Soil Structure Characteristics Research Articles

Effects of representative elementary volume size on three-dimensional pore characteristics for modified granite residual soil

The determination of the Representative Elementary Volume (REV) is vital for comprehending the behavior of soil structural characteristics within the micro-to-macro framework. This study utilizes X-ray computed tomography to provide a detailed microscopic exploration of how waste cement, glass powder, and straw fibers contribute to the reduction of permeability in granite residual soils. Based on the pore reconstruction analysis of soil samples, the effect of REV size on the three-dimensional pore characteristics of modified granite residual soil is extensively studied. The results indicate that varying sizes of REV greatly affect the pore structure, porosity, fractal dimension, and permeability. Specifically, as the REV size increases, these parameters initially exhibit fluctuations characterized by uncertainty, ultimately stabilizing at a threshold value of 5000 μm. The incorporation of glass powder and straw fibers enhances the compactness of the soil while reducing the average diameter of connected pores. The alteration in the frequency distribution of connected pores redefines flow pathways, disrupting the preferential channels originally provided by larger pores, which is a primary factor that leads to the reduced permeability of the modified soil. These findings offer valuable references for determining the REV in modified soils, aiding future research in effectively saving time and computational costs.

A Ground-Penetrating Radar-Based Study of the Structure and Moisture Content of Complex Reconfigured Soils

To increase the detection accuracy of soil structure and moisture content in reconstituted soils under complex conditions, this study utilizes a 400 MHz ground-penetrating radar (GPR) to examine a study area consisting of loess, sandy loam, red clay, and mixed soil. The research involves analyzing the single-channel waveforms and two-dimensional images of GPR, preprocessing the data, obtaining envelope information via amplitude envelope detection, and performing a Hilbert transformation. This study employs a least squares fitting approach to the instantaneous phase envelope to ascertain the thickness of various soil layers. By utilizing the average envelope amplitude (AEA) method, a correlation between the radar’s early signal amplitude envelope and the soil’s shallow dielectric constant is established to invert the moisture content of the soil. The analysis integrates soil structure and moisture distribution data to investigate soil structure characteristics and moisture content performance under diverse soil properties and depths. The findings indicate that the envelope detection method effectively identifies stratification boundaries across different soil types; the AEA method is particularly efficacious in inverting the moisture content of reconstituted soils up to 3 m deep, with an average relative error ranging from 2.81% to 7.41%. Notably, moisture content variations in stratified reconstituted soils are more pronounced than those in mixed soil areas, displaying a marked stepwise increase with depth. The moisture content trends in the vertical direction of the same soil profile are generally consistent. This research offers a novel approach to studying reconstituted soils under complex conditions, confirming the viability of the envelope detection and AEA methods for intricate soil investigations and broadening the application spectrum of GPR in soil studies.

Vegetation at the former open-pit Ningyo-toge mine, 36 years after closure treatment: Impact of soil cover on woody plant establishment and dominance of the perennial herb Miscanthus sinensis

Soil cover is a prevailing method used at mine sites to ensure the safety of hazardous materials and restore ecological functions when the base materials are unfavorable for plant growth. The former open-pit Ningyo-toge Mine was backfilled with overburden and neutralized smelting residues and covered with soil in 1987. After 36 years, the vegetation remained dominated by the perennial herb Miscanthus sinensis, and woody plant establishment did not progress successfully. This study investigated the factors that inhibited woody plant establishment at the site. The soil profile survey revealed that the soil cover formed Bg horizons (pseudogley soil) with cloudy mottling, representative of poorly drained soil. In the Bg horizon, woody plant roots of Pinus densiflora and Weigela hortensis exhibited growth inhibition. Elemental analysis revealed that in the Bg horizon the roots of P. densiflora and W. hortensis accumulated high Fe concentrations exceeding 10,000 mg/kg DW at critical levels. Our results suggested that woody plant roots in the Bg horizon may have suffered from chronic oxygen deficiency accompanied by excessive Fe stress in the soil cover. Topsoil water content (<50 mm) and microtopographic features were not critical factors disrupting woody plant establishment because some individuals were growing in areas with high soil water content, exceeding 60%. Considering that woody plant roots were developed primarily in the shallow A horizon, A horizon formation by M. sinensis is a key step in initiating woody plant establishment by improving the soil structure and physiochemical characteristics of the soil cover, such as carbon content, exchangeable nutrients, and air-filled porosity. For successful mine pollution control and vegetation recovery, implementing an appropriate topsoil system, such as native forest soil, loosely graded and minor infiltration layer above the overburden would be necessary.

Structural, soil-water, and dynamic characteristics of clay with different moisture and temperature histories

Variations in the hydro-mechanical properties of pavement subgrade soils are complex under long-term, repeated, and interlaced moisture and temperature (M-T) effects, such as wetting-drying (WD) and freeze-thaw (FT) processes. This study compares the soil structure, soil-water characteristic curves, and accumulated plastic strain (ɛ p) of compacted Heilongjiang clay with three different M-T histories. Experimental results demonstrated that (i) after M-T actions, structural pores develop while textural pores shrink, leading to a reduction in the water retention capacity and an increase in the desaturation rate. Following the stabilization of the M-T effects, the soil structure and soil-water characteristics of specimens with different M-T histories become similar; (ii) at high moisture content (w), ɛ p is more sensitive to moisture changes (including w and suction, s). Following the FT cycles, ε p and ε pa (the difference between the ε p at 5000th and 3000th cyclic loading) become more sensitive to moisture changes; (iii) after M-T effects, the ε pa-w relationship is nonlinear while the ε pa-logs relationship is linear. Different M-T histories generated differences in only the ε p at the beginning of the FT processes while such differences disappear after M-T effects have stabilized. The experimental data presented in this paper could prove valuable in understanding the behaviors of pavement soils under complex environmental conditions.

Numerical investigation on the effect of repeated surface surcharge loading on soil deformation and tunnel displacement in structured soft clay

Shanghai soft clay is a typical marine clay with specific structural characteristics. The tunnel and overlying soft clay may undergo repeated surface surcharge loading, such as the temporary soil stacking. Assessing the extent of structured soft clay deformation and tunnel displacement caused by repeated surface surcharge loading is of great significance for evaluating of the safety of ground structures and underground tunnels. In this study, the effects of repeated surface surcharge loading on the soil and tunnel displacement were numerically investigated. The finite element code DBLEAVES with an elasto-plastic constitutive model (Shanghai model) that describes the mechanical properties and structural characteristics of natural clay was used to simulate the soil response. The parameters of the constitutive model were obtained through geotechnical testing. The effects of the soil structural characteristics, seepage conditions, and loading conditions on the soil response and tunnel displacement were analyzed. The numerical results show that the maximum excess pore pressure of clay decreased as the number of loading cycles increased. The effects of the structural characteristics cause greater displacement, whereas the effects of the degradation parameters of the structure are more significant than the initial degree of the structure. The differences in the vertical displacement of the tunnel and overlying soils owing to the structural characteristics become apparent with an increase in surface surcharge loading. However, the effects of structural characteristics become less significant as the depth increases. The seepage conditions and loading method primarily affect the build-up of excess pore pressure and the development of effective stress paths. For soils inside the surcharge area, a flexible surcharge produces a greater vertical displacement than a rigid surcharge. As the burial depth increased, the effects of the seepage conditions and loading method showed a declining tendency.

Effects of different ecological restoration methods on the soil physicochemical properties and vegetation community characteristics of the Baotou light rare earth tailings pond in Inner Mongolia, China.

This study investigated the soil physicochemical properties and vegetation community characteristics of the Baotou light rare earth tailings pond after 10years of aggregate spray seeding ecological restoration (S1) and ordinary soil spray seeding ecological restoration (S2), and the naturally restored dam slope area without human intervention (S3). The results showed that the vegetation community of S1 was dominated by Caragana korshinskii Kom, and its importance and abundance values were 0.40 and 38.4, respectively, while the vegetation communities of S2 and S3 mainly comprised herbaceous plants. Additionally, the vegetation biomass of S1 was significantly higher than that of S2 and S3 by 215.20% and 1345.76%, respectively, and the vegetation diversity index of S1 was the highest among the three treatment groups. The soil porosity (SP), water content (W), electrical conductivity (EC), and available K were significantly improved in S1, while soil bulk density (BD) was significantly reduced compared with that of S2 and S3. In addition, redundancy analysis revealed that SP, EC, W, and K positively correlate with the biomass, Shannon, Pielou, Simpson, and Marglef indices. Principal component analysis further showed that the comprehensive score of S1 (0.983) was higher than that of S2 (- 0.261) and S3 (- 0.648). Collectively, these findings indicate that appropriate ecological restoration can improve soil structure and vegetation community characteristics, thereby accelerating vegetation restoration, ultimately increasing the stability of the ecosystem.

Effects of fall-spring cement applications on soil physico-mechanical quality of seed bed and seedling emergence.

The physico-mechanical quality of the seed bed is extremely important not only for the soil air-water dynamics, but also for the germination, seedling emergence, and development of the plants. The crust layer formed after precipitation and irrigation in soils with poor structural properties is among the most important indicators of the lower seedbed quality. While there are different applications to increase the physico-mechanical quality of the seedbed, there are also cement applications that provide rapid aggregate formation and stability. The effects of cement application on the soil mechanical quality and seedling emergence of clay textured soil with poor structural characteristics were investigated in the present study. For this purpose, a total of 36 small plots with a size of 2.4 m2 were created. Cement was applied at 0.25-0.5-1 and 2% doses to 18 plots in the fall period, and to the other 18 plots in the spring period. After the treatment, soil samples were taken for analysis before the planting period and the number of seedling emergence was determined by planting the bean plant during the planting period. According to the results of the study, it was found that cement applied in two periods caused an increase in soil aggregate stability, decreased penetration resistance, modulus of rupture, and dispersion rate, and increased water holding capacity to a limited extent. On the other hand, cement application also had positive impacts on the emergence of the bean plant. The 1% dose of the spring application of cement was more effective on the determined soil structural characteristics and seedling emergence.

Effects of Soil Erosion on the Tillage-Layer Quality and Limiting Factors of Sloping Farmland

Soil erosion is the key factor leading to the degradation of tillage-layer quality, which directly threatens regional food and ecological security. To study the characteristics of soil structure, water retention capacity, and nutrient changes in the tillage layer of purple soil sloping farmland under different erosion conditions, a shovel soil erosion test was performed to distinguish the factors that hinder the tillage-layer quality of sloping farmland under different erosion degrees. The degradation of soil structure showed that with the intensification of erosion, soil bulk density, soil capillary porosity, and sand content displayed an overall increasing trend; the soil water retention degradation was expressed by the average increase in the soil water holding capacity and the average decrease in the infiltration rate; soil nutrient degradation was derived from the average decrease in soil nutrient content. At the initial stage of erosion, the soil nutrient degradation was extremely sensitive to soil erosion, which was the limiting factor of the tillage layer; when the erosion reached stage E-15 (erosion 15 cm), the soil nutrients, soil permeability, and soil capillary porosity became the limiting factors; for E-20 (erosion 20 cm), the limiting factors added an index on the basis of stage E-15, namely, soil total porosity. When soil erosion continued for 53 years, the tillage-layer quality index was lower than the threshold value (0.46). Reconstructing soil profile of the tillage layer is an effective way to break the limitations of the barrier factors and improve the tillage-layer quality.

A new approach to determine the long-term effect of efficiency losses due to different dust types accumulation on PV modules with artificial neural networks

Photovoltaic modules are faced with many kinds of environmental effects. One of the most important factors on the efficiency of these systems is dust accumulation on the module surfaces. Airborne particles of dust from various sources, gradually accumulates on the surface of PV modules, thereby lowering the incident radiation reaching to the solar cells. The formation of dust accumulation changes depending on the air temperature, humidity, wind patterns, soil structure, and vegetation characteristics of the region where these systems are installed. Although there are many studies focused on the short-term and medium-term effects of dusting on photovoltaic modules, the long-term studies are quite limited due to some involved problems. In the present study, to fill this gap, the effects of long-term dust accumulation amounts were determined by interpreting the effects of short-term dust accumulation from different origins with a developed artificial neural network model. In the study, clay, calcareous and urban dust samples were used to reveal the effect of different dust sources. Although the effect of dusting on efficiency was given over time, the amount of dust accumulated on the module surface was also expressed in mass in order to find out a general insight. Based on the findings, after 1 month of exposure to clay, calcareous, and urban dusts, the solar modules experienced efficiency losses of approximately 18%, 26%, and 28% respectively, when compared to clean modules. Subsequently, at the end of 3 months, the efficiency losses increased to approximately 46%, 61%, and 63% respectively, and after 6 months, the losses reached approximately 67%, 77%, and 78% respectively. All dust types, particularly urban and calcareous dust, led to substantial efficiency losses in photovoltaic modules. Consequently, regular cleaning of the modules is recommended to prevent these losses.

Study and application of coupling relationship between water-salt-resistivity-soil structure in saline soils in arid and semi-arid areas of northwest China

Widespread saline soils in Northwest China pose a serious threat to the region's ability to use infrastructure safely because they are prone to soil structure damage when subjected to external environmental fluctuations, which in turn affects the stability of the foundations for buildings. The non-destructive approach of measuring resistivity can be used to swiftly reflect the subsoil body's state and make assumptions about its safety. However, the electrical resistivity of the underground soil body can be used to quickly identify unstable areas because the resistivity is influenced by the water content, salt content, and structural characteristics of the soil body. To do this, it is necessary to understand the coupling relationship between various factors. In this study, we first constructed samples with various water, salt, and soil structure characteristics, and then used indoor tests, such as soil resistivity measurement and thermogravimetric analysis, to analyze the multiple factors affecting the resistivity characteristics of the soil. The relationship between soil resistivity and actual saline soil diseases in Northwest China was then further discussed in conjunction with the results of the indoor tests and analyses. subsequently, the resistivity and soil properties have been measured in the field at specific locations in Northwest China where railway roadbeds are diseased. The study's findings can theoretically support a deeper comprehension of the law and mechanism of soil resistivity change, as well as provide assistance for building infrastructure in Northwest China.

Visual evaluation of soil structure in low‐intensity land use systems of steppe zone of Ukraine

AbstractThe network of natural forests and shelterbelts is a crucial element of agroforestry systems for the efficient and environmentally sustainable land use in Ukraine. From 2016 to 2021, we studied the quality of black soils structure under steppe wildland herbaceous vegetation, man‐made tree plantations of Robinia pseudoacacia L. and Quercus robur L., and native forest vegetation of ravines and floodplains in the steppe zone of Ukraine. According to the visual evaluation of soil structure (VESS) scores, the content of the agronomically valuable fraction (AVF), soil organic carbon (SOC) and earthworm casts, native forest soils (Chernozems and Phaeozems) had a significantly (p &lt; .05) higher soil structural quality in 0–25 cm layer as compared with the Chernozems under the steppe vegetation and shelterbelt plantations. In the conditions of steppe landscapes, VESS methods were shown to provide efficient diagnostics to differentiate the black soil structural quality of low‐intensity land use systems, that is steppe wildlands, shelterbelts, native forests: VESS indicators significantly (p &lt; .05) correlated with quantitative characteristics of soil structure. The most significant dependence was found between VESS parameters and earthworm casts content. The need to improve VESS method was demonstrated, that is to assign higher weight to the earthworm bioturbation process as one of the key indicators of soil structural quality.

Grain size characteristics of surface sediment in the Jilantai Salt Lake Protection System after long‐term wind‐sand activities

AbstractIn order to explore the influence of vegetation on homogeneity of surface particle size distribution (PSD) and heterogeneity of soil structure, observations, theory, and multifractal results were synthesized to highlight the evolution of the soil particle composition in the Jilantai Salt Lake Protection System (Jilantai system) after long‐term wind‐sand activities and its soil structure characteristics. From flowing sand dune to saline‐alkali wasteland areas, the mean grain size and surface particle sorting degree gradually increased and decreased, respectively, whereas the shape of the particle frequency curve gradually changed from extremely positive deviation to negative deviation, and the peak shape of the curve gradually changed from narrow to wide. Furthermore, the inhomogeneity of the soil particle composition gradually decreased, whereas the range of the soil PSD gradually increased, and the soil increasingly became fine‐grained. Therefore, the contents of clay and silt in shelterbelt soil increased by 16% and 18.36%, respectively, over 1986 levels. Additionally, clay and silt play a vital role in determining soil particle parameters such as standard deviation (SD), skewness (SKI), and monofractal (D), while vegetation factors are the main controlling factors of clay and silt. In conclusion, the Jilantai system could increase heterogeneity and homogeneity and decrease the concentration of soil PSD by changing the sedimentary environment, while this affect depends largely on the fractional vegetation cover, vegetation height, and light penetrating porosity. Moreover, the multifractal and particle parameters could describe the soil structure characteristics and sedimentary process, respectively, after long‐term wind‐sand activities.

Semi-supervised segmentation of multi-scale soil pores based on a novel receptive field structure

The study of soil pores using computed tomography (CT) technology and deep learning has been proven to be effective. However, conventional neural networks struggle to accurately segment both large connected pores and small scatter pores in soil CT images at different scales. To address this limitation, this paper proposes a semi-supervised multi-scale segmentation method (SMS). The SMS method comprises two parts: 1) Upstream multi-scale pore segmentation branches that generate multi-feature pore segmentation maps based on a novel receptive field structure, and 2) Downstream semi-supervised classification task that selects the optimal pore feature map for output. Experimental results demonstrate that SMS effectively enhances segmentation performance for multi-scale soil pores, achieving the highest accuracy, precision, recall, and F1-score values of 99.55 %, 83.76 %, 96.12 %, and 89.35 %, respectively. These results outperform four common deep learning methods and three traditional image processing software. This study represents a significant advancement in high-precision automated segmentation of soil pores, providing valuable image processing support for investigating soil structure characteristics, soil conservation, and soil ecosystem services.

Spatial analysis of Texture and Soil Structure Characteristics and their effect on wheat and barley producation in Ranya District

Spatial analysis of Texture and Soil Structure Characteristics and their effect on wheat and barley producation in Ranya District

Response mechanism of soil structural heterogeneity in permafrost active layer to freeze–thaw action and vegetation degradation

The soil structure is the key parameter that regulate soil water–heat–solute migration. To date, much remains unknown about the interaction mechanism between soil structure and the external environment in the permafrost regions. In this study, the undegraded meadow and degraded bare land in the permafrost region of the Qinghai–Tibet Plateau were used as research objects, and the soil structure characteristics and their influencing factors of the two sample sites were studied based on in situ hydrothermal observation data and CT scan. The results showed that the macropore system of the undegraded meadow was dominated by connected pores, with a small number of macropores, but the large volume, the shape mainly was elongated, and the connectivity was good. The degraded bare ground was dominated by isolated pores, with more large pores but smaller volume, more regular pore shape, and less pore connectivity than undegraded meadow. The macropore structure in both samples was affected by vegetation, freeze–thaw action, and soil moisture content. The undegraded meadow formed connected pores with mainly tubular pore aggregates in the soil layer above 23 cm due to the protective effect of vegetation roots, and only a few isolated pores existed in the deep soil layer below 23 cm due to weak freeze–thaw action and low moisture content. The daily freeze–thaw cycle days were long, and the complete freezing days were short for the degraded bare land. The frequent freeze–thaw action produced connected pores dominated by fractures, and many isolated pores, while the high water content of the deep soil intensified the freeze–thaw action, producing a large number of isolated pores and also increasing the depth of occurrence of macropores. The difference in the soil pore deepens the understanding of the relationship between the soil macropore and the soil hydrothermal process.

Structural characteristics of the moss (bryophyte) layer and its underlying soil structure and water retention characteristics

The influence of the moss layer on soil structure and soil water retention is not well understood. Therefore, this study aims to investigate the changes in soil structure and soil water retention under moss layer and to reveal the influencing factors of these changes. 3D networks of moss layer and soil macropores were quantified using CT scanning and image analysis techniques, and soil water retention characteristics were explored through soil water retention curves (SWRCs) and VG model. The length densities of the soil macropores under the thin moss and thick moss layers were approximately 2.7 and 1.6 times higher than that under no moss cover. The soil water retention under the thin and thick moss layers were greater than those under no moss cover, with the highest plant-available water capacity under the thin moss layer. The maximum water-holding capacity of the moss layer was significantly positively correlated with the field water-holding capacity of the soil and negatively correlated with the equivalent diameter of the macropores, while the storage capacity of the moss layer was significantly and negatively correlated with the maximum effective water content of the soil. The field capacity (FC) and permanent wilting point (PWP) were significantly and positively correlated with the soil organic matter. The effect of the moss layer on water retention may be mainly realized by influencing the pore distribution and organic matter accumulation. The moss layer had a positive ecohydrological effect on soil water retention and even water conservation in forest soils.

Effects of Chinese Milk Vetch Returning Incorporated with Chemical Fertilizer Reduction on the Composition and Function of Soil Bacterial Communities in Paddy Fields

Chinese milk vetch (Astragalus sinicus L.) is an important organic nutrient resource in the southern Henan rice-growing area. Thus, the effects of Chinese milk vetch (MV) returning incorporated with reduced chemical fertilizer on the physicochemical properties and bacterial community characteristics in paddy soil were studied. These results can provide a certain theoretical basis for the improvement of soil fertility and reduction of chemical fertilizer in this area. A field experiment was conducted for 12 consecutive years, involving six fertilization treatments (blank control, CK; 100% chemical fertilizer, F100; 80% chemical fertilizer+22.5 t·hm-2 MV, MV1F80; 80% chemical fertilizer+45 t·hm-2 MV, MV2F80; 60% chemical fertilizer+22.5 t·hm-2 MV, MV1F60; and 60% chemical fertilizer+45 t·hm-2 MV, MV2F60). The high-throughput sequencing method was used to compare the effects of different fertilization treatments on soil bacterial community diversity, composition, and structural characteristics. The FAPROTAX function prediction method was used to analyze the abundance differences of functional groups between different fertilization treatments. Additionally, combined with soil physicochemical properties and bacterial community characteristics, we explored the key soil environmental factors that changed the structure and functional characteristics of the soil bacterial community. Compared with that under CK, the soil bulk density (BD) under the MV returning incorporated with reduced chemical fertilizer treatment was decreased, whereas soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), and total potassium (TK) were increased by 12.7%-35.5%, 38.2%-65.7%, 66.7%-95.2%, and 20.3%-31.6%, respectively. Compared with that under the F100 treatment, the Sobs index and Shannon diversity index of the bacterial community under the MV returning incorporated with reduced chemical fertilizer were decreased, and the Sobs index and Shannon diversity index were significantly positively correlated with BD (P<0.05) but significantly negatively correlated with SOC and TN (P<0.05). Compared with that under the F100 treatment, the relative abundances of Firmicutes under the MV1F80 and MV2F60 treatments were significantly increased by 82.2% and 67.4% (P<0.05), but the relative abundances of Acidobacteria were significantly reduced by 32.6% and 40.5% (P<0.05), respectively. The relative abundance of Actinobacteria under the MV2F60 treatment was significantly increased by 30.0% (P<0.05) compared with that under the F100 treatment. According to RDA analysis, soil SOC, TN, and TK were the main soil environmental factors that significantly affected bacterial community (P<0.05). Compared with that under CK and the F100 treatment, the abundance of functional groups of chemoheterotrophy, nitrogen fixation, fermentation, and ureolysis under the MV returning incorporated with reduced chemical fertilizer treatment were improved, whereas the abundance of functional groups of animal parasites or symbionts, all human pathogens, and human pathogen pneumonia were reduced, particularly under MV1F80 and MV2F60. To summarize, the long-term MV returning to the field incorporated with reduced chemical fertilizer improved the soil physical and chemical properties, thus changing the structure and functional characteristics of the soil bacterial communities, contributing to the improvement in the soil fertility, stability, and health of micro-ecosystems in paddy fields, thus ensuring the green and sustainable development of regional agriculture.

Generalized stacked LSTM for the seismic damage evaluation of ductile reinforced concrete buildings

AbstractTo organize accurate and effective emergency responses after an earthquake, it is vital to conduct an early and precise assessment of damage to structures. The use of fragility/vulnerability curves is an advanced evaluation approach for structural damage assessments. However, the analysis based on fragility curves significantly varies depending on soil conditions, ground motion, and structural characteristics. To overcome this issue, a stacked long short‐term memory network was proposed in this research. Unlike previous studies, two input features (acceleration time history in the form of vector and the number of stories in the scalar) are utilized to generalize the results for the same plan building frames with different stories. Three different approaches are presented in this work to link the ground motion time history with the number of stories (2, 4, 8, 12, and 20 stories) in the reinforced concrete building frame, and the networks were tested for unknown ground motions. Of the three approaches, those providing good results were selected for further analysis. For the approaches chosen, the network architectures were changed to a diamond shape and an autoencoder‐like shape with more hidden units (to obtain higher accuracy), which were tested for unknown same plan layout frames. The accuracy obtained using these approaches was significantly high (80%–90%) with a low training time. The proposed model is compared with other techniques and shows significant accuracy. The suggested networks exhibited a number of scenarios for estimating the damage state for unknown ground motions, as well as for unknown frames with various stories. Moreover, the capability of the networks to handle more scalar input features is examined by adding them probabilistically; with additional input variables, the networks predicted the damage state with higher accuracy.

Modeling of dual-permeability gas and solute reactive transport in macroporous agricultural soils with a focus on GHG cycling and emissions

Agricultural soil is the domain where biogeochemical C-N turnover is affected by atmospheric and hydrologic processes, playing a vital role in anthropogenic greenhouse gas (GHG) emissions and thus affecting global climate change. GHG cycling and emissions are further complicated by the characteristics of soil structure, in particular macropores (i.e., preferential flow pathway). In this study, the processes of non-equilibrium gas diffusion and gas exchange were implemented into an existing dual-permeability flow and reactive solute transport model. The model was then used in a sensitivity analysis to evaluate the suitability of the modeling approach to account for development of anaerobic hotspots, with an emphasis on assessing N2O production and emissions. The sensitivity analysis combined with characteristic time scale analysis suggests that the development of anaerobic hotspots is controlled by a combination of both physical and geochemical parameters. Time scale analysis of O2 supply and consumption indicates that the occurrence of anaerobic hotspots is determined by the balance between characteristic times of O2 diffusion through the soil profile or exchange between macropores and the soil matrix, and the characteristic time of O2 consumption. Motivated by these findings, the present model was applied to simulate GHG cycling at a field site in Ontario, Canada, featuring macroporous agricultural soil. The model generally reproduced observed spatiotemporal variations in pore gas O2 and GHG concentrations and fluxes. Simulation results suggest that at this site, gas exchange processes between regions of preferential flow and the soil matrix play an important role in controlling the spatial variation of O2 in the soil. The simulations illustrate how the release of GHGs from the soil matrix into the macropores can lead to GHG emissions to the atmosphere. The modeling approach presented here, including dual domain flow and solute transport, as well as dual domain gas transport, shows promise for future studies with the aim to develop a more complete understanding of how soil structure affects complex GHG cycling in agricultural soils.

Novel insights into the predominant factors affecting the bioavailability of polycyclic aromatic hydrocarbons in industrial contaminated areas using PLS-developed model

Bioavailability is recognized as a useful technical standard for risk assessment and pollution rehabilitation. However, knowledge on the bioavailability of polycyclic aromatic hydrocarbons (PAHs) in contaminated site soils is still limited, especially concerning the influential mechanism. With an abundance of soil collections from nine industrial areas in China, the bioavailabilities, as conceptually defined as bioconcentration factors (BCFs) of PAHs were analyzed using biomimetic extraction of hydroxypropyl-β-cyclodextrin (HPCD). Apart from the total content of PAHs varying with the different pyrogenic sources, the BCFs were greatly dependent on the soil physicochemical properties from the spatial scale and inversely proportional to the number of rings. Pearson correlation analysis indicated a weak relationship between bioavailability and the soil dissolved organic matter (DOM), pH and particle size. To incorporate the soil physicochemical properties and structural characteristics of PAHs determined by density functional theory (DFT), the optimum model for bioavailability was developed for BCFs by partial least square (PLS) analysis. The PLS-derived model was shown to be predictive within the applicability domain (AD). The structural characteristics, e.g., molecular polarizability and frontier orbital energy level that favor the soil adsorption of PAH isomers via dispersion interactions, and electron exchanges were indicated to be more impactful on bioavailability than soil environmental factors. However, soil factors should not be neglected, because the pH, DOM, etc. were significantly influential. It makes sense that the higher DOM causes greater bioavailability via increasing the free-dissolved fractions of PAHs. Interestingly, the effect of pH on bioavailability was spectrally validated by excitation-emission matrix (EEM) fluorescence, showing that the interaction between DOM and pyrene strengthened the fluorescence quenching of chromophores with the decline in pH.