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Artemisia ordosica is an excellent sand-fixing shrub for sand stabilization in northwestern China. Sand dune stabilization, a critically important process, leads changes in abiotic factors, such as soil structure and nutrient contents. However, the effects of factors on an A. ordosica community following sand stabilization remain unclear. In this study, we used canonical correspondence analysis （CCA） to examine the relationships between A. ordosica communities and environmental factors at three habitats： semi-fixed dune （SF）, fixed dune with low-cov- erage biological soil crust （F）, and fixed dune with high- coverage biological soil crust （FC） in Mu Us desert. The mean height and coverage of plants increased with sand stabilization, while species diversity and richness increased initially and then reduced significantly. Correlation analysis and CCA revealed that slope, soil organic carbon, and nutrient contents, proportion of fine soil particles, soil moisture, and thickness of biological soil crust were all highly correlated with vegetation characteristics. These environmental factors could explain 40.42 % of the vege- tation-environment relationships at the three habitats. The distribution of plant species was positively related to soil moisture in the SF dune. Soil moisture, soil nutrient, and fine-particle contents mainly affected plants distribution in the F dune. In the FC dune, distribution of plant species was positively and negatively correlated with the thickness of biological soil crust and soil moisture at a depth 0-20 cm, respectively. The dominance value of typical steppe species increased significantly following sand-dune stabilization and relations between species and samples in CCA ordination bi-plots showed that perennial grasses could invade the A. ordosica community on FC, indicating A. ordosica communities had a tendency to change into typical steppe vegetation with the further fixation. We conclude that the significant differentiation not only occurred in community characteristics, but also in the relationships between vegetation and environmental factors among the three stages of dune fixation. So, restoration of degraded dune ecosystems should be based on habitat conditions and ecological needs.

This study evaluates the efficacy of TerraZyme (bioenzyme) and Xanthan Gum (biopolymer) in improving the mechanical behavior of Sand-Kaolin mixtures for sustainable soil stabilization. Sand and 15% Kaolin blend were treated with different additive dosages, and the specimens were evaluated via static triaxial testing under unconsolidated undrained conditions, the results are supported by further microstructural and chemical spectroscopy analyses. The optimum dosages found to be 0.075 mL/kg for TerraZyme and 1% (w/w) Xanthan Gum for increasing the shear strength up to 2.5 times after curing for 30 days. TerraZyme facilitated biochemical interaction, forming cemented bonds between sand particles and Xanthan Gum connected the particles via a polymeric network improving interparticle bonding. The results reveal that the use of bioenzymes and biopolymers in stabilization is an environmentally friendly, low-carbon option for ground improvement compared to that of chemical stabilizers.

Desertification and wind erosion in arid regions demand sustainable solutions beyond conventional methods. This study investigates the efficacy of Microbially Induced Carbonate Precipitation (MICP) for sand stabilization in the Taklimakan Desert, employing Sporosarcina pasteurii to induce calcium carbonate crust formation. Field trials on man-made dunes and trapezoidal sandy land applied bacterial and cementation solutions (urea, calcium chloride, nutrients) in varying frequencies (1–8 spray cycles). Comprehensive evaluations included bearing capacity tests, wind erosion measurements (erosion pins), crust thickness analysis, and permeability assessments, supported by SEM, XRD, and EDS to elucidate microstructural changes. Results demonstrate that MICP treatment significantly enhances surface stability, achieving bearing capacities of 346.67 kPa (trapezoidal land) and 298.67 kPa (dunes) while reducing wind erosion by 95% (from 100.56 mm to < 5.06 mm). Crust thickness reached 21.02 mm, with SEM revealing dense CaCO₃ networks filling > 90% of interparticle pores. The treatment’s environmental resilience was validated through dry-wet cycle tests (5 cycles, < 2.9% mass loss) and reduced permeability (1.2 × 10⁻⁴ cm/s), confirming its durability under fluctuating climatic conditions. The 8-spray-cycle protocol emerged as optimal, leveraging sequential bioaugmentation and biostimulation to maximize calcite precipitation. These findings position MICP as a scalable, eco-friendly alternative to traditional methods, offering superior mechanical performance, environmental compatibility, and long-term viability for desertification mitigation in arid ecosystems.

Biocementation, driven by ureolytic bacteria and their biochemical activities, has evolved as a powerful technology for soil stabilization, crack repair, and bioremediation. Ureolytic bacteria play a crucial role in calcium carbonate precipitation through their enzymatic activity, hydrolyzing urea to produce carbonate ions and elevate pH, thus creating favorable conditions for the precipitation of calcium carbonate. While extensive research has explored the ability of ureolytic bacteria isolated from natural environments or culture conditions, bacterial synergy is often unexplored or under-reported. In this study, we isolated bacterial strains from the local eutrophic river canal and evaluated their suitability for precipitating calcium carbonate polymorphs. We identified two distinct bacterial isolates with superior urea degradation ability (conductivity method) using partial 16 S rRNA gene sequencing. Molecular identification revealed that they belong to the Comamonas and Bacillus genera. Urea degradation analysis was performed under diverse pH (6,7 and 8) and temperature (15 °C,20 °C,25 °C and 30 °C) ranges, indicating that their ideal pH is 7 and temperature is 30 °C since 95% of the urea was degraded within 96 h. In addition, we investigated these strains individually and in combination, assessing their microbially induced carbonate precipitation (MICP) in silicate fine sand under low (14 ± 0.6 °C) and ideal temperature 30 °C conditions, aiming to optimize bio-mediated soil enhancement. Results indicated that 30 °C was the ideal temperature, and combining bacteria resulted in significant ( p  ≤ 0.001) superior carbonate precipitation (14–16%) and permeability (> 10 − 6 m/s) in comparison to the average range of individual strains. These findings provide valuable insights into the potential of combining ureolytic bacteria for future MICP research on field applications including soil erosion mitigation, soil stabilization, ground improvement, and heavy metal remediation.

Sand dune encroachment poses a significant environmental challenge for peri-urban and rural communities in the North African desert, which is home to more than one-third of the region’s population. The continuous movement of sand dunes disrupts residential development, infrastructure, and agricultural systems, threatening food and energy supplies in regions already sensitive to climate variability. The subsequent decline in habitability in such areas often leads to external migration, which triggers heightened socioeconomic and geopolitical instability. As part of the North African Sahara, the West El-Minya Governorate in Egypt is a crucial case study for Saharan areas where growing dune encroachment compromises extensive and critical agricultural developments. We investigate and quantify the primary drivers of sand movement, including wind speed and direction, surface elevation, slope, land use, vegetation cover, and soil cohesion, through the Sand Dune Encroachment Vulnerability Index. Our results reveal that agricultural soils with inadequate irrigation, particularly those adjacent to bare lands, are most susceptible to encroachment. Furthermore, 14% of the total cultivated area is affected by dune encroachment, resulting in estimated annual economic losses of $263 million. Moreover, ~42% of newly established agricultural lands are situated in zones of very high vulnerability, with anticipated productivity reductions of 25% and annual rehabilitation costs approximately $52 million. Transport infrastructures are also impacted, with key highways incurring $6.5 million annually in sand clearance due to recurring dune interference. The proximity of dune-encroached areas to irrigation canals escalates sedimentation rates, deteriorating water quality and incurring additional dredging expenses of $31.3 million per year, with adverse repercussions for agriculture and fisheries. Our study reveals growing dune encroachment, highlighting the urgent need for targeted, nature-based dune stabilization interventions, such as dune leveling and reclamation, in peri-urban Saharan regions. These measures are crucial for preventing further land degradation, reducing population displacement and regional conflict risks, and maintaining the habitability of arid areas.

Rice husk ash (RHA) is an excellent pozzolana and associated with hydrated lime (HL), it becomes an alternative binder to Portland cement in soil stabilization. In the context of waste valorization, waste foundry sand (WFS) and carbide lime (CL) have been investigated in civil construction and environmental geotechnical applications. However, stabilizing WFS with alternative binders to Portland cement represents a large field of research to be explored. This study evaluated the stabilization of WFS with a binder based on RHA and CL, compared to the use of RHA-HL. An experimental design was carried out to evaluate the influence of different dry-specific weights (12.00, 12.75, and 13.50 kN/m 3 ), RHA contents (10%, 20%, and 30%), and curing times (28, 60, and 90 days) under unconfined compressive strength (UCS). UCS results were submitted to statistical analysis and correlated to the porosity/binder content index (η/B iv ). Healing capacity, mineralogy, microstructure, and leaching of metals from mixtures of interest were evaluated. The results showed that higher specific weights and higher percentages of RHA promoted better strength. The η/B iv 0.28 index proved to be an adequate parameter to assess the UCS of WFS-RHA mixtures with different limes (CL and HL), lower porosity, and higher binder content leading to higher strengths. The mixture’s mineralogy and microscopy showed the formation of cementing gels, corroborating the strength gains. WFS stabilized with both binders (RHA-CL and RHA-HL) presented satisfactory environmental performance, allowing the immobilization of metals in the waste compositions.

The increasing need for efficient and sustainable construction materials has prompted the investigation of local and recycled resources to improve the characteristics of poor soils. This research aims to enhance dune sand (DS)—a plentiful yet geotechnically weak material—by integrating rubber crumb (RC) and brick powder (BP), with the objectives of soil stability and waste valorization. Experimental formulations were created with RC at concentrations of 10%, 30%, and 50%, and BP at concentrations of 1%, 2%, and 3%. A response surface methodology (RSM) and artificial neural network (ANN) techniques were utilized to examine the influences of RC and BP content on three primary responses: maximum dry density (MDD), internal friction angle (ϕ), and cohesion (C). Ideal conditions with 40.7% RC and 3% BP were achieved through optimization utilizing RSM and ANN-GA, greatly enhancing compaction and shear strength for geotechnical applications. According to Life Cycle Assessment (LCA), a high CR content raises energy consumption (E-Energy) and greenhouse gas emissions (E-CO₂), primarily as a result of rubber recycling. However, the reduction in sand mining and the diversion of tyre waste balance these effects. Therefore, the combination of RC with BP is turning out to be a viable and efficient infrastructure solution, especially in dry regions.

Aims The artificial cultivation of cyanobacterial crusts represents a novel technique for sand stabilization. Herbaceous plants are the main components of desert biodiversity and are important for ecological restoration efforts in dryland areas. However, there is a lack of research on the interaction between artificially-cultivated cyanobacterial crusts and herbaceous plant diversity. Methods Artificially-cultivated cyanobacterial crusts were monitored for three years after inoculation, as well as the composition, growth and diversity of associated herbaceous plant communities. Results (1) The percent cover, thickness, and chlorophyll a content of the artificially-cultivated cyanobacterial crusts gradually increased over time, with the chlorophyll a and exopolysaccharide content eventually matching that of eleven-year-old naturally-developed biological soil crusts. (2) Ten herbaceous species belonging to five families and ten genera were identified in association with the artificial cyanobacterial crusts, and herb cover, biomass, richness and abundance generally increased over time with significant differences among years( P  < 0.05). (3) Correlation analyses revealed that the relationship between the artificial cyanobacterial crust and herbaceous plant communities shifted from positive to negative over time. Conclusion Artificial cyanobacterial inoculation fostered the co-development of biocrusts and herbaceous plants, potentially accelerating the recovery of desert ecosystem functions. This study provides a theoretical basis for the further promotion and large-scale application of artificially-cultivated cyanobacterial crusts.

Induced biological soil crust (IBSC) technology has proved to be an effective means for speeding up the recovery of biological soil crusts (BSC) in arid and semi-arid regions. This study aims at improving the IBSC technology by using sodium alginate (SA) due to its sand-stabilizing ability in the early development stage of IBSCs. Results showed that SA can easily form a thin film on the surface of soil and can significantly enhance the compressive strength of the topsoil. More importantly, no negative effects of SA on the development and physiological activity of IBSCs were observed, and SA could facilitate the colonization and growth of cyanobacteria on sand. Moreover, the application of SA was much cheaper than the straw checkerboard barriers which are widely used in desertification control. This study suggests that SA can promote and accelerate the formation of BSCs; thus, it can be applied in IBSC technology to enhance the sand-stabilizing property of BSCs in the early stage.

Aeolian sand widely exists in the desert of western China. The reinforcement of aeolian sand is of considerable significance to the construction of transmission lines in the desert. In order to study the impact of different cement contents and moisture content on the performance of the cement-stabilized aeolian sand, 18 types of samples of aeolian sand with different water and cement contents were prepared. The confined and unconfined compression tests of the aeolian sand samples were conducted on the TSZ series automatic triaxial instrument. The microscopic observation methods and macroscopic strength tests were adopted to understand the cement-stabilized mechanism. The results of the triaxial test manifest that both the moisture content and the cement content affect the stress-strain behavior of the cement-stabilized aeolian sand. The cement-stabilized effect on aeolian sand can be estimated by the degree of hydration reaction. Microscopic test results show that as the cement content increases, the pores in the microstructure decrease, and some crystalline substances appear. The content of calcium silicate hydrate (C-S-H), which is one of the hydration products, is measured by the X-ray diffraction method. The results indicate that the solidification effect of cement is related to the C-S-H percentage. For 3% water content, the percentage of C-S-H goes up first with the increase of cement content and then gradually decreases at the cement content of 6%. When the water content goes up to 5% and 7%, it is found that the production of C-S-H gel increases with cement content.