered the sedimentary organic matter, classifying it into amorphous organic matter, phytoclasts (subdivided into eight subgroups), and palynomorphs (with six subgroups). Integrating the results enabled an understanding of the depositional context, which is closely related to water dynamics and climate seasonality. The shallow lake system interpreted during the wet phases recorded interruptions in the normal sedimentation of the central lake due to turbidite deposits associated with ephemeral rivers. Conversely, during dry phases, salt precipitation occurred with subsequent substitution and aerial exposure of the surface when the water balance was negative. Eodiagenetic events were inferred and are considered throughout the article. The alternation of the hydrological regime allowed the deposition in proximal, transitional, and distal environments, creating a distinctive mosaic of wetland landscapes. The data presented indicate humid conditions within a context of increasing aridity in the studied location, particularly in the upper part of the Pedra de Fogo Formation.

Spatio-temporal change and driving mechanisms of land use/cover in Qarhan Salt Lake area during from 2000 to 2020, based on machine learning

The significance of land use classification has garnered attention due to its implications for climate and ecosystems. This paper establishes a connection by introducing and applying automatic machine learning (Auto ML) techniques to salt lake landscape, with a specific focus on the Qarhan Salt Lake area. Utilizing Landsat-5 Thematic Mappe (TM) and Landsat-8 Operational Land Imager (OLI) imagery, six machine learning algorithms were employed to classify eight land use types from 2000 to 2020. Results show that XGBLD performed optimally with 77% accuracy. Over two decades, salt fields, construction land, and water areas increased due to transformations in saline land and salt flats. The exposed lakes area exhibited a rise followed by a decline, mainly transforming into salt flats. Agricultural land areas slightly increased, influenced by both human activities and climate. Our analysis reveals a strong correlation between salt fields and precipitation, while exposed lakes demonstrate a significant negative correlation with evaporation and temperature, highlighting their vulnerability to climate change. Additionally, human water usage was identified as a significant factor impacting land use change, emphasizing the dual influence of anthropogenic activities and natural factors. This paper addresses the void in the application of Auto ML in salt lake environments and provides valuable insights into the dynamic evolution of land use types in the Qarhan Salt Lake region.

Effect of In Situ Polymerization of Super Absorbent Polymers on the Protection of Earthen Heritage Sites in Semi-Arid Regions

As precious cultural heritage, earthen sites are susceptible to various natural factors, leading to diverse forms of degradation. To protect earthen sites, the effects of super absorbent polymers (SAPs) on soil water retention, physical properties, and color compatibility at different concentrations were studied. After applying SAP treatment to an earthen site with different degrees of weathering, we drew the following conclusions. SAP-2 improved soil water retention capacity, increased soil water content, and slowed down the precipitation of soluble salts. At the same time, SAP-2 had the least effect on soil color difference and reduced the development of cracks by filling soil pores and enhancing the cohesion between soil particles, thus giving the earthen sites better weathering resistance. Therefore, the results provide a useful reference for the surface cracking of earthen sites in semi-arid areas and the degradation caused by flaking and block spalling.