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In the geotechnical engineering field, the rapid speed of urbanization triggers the need for direct measurements of sub-soil parameters through in situ testing, accompanied by instant results. At this juncture, the cone penetration test (CPT) is selected for this study. Here, an attempt is made to develop a correlation between cone penetration resistance (qc) and standard penetration blow count (SPT N) in order to predict a reference range of qc for cohesive (silty clay/clayey silt) sub-soil of different SPT-based consistencies. In this context, 25 CPT were conducted adjacent to conventional boreholes accompanied by SPT tests at eight important locations in West Bengal (WB) and Odisha (OR), India, focusing on infrastructure development. Primarily, sub-soil is characterized by bulk unit weight (γ) along with soil behavior type index (IC) estimated from the CPT and compared with the sub-soil profile identified from conventional boreholes. Further, a comparison of qc with SPT N is made to establish a correlation. Also, an attempt is made to tally the established correlation with the earlier correlations established for different regions. This study quantitatively establishes a quadratic correlation (R2 = 0.84) between qc and SPT N, which is found to be in good agreement with the previous correlations. Overall, the key findings of this study, i.e., the predicted range of qc, reveal a reliable method for assessing the consistency of cohesive sub-soil by virtue of the qc. However, this correlation is limited to soft to very stiff silty clay/clayey silt sub-soil formation. [ABSTRACT FROM AUTHOR]

Biopores formed by the actions of decaying roots of plants and soil fauna are essential for providing preferential growth pathways into deeper soil when the subsoil is compacted. Biopores help with rapid transportation of oxygen which increases microbial activity. These positive impacts help to increase the yield of crops even in adverse environmental conditions. However, the impact of biopores depends on various climatic and soil conditions. Understanding the mechanisms of different factors controlling the influences of biopores on the growth and development of plant roots is essential for getting more benefits in crop production. While several reviews have explored biopore-root interactions in crop production, there remains a lack of systematic studies on the factors influencing these interactions. In this review, we discussed different factors affecting the impacts of biopores on various crops in different situations based on current literature. It is also explained how we can maximize these impacts for getting benefits in sustainable crop production. Biopore improves the soil structure which has vital role on the growth of crops. On the other hand, clumping of roots within the biopores was also observed which may negatively affect crop growth. Similarly, biopores increase water infiltration as well as the leaching of nutrients. The influences of biopores depend on pore characteristics, abundance of biopores, moisture content, management practices, edaphic conditions, plant species etc. Understanding the factors influencing biopore-root interaction can contribute to improve root accessing into the deeper soil, enhancing their adaptation in stressful soil conditions. [ABSTRACT FROM AUTHOR]

Biogas slurry is increasingly adopted as a substitute for chemical fertilizer to improve soil fertility and control soil degradation. But little is known about its long-term effects on different soil layers. This study aims to test if biogas slurry substitution alters soil nutrients and aggregates differently in different layers and how the effects are influenced by straw return. A five-year field trial of a winter wheat–summer maize rotation was established to evaluate the effects of biogas slurry substitution [treatments: control without fertilizer (CK); chemical fertilizer (CF); 50% biogas slurry substitution (BSCF); 100% biogas slurry substitution (BS)] on two soil layers (0–20 and 20–40 cm) under equal N, P, and K fertilization in a Fluvisol. The result showed that compared with CK, fertilization was necessary to maintain soil available nitrogen (AN) and available potassium (AK) in the 0–20 cm layer. Also, fertilization had positive effects on soil EC, TN, and AP, especially in the topsoil. In terms of increasing the degree of water-stable macroaggregation, improving aggregate stability and reducing their crushing rates, CF was superior to biogas slurry substitution because of the greater accumulations of soil N, the most important physicochemical factor regulating soil macroaggregation and stability. The effects of biogas slurry substitution changed with soil layers. In surface soil, BD, water-stable macroaggregates, and aggregate stability significantly increased due to the positive regulatory effects of straw, AP, and EC; whereas in subsoil, they decreased. Inorganic fertilization with straw return functions well in soil structural degradation control and N fertility improvement, especially in the topsoil. Whereas in fields without straw return, biogas slurry substitution may be a feasible and economical choice to improve topsoil structure and also an excellent supplement to provide P and K. [ABSTRACT FROM AUTHOR]

Background and aim: Deep roots are important for crops to access water when the topsoil is dry. Root anatomy and activity play an important role in water uptake. However, little is known about the effects of root distribution and anatomical structure on water uptake and grain yield under different water conditions. This study aimed to reveal the contribution of deeper roots, root anatomy and root activity on grain yield and water use efficiency. Methods: A field experiment and Rhizobox experiment were performed to evaluate the effects of changes in root distribution, root anatomy and root activity on grain yield and water use efficiency under three water conditions. Three dryland wheat cultivars (BM1, CH58 and CH1) were compared. Results: BM1 formed a root system, which limited the acquisition of water in the subsoil, resulting in lower grain yield and water use efficiency in field and rhizobox experiments. In contrast, cultivars CH58 and CH1 exhibited greater root biomass and root length density in the subsoil, optimizing subsoil water uptake, thereby increasing grain yield and water use efficiency. CH58 had a smaller root diameter and vessel diameter, thicker cortex thickness, higher root cortex thickness-to-diameter ratio and higher root activity. Conclusion: This study demonstrated that, deeper roots, root anatomy and root activity are important traits in selecting wheat cultivars that maintain yield under low water conditions. Therefore, wheat crop development and breeding to improve grain yield should also consider optimizing root anatomy and improving root activity while promoting deep root development. [ABSTRACT FROM AUTHOR]

Water clarity on the inshore Great Barrier Reef (GBR) is greatly influenced by terrestrial runoff of suspended particulate matter (SPM). Catchment sediment tracing studies often do not extend into the marine environment, preventing the analysis of preferential marine transport. This study employs novel collection and sediment tracing techniques to examine the transport of the terrigenous ‘mineral’ component of plume SPM within the GBR lagoon for two flood events. Utilising geochemical, radionuclide and clay mineral analysis, we trace terrigenous mineral sediments > 100 km from the river mouth. We show that the SPM geochemistry is highly influenced by particle-size fractionation, desorption, and dilution within the plume, rendering traditional tracing methods unviable. However, the ratios of rare earth elements (REE) to thorium (Th) provide stable tracers of mineral SPM transported across the catchment to marine continuum and allow the identification of discrete catchment sources for each flood event. Plume sediment radionuclides are also stable and consistent with sub-surface erosion sources. [ABSTRACT FROM AUTHOR]

We present an integrated site investigation of a proposed estate with a view to generating baseline data required for safe design and construction of structures and groundwater schemes, installation and protection of utilities, and post-construction environmental issues. An electrical resistivity survey involving 1D and 2D imaging techniques was involved. The 1D resistivity imaging involved the Schlumberger Vertical Electrical Sounding (VES) with half current electrode spacing of 1–125 m, whose data were interpreted for layer resistivities and thicknesses using segment-by-segment curve matching and 1D forward modeling with W-Geosoft/WinSev 5.1 code. The 2D dipole-dipole resistivity imaging utilized 20 m dipole length and an expansion factor (n) ranging from 1 to 5. The 2D data were inverted to 2D resistivity images with DIPRO software. The 1D and 2D interpretation models delineated five subsurface layers comprising topsoil, fill, laterite, weathered basement, and fresh basement. The weathered basement is the main aquifer with thicknesses ranging from 11.9 to 64.4 m with prospect for groundwater development. The essentially lateritic subsoils in the upper 10 m with resistivity values generally > 450 Ωm are adjudged moderately to highly competent. The low-porosity/permeability lateritic layer overlying the weathered layer aquifer constitutes a sealant against infiltrating pollutant with the groundwater significantly protected. Except within the stream channel, the soils/subsoils are practically non-corrosive. [ABSTRACT FROM AUTHOR]

The high-speed rail networks are engineered to enable rapid and effective transit. They are expected to be fully functional even during adverse operational conditions such as heavy rain, fluctuating water level, and the dynamic nature of external loadings. However, several case histories and recent research development exhibited the limitations of the effectiveness of embankment stability confronted with severe and prolonged precipitation and adverse saturated subsoil conditions. Besides, the mechanism of shear reinforcement and the effects of soil–water characteristics on the dynamic stability of embankment needs to be better understood. Therefore, conducting dynamic analyses for high-speed railways (HSR) considering fluctuating saturated subsoil conditions is vital for railway embankment's structural robustness and operational serviceability. The presented study focuses on the dynamic analysis of an HSR embankment, considering the intricate interaction between pore pressure dynamics and associated deformations. The embankment positioned alongside the railway track is subjected to varying levels of precipitation and groundwater exposure. The analysis commences with a gravitational assessment, probing the embankment's behavior under the influence of both elastic and plastic properties inherent to the constituent soil layers. Employing a 2D dynamic inelastic framework, the study rigorously integrates the reciprocal influence of pore-pressure dynamics and deformation effects. This sophisticated analysis methodology leverages the OPENSEES framework. Implications of interaction between the degree and extent of saturation in the subsoil and associated embankment deformation are also discussed. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) persistence is predominantly governed by mineral protection, consequently, soil mineral-associated (MAOC) and particulate organic carbon (POC) turnovers have different impacts on the vulnerability of SOC to climate change. Here, we generate the global MAOC and POC maps using 8341 observations and then infer the turnover times of MAOC and POC by a data-model integration approach. Global MAOC and POC storages are 975 964 987 Pg C (mean with 5% and 95% quantiles) and 330 323 337 Pg C, while global mean MAOC and POC turnover times are 129 45 383 yr and 23 5 82 yr in the top meter, respectively. Climate warming-induced acceleration of MAOC and POC decomposition is greater in subsoil than that in topsoil. Overall, the global atlas of MAOC and POC turnover, together with the global distributions of MAOC and POC stocks, provide a benchmark for Earth system models to diagnose SOC-climate change feedback. Separating soil organic carbon into mineral-associated and particulate organic carbon enables a more accurate prediction of soil vulnerability to climate change. The authors generate the global atlas of stocks and turnover times of these two fractions. [ABSTRACT FROM AUTHOR]

The site investigation is a key part of the design of tunnel construction projects, as it provides accurate geotechnical parameters. A systematic site investigation, which consists of mainly in situ tests and laboratory sample tests, was conducted for the Haimen-Taicang river-crossing tunnel project on Yangtze River. This paper aims to analyze and compare the piezocone penetration testing (CPTU) and dilatometer test (DMT) results of both onshore and under-river subsoils to provide insights into the interpretation of the in-situ tests. The accuracy of well-documented interpretation methods based on CPTU and DMT was discussed. Current empirical correlations between in-situ test results and unit weight, undrained shear strength and constrained modulus of the subsoils were checked, and their site adaptability was discussed in detail. A series of site-specific correlations were derived based on the analysis of the in-situ tests and the comparison between the in situ tests interpretation and the laboratory results. In order to reduce the errors between testing locations caused by soil variability and get the consistent understanding of soil behaviors, CPTU–DMT correlations were reviewed and improved based on local testing results. [ABSTRACT FROM AUTHOR]

Large-scale digital soil maps are essential for rational and sustainable land management as well as accurate fertilizer application. This study focuses on digital mapping of soil properties, namely soil organic carbon (SOC), pH, nitrogen (N), phosphorus (P), and potassium (K) in Chernozem topsoil and subsoil. The study was conducted on two arable fields in the Cis-Ural forest-steppe zone of the Republic of Bashkortostan (Russia). The random forest algorithm in combination with terrain attributes and Sentinel-2A satellite data was applied for spatial prediction of soil properties. The root-mean-square error (RMSE) and coefficient of determination (R2) were used to determine the model performance. According to the Pearson correlation, a significant positive relationship between SOC and N content was found at all sites and depths (R = 0.76–0.92). A cross-validation revealed that SOC (R2 = 0.22–0.62, RMSE = 0.35–0.89%) and N (R2 = 0.16–0.60, RMSE = 21.11–36.6 mg kg−1) were best predicted among other properties at all depths using remote sensing data, whereas the performance of predictive models decreased with depth. However, a relationship between the content of some soil properties and their spatial distribution at study depths was observed, which can be used as an additional explanatory variable. We suppose that digital mapping of soil properties at the arable field scale should not be limited to topographic and remote sensing variables. Based on this information, the use of auxiliary variables, such as collocated soil information in combination with relief and remote sensing data can be effective in more accurately estimating the spatial distribution of properties across arable fields at different depths. Overall, this study provides valuable insights into spatial modelling of the vertical distribution of soil properties, highlighting the significance of remote sensing data at the arable field scale. The findings can be valuable for land managers, agronomists, and policymakers seeking sustainable land management practices and efficient fertilizer application, as well as for developing further mapping procedures for arable fields. [ABSTRACT FROM AUTHOR]

Purpose: Straw incorporation is an important management practice in global agriculture. However, present straw returning usually focus on returning straw into the topsoil, while neglecting the amendment of subsoil. The study aims to investigate the effect of different straw returning strategies on soil quality and wheat productivity, and to develop recommendations regarding sustainable agriculture. Methods: A 2-year field experiment was conducted to evaluate the effects of five straw returning strategies on the soil quality and wheat yield in a winter wheat-summer maize cropping system in the North China Plain. Soil quality is defined as an index approach, including soil physical, chemical, and biological properties. The five treatments were straw removal (SR), straw mulching (SM), straw incorporation into topsoil (SI), deep-ploughing straw incorporation (DP-SI) and deep-injected straw incorporation (DI-SI). Results: Our results showed that straw returning improved soil quality across 0–40 cm depth relative to SR. The DP-SI and DI-SIa (above straw cluster) significantly increased topsoil quality by 20.5–26.2% and 13.6–19.0% compared with SI and SM. The DI-SIa also enhanced the subsoil quality, which was characterized by a significant increase in soil nutrients, compared to other straw returning strategies. The soil quality of 0–40 cm layer under DP-SI and DI-SI was significantly higher than that of other treatments. In addition, a positive correlation between soil quality and wheat yield was observed. Thus, the higher soil quality under DP-SI and DI-SI improved the average wheat yield by 9.6% and 10.7% compared with SI, respectively. Conclusion: These results indicates that DI-SI may improve subsoil properties and wheat yields and is likely an effective measure for sustainable development of a wheat-maize rotation system. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) is a soil health indicator and understanding dynamics changing SOC stocks will help achieving net zero goals. Here we present four datasets featuring 11,750 data points covering co-located aboveground and below-ground metrics for exploring ecosystem SOC dynamics. Five sites across England with an established land use contrast, grassland and woodland next to each other, were rigorously sampled for aboveground (n = 109), surface (n = 33 soil water release curves), topsoil, and subsoil metrics. Commonly measured soil metrics were analysed in five soil increments for 0–1 metre (n = 4550). Less commonly measured soil metrics which were assumed to change across the soil profile were measured on a subset of samples only (n = 3762). Additionally, we developed a simple method for soil organic matter fractionation using density fractionation which is part of the less common metrics. Finally, soil metrics which may impact SOC dynamics, but with less confidence as to their importance across the soil profile were only measured on topsoil (~5–15 cm = mineral soil) and subsoil (below 50 cm) samples (n = 2567). [ABSTRACT FROM AUTHOR]

Many design guidelines have been proposed for piled embankments, most of which consider piles or columns as rigid inclusions. In this study, a small-scale physical model test was performed to investigate the load transfer mechanism of a geotextile-reinforced sand layer over a soft subsoil improved by semirigid columns. A multi-stage load was applied at the top of the sand layer until the columns started to yield. When the columns yielded, a reverse load transfer was observed. Vertical stresses were measured and analyzed in terms of efficacy and stress reduction ratio (SRR) with a comparison of existing design guidelines for assessing soil arching. Among the reviewed guidelines, the approach recommended by the Dutch guidelines provided the closest results to the experimental data, whereas the one adopted by the American guidelines predicted well the change in efficacy and SRR under different surcharge loads. However, the load transfer mechanism after the yielding of columns is beyond the scope of the existing design guidelines. In addition, it was found through regression analysis that the increment of vertical stresses on columns and surrounding soil followed an inclined line under partially undrained conditions during loading stages and a curve during consolidation. [ABSTRACT FROM AUTHOR]

The article focuses on formulation and substantiation of a problem of safe subsoil management in view of the more and more difficult geological and climatic conditions, as well as growing depth and scale of mineral mining. It is shown that the current basic and applied research has created prerequisites for a successful solution of this problem. In Russia these prerequisites are connected with finding energy-based mechanisms of origination and growth of high-stress concentration and destruction zones in rock masses and geomaterials which feature a hierarchical block structure and many phases, and show properties of open self-organizing geosystems in the tectonic stress and strain field. Using advances in nonlinear geomechanics and geophysics, and cloud technologies of Big Data, a new methodology, technologies and software systems are developed for shaping a multilayer geoinformation and monitoring system for diagnostics, control and prediction of the industrial and ecological safety of mining regions in Russia. [ABSTRACT FROM AUTHOR]

Bengkulu City in Indonesia is one of the areas prone to earthquakes, yet it has developed increasingly in the last five years. One of the prospective areas in Bengkulu City, called Singaran Pati, is located close to the Dendam Tak Sudah Lake, a natural tropical lake. This research aims to interpret geological characteristics for the spatial plan development in the study area. Microtremor measurement and site investigation are implemented to observe the geophysical and geological characteristics of the study site. Inversion analysis using Monte Carlo simulated annealing is conducted to generate a shear wave velocity profile. Based on the shear wave velocity, the identified bedrock surface is illustrated in a 3D geological model. A simple analysis of the natural period to estimate allowable structural building storeys is also performed. Results show that the depth of the bedrock surface is around 4.5–147 m. The study area is dominantly categorised as Site Classes C and D. Low- to medium-rise buildings are appropriate to construct based on the geophysical and geotechnical information. The findings can provide preliminary guidelines on geotechnical and geological information for the seismic site conditions in the study area in Bengkulu City. [ABSTRACT FROM AUTHOR]

Permafrost soils in the northern hemisphere are known to harbor large amounts of soil organic matter (SOM). Global climate warming endangers this stable soil organic carbon (SOC) pool by triggering permafrost thaw and deepening the active layer, while at the same time progressing soil formation. But depending, e.g., on ice content or drainage, conditions in the degraded permafrost can range from water-saturated/anoxic to dry/oxic, with concomitant shifts in SOM stabilizing mechanisms. In this field study in Interior Alaska, we investigated two sites featuring degraded permafrost, one water-saturated and the other well-drained, alongside a third site with intact permafrost. Soil aggregate- and density fractions highlighted that permafrost thaw promoted macroaggregate formation, amplified by the incorporation of particulate organic matter, in topsoils of both degradation sites, thus potentially counteracting a decrease in topsoil SOC induced by the permafrost thawing. However, the subsoils were found to store notably less SOC than the intact permafrost in all fractions of both degradation sites. Our investigations revealed up to net 75% smaller SOC storage in the upper 100 cm of degraded permafrost soils as compared to the intact one, predominantly related to the subsoils, while differences between soils of wet and dry degraded landscapes were minor. This study provides evidence that the consideration of different permafrost degradation landscapes and the employment of soil fractionation techniques is a useful combination to investigate soil development and SOM stabilization processes in this sensitive ecosystem. [ABSTRACT FROM AUTHOR]

Biological soil crusts (BSCs) are common in arid and semi-arid ecosystems and enhance soil stability and fertility. Highway slopes severely deplete the soil ecological structure and soil nutrients, hindering plant survival. The construction of highway slope BSCs under human intervention is critical to ensure the long-term stable operation of the slope ecosystem. This study investigated the variation rules and interaction mechanisms between soil nutrients and microbial communities in the subsoil BSCs on highway slopes. Bacterial 16S rRNA high-throughput sequencing was employed to investigate the dynamic compositional changes in the microbial community and perform critical metabolic predictive analyses of functional bacteria. This study revealed that the total soil nitrogen increased significantly from 0.557 to 0.864 g/kg after artificial inoculation with desert Phormidium tenue and Scytonema javanicum. Actinobacteria (44–48%) and Proteobacteria (28–31%) were the dominant phyla in all samples. The abundance of Cyanobacteria, Cytophagaceae, and Chitinophagaceae increased significantly after inoculation. PICRUST analysis showed that the main metabolic pathways of soil microorganisms on highway slopes included cofactor and vitamin, nucleotide, and amino acid metabolisms. These findings suggest that the artificial inoculation with Phormidium tenue and Scytonema javanicum could alter soil microbial distribution to promote soil development on highway slopes toward nutrient accumulation. [ABSTRACT FROM AUTHOR]

Background: Pelargonic acid is a non-selective herbicide derived from natural sources with a range of potential applications in areas where synthetic herbicides may be less acceptable. One such use area is weed control on railway tracks. To assess the potential leaching of pelargonic acid to groundwater for this specific use, we conducted degradation and sorption studies with soils from railway tracks and, for comparison, with a range of topsoils. Results: Degradation of pelargonic acid was very rapid in subsoils from railway tracks with half-lives (DT50) of < 1 day (geom. mean DT50, 5.8 h), and even faster in the selected agricultural topsoils (1.5 h). The starting concentration had a strong influence with much slower degradation at higher spike levels. Adsorption to the railway soils (alkaline soils with low organic matter content) was expectedly weak (Freundlich adsorption coefficients KF of 0.06–0.31 mL/g) and clearly stronger in the topsoils (0.2–40 mL/g). Organic carbon normalized adsorption coefficients (KFoc) ranged from 11 to 371 mL/g (all soils) and were pH dependent, consistent with the behaviour of weak acids. Computer modelling using the software PELMO and a set of scenarios for herbicide use on railway tracks developed for the authorisation in Germany yielded predicted environmental concentrations in groundwater of < 0.001 µg/L when parameterised with the adsorption and degradation endpoints from subsoils. Conclusions: The leaching potential of pelargonic acid may be considered low even in application scenarios with sandy soils with low organic matter content such as those found below railway tracks. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to investigate how changes in substrate availability (stimulating root exudate input) affect the temperature response (Q10) of soil organic carbon (SOC) mineralization across different soil profiles to increase our ability to predict the response of soil organic matter dynamics to climate change. Materials and methods: We sampled the topsoil and subsoil of two typical mineral soil profiles and one buried soil profile. Soils were incubated at 10–25 °C at 0.75 °C intervals, SOC mineralization rates were continuously measured with and without glucose addition, and Q10 was calculated. Results and discussion: Our results showed that Q10 decreased with increasing depth in typical mineral soils, but decreased before increasing with depth in buried soil. As expected, substrate addition significantly increased Q10 across soil depths; however, the magnitude of this increase (ΔQ10) differed with soil depth and type. Unexpectedly, in typical mineral soils, ΔQ10 was higher in topsoil than in subsoils, and vice versa for buried soil. ΔQ10 was negatively correlated with initial soil substrate availability (CAI) and positively correlated with soil inorganic N. Conclusions: Overall, our results suggested that increased substrate availability under climate change scenarios (i.e., increased root exudates with elevated CO2 concentrations) could further strengthen the temperature response of SOC mineralization, especially in soils with high inorganic N content or regions with high N deposition rates. [ABSTRACT FROM AUTHOR]

Based on PLAXIS 3D finite element software, a 34-floor multi-story building piling group foundation under vertical loads and large moments is examined. It comprises seven different strata with different properties, with groundwater located 19.6 m below ground level. In drained situations, the soil is modeled as hardening soil, while piles are modeled as embedded beams. The study involved extensive parametric analysis. It includes pile spacing-diameter ratios, number of piles, pile slenderness ratios, square or triangular pile layout patterns with equal or variable pile length, raft, pile, and subsoil load sharing, pile modeling as an embedded or volume pile, gap effects between rafts and subsoils, and type of pile connections to evaluate their effects on rectangular unpiled and pile raft foundations in planning under large moments and vertical loads. Analysis results show volume piles yield less raft settlement and pile moment than embedded piles. Further, moment load effects increased raft bending moments by 2.2, 5.4, and 6.1 and absorbed loads by 1.4, 1.7, and 2.2 ratios for 24, 40, and 60 pile groups, respectively. In square and triangle pile configurations, at specified pile spacing, raft bending moments decrease with pile length. In contrast, it increases as pile spacing decreases. Thus, s/dpile = 4 gives the highest bending moment, with its variation along pile lengths depending on the pile head's hinge or fixation. A 0.2-m gap between raft and subsoil allows piles to absorb 71% of the load and rafts 29%, compared to 65% for piles, 29% for rafts, and 6% for subsoil without a gap. [ABSTRACT FROM AUTHOR]

Mud volcanoes are geological structures observed throughout the world that arise from the upwelling of deep fluids along discontinuities in the subsoil. The detection of mud fluid migration pathways can be challenging, even when using Electrical Resistivity Tomography (ERT) as detectability issues may arise from complex geological settings. This paper presents new results from 2D and 3D ERT synthetic modelling for the investigation of the shallow, internal structure of terrestrial mud volcanoes. This study revealed the internal structure of the 'Cenerone-Pineto' mud volcano (Central Italy) and provided further clues as to its internal structure. The main results of the study are: the presence of a mud chamber, which represents the last phase of mud accumulation before final emission, not located beneath the crater but laterally offset, as well as the presence of a narrow, shallow feeder channel; these findings represent evidence of a much more complex structure than one would expect. This means that the mud volcano is not supplied with mud fluids directly from below as would be the case with an uprising of deep fluid along a near-vertical open fracture and that the shallow mud fluid reservoir is not correlated to the distribution of any mud volcano observed on the surface. Findings from this study are consistent with the observed structural features already noted in ERT and seismic field data collected at the 'Cenerone-Pineto' mud volcano and may be helpful in explaining the mechanisms and processes involved in mud volcanism in similar geological settings. [ABSTRACT FROM AUTHOR]

Between September and December 2021, the first subaerial volcanic eruption in the Canary Islands in 50 years took place on the island of La Palma. Since November 2021, we have been conducting a long-period magnetotelluric (MT) monitoring experiment at a site located 2.4 km east of the volcanic cone. Having continuously recorded data since then, the obtained dataset shows significant changes in resistivity over the fourteen months following the eruption: more than ± 20% in apparent resistivity and ± 2 degrees in phase. These temporal variations in electrical resistivity, recorded continuously using long-period MT during both the syn- and post-eruptive stages, have not been reported to date, making this dataset unique. Four estimated impedances have been selected as representatives of the major temporal changes observed and inverted to generate new 3-D resistivity models. The results provide novel key information on the spatiotemporal evolution of the subsoil's electrical resistivity, enabling the characterization of a set of structures acting as preferred magmatic fluid pathways. Therefore, our study highlights the strong potential of MT as a volcanic monitoring tool and provides new insights about the evolution of the fluid pathways during the post-eruptive stage. These findings enhance our understanding of the magmatic system and may contribute to volcanic hazard mitigation in the future. [ABSTRACT FROM AUTHOR]

Forest stand and environmental factors influence soil organic carbon (SOC) storage, but little is known about their relative impacts in different soil layers. Moreover, how environmental factors modulate the impact of stand factors, particularly species mixing, on SOC storage, is largely unexplored. In this study, conducted in 21 forest triplets (two monocultures of different species and their mixture on the same site) distributed in Europe, we tested the hypothesis that stand factors (functional identity and diversity) have stronger effects on topsoil (FF + 0–10 cm) C storage than environmental factors (climatic water availability, clay + silt content, oxalate-extractable Al–Alox) but that the opposite occurs in the subsoil (10–40 cm). We also tested the hypothesis that functional diversity improves SOC storage under high climatic water availability, clay + silt contents, and Alox. We characterized functional identity as the basal area proportion of broadleaved species (beech and/or oak), and functional diversity as the product of broadleaved and conifer (pine) proportions. The results show that functional identity was the main driver of topsoil C storage, while climatic water availability had the largest control on subsoil C storage. Functional diversity decreased topsoil C storage under increasing climatic water availability, but the opposite was observed in the subsoil. Functional diversity effects on topsoil C increased with increasing clay + silt content, while its effects on subsoil C were negative at increasing Alox content. This suggests that functional diversity effect on SOC storage changes along gradients in environmental factors and the direction of effects depends on soil depth. [ABSTRACT FROM AUTHOR]

Background: The intricate pathogenesis of metastatic neuroblastoma (MNB) and the lack of effective diagnosis model are two main reasons for higher mortality of MNB than that of non-metastatic neuroblastoma (non-MNB). Objective: The biofunctional variation of MNB was investigated to explore pathogenesis and diagnostic models were developed to improve the early diagnosis of MNB. Methods: The differentially expressed genes (DEGs) and the biofunctional variation of MNB were studied by analyzing the transcriptome of 39 MNB and 17 non-MNB tissue samples. In addition, a diagnostic model of MNB was developed based on logistic regression analysis using three DEGs. Results: A total of 1142 mRNAs showed significantly altered, of which 814 were upregulated and 328 were downregulated. GO analysis showed that the DEGs were mainly involved in tumor microenvironment (TME). KEGG analysis showed that the DEGs played biological roles mainly by participating in neuroactive ligand-receptor interaction. An early diagnosis model was constructed based on CGA, CXCL9 and UNC5D genes, with sensitivity of 93.3%, specificity of 80% and AUC of 0.907. Conclusions: The disorder of TME and the dysfunction of neuroactive ligand-receptor interaction are imperative pathogenesis for the occurrence and development of MNB, which can lay a foundation for further research of MNB. The non-invasive plasma model based on CGA, CXCL9 and UNC5D is expected to be used in NB metastasis diagnosis. [ABSTRACT FROM AUTHOR]

The construction history of a site is partially preserved underground and can be revealed through archaeological investigations, including excavations, integrated with earth observation (EO) methods and technologies that make it possible to overcome some operational limits regarding the areal dimensions and the investigation depths along with the invasiveness of the excavations themselves. An integrated approach based on EO and archaeological records has been applied to improve the knowledge of Machu Picchu. The attention has been focused on the first construction phase of Machu Picchu, and for this reason the investigations were directed to the imaging and characterization of the subsoil of the Plaza principal, considered the core of the whole archaeological area. Archaeological records and multiscale remote sensing (including satellite, UAS, and geophysical surveys) enabled the identification and characterization of the first construction phase of the site, including the preparation phases before building Machu Picchu. The interpretative hypothesis on the constructive history of Machu Picchu started from the identification and use of the quarry, followed by the planification and set of the drainage systems and by the next steps based on diverse reshaping phases of what would be the central plaza. [ABSTRACT FROM AUTHOR]

Background: The contribution of long-term fertilization to soil organic carbon (SOC) storage has been of great concern. To assess the effects of long-term fertilization on SOC storage and stability in top and sub-soil layers, soil samples were collected from a 29-year field experimental station in a typical paddy soil in southern China. The SOC storage of whole soil and SOC fractions was quantified at three soil depths (0–20, 20–40, 40–60 cm) under four treatments: no fertilization (Control), a combination of nitrogen, phosphorus and potassium (NPK), double the rates of NPK (2NPK), NPK plus manure (NPKM). Results: The increase of Cinput-total was significantly higher than that of SOC storage among different treatments (p < 0.05), indicating that soil fixation of exogenous carbon is limited. Besides, the SOC accumulation and sequestration rates patterned as NPKM > 2NPK > NPK, and these rates were higher at 0–20 cm depth as compared to other depth intervals. Furthermore, for the whole profile, the SOC storage of active pool was higher in the Control (39.6 t C ha−1) than in other treatment (36.2 t C ha−1, p < 0.05). Whereas, fertilization increased the SOC storage of passive pool, ranked as NPKM > 2NPK≈NPK > Control (p < 0.05), indicating that fertilization, especially organic combined with inorganic fertilization, improved SOC stability. From the perspective of soil layers, the difference of SOC storage among treatments for passive pool was mainly resulted from the difference at surface soil, and for active pool were the deeper layers. Additionally, manure application increased the difference among soil layers. Conclusion: This study concluded that non-fertilized treatment could improve the SOC storage of active pool especially in deep soil layers, while fertilization especially manure application could improve the SOC storage and stability in surface soil and increased the difference among soil layers. [ABSTRACT FROM AUTHOR]

Background and Aims: Biocrusts cover approximately 30% of the global dryland surface area, constituting a crucial atmosphere–soil interface. Bacteria living at this interface participate in almost all biogeochemical cycling processes that may profoundly alter soil and ecosystem multifunctionality and speed up ecosystem restoration. However, the successional dynamics of bacterial communities in both biocrusts and subsoil remain largely unclear. Methods: This study used α and β diversity assessments and molecular ecological networks to reveal the bacterial community succession in biocrusts and subsoil along a 65-year succession sequence (a succession of biocrust types ranging from cyanobacteria to lichens to mosses) on the southeastern edge of the Tengger Desert. Results: Our results showed that the bacterial α and β diversity and network complexity in the biocrusts and subsoil increased with succession. In the process of succession, there were distinct differences observed in bacterial community diversity and network complexity and stability between biocrusts and subsoil. In particular, the subsoil bacterial network properties, including nodes, links, average links per node, average clustering coefficient, connectance and relative modularity, were significantly higher than those of biocrust in late succession. Based on piecewise SEM, we also found that succession, soil physicochemical conditions, and biocrust bacterial community composition were the strongest direct drivers of subsoil bacterial community composition. The plant communities and biocrust bacterial community composition directly drove the network complexity and stability of the subsoil bacterial community. Conclusion: Our findings indicate that under the cover and protection of the biocrust layer, the diversity of the bacterial community in the subsoil layer increased more obviously, and the network was more complex and stable. This may emphasize the important roles of biocrusts as mediators of soil microbial communities. [ABSTRACT FROM AUTHOR]

In strong seismicity areas, the structures experience seismic excitations that are affected by earthquake source effects and their propagating path, local site effects, and soil–structure interaction effects (SSIE). This study explores the impact of SSIE associated with site effects (SE) on the seismic response of multi-story buildings through a frequency domain solution within the EC-8 and ASCE7-16 code provisions. Low-to-mid-rise multistoried buildings are selected via their slenderness ratio to form systems associated with a wide range of soil profiles simulated using the random field theory. Shaking intensity ranging from moderate to strong is considered through an appropriate range of seismic magnitudes and shows that when the superstructure interacts with the nearby subsoil layers, the ground shaking level either amplifies or reduces the structural responses depending on the site category and the structure's slenderness ratio. Results indicate that, in contrast to most common SSI investigations, seismic magnitude connected with the local geology affects the response of the structure and, in certain situations, makes SSIE unfavorable. The study's findings are presented in such a way that ratios can be utilized to show how SSIE differ from SE in terms of their impact on seismic base shear (BS) and roof displacement. [ABSTRACT FROM AUTHOR]

Integrated geophysical analysis using different methods along with a priori information from wells, is a proven approach to investigate the geology and the petro-physical characteristics of subsoil. We collected seismic and geoelectric data in an area located on the Adriatic coast in North-Eastern Italy, aimed at characterizing the quaternary sediments and the shallow geological structures. Compressional and shear-wave data provided information about geometry and velocity of the quaternary sedimentary succession, while geoelectric data provided information about the resistivity in the shallower formation, which strongly depends on the presence of groundwater (brine) and on its salinity. Clustering analysis allowed us to subdivide the study area into subdomains showing similar values of resistivity and compressional- and shear-wave velocity, enabling for a better interpretation of the processed seismic sections. Then, we calculated the petro-physical properties of the investigated sediments, i.e., brine saturation and resistivity, porosity, and clay content, for each cluster. This inverse problem involves rock-physics theories and an optimization algorithm based on the simulated annealing global-search method. The results, validated using borehole stratigraphy, provided information about the salty water wedge intrusion. [ABSTRACT FROM AUTHOR]

Background and Aims: Root restricting layers often hinder crops from accessing the large reservoir of bioavailable mineral nutrients situated in subsoil. This study aims to explore changes in the mean nutrient uptake depth of cereal crops when removing root restricting layers through subsoil management. Methods: Subsoil management was performed by deep loosening, cultivation of lucerne as deep-rooting pre-crop, and their combination with compost incorporation. Management effects were evaluated by means of shoot biomass and element concentrations in shoots and soil compartments. The mean nutrient uptake depth was fingerprinted by graphically matching the 87Sr/86Sr ratios in shoots with the 87Sr/86Sr ratios in the exchangeable fraction in soil. Nutrient uplift from depth to topsoil was inferred from element concentrations in the exchangeable fraction in soil. Results: Shoot biomass remained constant in management and control plots. The mean nutrient uptake depth changed with subsoil management in the order: deep loosening < control < deep loosening with compost incorporation. The latter coincided with a reallocation of compost-derived Na and hence resulted in increased levels of bioavailable Na below the depth of compost incorporation, which may have led to an improved water use efficiency of the crops. Thus, Na relocation triggered the deepening of the mean uptake depth of water and nutrients. Moreover, nutrient uplift from depth to topsoil was evident 21 months after subsoiling. Conclusion: Subsoil management by deep loosening with compost incorporation provides a sustainable use of soil resources because otherwise unused deep geogenic-derived nutrient reservoirs were additionally involved in crop nutrition. [ABSTRACT FROM AUTHOR]

Purpose: The response of soil organic carbon (SOC) fractions to climate warming plays an important role in influencing the fate of soil C stocks. Coastal wetlands have high C sequestration; however, complex water and salt stress conditions lead to a large uncertainty in the effects of warming on SOC dynamics. Further, numerous short-term warming studies cannot provide an unbiased estimate of the warming impacts and mechanisms. Methods: In our study, the topsoil (0–10 cm) and subsoil (20–40 cm) were collected to assess the changes in SOC dynamics after seven-year experiment warming in a coastal wetland in the Yellow River Delta. Additionally, we conducted a short-term dynamic temperature ramping incubation experiment to evaluate the SOC decomposition rate and its temperature sensitivity. Results: Warming significantly decreased the SOC content by 38.7% in the topsoil but had no effect in the subsoil. Warming significantly decreased the labile SOC fractions, including dissolved organic C (DOC) and particulate organic C (POC) in the topsoil but not in the subsoil. By contrast, warming did not alter the recalcitrant mineral-associated organic C (MAOC) fraction in both topsoil and subsoil. Warming-induced elevated soil salinity caused a decrease in labile SOC fractions, presumably through weakening the quantity of plant inputs. In addition, warming significantly increased the SOC mineralization rate in the topsoil, but did not change its temperature sensitivity in both the topsoil and subsoil. Conclusions: Overall, our findings highlight the importance of considering the varying responses of labile and recalcitrant SOC fractions to warming, which would aid in obtaining more accurate projections of SOC dynamics in coastal wetlands under future climate change. [ABSTRACT FROM AUTHOR]

This study presents a novel method to estimate the aggregate pollution index (API) within the residential communities around a limestone mining and cement producing environment. The ranges for the air quality index (AQI), pollution load index in the topsoil (PLIt), pollution load index in the subsoil (PLIs), heavy metal pollution index in the water (HPI), and radiological external hazard index (Hex) were 5.99 to 57.97, 1.65E-07 to 3.6E-04, 1.7E-08 to 3.5E-04, 52.17 to 1053.13, and 0.0694 Bq.kg−1 to 0.550, respectively. The AQI, PLIt, PLIs, HPI, and Hex revealed nonuniform patterns of variations across the communities, though there was a significant correlation between the PLIt and the PLIs, and between the HPI and the Hex; and a moderate correlation between the HPI and the AQI, between the HPI and the PLIt, and between the HPI and the PLIs. The measured quality indicators (MQI), and the calculated pollution indices (CPI) were subjected to the multivariate analysis. The principal components (PC) split the ten communities the same way in the CPI and the MQI. The API, using the PC, ranged from 3 to 9. The Afami, Balogun, and Akinbo communities had the highest API, while the Ewekoro and Itori communities had the lowest. The CPI was 41% of the MQI, with respect to the within-cluster variance, indicating that the CPI-based clustering was more reliable. Both the CPI and the MQI attributed a unique pollution signature to the Ewekoro community, while the remaining nine communities shared a common pollution status with the Ibese community. [ABSTRACT FROM AUTHOR]

Heterogeneous flow pathways through the soil determine the transport of dissolved and particle-bound nutritional elements like phosphorus (P) to ground and surface waters. This study was designed to understand the spatial patterns of P in agriculturally used soils and the mechanisms causing P accumulation and depletion at the centimetre scale. We conducted dye tracer experiments using Brilliant Blue on a loamy Stagnosol in North-Eastern-Germany. The plant-available P was analysed using double lactate extraction (DL-P). The plant-available P content of the topsoil was significantly higher than that of the subsoil in all three replicates (p < 0.001). The topsoil's stained areas showed significantly higher P contents than unstained areas (p < 0.05), while the opposite was found for the subsoil. The P content varied enormously across all observed soil profiles (4 to 112 mg P kg−1 soil) and different categories of flow patterns (matrix flow, flow fingers, macropore flow, and no visible transport pathways). The P contents of these transport pathways differed significantly and followed the order: Pmatrix flow > Pfinger flow > Pno visible transport pathways > Pmacropore flow. We conclude that P tends to accumulate along flow pathways in the topsoil in the observed fertilized and tilled mineral soil. In contrast, in the subsoil at a generally lower P level, P is depleted from the prominent macroporous flow domains. [ABSTRACT FROM AUTHOR]

Researchers of the Nekrasov Iron & Steel Institute, National Academy of Sciences of Ukraine, conduct studies aimed at developing analytical methods for predicting the strength characteristics of pellets. These studies use analyses of phase interaction mechanisms within free-flowing media to develop theoretical ideas on the formation of strong bonds in the pellets through adhesion. This led to the establishment of local models of adhesion processes for two basic particle interaction schemes: 'particle + particle' and 'particle + liquid phase + particle'. Experimental studies undertaken in laboratory premises of the Nekrasov Iron & Steel Institute for the 'particle + particle' interaction scheme provided the foundation for a method to determine the strength characteristics of pellets made from fine-grained materials with zero moisture at compaction pressures ranging from 50 to 220 MPa. The first part of the paper justified methodological prerequisites for experiments to study strong bonds within the compacts for the 'particle + liquid phase + particle' interaction scheme. The methodological prerequisites accounted for the mechanical, physical, and physicochemical interactions, both between individual particles of the pelletized material and between the charge components (liquid phase). A generalized analysis of the experimental findings allowed evaluating a range of potential adhesion processes for the 'particle + liquid phase + particle' interaction scheme, pinpointing their manifestation, examining their nature, and assessing the effect of a liquid phase introduced into the pelletized charge, considering the compaction pressures applied. This paper focuses on experimental findings for the 'particle + liquid phase + particle' interaction scheme, establishing analytical relationships between the strength characteristics of pellets and integral indicators of the adhesive bond mechanism in this interaction scheme (in particular, relationship between the bulk density (ρ0) and moisture content (Wm) for materials in the first group of systematization). Additionally, an analytical relationship between the compaction factor for compacts produced at a pressure (P) of 220 MPa (Kcomp220), considering their loosening, and the bulk density of materials (ρ0) in the first group of systematization was established for the first time. Analysis of the findings led to a hypothesis suggesting that the amount of the liquid phase (in particular, water) introduced into the material should be balanced by its potential displacement during compaction to achieve maximum compact strength. Based on the hypothesis, a novel equation was derived to calculate the amount of liquid binder (water) to promote the most favorable conditions for the adhesion processes, thereby imparting the maximum strength to compacts from materials in the first group of systematization. A comparative analysis between the experimental findings and calculations confirmed that the equation was accurate. Consequently, an analytical method was proposed to determine the moisture content needed in the charge to produce compacts with maximum strength from materials in the first group of systematization (ρpycn ≥ 4.64 × × 10–3). [ABSTRACT FROM AUTHOR]

The aim of the paper is to carry out a comparative engineering-geological study of four different waste landfills using the evaluation criteria for the geological subsoil as a natural sealing barrier. The study evaluates 4 localities (Velké Pavlovice, Kvítkovice, Prakšice and Horní Suchá) using three variants (based on two standards) which approach the geological barrier requirements as a combination of impermeability requirements based on a filtration coefficient limit value. and the required geometry represented by investigation depths. The research was carried out in landfills in Moravia, in the east of the Czech Republic. The study's motivation is to point at the differences in engineering-geological investigations of waste landfills (as for the requirements for impermeable geological subsoil as a natural sealing barrier) when compared with other engineering structures (where the main goal is to evaluate load-bearing capacity and settlement). The purpose of the geological barrier is to prevent the spread of contamination, and the paper shows this can be approached differently, as shown in two different methodologies investigated herein. The first model (Model 1) assumes there is a 3-m-thick subsoil below the landfill's footing bottom, which manifests impermeability characterized by the filtration coefficient Kf ≤ 1.0 * 10–9 m/s, or a 30-m-thick subsoil of Kf ≤ 1.0 * 10–8 m/s. The second model (Model 2) assumes a 1-m thick, impermeable subsoil massif of Kf ≤ 1.0 * 10–9 m/s. We found that none of the landfills in the four selected localities had an impermeable layer in the required depth (a filtration coefficient Kf from 1.8 * 10–9 to 3.9 * 10–9 m/s), and thus did not comply with the limiting conditions. As a result, an anthropogenic technical barrier had to be installed. An important goal of the study from an environmental point of view was to assess the existence of a suitable geological barrier under the proposed landfills. The most important criterion from this point of view is permeability. An additional technical objective of the project was also the assessment of the possible creation of a technical anthropogenic isolation barrier. In the event that the natural sealing barrier would not be sufficient. This was shown in all solved case studies of engineering geological investigations of waste landfills. [ABSTRACT FROM AUTHOR]

We performed one dimensional equivalent linear site response analysis for 11 soil profiles of Dhanbad city. To explore the effect of subsoil on the induced effect of earthquakes at the ground surface, the site response analyses is complemented with shear wave velocity models found from destructive geotechnical as well as non-destructive geophysical surveys, such as standard penetration test (SPT) and horizontal-to-vertical spectral ratio (HVSR). The bedrock depths obtained from shear wave velocity models, constructed from HVSR method, are validated using electrical resistivity tomography (ERT). Our results reveal that Dhanbad city consists of alluvium deposits, such as silty sand, sandy clay, silt + sand and sand + clay mixture. We used the 2015 Nepal (MHA = 0.15 g), 2016 Imphal (MHA = 0.18 g) and 2022 Nepal (MHA = 0.10 g) earthquakes as input motions at the bedrock level. Predominant frequency, soil thickness, surface PGA and Vs30 are found to follow a consistent trend relative to each other. The soil's transfer function, obtained from site response analysis (SRA), correlates generally well with the peak's predominant frequency of HVSR curves at all sites. The influence of input ground seismic motions on soil profiles is discussed, which shows that the soil deposit of Dhanbad city lies in a short period region. Our results would play an important role for Indian government agencies such as the Central Public Works Department (CPWD), Geological Survey of India (GSI) and National Disaster Management Authority (NDMA) to mitigate earthquake effects and to plan better to build an earthquake resilient society. [ABSTRACT FROM AUTHOR]

Aims: A modified sowing pattern (MSP) consisting of wider seedling strips has been shown to improve the nitrogen (N) use efficiency of winter wheat by enhancing N uptake from soil. However, the effects of MSP on root size, 15N-uptake efficiency, and N uptake from different soil depths have not been yet elucidated. Methods: The seedling strip width in the MSP was 8–10 cm compared with 3–4 cm in the conventional sowing pattern, with a fixed row spacing of 27 cm. Both were used to investigate root size, root spatial distribution, and N uptake from different soil depths. Results: The increased intra-row spacing of the MSP resulted in increases in the number of tillers and roots and in dry matter per unit area. The total root weight increased due to the higher root/shoot ratio induced by the enhanced nutrient requirements. Together with the increase in root number, the greater total root weight led to increases in root length and surface area, with a constant specific root length and surface area based on the total root weight. The absolute increases in root length and surface area densities declined with soil depth. Root 15N-uptake efficiency based on root length and surface area decreased in the topsoil but increased or remained unchanged in the subsoil. Conclusions: 15N-uptake from each soil layer increased, with the largest increase occurring in the 40 to 80 cm soil layer. Due to the enhanced N uptake, particularly from the subsoil, the MSP may be used to reduce N inputs without penalizing yield. [ABSTRACT FROM AUTHOR]

In this paper, we discuss the results of laboratory tests and field surveys using ground penetrating radar (GPR) method to detect qanats at the main campus of Shahid Bahonar University of Kerman (SBUK), Iran. The main purpose of laboratory experiments was to explore the optimum frequency of GPR surveys to detect qanats for the subsoil in the study site. We performed a variety of laboratory tests with a 3 GHz antenna to detect qanats (simulated using dielectric empty targets) hosted by sand with volumetric water content (VWC) values in the range 1.5–8%. The depth to each target was progressively increased until either approaching the edges of the sandbox or modelling a qanat depth for which GPR data could not detect the target anymore. The scaling factors were calculated for each test to estimate the maximum depth of detecting qanats as a function of the scaled GPR frequency. The results showed that in areas where the subsoil is dominated by sand, medium-frequency GPR antennas can penetrate to depths of a few tens of meters, but the penetration depth considerably decreases when the soil moisture and/or clay content of the medium increase. Based on the results of laboratory simulations, qanats are detectable at a maximum normalized depth of about 15–17 times of the wavelengths in very dry sands with VWC less than 5% while the detectable range rapidly drops down to less than 3 or 4 times of the wavelengths in more humid sands with VWC of about 8%. We also discuss the results of a few field GPR surveys that were measured using antennas with the 50 MHz and the 250 MHz frequencies in the northwestern part of the study area. The processed GPR images could detect a qanat in the position compatible with the results of previous remote sensing studies performed in the area. The depth to the detected qanat is 13.5 m, which is a little bit beyond the maximum limit predicted by the laboratory tests. [ABSTRACT FROM AUTHOR]

This study aims to evaluate the possible occurrence during seismic shaking of interaction effects between the shallow subsoil and the overlying buildings of the Villa d'Agri town (Southern Italy). From the geological and building heritage points of view, the investigated area represents a typical town along the Apennines chain and therefore the obtained results could be easily exported to similar urban areas. A total of 239 single-station seismic ambient noise measurements were thus performed, 154 on the urban soils and 85 within buildings. Both subsets of measurements were planned to cover the main outcropping lithologies and building typologies. By means of the Horizontal-to-Vertical Noise Spectral Ratio technique, isofrequency and isoamplitude maps have been reconstructed for the whole area. The results evaluated on the 65 tested buildings allowed to infer the empirical relationship between the first vibrational period, T(s), and their height, H(m). Using this relationship and available information on the height of each building, the first vibrational frequency was estimated for 659 buildings belonging to the urban area of Villa d'Agri. Finally, in order to assess the possible occurrence of the double resonance phenomenon, we compared the main frequency of each building with that interpolated for the underlying foundation soil. The results show that the probability of being affected by the double resonance effect is very high only for a couple of buildings, high for about 16% of the buildings, moderate for the 23% and practically null for most buildings (60%). [ABSTRACT FROM AUTHOR]

Purpose: Environmental controls of soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) in the subsoil are important for understanding nutrient cycles; however, these are poorly understood in subtropical paddy soils, especially lacking systematic regional soil profile investigations in the subsoil. The study aims to evaluate the role of environmental factors on concentrations and ratios of SOC, TN, and TP in subsoil (20–100 cm) vs. topsoil (0–20 cm). Methods: We sampled 166 soil cores (1-m depth) from paddy fields across 10 typical counties in 4 provinces of subtropical China. Soil properties of SOC, TN, TP, pH, bulk density, and clay were determined in each soil layer. Spearman correlation analysis and random forest model were performed to correlate environmental factors with soil nutrients and to rank their relative importance throughout the soil profile. Results: SOC was strongly coupled with TN and both decreased with soil depth. However, TP was high in topsoil and did not change in the subsoil. Thus, the soil C to N ratio (12.88–14.93) exhibited minimal variation, whereas N to P (30.93–68.99) and C to P (2.52–5.59) ratios decreased markedly with the soil depth. As compared with topsoil, subsoil revealed similar dominant negative effects of climate (temperature, precipitation) and bulk density on the concentrations and ratios of SOC, TN, and TP. The soil clay had no effect on SOC and TN, but was the dominant control on TP throughout the soil profile. The influences of straw incorporation and chemical fertilization on SOC and TN were primarily observed in topsoil. Conclusions: There were dominant climate controls (temperature and precipitation) of soil C–N–P concentrations and ratios in the subsoil, although different soil factors control SOC and TN vs. TP. These findings highlight the importance of managing subsoil nutrients in subtropical paddy soils, since they are consistently sensitive to climate as topsoil nutrients. [ABSTRACT FROM AUTHOR]

Current geotechnical design requires an appropriate number of in-situ tests to obtain sufficient underground information. Subsoil properties are known to have high spatial variability and often fluctuate with location. Random field model considering soil spatial variability for reliability analysis in geotechnical engineering requires site statistical data. This study presents a statistical characterisation of subsoil properties in Bangkok. The boring log data of Bangkok subsoil was gathered and used to develop a 3D geological model. The statistical analysis of geotechnical data was performed to describe the spatial variability of soil properties. The mean, coefficient of variation, and scale of fluctuation of the undrained shear strength, standard penetration test, total unit weight, plasticity index, and thickness of soil layers were evaluated in detail using random field model. The lognormal distribution and decay exponential function were adopted to describe the fluctuation trend of soil properties. Based on the data, the empirical correlations between soil shear strength and index properties can be also established. The results of this research can help civil engineers to describe the influence of spatial variability of soil properties in geotechnical engineering analysis. [ABSTRACT FROM AUTHOR]

Purpose: Long-term excessive application of nitrogen fertilizer under diverse land uses has caused serious environmental problems on the North China Plain. Current studies focus on denitrifiers and bacterial communities in topsoil under diverse land-use types; however, few studies have studied denitrifiers and microbial communities in subsoils. Materials and methods: The variations in soil bacterial communities and denitrifiers with soil profiles (0–300 cm) under crop, apple orchard, and vegetable fields were investigated through high-throughput sequencing and quantitative PCR technologies. Results and discussion: NO3−-N largely accumulated in the deeper soil layers (100–300 cm) in the apple orchard, resulting in a higher risk of NO3−-N leaching. The soil bacterial community structure at the 0–100 cm soil depth had a marketable difference from that at 100–300 cm under these three land-use types, and the C:N ratio was the main driving factor for their vertical distribution. The bacterial α-diversity decreased with soil depth; the crop field had the highest α-diversity across all horizons except 100–200 cm, and total carbon was the most important factor driving α-diversity. In addition, the absolute abundance of the nirK, nirS, and nosZ genes decreased with soil depth and varied with land-use type, which was deeply affected by multiple soil properties, such as soil organic matter and total nitrogen. Conclusion: Our findings highlighted that potentially important and unique functions remain to be revealed in subsoils, which may provide new insights into mitigating nitrate leaching in various land-use types. [ABSTRACT FROM AUTHOR]

Purpose: Carbon amendment can steer both denitrifying and dissimilatory nitrate reduction to ammonium (DNRA) bacterial communities to reduce nitrate leaching. The purpose of this study was to uncover changes in the abundance and diversity of denitrifying and DNRA bacterial communities by carbon amendment in anaerobic subsoil. Methods: High throughput sequencing and qPCR analyses of narG, napA, nirK, nirS, nrfA, and 16S rRNA were used to identify changes in the abundance and diversity of total, denitrifying, and DNRA bacterial communities in the subsoil as responses to straw amendment under 0, 800, or 1600 kg N ha−1 nitrate fertilization. Results: The straw amendment resulted in over 81% of reduction in nitrate leaching, 3.2–5.1 folds' increase in dissolved organic matter (DOM), 102.2–147.5% of increase in the total N content in subsoil, and 2.6–43.1 folds' increase of narG, napA, nirK, nirS, nrfA, and 16S rRNA, as compared to the corresponding non-amended control. The straw amendment could explain 32–52% of the variation in the community composition of total, denitrifying, and DNRA bacteria, and it also enriched denitrifying Proteobacteria, DNRA bacteria of Nitrospira or Planctomycetes, and cellulose degraders such as Cellulomonas, Opitutus, and Lysinibacillus. These responding communities formed a co-occurrence network of high density, highlighting the importance of carbon amendment on the reassembly of microbial communities in the anaerobic subsoil. Conclusion: Straw amendment in the subsoil greatly reduced nitrate leaching via straw decomposer, dissimilatory, and assimilatory nitrate-reducing bacterial communities. [ABSTRACT FROM AUTHOR]

Incorporating trees into agricultural systems, including grasslands, increases the soil organic carbon sequestration and contributes to climate change mitigation. Site preparation for tree establishment is a common practice that can involve a variety of techniques and agricultural implements such as subsoiling. This study aimed to evaluate the long-term effects of subsoiling on soil organic carbon (SOC) concentrations and stocks in a Mediterranean grassland afforested with holm oaks 22 years ago and now converted into a Dehesa agroforestry system. The study was conducted in a dehesa farm in Southwest Spain. Soil samples were taken at six depths under 10 tree canopies within and outside the original subsoiling line. Subsoiling significantly decreased SOC concentration. Mean SOC concentration in the first 20 cm was 30% lower at the subsoiling line. SOC stocks for the first 60 cm were 2660 g m−2 within the subsoiling line and 4320 g m−2 outside the line. There was a clear reduction in SOC concentration and stock with increasing depth. Root abundance and deeper rooting increased with subsoiling but did not translate into sufficient carbon accumulation in the soil, which is moderate even after 22 years. This study reveals that, in the long term, there is a trade-off in CO2 sequestration between tree planting and soil subsoiling, highlighting the need for further research into the potential benefits and detriments of subsoiling. [ABSTRACT FROM AUTHOR]

Sheet pile wall structures are commonly applied in coastal projects, particularly for the quay wall. This structural type normally is used in places where the ground has a low bearing capacity and is easily penetrable. Many sheet pile quay walls constructed in the past had low front water depth and did not satisfy the requirements of current standards. This issue could be addressed by improving the ground in front of the wall using cement deep mixing (CDM) and then excavating to increase the water depth in front of the wall. This paper numerically evaluated the dynamic behavior of the sheet pile wall after renovation. The numerical model was performed based on the finite element method (FEM) using the PLAXIS 2D program. The study focused on investigating typical parameters of the quay wall improved using the CDM, such as bending moment and displacement of sheet pile and the development of excess pore water pressure (EPWP) in the backfill. These results were compared to those of the quay wall without the CDM to elucidate the advantages of this method. In addition, the influence of some factors on the quay wall behavior, such as earthquake excitation characteristics, CDM area, and CDM strength, was also evaluated. The results demonstrated that the ground improvement using the CDM significantly decreased the bending moment and displacement of the sheet pile wall. The excitation characteristics did not affect the deformed shape of the sheet pile. With the constant CDM depth, the sheet pile displacement decreased with an increase in the improvement width until it reached a limitation. The increasing CDM strength also decreased the displacement of the wall until it raised a certain value. This demonstrated that this method was technically feasible, and it could be considered to study further by experiment before applying in practice. [ABSTRACT FROM AUTHOR]

Neighbouring buildings, even though disconnected from the structural viewpoint, may interact through the underlying soil especially when they are founded on very soft soils. Despite some pioneering studies since the early 1970's, structure–soil–structure interaction has yet to be further investigated to reveal the effects that could be exerted on both the static and dynamic response of nearby structures. The present work aims at expanding the theoretical knowledge on this phenomenon through an extensive parametric study based on a truly 3D continuum approach solved through the Flac3D finite difference software. The impedance functions of two closely-spaced shallow foundations have been numerically calculated by varying the distance between the nearby footings and the subsoil configuration (homogeneous or layered). The numerical results have elucidated important effects of cross interaction between two neighbouring foundations. The static stiffness reduces, and this effect is increasingly significant as the foundations are closer whatever the subsoil conditions are. The dynamic coefficients increase with respect to those corresponding to the single footing over halfspace. Such effect is less important for the layer-over-halfspace soil configuration, for which the dynamic coefficients are mainly affected by the frequency response of the stratum. Finally, in the realm of the sub-structure approach, a novel simplified design approach, based on group factors for closely-spaced shallow foundations, was proposed to compute the soil-foundation impedance matrix englobing the foundation–foundation interaction in addition to the soil–foundation interaction. [ABSTRACT FROM AUTHOR]

Microbes depolymerize soil organic matter to supply themselves with carbon (C), and nutrients such as nitrogen (N) and phosphorus (P). In this way, microbial resource limitations play an important role in characterizing the biogeochemical cycle dynamics of the ecosystem. However, the effect of warming on microbial resource limitations, especially in resource-poor subsoils, remains unclear. Therefore, this study aimed to examine the effects of warming (+ 5 °C above ambient) on microbial resource limitation and explored their relationships with soil physicochemical properties and microbial community structure in topsoil (0–10 cm) and subsoil (40–60 cm) in a Chinese fir (Cunninghamia lanceolata) plantation in southern China. Microbial resource limitation with warming treatment was assessed via vector analysis of soil extracellular enzymatic stoichiometry after two years. We found warming aggravated microbial C limitation in the topsoil but alleviated microbial C limitation in the subsoil, while it shifted the relative nutrient limitation from P limitation to N limitation in the subsoil. Soil microbial C limitation was explained by soil properties (specifically, ammonium nitrogen) in the topsoil while by microbial community composition in the subsoil based on variance partition analysis. The soil microbial nutrient limitation was explained by soil properties in the topsoil and subsoil. The decrease in actinomycetes abundance in the warming treatment may have led to a decreased microbial C limitation in the subsoil. Our study highlighted the differences in warming effects between the topsoil and subsoil. We argue that the microbial resource demand of the subsoil should be further implemented in the study of soil biogeochemistry to improve the prediction of the impact of climate warming on soil C dynamics. [ABSTRACT FROM AUTHOR]

There is evidence of increased soil organic carbon (SOC) and inorganic carbon (SIC) under fertilization in dry croplands of arid and semi-arid areas. However, not much is known about the responses of SOC and SIC in coastal saline − alkaline paddy soils that undergo flooding − draining cycles. Here, we assess the impacts of various combinations of organic and phosphorus fertilization on SOC and SIC and other soil properties in a saline − alkaline paddy field of the Yellow River Delta. Our study showed that organic fertilization resulted in an increase of SOC by 11.9% over 0 − 20 cm and 13.3% over 20 − 100 cm (i.e., 140 − 250 g C m−2y−1 over 0 − 100 cm) whereas phosphorus fertilization only led to a significant increase of SOC in subsoils (or ~ 75 g C m−2y−1 over 0 − 100 cm). There were little differences in SIC over 0 − 20 cm among the treatments; but SIC showed a significant decrease over 20 − 100 cm under organic fertilization combined with lower rate of phosphorus fertilization. However, high rate of phosphorus fertilization combined with organic amendment led to an increase in SIC stock, but a decrease in SOC stock in the subsoil. There was a significant negative relationship between SIC and SOC stocks in this paddy soil. This study demonstrated that fertilization practices could have complex influences on SOC and SIC in saline − alkaline paddy fields due to the flooding − draining cycles that lead to changes in soil conditions. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) in shrublands is an important component of global carbon cycling. However, there is a dearth of large-scale systematic observations of SOC stocks at different soil depths, and it remains uncertain whether and how the relative importance of biotic and abiotic variables in regulating SOC stocks changes with soil depth. Here, we quantified large-scale patterns and controlling factors of SOC storage per area (SOCD, kg m−2) for both topsoils (0–30 cm) and subsoils (30–100 cm) by taking full advantage of a consistent stratified random sampling study of one-meter soil profiles across 1211 sites in Chinese shrublands. We found that subsoils stored about 53.30% of total SOCD, falling into the range of previously reported values for terrestrial ecosystems. SoilGrids250m model-derived assessments overestimated SOCD by 13.72 and 65.49% for topsoils and subsoils, respectively. The effects of climate means and seasonality on SOCD were equally strong in both topsoils and subsoils. The predominant effects of edaphic properties on SOCD were more robust in subsoils than in topsoils. Belowground biomass of shrublands was the only significant predictor of topsoil SOCD, but it did not predict subsoil SOCD accurately. These findings have refined our understanding of the pivotal role of shrublands in SOC storage and sequestration potential and could serve as an ecologically valuable baseline for large-scale improvement and validation of depth-dependent SOC dynamics for multilayer SOC modules in Earth Systems Models. [ABSTRACT FROM AUTHOR]