Silt Content Research Articles

Exploring the temporal toxicity signature: A baseline evaluation of the heavy metal concentration in estuarine core sediments in the coastal region of cauvery delta, bay of bengal.

Globally, the concentration of heavy metals and sediment toxicity analysis are significant liabilities to aquatic environments. This scrutiny outlines the sediment textures, heavy metals and toxicity status associated with environmental pollution indices in the core sediment of the Cauvery and Vettar estuaries, East coast of India. The impact of rapid industrialization, urbanization, harbour activities and agricultural activities influences on the twain estuary is a significant concern to designate the environment. The contamination status of the sediments affects the potential biodiversity, ecological risks and human health. A total of two core sediments were recovered from the Cauvery and Vettar estuaries in March 2023 to decipher the environmental pollution status. Meticulous observation of the textural studies underscores the prevalence of sand content in Cauvery, and Vettar sediments consist of predominate clay content and minor silt contents. Furthermore, the organic matter is augmented in the Vettar River due to the higher input of waste disposal, seaweeds and algae due to the surrounding landmass. Twain core sediments argue that heavy metal concentration is decreasing in order as Fe > Zn > Ni > Pb > Cu > Cr by using portable X-ray fluorescence (pXRF) spectrometry. Remarkable results of environmental pollution indices such as Igeo, Ef, Cf, Cd and mCd state very highly polluted, extreme enrichments, high contamination and very high degree of contamination. Furthermore, the potential ecological risk indices such as PLI, SQGs, and PERI argue polluted, medium to high toxicity and moderate adverse ecological risk to the estuarine regions. Statistical analysis of the heavy metal affirms the enrichment of Fe metals may derive from lithogenic and/or anthropogenic influences, and the other studied metals such as Cu, Ni, Zn, Pb and Cr may be influenced by the anthropogenic activities in the aspect of point and non-point pollution sources. This could result from both estuaries undergoing higher pollution, in which the Vettar estuary is a considerable environmental risk zone compared to the Cauvery river due to the impact of industrial effluents and rapid urbanization activities. This finding underscores the urgent need for enhanced estuarine sediment quality study and comprehensive assessment of sediment toxicity, regulating the beneficial acumen for the government to follow the suitable remediation on the embellish policy of river and marine environments.

Landscape and soil cover diversity in Polissia and Forest-Steppe of Ukraine

Recent research has revealed the patterns of spatial and temporal variability of crop yields for the Polissia and the Forest-Steppe regions of Ukraine. In addition, the approaches to differentiating agroeconomic and agroecological components in the variability of the productive potential of the territories were developed. Approaches have been developed to quantify the spatial and temporal variability of soil erosion for individual areas of the region. The issue of assessing the impact of erosion processes on crop yields at the regional level remains unresolved. The diversity of landscapes and soil cover in Polissia and the Forest-Steppe of Ukraine was assessed in this article. The research covered 10 administrative regions of the north and northwest of Ukraine, which are located mainly within mixed forests (Polissia) and the eastern European forest steppe (Forest-Steppe). Part of the territory is tangential to the Carpathian mountain forests and the Pontic steppe. Within the study area, 30 WRB soils were identified. The largest area is occupied by Phaeozems Albic (21.7% of the total area of the region). These soils are located mainly in the southern and central parts of the region. In the north of the region, Phaeozems Albic form an almost continuous cover, and to the north, the areas of these soils become island-like. Phaeozems Luvic cover 12.1% of the region's territory. The Phaeozems group also includes Phaeozems Gleyic (0.93%), Phaeozems Haplic (0.13%), and Phaeozems Sodic (1.78%). Albeluvisols Umbric (17.1%) occupy a significant part of the region's territory. These soils occupy the north of the region and extend south along the Dnipro River floodplain. Spatially close to these soils are Albeluvisols Gleyic (12.8%). In the western part of the region, in Prykarpattia, there are Albeluvisols Stagnic (0.82%). The organic carbon content in the soils of the administrative districts of the region in the 0-5 cm layer was 5.2±3.3% and ranged 0.5% to 23.9%. In the layers of 5–15 and 15–30 cm, this figure decreased to 1.9 ± 1.1% and 1.9 ± 1.0%, respectively. In the 30–60 cm layer, the organic carbon content was 1.4 ± 0.8% and ranged 0.1% to 6.1%. The lowest organic carbon content was observed in the north central part of the region, and the highest content was observed in the north-east and north-west of the region. In the south of the region, there was found a strip of soils with moderate organic carbon content. The lowest content of organic carbon is characteristic of Albeluvisols and Podzols, which are located in the north of the region. In turn, the highest content of organic carbon is characteristic of organogenic Histosols, which, together with Albeluvisols and Podzols, form the basis of the soil cover structure of the territories in the northeast and northwest of the region. It should be noted that the agronomic role of these soils is insignificant, and their organic carbon content cannot be considered as a traditional indicator of fertility. Nevertheless, organic carbon is a reliable indicator of the anti-erosion properties of both natural and agricultural soils. The organic carbon content of Chernozems is quite high, which is a factor in the high fertility of these soils and their importance in agricultural production. The organic carbon content of Fluvisols and Gleysols is naturally high. The importance of these hydromorphic soils is due to their high productive potential, which ensures their use in agriculture. It is also worth noting their high seed protection potential. Phaeozems cover a large area of the region and contain a high level of organic carbon. These soils form the basis of agricultural production and forestry in the region. The silt content in the region's soils measured 45.6 ± 8.5%, ranging 19.1% to 57.6%. The north of the region is represented by soils with the lowest silt content (19–41%). In the center, in the west of the region, there is a zone with the highest silt content (53–58%). In other parts of the region, there are transitional levels of silt content in the soil. The clay content in the soils was 30.7 ± 13.8% and ranged 7.4% to 36.0%. The zone with the lowest clay content in soils has been formed in the north. The highest clay content in soils is typical for the southern part in the center of the region. The sand content in soils is highest in the northern part of the region, and the lowest in the southwestern and southern parts of the region.

Soil Chemical and Physical Properties in Taungya and Non-Taungya Plots at Sao Hill Forest Plantation, Tanzania

This study compared soil physical and chemical properties in Tungya and Non-Taungya plots at Sao Hill Forest plantation, Tanzania. Soil samples were collected from 0-20cm depth in February and May Using a zigzag pattern to ensure representative coverage. Physical properties (bulk density, porosity, Soil moisture content, soil texture) and chemical properties (soil pH electrical conductivity, total nitrogen and available phosphorous) were analyzed using standard laboratory methods. Results showed significant differences between the two management practices. In February Non-Taungya plots had higher bulk density(1.33±0.151/cm3) compared to Taungya plots (1.16±0.107 g/cm3; p<0.001), while Taungya plots showed higher porosity (56.12%±4.06p<0.001). May sampling also revealed differences with non-Taungya plots maintaining higher bulk density (1.32±0.15 g/cm3) compared to Taungya plots (1.08±0.09 g/cm3); p<0.001). Soil texture analysis showed no significant differences in sand content between treatments. However, silt content was significantly higher in Taungya plots (13.27 ± 3.849%) compared to non-Taungya plots (10.69 ± 3.23%; p=0.007), while clay percentage did not differ significantly. Soil chemical properties, non-Taungya plots had higher pH (4.67±0.47) compared to Taungya plots (4.3±0.22; p<0.001) while electrical conductivity (0.04±0.04 dS/m) compared to Taungya plots (0.01±0.01 dS/m; p<0.001). Taungya plots showed higher total nitrogen (0.04±0.01%; p<0.0031) compared to non-Taungya plots (0.035±0.01%). In additional May available phosphorous in Taungya plots was (3.95±0.55 mg/kg; p<0.001) compared to non-Taungya plots (1.97±0.32 mg/kg). These results suggest that Taungya practices significantly influence soil properties, potentially impacting soil quality and forest productivity. The study provides valuable awareness for sustainable forest management and highlights the need for long-term monitoring of soil properties under different management systems in plantation forests

Tree mortality by ecological groups in the amazon region: Influence of forest structure, soil characteristics, and extreme climatic events after logging

Mortality of remaining trees tends to increase after logging, and adapting forest management to climate change is another significant challenge to ensure the sustainability of forests, timber production, and provision of ecosystem services. This study investigated mortality in remaining trees (DBH ≥ 20 cm) in different ecological groups (pioneer, light-demanding, and shade-tolerant) during different phases of forest monitoring (initial, intermediate, and final), as well as their relationship with structural, climatic, and environmental characteristics. The research was conducted in five managed areas in the Brazilian Amazon (Jari, Km114, Km67, Peteco, and Moju) with continuous monitoring over six to 33 years. We analyzed a total of 212 permanent plots containing 62 pioneer species, 250 light-demanding species, and 304 shade-tolerant species. The mortality rate for the three monitoring phases in logged forests was 1.27 %, 1.49 %, and 0.75 % year−1, respectively, while the rate in unlogged forests was 1.04 %, 1.33 %, and 0.50 % year−1. In post-logging forests, mortality was high for pioneer and light-demanding species, especially in the initial phase. For shade-tolerant species, mortality rate was influenced by soil silt and sand content, presence of phosphorus, and total carbon content. In unlogged forests, forest structure variables such as average height and total basal area, soil characteristics like phosphorus content, and climate factors such as intensity of dry months were most important for pioneer and light-demanding species. In the intermediate and final monitoring phases in logged forests, tree mortality was related to soil characteristics like sand and clay content, total carbon, and cation exchange capacity. Extreme climatic events such as severe drought, El Niño, and extreme temperatures also influenced tree mortality, along with time elapsed after logging. These findings highlight the complex interaction between soil characteristics, climate, and forest structure and tree mortality and ecology. These correlations are crucial to understand mortality processes in logged and unlogged forests, underscoring the importance of these factors for managing and conserving these ecosystems in the face of extreme climatic events and forest management practices.

Strength characteristics and solidification carbonization mechanism of MgO based shield tunneling centrifugal waste silt

In response to the problem of the accumulation of waste silt produced by slurry shield tunneling, which is difficult to directly utilize, MgO carbonization acceleration technology is adopted. Carbonization modification equipment is used to test the water content (w) and unconfined compression strength (UCS) of waste silt produced by slurry shield tunneling under different soil curing agent content (as), curing time (T), and carbonization time (t). The strength characteristics of the process of MgO solidification carbonization shield tunneling centrifugal waste silt were clarified. The micro mechanism was revealed and its engineering usability was also explored. The results show that MgO cooperated with carbonization acceleration technology can improve the properties of waste silt, with a maximum decrease of 9.3∼31.7 % and UCS can be increased to a maximum of 776.8 kPa. The maximum UCS of MgO solidified carbonized silt was higher than that of CaO solidified carbonized silt at various contents. Under the condition of T=7d, by comparing UCS, it was concluded that MgO carbonated solidified silt is more suitable for building foundation filling. And as =7 % while t=1 h modified silt can meet the strength requirement of 180 kPa under the condition of small MgO content. An improved three-phase model diagram of MgO solidification carbonation process based on water conversion research has been proposed for centrifugal high liquid limit silt in slurry shield tunneling. It can be divided into three stages: solidification reinforcement, carbonation reinforcement, and carbonation deepening, with strength growth mainly concentrated in the solidification reinforcement stage. During the solidification process, the hydration product Mg(OH)₂ and the reaction products MSH and MAH from the pozzolanic reaction are gradually transferred into various carbonization products, These products agglomerated and bonded with each other to form a whole, enhancing the bonding strength between particles and improving the strength of the silt. During the carbonization process, it is necessary to avoid the strength reduction caused by too long carbonization time.

Distinct features of topsoil carbon fractions across urban forests in eastern China

AbstractRapid urbanization has increased the areas of urban forests that store considerable soil carbon (C). Different soil C fractions may show distinctive contents and spatial patterns in view of their contrasting sensitivities to various drivers. However, current studies on soil C fractions are mostly limited to natural ecosystems and little is known about the large‐scale patterns and drivers of soil C fractions in urban forests. Based on a field survey of urban forests across a north–south transect in eastern China, we analysed the spatial variations and main drivers of topsoil (surface layer, 0–10 cm; subsurface layer, 10–20 cm) C fractions (i.e., soil organic C, SOC; soil inorganic C, SIC; particulate organic C, POC; mineral‐associated organic C, MAOC). Our results showed that topsoil contents of POC, MAOC and SOC changed non‐linearly with latitude, with lowest values occurring in the cities in the warm temperate region. In contrast, SIC content showed the highest values in the warm temperate region. POC instead of MAOC was found to be a major fraction of SOC in urban forests. The spatial variation in topsoil POC content was mainly explained by mean annual temperature, soil clay and silt content, and park age. The spatial variation in MAOC content was mainly explained by soil clay and silt content, mean annual precipitation, mean annual temperature and park age. In contrast, the spatial variation in SIC content was mainly explained by mean annual precipitation and soil pH. These findings demonstrate distinct features of different soil C fractions in urban forests and provide useful implications for urban soil carbon management.

Soil and stone terraces offset the negative impacts of sloping cultivation on soil microbial diversity and functioning by protecting soil carbon

Cultivation of sloping land is a main cause for soil erosion. Conservation practices, such as soil and stone terraces, may reduce the impacts of erosion but their impacts on soil microbial diversity and functioning related to carbon (C) and nutrient metabolisms remain unclear. This study was conducted to evaluate the effects of slope gradients (5°, 8°, 15°, 25°) and conservation practices (cultivated, uncultivated, soil terrace, and stone terrace) on bacterial and fungal diversities, metagenomic and metabolomic functioning associated with basic soil properties. Our results showed that steep slopes at 25° significantly decreased soil pH, silt percentage, and bacterial and fungal abundances, but that soil and stone terraces increased soil organic C (SOC), silt and clay contents, and fungal abundance compared to sloping cultivated lands. In addition, soil and stone terraces increased both bacterial and fungal alpha diversities, and relative abundances of Crenarchaeota, Nitrospirota, and Latescibacterota, but reduced the proportions of Actinobacteriota and Patescibacteria, thus shifting microbial beta diversities, which were significantly associated with increased SOC and silt content. For metagenomics, soil and stone terraces greatly increased the relative abundance of functional genes related to Respiration, Virulence, disease and defense, Stress response, and nitrogen and potassium metabolisms, such as Denitrification and Potassium homeostasis. For soil metabolomics, a total of 22 soil metabolites was enriched by soil and stone terraces, such as Lipids and lipid-like molecules (Arachidonic acid, Gamma-Linolenic acid, and Pentadecanoic acid), and Organoheterocyclic compounds (Adenine, Laudanosine, Methylpyrazine, and Nicotinic acid). To sum up, soil and stone terraces could reduce some of the negative impacts of steep slope cultivation on soil microbial diversity as well as their metagenomic and metabolomic functioning related to C and nutrient metabolism useful for soil health improvement, potentially bolstering the impact of sustainable practices in erosion hotspots around the world.

WITHDRAWN: Characterization of soil response in mining with grouting into overburden bed-separation based on similar material simulation

Revealing the response laws of soils under various mining conditions is of significance for the scientific protection of farmland in mining areas. To avoid the interference from the spatial heterogeneity of natural soil on the research results, similar simulation experiments were employed. Two models for soil responses under mining with and without grouting into overburden bed-separation were designed, and monitoring was conducted for soil quality factors (moisture content, silt and clay content, and bulk density) and surface deformation factors (subsidence, inclined, and horizontal deformation). The results indicate that it can significantly control surface subsidence in mining with grouting into overburden bed-separation, the maximum subsidence value was reduced by 66.67%, the average subsidence value of each measuring point in the main section was reduced by 78.92%, and the subsidence area was reduced by 34.68%. The coefficient of variation of soil quality factors in the mining-affected area was obviously higher than that in the control area and the initial value before mining. Compared with mining without grouting, the variation coefficient of soil quality factor under mining with grouting was reduced by 2.71-6.79%. Soil quality factors and surface deformation factors show a significant quadratic function relationship, among which horizontal deformation has the greatest influence on soil quality factors, followed by subsidence and inclination. Therefore, it can effectively control surface subsidence and protect cultivated land when mining with grouting into overburden bed-separation.

Topography Controls Variability in Circumpolar Permafrost Thaw Pond Expansion

AbstractOne of the most conspicuous signals of climate change in high‐latitude tundra is the expansion of ice wedge thermokarst pools. These small but abundant water features form rapidly in depressions caused by the melting of ice wedges (i.e., meter‐scale bodies of ice embedded within the top of the permafrost). Pool expansion impacts subsequent thaw rates through a series of complex positive and negative feedbacks which play out over timescales of decades and may accelerate carbon release from the underlying sediments. Although many local observations of ice wedge thermokarst pool expansion have been documented, analyses at continental to pan‐Arctic scales have been rare, hindering efforts to project how strongly this process may impact the global carbon cycle. Here we present one of the most geographically extensive and temporally dense records yet compiled of recent pool expansion, in which changes to pool area from 2008 to 2020 were quantified through satellite‐image analysis at 27 survey areas (measuring 10–35 km2 each, or 400 km2 in total) dispersed throughout the circumpolar tundra. The results revealed instances of rapid expansion at 44% (15%) of survey areas. Considered alone, the extent of departures from historical mean air temperatures did not account for between site variation in rates of change to pool area. Pool growth was most clearly associated with upland (i.e., hilly) terrain and elevated silt content at soil depths greater than one meter. These findings suggest that, at short time scales, pedologic and geomorphologic conditions may exert greater control on pool dynamics in the warming Arctic than spatial variability in the rate of air temperature increases.

Impacts of land use and management methods on soil quality dynamics in central highlands of Ethiopia.

Land degradation often results in poor soil quality in many parts of Ethiopia, including the study area. To address this issue and promote sustainable land management practices, various land use and management methods (LUMMs) have been implemented. However, little information is available regarding how these management practices influence overall soil quality dynamics of the study area. This study aimed at evaluating soil quality dynamics in the Urago micro-watershed, central highlands of Ethiopia, under major LUMMs: barren land (BL), grassland (GL), established farm boundary (EFB), restored degraded land (RDL), and stone-supported soil bund (SSB). Forty-five disturbed and fifteenundisturbed soil samples were collected from the ploughed soil layer (0-20cm) of each LUMM and analysed for selected physicochemical properties to be used as indicators of soil quality. Principal component analysis and multiple correlation were used to select the minimum data set (MDS) to evaluate the overall soil quality index (SQI). The MDS included SOC, clay content, exchangeable Mg2+, and available P, which could replace other indicators for assessing the overall soil quality dynamics of the study watershed. The result showed notable variations in particle-size fractions, soil organic carbon (SOC), total nitrogen (TN), available P (av. P), and exchangeable Na+, K+, and Mg2+ levels among the LUMMs. RDL had higher sand and silt contents than SSB, whereas SSB had higher clay content compared to RDL, GL, and BL. GL, RDL, and EFB showed significantly higher levels of SOC, TN, and av. P, respectively, compared to other LUMMs. The obtained SQI showed that GL had the highest score (0.847), followed by SSB (0.703), RDL (0.701), EFB (0.644), and BL (0.628). This underscores the significance of stone-supported soil bund and restored degraded land as an efficient management method to enhance soil quality and agro-ecosystem through conserving soil and encouraging sustainable farming practices.

Mineralogical Vertical Distribution of Sediments for Selected Area in Basrah, Southern Iraq

The presence of clay in the sediments can lead to various engineering problems. For this reason, a study was conducted on both clay minerals and non-clay minerals to determine their distribution spatially and vertically and to analyze the grain size distribution. Sediments were studied in various locations in the Basrah Ring Road, to know the mineral diversity and grain size gradation in these deposits, 12 samples were collected from recent sediments to a depth of seven meters, and an analysis of grain size was done. The analyses revealed that the predominant component is silt, followed by clay, while the proportion of sand is very low. The main non-clay minerals in the study area are represented by quartz, calcite, dolomite, feldspar, and halite, whereas the mixed layers of montmorillonite-chlorite, kaolinite, palygorskite, and illite indicate the clay minerals. The montmorillonite and quartz are the main minerals in the clay and non-clay minerals, respectively. The predominant of quartz in the sediment is attributed to the higher silt content compared to clay in the study area.

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.

Hedgerows enhance the size selectivity of eroded sediment from sloping farmland under simulated rainfall experiment

AbstractThe particle size distribution (PSD) of eroded sediment can effectively reflect changes in erosion processes. Hedgerows provide significant soil and water conservation benefits and influence erosion processes. However, the impact of hedgerows on the PSD of eroded sediment remains unclear. Therefore, three slope conditions (control check, CK; only hedgerow root, R; and whole hedgerow, P) involving the configuration of two slope gradients (15 and 25°) were established, and simulated rainfall experiments were conducted under three rainfall intensities (60, 90, and 120 mm/h). The PSD, sediment sorting process, and sediment particle agglomeration degree under the different slope conditions were compared to evaluate the influence of hedgerows on the size selectivity of eroded sediment during water erosion. Moreover, the direct and indirect effects of hedgerows on the sorting process and sediment particle agglomeration degree were revealed via correlation analysis and partial least squares path modelling (PLS–PM). Compared with those under CK slope conditions, the average clay, fine silt, and coarse silt contents under R slope conditions decreased by 1.37%, 0.06%, and 1.71%, respectively, whereas the sand content increased by 0.46%. Under P slope conditions, the average clay, fine silt, and coarse silt contents increased by 32.61%, 38.71%, and 36.14%, respectively, whereas the average sand content decreased by 47.30%. Under CK slope conditions, sediment sorting occurred primarily during the early stages of rainfall. R slope conditions caused an increase in the duration of early‐stage sediment sorting but caused a reduction in the degree of sorting, whereas P slope conditions exhibited interceptive sorting of sand throughout the rainfall event. Under R slope conditions, more aggregates were dispersed into individual particles due to raindrop impact, whereas under P slope conditions, more fine particles aggregated initially, but loose aggregates were dispersed into individual particles during the later rainfall stages. The enrichment rates of fine silt and coarse silt were positively correlated with slope conditions, whereas they were negatively correlated with the enrichment rate of sand. However, there was no significant relationship between the slope conditions and the aggregation rates of particles of various sizes. PLS–PM indicated that hedgerows directly and indirectly affect sorting processes and sediment particle agglomeration degree by regulating runoff and sediment erosion, and the direct effects exceed the indirect effects. These findings provide a comprehensive understanding of the influential mechanisms of hedgerows on controlling soil erosion.

Skin Factor Test Experiment of the Combined Structure of Blind and Screen Pipes

During the drilling process of horizontal wells in offshore oil fields, when encountering highly clayey shale or sandy shale sections, a common practice is to use a combination of blank pipes and screen pipes in the completion column to isolate high clay content layers. This helps prevent significant clay blockage in the screen pipes or wellbore, thereby reducing production loss. However, when blank pipes cannot effectively isolate clayey or sandy shale sections, the migration of clay content can lead to screen pipe blockage, adversely affecting production capacity. Given the current lack of evaluation methods for the impact of combined blank and screen pipe completion columns on production capacity, an experiment was designed to evaluate the skin factor of the completion column with a combination of blank and screen pipes. Through the calculation of the skin factor, the variation patterns of the skin factor for completion columns with blank and screen pipes under different conditions were obtained. These findings were then applied to a production evaluation. The research results revealed the following: (1) As the proportion of blind pipes increases, the skin factor of the combination of blind pipes and screen pipes in the completion tubing also increases. Excessive blind pipe ratios reduce production capacity. (2) In cases where the annular space is not completely filled, the influence of the blind pipe proportion on production capacity can be negligible. However, when the annular space is 100% filled, a higher proportion of blind pipes and silt content results in a larger skin factor, which leads to reduced production. In the application of the XH horizontal well case study, using the calculated model for the skin factor of the combination of blind pipes and screen pipes in the completion tubing established in this paper, it was determined that when the annular space was not completely blocked and 20 m of blind pipes were not placed in the designated position, the impact on the production index was 0.73%. However, when the blind pipes were not placed in the designated position for 100 m, the impact on the production index reached 1.47%. The method developed in this paper provides theoretical guidance for the optimization of completion tubing in mudstone and sandy mudstone sections and for production evaluation.

Advancing soil property prediction with encoder-decoder structures integrating traditional deep learning methods in Vis-NIR spectroscopy

The technology for estimating soil properties using visible and near-infrared spectroscopy has been maturing, with corresponding advances and breakthroughs in deep learning models. In this study, based on the large soil spectral library LUCAS, we explore the potential of encoder-decoder structures to improve convolutional neural network regression predictions. By introducing an encoder-decoder structure into the feature channels of a six-layer CNN model (TRNN model), we significantly enhanced the performance of shallow CNN models and successfully carried out regression predictions for seven soil properties. We employed IntegratedGradients, DeepLift, GradientShap, and DeepLiftShap methods to interpret the output of the TRNN model. Our TRNN model, built on raw spectra, demonstrated high accuracy in predicting multiple soil properties, outperforming residual architectures, LSTMs, various CNN architectures, and other traditional machine learning methods proposed in previous studies. We also investigated the impact of multi-task output structures (TRNN 1-M and TRNN M−M) and single-task output structures (TRNN 1-1) on model performance. For the TRNN model with an encoder-decoder structure, multi-task output structures resulted in a reduction in performance. The TRNN showed outstanding results in regression analysis of the seven soil properties selected in this study (cation exchange capacity, organic carbon content, calcium carbonate content, pH, clay content, silt content, and sand content), with R2 values exceeding 0.93 for all seven properties. Different soil characteristics correspond to different wavelengths, with multiple characteristic peaks commonly observed. This research convincingly demonstrates the enormous potential of combining large model architectures with traditional deep learning approaches for predicting soil properties, which could significantly advance precision agriculture.

Glomalin-Related Soil Protein Plays Different Roles in Soil Organic Carbon Pool Maintaining among Different Grassland Types

Glomalin-related soil protein (GRSP) is an important component of soil organic carbon (SOC), which can promote long-term SOC sequestration. However, GRSP distribution characteristics and its contribution to the SOC pool among different grassland types remain poorly understood. Therefore, six grassland types (alpine meadow, mountain meadow, temperate meadow steppe, temperate steppe, temperate desert steppe, and temperate desert) were chosen to evaluate the contribution of GRSP to the SOC pool and the factors that influence GRSP accumulation in the Irtysh River Basin in China. The results revealed that GRSP (EE-GRSP, T-GRSP) accumulated more in the 0–10 cm soil layer than in the 10–20 cm soil layer (p < 0.05). GRSP content was higher in alpine grasslands (15.69 mg·g−1) than in desert grasslands (5.45 mg·g−1). However, their contribution to the SOC pool exhibited an opposite trend, whereas GRSP-C/SOC even accounted for 11.88% in the desert grasslands. The redundancy analysis (RDA) showed that SOC was the top important positive regulator for GRSP accumulation both in the two layers (explanatory rate > 80%). Besides the SOC factor, the two soil layers had different factors in regulating GRSP accumulation. Changes in GRSP content in the 0–10 cm soil layer were more strongly associated with mean annual temperature (MAT), sand content, soil water content (SWC), and silt content. In contrast, in the 10–20 cm soil layer, GRSP content was more influenced by SWC, electrical conductivity (EC), and pH (p < 0.05). Additionally, the main factor in the GRSP content variation was the interaction between climate and soil in the two soil layers (explanatory rate > 80%). Our findings underscore the critical role of GRSP in facilitating SOC sequestration within desert grasslands and elucidate the primary factors driving GRSP distribution across varying soil depths.

Soil texture contributes to shaping comammox Nitrospira communities in rice-wheat rotation soils

Complete ammonia oxidizers (comammox Nitrospira) are intriguing discoveries that mark a significant milestone in the global nitrogen cycle. While numerous soil physiochemical variables have been identified as key influencers of comammox Nitrospira distribution, the role of soil texture in shaping these communities remains largely uncertain. Here, we explored the diversity, community structure of comammox Nitrospira, and their driving factors, including soil texture in 237 rice-wheat rotation soils. The results indicated that soil pH and texture were the primary factors influencing the Shannon diversity and richness of comammox Nitrospira. Comammox Nitrospira Shannon diversity and richness were positively associated with soil pH and silt content, but negatively correlated with clay content, suggesting that finer-textured soils harbored lower comammox Nitrospira diversity. Additionally, silt content emerged as the second most influential factor, after pH, shaping comammox Nitrospira community structure. Clade A.2 was found as the predominant comammox Nitrospira clade in rice-wheat rotation soils, representing 59.3 % of the total sequences. Clade A.2 exhibited a positive correlation with sand and clay contents but a negative association with silt content. Conversely, Clades A.3 and B demonstrated the opposite pattern. Overall, our study underscores the critical role of soil texture as a mediator of comammox Nitrospira diversity and community structure, emphasizing the need to consider soil texture in investigations of comammox Nitrospira.

Construction and Application of the Phaeozem Health Evaluation System in Liaoning Province, China

Soil degradation has led to a continuous decline in the quality of phaeozem, which is seriously threatening the foundation of national food security. Therefore, precisely evaluating the health status of phaeozem resources and their spatial and temporal variations are crucial for ensuring the effective implementation of soil degradation prevention and control strategies. In this study, soil data from 140 sites were collected, and eight physical and chemical indices (sand content, silt content, pedon thickness, organic matter, total potassium, total nitrogen, total phosphorus, and pH) were utilized to assess the soil health status of phaeozem in Liaoning Province. The results showed the following: (1) The minimum data set is aligned with previous research findings and effectively mirrors the soil’s health condition. (2) The substantial coefficients of variation observed for pedon thickness, sand content, and silt content across regions suggest notable differences, likely influenced by climatic variations, parent material differences, and anthropogenic activities. (3) The study area’s average soil pH of 6.39 indicates an overall acidic nature, potentially attributed to intense soil weathering and suboptimal fertilization practices. (4) The soil health index (SHI) ranged from 0.33 to 0.91, with an average of 0.62, which indicates that the majority of the phaeozem in Liaoning Province are in a sub-healthy state (SHI < 0.6 = unhealthy, SHI 0.6–0.8 = sub-healthy, SHI ≥ 0.8 = healthy). These sub-healthy areas are primarily located in hills, mountains, and the Liaohe Plain, and are significantly impacted by rainfall and wind erosion. Meanwhile, unhealthy areas are concentrated in the south and center of the province, characterized by fragile ecological environments and challenging agricultural conditions.

SOIL CONSERVATION STRATEGIES FOR THE REDUCTION OF BIODIVERSITY IN MOUNTAIN SOILS: EXAMPLE OF ULUDAĞ NATIONAL PARK

Uludag National Park in Turkey is famous for its rich biodiversity. The park serves as an essential habitat for a wide variety of flora and fauna and contributes significantly to the conservation of various species. This study examines biodiversity conservation strategies in Uludağ National Park. Soil samples were taken from 17 locations near the summit where endangered endemic plants grow. Analyses of the soil samples reveal the relationships between elevation and soil texture components. According to the soil analysis results, there was a weak positive correlation between elevation and silt content (r = 0.414) and a weak negative correlation between elevation and sand content (r = -0.375). These findings indicate that silt content tends to increase and sand content tends to decrease with increasing elevation. The geomorphological features and soil structure of Uludağ National Park were also an essential part of the research. The region's metamorphic mica schists, granites and marbles affect the soil's physical properties. For example, soils are generally sandy and permeable in areas where granite parent material is present. In contrast, areas where mica-schist parent material is distributed are less resistant and more susceptible to erosion. As a result, effective soil conservation strategies must be implemented to protect biodiversity in Uludağ National Park. These strategies are essential to reduce soil erosion, increase organic matter accumulation and minimise the impacts of climate change. Furthermore, community participation and adaptive management strategies must be adopted for sustainable development and resource management. This study provides essential information for biodiversity conservation in the Uludağ region and contributes to developing conservation strategies.

Laboratory investigation of the influence of fines content on the mechanical behavior of sand

The present article seeks to examine and discuss the experimental results that were obtained from a series of straight box shear tests. For this, different soils were prepared with clean sand, which was brought from the Wilaya (Province) of Chlef that is located in northern Algeria, mixed with silt from the same site, clay from the town of M'zilla or clayey loam that is composed half of this same clay and half of silt. The percentages of sand replacement by the selected additions were 0, 10, 20, 30, and 40% in mass ratio. The samples thus prepared were then tested with respect to dry shear, under the normal stresses equal to 100, 200, and 400 kPa. The results obtained showed that the shear strength of the sand from Chlef decreases when the silt content increases from 0 to 40%. With regard to the sand-clay and sand-silt-clay mixtures, it was found that the shear strength decreases until reaching a threshold value that coincides with the addition content of 20%. Then, beyond that value, it begins to increase as the addition fraction increases. Likewise, it turned out that cohesion increases with increasing silt content, while for sand-clay and sand-silt-clay mixtures, this cohesion increases until reaching a maximum value which coincides with the addition of 20% silt content. The same trend was observed for the variation of the direct shear strength, while the friction angle exhibited an inverse behavior.