Mixture Of Sand Research Articles

Transport of a Mixture of Sand and Water Through a Pump Characterized by Dual Inlets and a Double-Layered Impeller

A centrifugal pump incorporating two inlets and a double-layered impeller is proposed for transporting a mixture of sand and water. The double-layered impeller (primary impeller) encircles a secondary impeller. To reveal the operating and flow characteristics of such a pump, numerical work is conducted with a validated numerical method. The effects of the feed rate of sand and the rotational speed of the impeller are investigated. The results show that the pump efficiency is not monotonically related to the solid volume fraction. At a feed rate of sand of 2.10 m3/min and a rotational speed of 950 rpm, the lowest pump efficiency is reached. In the volute chamber, vortices of various sizes are evidenced. With increasing rotational speed, the overall solid volume fraction in the pump decreases. Meanwhile, when the solid volume fraction attains 0.28, sand particles tend to accumulate near the outer rim of the volute chamber. The axial force acting on the primary impeller increases with the rotational speed. Under different operating conditions, the radial forces point unanimously toward the third and fourth quadrants.

Induced polarization of clay-rich materials. 4. Water content and temperature effects in bentonites

Deep geological disposals (DGDs) are widely seen to be the best solution to contain high-level radioactive wastes safely. Compacted bentonite and bentonite-sand mixtures are considered the most appropriate buffers or sealing materials for access drifts, ramps, and shafts due to their favorable physicochemical and hydro-mechanical properties. Bentonite-sand mixtures are expected to swell and seal all voids when in contact with water, forming an impermeable barrier to radioactive elements. The parameters that will most affect the hydraulic performance of these seals are their water content, dry density, water salinity, and temperature. Monitoring and assessing these parameters are, therefore, crucial to confirm that the seals’ safety functions are fulfilled during the life of a DGD. Induced polarization (IP) is a nonintrusive geophysical method able to perform this task. However, the underlying physics of bentonite sand mixtures has not been checked. The complex conductivity spectra of 42 compacted bentonite-sand mixtures were measured in the frequency range of 1 Hz–45 kHz in order to develop workable relationships between in-phase and quadrature conductivities versus water content and saturation, pore water conductivity, bentonite-sand ratio (10% to 100%), temperature (10°C–60°C), and dry density (0.97 to 1.64 g cm−3). We observe that conductivity is mostly dominated by surface conductivity associated with the Stern layer (SL) coating the surface of smectite, the main component of bentonite. At a given salinity and temperature, the in-phase and quadrature conductivities obey the power law relationships with water content and saturation. The in-phase and quadrature conductivities depend on the temperature according to a classical linear relationship with the same temperature coefficient. An SL-based model is used to explain the dependence of the complex conductivity with water content, dry density, water salinity, and temperature. It could be used to interpret the IP field data to monitor the efficiency of the seal of DGD facilities.

Shotcreting with Cement–Sand Mixtures Under the Influence of an Electrostatic Field

One of the primary and still unresolved problems of shotcreting is the high rebound rate of the material, which reaches over 20% in “dry” shotcreting. There is a practical need to improve the very principle of shotcreting and methods for optimizing the movement of torch particles. Materials and Methods: The purpose of this study was to justify the use of the electrostatic treatment of cement–sand mortar in the process of performing shotcreting works using the dry method. It was proposed that the binder and then the finished mixture be ionized step-by-step (by passing it through a non-uniform electrostatic field formed by corona electrodes). As a result, the shotcrete will be held on the fence. Results: Analysis of the modeling results shows that the presence of an electrostatic field slows down the particle and reduces the kinetic energy of the rebound. After theoretical calculations, experiments were conducted, during which, the torch size and the plant productivity were changed, and the rebound mass was weighed. After application to the surface, prototypes were formed and subjected to strength tests. It was determined that gunning in a sharply non-uniform electric field demonstrates its practical and economic efficiency due to the uniform deposition of charged particles on the treated surface and low power consumption. Conclusions: It was established that the electrostatic treatment of a cement–sand mixture during application allows concrete particles to be retained on the shotcrete surface, the rebound of the material to be reduced and the strength of concrete to be increased.

Sorption/desorption of phenanthrene and ofloxacin by microbial-derived organic matter-mineral composites

IntroductionSoil organic matter plays an important role in the long-term “locking” of organic contaminants in soil environment. Recently, microbial-derived organic matter have been recognized as essential components of stabilized soil carbon pools. However, the contribution of microbial-derived organic matter to sorption of organic contaminants remains unclear.MethodsHere, we obtained microbial-derived organic matter-mineral composites by inoculating model soil (a mixture of hematite and quartz sand (FQ) or montmorillonite and quartz sand (MQ)) with natural soil microorganisms and different substrate-carbon (glycine (G), glucose (P), or 2, 6-Dimethoxyphenol (B)), which were named GF, PF, BF, GM, BM, and PM, respectively. Batch sorption/desorption experiments were conducted for phenanthrene (PHE) and ofloxacin (OFL) on the composites.Results and DiscussionThe composites cultured with 2,6-dimethoxyphenol had the highest carbon content (0.98% on FQ and 2.11% on MQ) of the three carbon substrates. The carbon content of the composites incubated with MQ (0.64%–2.11%) was higher than that with FQ (0.24%–0.98%), indicating that montmorillonite facilitated the accumulation of microbial-derived organic matter owing to its large specific surface area. The sorption of PHE by microbial-derived organic matter was mainly dominated by hydrophobic partitioning and π-π conjugation, whereas the sorption of OFL was mainly dominated by hydrophobic hydrogen bonding and π-π conjugation. The sorption of OFL onto the composites was more stable than that of PHE. Microbial-derived organic matter -mineral composites can reduce the risk of organic contaminant migration in soil, particularly ionic organic contaminants.

Effects of seawater on properties of bentonite cut-off walls with/without cement addition

Bentonite-based cut-off walls have been widely used to protect coastal areas against seawater intrusion. However, salts contained in coastal soils affect the properties of bentonite cut-off walls, and the interactions between seawater and bentonite minerals with or without cement remain unclear. The aim of this study was therefore to evaluate the effects of seawater on the workability, strength and permeability of bentonite-based mixtures, prepared using three types of bentonite (sodium, calcium and seawater bentonite). The underlying mechanisms were further investigated through Atterberg limits, mineralogical and microstructural analyses. The results showed that cation exchange between seawater and bentonite leads to alterations in montmorillonite type and particle arrangement. This leads to a significantly reduced liquid limit and a slightly decreased plastic limit of bentonite, therefore narrowing the range of workable water content for bentonite–sand mixtures. Compared with sodium/calcium bentonite, seawater bentonite was less impacted by seawater, but showed a larger increment in workability after cement addition due to palygorskite dissolution. Under similar workability, the bentonite–sand–cement mixture with calcium bentonite yielded the highest strength and the lowest permeability. These findings illustrate correlations between bentonite mineral alterations and the properties of bentonite–sand mixtures with or without cement, and offer guidance for the construction of cut-off walls in coastal regions.

Particle tracking-aided digital volume correlation for clay–sand soil mixtures

In this study, a novel, interdisciplinary method is introduced that merges fundamental geomechanics with computer vision to develop an advanced hybrid feature-aided digital volume correlation (DVC) technique. This technique is specifically engineered to measure and compute the full-field strain distribution in fine-grained soil mixtures. A clay–sand mixture specimen composed of quartz sand particles and kaolinite was created. Its mechanical properties and deformation behaviour were then tested using a mini-triaxial apparatus, combined with micro-focus X-ray computed tomography (μCT). The CT slices underwent image processing for denoising, segmentation of distinct phases, reconstruction of sand particles and feature extraction within the soil specimen. The proposed approach incorporated a two-step particle tracking method, which initially uses particle volume and surface area features to establish a preliminary matching list for a reference particle and then use the iterative closest point method for precise target particle matching. The soil specimen's initial displacement field was then mapped onto the DVC method's grid, and further refined through sub-voxel registration by way of a three-dimensional inverse compositional Gauss–Newton algorithm. The proposed method's effectiveness and efficiency were validated by accurately calculating the displacement and strain fields of the soil mixture sample, and comparing the results with those from a traditional DVC method. Given the soil's compositional and microstructural characteristics, these image-matching techniques can be integrated to create a versatile, efficient, and robust DVC system, suitable for a variety of soil mixture types.

Performance of geocell reinforced rubber sand mixtures under undrained triaxial test

Large quantities of scrap tires are produced by the automobile industry each year, which causes disposal challenges and impacts the environment. However, scrap tires exhibit various properties, including tensile strength, abrasion resistance, durability, thermal conductivity, elasticity, and more. Due to their versatile characteristics, these scrap tires can be utilized as construction materials for various civil engineering works to reduce their negative environmental effects and conserve natural resources. This study aims to understand the shear strength behaviours exhibited by geocell-reinforced mixtures of rubber and sand through the unconsolidated undrained triaxial test. Various parameters, including rubber sizes (425 μm to 12 mm), rubber contents (10% to 40% by volume), confining pressures (50 to 300 kPa), and geocell heights (0.2H to 0.8H, where H is the height of triaxial sample), were systematically examined to understand their impact on shear strength characteristics. The experimental findings reveal that deviatoric stress is enhanced with increasing confining pressure and rubber sizes. The maximum benefits of the rubber-sand mixture were observed at 30% rubber content. Geocell-reinforced rubber sand mixture has a higher shear strength with respect to the unreinforced mixture. Furthermore, the energy absorption capacity of the geocell-reinforced rubber sand mixtures was much better as compared to either the clean sand or rubber-sand mixture. The findings of this research demonstrate that geocellreinforced rubber sand mixtures are suitable for various geotechnical engineering works.

Adding barium sulfate (BaSO4) to fly ash geopolymer increases its compressive strength as X-ray shielding for medical imaging applications

BackgroundGeopolymers, a novel cementitious material, have the potential for reducing carbon dioxide wastes resulting from the manufacture of cement. PurposeThis study presents an experimental inquiry conducted to produce a fly ash geopolymer mortar with a good of compressive strength of the batch. MethodsActivation of the mortar is accomplished through the use of sodium hydroxide and sodium silicate. The mortar is created from a mixture of fly ash and sand. In order to determine the maximum load that a material is capable of bearing before experiencing failure, the compressive strength test was utilized. ResultsAccording on the findings of the compressive strength testing device, the fly ash geopolymer with 15 % barium sulfate (BaSO4) demonstrates the highest compressive strength, which is measured at 56 MPa. When compared to the results obtained from cement mortar, this one is twice as high, which indicates that the strength improvement factor is 2. This study's findings highlighted the necessity of employing fly ash geopolymer that contains 15 % BaSO4 for the purpose of providing shielding protection. Conclusion: Therefore, in terms of its performance, fly ash geopolymer is superior to cement mortar. This is due to the fact that it is manufactured with a high compressive strength.

Approaches for predicting the soil-water characteristic curves of compacted quartz sand based on particle packing theory

The soil-water characteristic curve (SWCC) is an important basis for describing hydraulic properties, which is closely related to environmental problems such as the migration of toxic substances from groundwater and soil. The SWCC models vary considerably with respect to the void ratio or bulk density. However, the void ratio and bulk density of the same soil change at different depths or positions within a flat space. Accurate simulation or calculation requires a precise SWCC, but measuring every SWCC under each density or void ratio condition is difficult. In this study, two particle packing models, the Kwan model and the modified linear packing density model (MLPDM), were introduced into the van Genuchten (VG) model to predict the SWCC for soil at the minimum void ratio (the maximum dry density). Then, the prediction method of the SWCCs for the same soil with different densities or void ratios was given. A series of laboratory tests using quartz sand mixtures were conducted to verify the accuracy of two extended models (the K-VG model and the M-VG model). For the K-VG model, the average RMSE was 0.020. For the M-VG model, the average RMSE was 0.017. In general, the SWCCs predicted by the two extended models were consistent with the measured values.

Influence of fines and gravel particles on strength-dilatancy of river sand: Effect of depositional conditions

Understanding the effects of low plastic fines and gravel contents on the mechanical behavior of sandy soils in terms of the strength-dilatancy relationship is crucial for various geotechnical applications. To gain deeper insights, an extensive series of direct shear tests were performed on two distinct types of mixtures: sand-fines mixtures and sand-gravel mixtures. The study systematically varied Fc/Gc content from 0% to 30%, using dry and wet methods, at a medium density (Dr = 50%) and a range of normal stresses (σn = 100–300 kPa). The experimental findings provide remarkable trends. For dry pluviated specimens, an increase in fines content led to a decrease in the shear strength of the mixtures. Conversely, the wet deposited specimens exhibited an opposite tendency, where higher fines content induced larger shear strength. Notably, the incorporation of gravel substantially improved the mechanical performance of the sand mixtures, regardless of the preparation method employed. Dry pluviated specimens generally exhibited higher shear strength than that of the wet deposited ones for the same Fc/Gc. A developed set of equations has been suggested to predict the strength-dilatancy relationships for all-tested materials. These equations take into account the impacts of fines and gravel contents and both specimen preparation methods.

Influence of soil-contaminated water on clogging phenomenon of pervious concretes with different void contents

In many circumstances, water passing through pervious concrete (PC) is contaminated with soil sediments. In such cases, clogging of the PC with soil sediments affects its functional characteristics and service life. The clogging behaviour of PCs with different void contents under the influence of soil-contaminated water is not yet clearly understood. Therefore, the effects of three different kinds of soil-contaminated water (water contaminated with sand, clayey silt and a mixture of sand and clayey silt) on the pore clogging of PCs with different design void contents (DVCs) were examined. For the three types of PC with different DVCs, three different concentrations of soil-contaminated water were used to examine the clogging process. The clogging process was executed until the minimum permeability level of the PC was reached. The effectiveness of washing on the de-clogging behaviour of each clogged PC was also examined. Various characteristics of the different DVC-based PCs (strength, permeability, macroscopic pore distribution and leaching parameters) were assessed. The outcomes of this work disseminate consensus behaviour of PC, which should be helpful to provide a conceivable solution to develop desirable performance of PC for wide applications.

Mechanical behaviour of granular materials undergoing grain dissolution

Geotechnical engineering projects are often at risk from threats related to mineral dissolution and loss of particles that constitute the matrix of the geomaterial. Moreover, the impact of climate change can exacerbate these risks by accelerating the physical processes. To address such challenges, it is a pre-requisite to understand and quantify the effect of mineral dissolution on geomechanical behaviour. A general theoretical approach to mechanical consequences of geomaterials experiencing mineral dissolution was first proposed. Following, a series of oedometer tests were conducted using mixtures of salt and sand with various salt contents to observe and characterise the effect of dissolution on the mechanical behaviour of granular materials. The dissolution of salt crystals was performed in three different stress states to observe the stress-dependent response of the material. The effect of dissolution was dependent both on the amount of dissolved salt particles and the applied stress state. The laboratory experiments and the discussion followed shares insights into the effect of grain dissolution on the mechanical behaviour of granular materials and proved the potential of the framework presented in this paper. Finally, the paper ends by discussing the engineering implications bearing in mind the climate change we are facing today.

First report of Rhizoctonia blight caused by Rhizoctonia solani on Chinese cabbage (Brassica rapa subsp. chinensis) in India.

During January and February 2021, foliar blight symptoms were observed on the leaves of Chinese cabbage (Pak choi) at Lembucherra research farm, College of Agriculture, Tripura, India. The incidence of disease symptoms ranged from 5 to 10% of the plants observed in the field. The symptomatic leaves showed grayish colored water-soaked lesions with an irreguar shape and size. A total of 10 symptomatic leaves (1 leaf per plant) from Chinese cabbage infected plant were sampled, surface decontaminated with 1% NaOCl, washed twice in sterile water, plated on 2% water agar, and incubated at 25 ± 2°C. Hyphal tips from mycelium of 7-day old culture (2 isolates from two different plants) with right-angled branching were transferred to potato dextrose agar (PDA) media (SRL, India). Cream or light brown hyphae that branched at right angles, with septa near the point of the origin of hyphae, and a slight constriction at the base of the branch) were visible under a microscope. Olive-brown sclerotia were observed after 5 days of incubation. Multiple nuclei per cell were visible after staining with 4', 6-diamidino-2-phenylindole (Estandarte et al. 2016). Based on morphological characteristics (Parmeter et al. 1970) the isolates TP36 and TP37 were identified as Rhizoctonia solani. The internal transcribed spacer (ITS) region and glyceraldehyde-3-phosphate dehydrogenase gene (GAPDH) were amplified with ITS1& ITS4 (White et al. 1990) and (GAPDH F-5'- CAAGGAGAACCCAGGTGTTAAG-3' and GAPDH R- 5'-GGCGTCGAAGATAGAAGAGTGT-3') respectively for both isolates and sequenced (accession #. PP458158, PP458159, PP425343, PP425344). BLASTn analysis showed 99.26%( 668/673 nt) to 99.46% (659/664 nt) identity with R. solani sequences (GenBank MG397062.1 and KX674524.1) for ITS and 98.42% (552/562 nt) to 100% 540/540 nt)identity with R. solani sequences (GenBank HQ425709.1 and CP102644.1) for GAPDH. Isolates TP36 and TP37 were deposited in the Indian Type Culture Collection (ITCC), New Delhi as R. solani (nos. 9154 and 9319, respectively). Both isolates were amplified using (anastomosis group) AG1 subgroup specific primers (Matsumoto 2002; Prashantha et al. 2021) to identify their AG. The presence of a 265 bp amplicon for both isolates suggested that they belong to AG1-IA. A multilocus analysis of R. solani isolates from different host plants with concatenated sequences ITS and GAPH showed that TP36 and TP37 are closely related to rice isolate RS107. A pathogenicity test on five plants per treatment was conducted and repeated twice on one month old Chinese cabbage plants (hybrid, TOKITA, India) grown under glasshouse conditions in a sterilized mixture of soil and sand (3:1) at 27-28oC during January 2024 at ICAR-IARI, New Delhi. R. solani isolates TP36 and TP37 were grown on PDA and plants were inoculated by placing single sclerotia of 10-day old colony on different plant parts and covering it with moist cotton. After 7 day, typical lesions of R. solani infection were visible. No symptoms were observed on the control plants. The fungus was reisolated from the inoculated plants and identified as R. solani based on morphology. R. solani has previously been reported to cause disease on some members of Brassicaceae in different countries (Budge et al. 2009; Hua et al. 2014). Based on literature available this is the first report of R. solani infecting Chinese cabbage in India.

Effect of Various Potting Media on the Growth and Root Development of Bougainvillea (Bougainvillea spp.) Cuttings

The study aims to enhance the propagation efficiency of Bougainvillea, a popular ornamental plant, by evaluating the effects of different potting media on its growth and root development. The experiment was conducted over 180 days using Bougainvillea hardwood cuttings and was arranged in a Randomized Block Design (RBD). The study revealed that a mixture of soil, sand, FYM, and vermicompost significantly improved plant height, stem girth, number of branches, number of leaves, leaf area, root weight, and survival rate compared to other treatments, highlighting its potential as an optimal potting medium for Bougainvillea propagation.The highest root length was recorded in the combination of Soil +Sand + Rice husk (1:1:1).

Properties of a Sand and Bentonite Mixture as a Material for Spot Seals of Low Flood Embankments in the Area of Żuławy Elbląskie

Properties of a Sand and Bentonite Mixture as a Material for Spot Seals of Low Flood Embankments in the Area of Żuławy Elbląskie

Gas flow in frozen hydrate-bearing sediments exposed to compression and high-pressure gradients: Experimental modeling

Changes in temperature and pressure patterns in gas- and hydrate-saturated permafrost caused by natural geodynamic processes or human impacts can lead to the active flow of gas through unfrozen zones, and its explosive emission is often accompanied by crater formation. Gas flow and accumulation in the shallow permafrost can be explained by the conditions of gas pressure equal to or exceeding the overburden pressure and high-pressure gradients. For the first time, filtration tests were conducted on ice- and hydrate-saturated rocks under uniaxial compression at various negative temperatures using a developed methodology. The modeling of gas flow in a mixture of ice-saturated sand and 25 % montmorillonite at gas pressure gradients within 2 MPa, shows that gas flow can start at warm negative temperatures near the thaw point. Pore hydrate formation in frozen sand heated to positive temperatures and frozen back led to a linear decrease in gas permeability by up to eight times. However, the behavior of gas permeability during hydrate dissociation is nonlinear as it increased within a few hours after the onset of dissociation, but then decreased exponentially in the following 24 h.

Theoretical Basis for Forecasting the Expansion of the Diameter of the Leading Well in Water-Saturated Soil with a Crushed Stone Bored Pile

In the process of construction and operation of buildings and structures located on weak water-saturated clay foundations, there is often a need to change their physical and mechanical properties. Currently, various methods of surface and deep compaction are used to improve the characteristics of weak soils. It is known that in the process of deep compaction, the soil is compressed under the action of radial stress on the wall of the leading well using an auger (in reverse motion), pile foundation technology, a rotor, etc. In this paper, the main attention will be paid to solving the axisymmetric problem of consolidation of a soil cylinder under the influence of radial pressure. The diameter of the well in this case increases by 2–3 times and is filled with working material – sand and gravel mixture. The purpose of this study is to carry out a theoretical analysis based on a different approach to solving the problem of the stress-strain state of weak soil during compaction of weak foundations and determining the required characteristics of the compacted composite massif transformed by a bored crushed stone pile. The results of the study convincingly prove that the technology under consideration, based on the expansion of the diameter of the leading borehole in water-saturated soil using crushed stone pile drains, is one of the most cost-effective and efficient solutions. It can compete with traditional compaction methods and the more expensive use of deep foundations.

Nature‐based shoreline protection in newly formed tidal marshes is controlled by tidal inundation and sedimentation rate

AbstractMany tidal marshes have been lost by past land use changes, but are nowadays increasingly restored and created to provide valuable ecosystem services such as nature‐based flood and erosion protection along estuarine shorelines. To be functional for flood and shoreline erosion protection, restored and created tidal marshes should develop erosion resistant sediment beds. Here, we investigated which factors drive the spatial variations in sediment strength and erosion resistance in a developing tidal marsh restoration site. Our results show that decreasing tidal inundation frequency, decreasing sedimentation rate, and better drainage led to stronger consolidation in deeper sediment layers. This consolidation resulted in greater sediment strength, quantified here by shear strength and penetration resistance. Generally, sediment strength was greater when sediment had higher bulk density, while a higher water and fine fraction (= clay and silt) content decreased sediment strength. Overall, all measurement locations were relatively erosion resistant, likely caused by the dense root network and cohesive sediment. To restore or create resilient tidal marshes for nature‐based flood and shoreline erosion protection, we should thus aim for sites with relatively low tidal inundation frequency, moderate sedimentation rates, and cohesive sediment mixtures of clay, silt, and sand, which are well drained and have potential for vegetation establishment. These conditions have a high likelihood of resulting in restored or created tidal marshes that contribute to nature‐based flood and shoreline erosion protection.

Effect of Specimen Preparation on Shrinkage Behaviour of Compacted Bentonite–Sand Mixtures

Effect of Specimen Preparation on Shrinkage Behaviour of Compacted Bentonite–Sand Mixtures

Study on mechanical properties and corrosion damage mechanism of mixed sand concrete

In order to address the excessive utilization of river sand resources in Inner Mongolia, an investigation is being conducted on the utilization of wind-blown sand and machine-made sand for the production of mixed sand concrete. A study is conducted to examine the influence of including mixed sand in concrete on its mechanical qualities, working performance, and erosion resistant durability. The findings suggest that when the proportion of wind-blown sand in the mixed sand mixture increases, the compressive strength of the mixed sand concrete exhibits a general pattern of initially increasing and subsequently dropping. At a ratio of 1:1 between wind-blown sand and machine-made sand, there is a maximum point. Nevertheless, the capacity for stretching under tension, resilience, and the strength of the connection all demonstrate a consistent decline. The wind-blown sand content of 50 % in the mixed sand is the critical value. When the wind-blown sand content exceeds 50 %, the tensile deformation capacity, toughness, and bond strength experience a steep decline. Utilizing a combination of different types of sand diminishes the efficiency of concrete. Nevertheless, the efficacy of concrete can be enhanced by modifying the water-cement ratio and the quantity of water-reducing admixtures. It is worth mentioning that although the work performance can be improved, there might be a little reduction in the mechanical qualities of the concrete. The erosion depth in mixed sand concrete has a growth rate that is 0.027 mm/d lower compared to ordinary river sand concrete under erosion conditions. The compressive erosion resistance coefficient and saturated surface dry water absorption rate show significantly reduced damage in mixed sand concrete compared to standard river sand concrete. Moreover, when erosion-freeze-thaw coupling circumstances are present, the structural deterioration of mixed sand concrete is less significant in comparison to ordinary river sand concrete. By using a mixture of sand, the concrete's ability to withstand erosion is improved, resulting in a longer lifespan. This discovery establishes a theoretical foundation for the secure utilization of concrete in aquatic environments in Inner Mongolia.