The effectiveness of using vegetation to stabilise shallow soil slopes heavily depends on the survival of vegetation,yet the amplification of extreme events induced by climate change threatens the health of plants cov...The effectiveness of using vegetation to stabilise shallow soil slopes heavily depends on the survival of vegetation,yet the amplification of extreme events induced by climate change threatens the health of plants covering slopes.Hydrochar is an environmentally friendly soil amender that can achieve the potential benefits of promoting plant growth for slope stabilisation and facilitation of waste upcycling.The mechanism underlying the hydrochar effects on the mechanical behaviour of unsaturated soils remains unclear.This study investigated the influence of grass-derived hydrochar on the water retention,compressibility,and shear strength of a compacted siltyeclay sand.Soil microstructural changes due to hydrochar amendment were measured to explain the soilehydrochar hydromechanical interaction.The increase in suction resulted in a less significant increase in yield stress and a negligible reduction in compressibility of the hydrochar-amended soil compared with the unamended case.This phenomenon was observed because hydrochar addition reduced the large pores with diameters greater than the macropore peak of 60 mm due to pore filling by hydrochar particles,resulting in a less substantial volume contraction during drying.Hydrochar introduced more significant effects on the soil’s shear strength in an unsaturated state compared to a saturated case.Despite the similarity of the unsaturated amended soil with the critical-state friction angle to the saturated case,the former exhibited a greater shear strength because the hydrochar addition improved water retention capability.As a result,the degree of saturation and,hence,Bishop’s effective stress were higher than those for the unamended case for a given suction.展开更多
The conversion of subtropical red soils into farmland involves complex transformations of iron oxides.Investigating iron mineralogy can enhance understanding of magnetic minerals in relation to soil formation on farml...The conversion of subtropical red soils into farmland involves complex transformations of iron oxides.Investigating iron mineralogy can enhance understanding of magnetic minerals in relation to soil formation on farmland in subtropical regions.In this study,we investigated the properties of iron oxide and its environmental implications in the farmland of Meizhou city,Guangdong province.The results showed that farmland soils had higher magnetism than the red soils developed from the same metamorphic rock.The red soils displayed significantly higher concentrations of goethite and hematite than the farmland soils.The dominant factor influencing the magnetic changes in farmland and red soils was the concentration of fine-grained ferromagnetic minerals.Red soil magnetism is an indicator of soil weathering intensity,whereas farmland soil magnetism is closely related to human cultivation activities.In contrast to the red soils,the farmland soils lacked the pronounced transformation of ferromagnetic minerals into hematite and goethite.A vigorous oxidation process catalyzes the transformation of strong magnetic minerals into significant amounts of hematite and goethite,which promotes the reduced magnetism of red soils.The conversion of red soils into farmland soils initially increased the accumulation of ferromagnetic materials due to cultivation processes.However,long-term cultivation led to the gradual loss of fine-grained ferromagnetic minerals,while goethite and lepidocrocite became the dominant magnetic mineral types.展开更多
Water level fluctuations in the reservoir deteriorate soils and rocks on the bank landslides by drying-wetting(D-W)cycles,which results in a significant decrease in mechanical properties.A comprehensive understanding ...Water level fluctuations in the reservoir deteriorate soils and rocks on the bank landslides by drying-wetting(D-W)cycles,which results in a significant decrease in mechanical properties.A comprehensive understanding of deterioration mechanism of sliding-zone soils is of great significance for interpreting the deformation behavior of landslides.However,quantitative investigation on the deterioration characteristics of soils considering the structural evolution under D-W cycles is still limited.Here,we carry out a series of laboratory tests to characterize the multi-scale deterioration of sliding-zone soils and reveal the mechanism of shear strength decay under D-W cycles.Firstly,we describe the micropores into five grades by scanning electron microscope and observe a critical change in porosity after the first three cycles.We categorize the mesoscale cracks into five classes using digital photography and observe a stepwise increase in crack area ratio.Secondly,we propose a shear strength decay model based on fractal theory which is verified by the results of consolidated undrained triaxial tests.Cohesion and friction angle of sliding-zone soils are found to show different decay patterns resulting from the staged evolution of structure.Then,structural deterioration processes including cementation destruction,pores expansion,aggregations decomposition,and clusters assembly are considered to occur to decay the shear strength differently.Finally,a three-stage deterioration mechanism associated with four structural deterioration processes is revealed,which helps to better interpret the intrinsic mechanism of shear strength decay.These findings provide the theoretical basis for the further accurate evaluation of reservoir landslides stability under water level fluctuations.展开更多
Agricultural soil is related to food security and human health,antibiotics and heavy metals(HMs),as two typical pollutants,possess a high coexistence rate in the environmental medium,which is extremely prone to induci...Agricultural soil is related to food security and human health,antibiotics and heavy metals(HMs),as two typical pollutants,possess a high coexistence rate in the environmental medium,which is extremely prone to inducing antibiotic-HMs combined pollution.Recently,frequent human activities have led to more prominent antibiotics-HMs combined contamination in agricultural soils,especially the production and spread of antibiotic resistance genes(ARGs),heavy metal resistance genes(MRGs),antibiotic resistant bacteria(ARB),and antibiotics-HMs complexes(AMCs),which seriously threaten soil ecology and human health.This review describes the main sources(Intrinsic and manmade sources),composite mechanisms(co-selective resistance,oxidative stress,and Joint toxicity mechanism),environmental fate and the potential risks(soil ecological and human health risks)of antibiotics and HMs in agricultural soils.Finally,the current effective source blocking,transmission control,and attenuation strategies are classified for discussion,such as the application of additives and barrier materials,as well as plant and animal remediation and bioremediation,etc.,pointing out that future research should focus on the whole chain process of“source-processterminal”,intending to provide a theoretical basis and decision-making reference for future research.展开更多
Fifty agricultural soil samples collected from Fuzhou,southeast China,were first investigated for the occurrence,distribution,and potential risks of twelve organophosphate esters(OPEs).The total concentration of OPEs(...Fifty agricultural soil samples collected from Fuzhou,southeast China,were first investigated for the occurrence,distribution,and potential risks of twelve organophosphate esters(OPEs).The total concentration of OPEs(ΣOPEs)in soil ranged from 1.33 to 96.5 ng/g dry weight(dw),with an average value of 17.1 ng/g dw.Especially,halogenated-OPEs were the predominant group with amean level of 9.75 ng/g dw,and tris(1-chloro-2-propyl)phosphate(TCIPP)was the most abundant OPEs,accounting for 51.1%ofΣOPEs.The concentrations of TCIPP andΣOPEs were found to be significantly higher(P<0.05)in soils of urban areas than those in suburban areas.In addition,the use of agricultural plastic films and total organic carbon had a positive effect on the occurrence of OPE in this study.The positive matrix factorization model suggested complex sources of OPEs in agricultural soils from Fuzhou.The ecological risk assessment demonstrated that tricresyl phosphate presented a medium risk to land-based organisms(0.1≤risk quotient<1.0).Nevertheless,the carcinogenic and noncarcinogenic risks for human exposure to OPEs through soil ingestion and dermal absorption were negligible.These findings would facilitate further investigations into the pollution management and risk control of OPEs.展开更多
Ubiquitous contamination of the soil environment with volatile organic compounds(VOCs)has raised considerable concerns.However,there is still limited comprehensive surveying of soil VOCs on a national scale.Herein,65 ...Ubiquitous contamination of the soil environment with volatile organic compounds(VOCs)has raised considerable concerns.However,there is still limited comprehensive surveying of soil VOCs on a national scale.Herein,65 species of VOCswere simultaneously determined in surface soil samples collected from 63 chemical industrial parks(CIPs)across China.The results showed that the total VOC concentrations ranged from 7.15 to 1842 ng/g with a mean concentration of 326 ng/g(median:179 ng/g).Benzene homologs and halogenated hydrocarbons were identified as the dominant contaminant groups.Positive correlations between many VOC species indicated that these compounds probably originated from similar sources.Spatially,the hotspots of VOC pollution were located in eastern and southern China.Soils with higher clay content and a higher fraction of total organic carbon(TOC)content were significantly associated with higher soil VOC concentrations.Precipitation reduces the levels of highly water-soluble substances in surface soils.Both positive matrix factorization(PMF)and principal component analysis-multiple linear regression(PCA-MLR)identified a high proportion of industrial sources(PMF:59.2%and PCA-MLR:66.5%)and traffic emission sources(PMF:32.3%and PCA-MLR:33.5%).PMF,which had a higher R^(2) value(0.7892)than PCA-MLR(0.7683),was the preferred model for quantitative source analysis of soil VOCs.The health risk assessment indicated that the non-carcinogenic and carcinogenic risks of VOCs were at acceptable levels.Overall,this study provides valuable data on the occurrence of VOCs in soil from Chinese CIPs,which is essential for a comprehensive understanding of their environmental behavior.展开更多
Recently,Danziger et al.(2024)published a discussion on our paper(Zhang et al.,2023).In the discussed paper,seismic piezocone tests were conducted to characterize a granitic weathering profile.Pore pressure was measur...Recently,Danziger et al.(2024)published a discussion on our paper(Zhang et al.,2023).In the discussed paper,seismic piezocone tests were conducted to characterize a granitic weathering profile.Pore pressure was measured at both the cone mid-face and the shoulder.The effects of penetrometer size and penetration rate were considered.The results of the study were presented as several updated soil behavior charts.In this reply,the issues raised during the discussion are addressed,including the geotechnical behavior and laboratory and in situ tests of weathered granite.The constructive feedback from the discussers not only enriches the research works of the studied soils but also enhances the understanding of weathering geomaterials.展开更多
[Objectives]To investigate the performance of different efficiency-enhanced Diammonium phosphate(DAP)fertilizers in Xinjiang soils and identify new low-nutrient DAP formulations that promote maize growth in the region...[Objectives]To investigate the performance of different efficiency-enhanced Diammonium phosphate(DAP)fertilizers in Xinjiang soils and identify new low-nutrient DAP formulations that promote maize growth in the region.[Methods]Using 64%DAP(additive-free high-nutrient fertilizer)as the control,it compared with low-nutrient fertilizers:57%DAP additive Formula A,57%DAP additive Formula B,57%DAP additive Formula C,57%DAP additive Formula D,57%DAP additive Formula E,and 57%DAP additive Formula F.By measuring maize growth morphology,physiological indicators,and biomass under different treatments,the measured parameters were evaluated using statistical methods such as regression analysis.[Results]The addition of enhancing additives can promote root development in maize plants and increase physiological indicators such as chlorophyll content and plant height.Low-nutrient DAP with additives shows a trend of being superior to high-nutrient DAP fertilizers in promoting maize growth.Different additive formulas exert varying effects on maize,with 57%DAP additive Formula A,57%DAP additive Formula E,and 57%DAP additive Formula F demonstrating positive effects on maize promotion.[Conclusions]This study provides practical guidance for DAP selection and application in Xinjiang maize cultivation while establishing a foundation for cutting-edge research on high-utilization,low-nutrient fertilizers in arid regions.展开更多
This study aims to characterize the physical and mechanical properties of the soils from the Kenendé,Limbita 1,and Limbita 2 sites,located in the Dubréka prefecture,to develop a composite construction materi...This study aims to characterize the physical and mechanical properties of the soils from the Kenendé,Limbita 1,and Limbita 2 sites,located in the Dubréka prefecture,to develop a composite construction material based on soil and plant fibers that is more resistant to climatic and environmental conditions.To achieve this,soil samples were collected and subjected to various laboratory tests.The study assessed the physical and mechanical properties of these soils to develop a composite construction material incorporating soil and plant fibers.Laboratory tests revealed variations in water absorption capacity and compressive strength depending on the applied pressure(3,4,5 MPa)and the sample’s condition(dry or wet).After a 30-day maturation period,Kenendéexhibited a maximum dry-state strength of 2.66 MPa,while Limbita 1 and Limbita 2 recorded 0.95 MPa and 2.57 MPa,respectively.Soils compacted under high pressure demonstrated better performance,particularly in dry conditions.These results confirm the potential of the soils from the three sites for producing durable construction materials suitable for local climatic conditions,provided they undergo appropriate treatment and maturation,thereby contributing to sustainable construction in Guinea.展开更多
Sudden temperature drops cause soils in natural environments to freeze unidirectionally,resulting in soil expansion and deformation that can lead to damage to engineering structures.The impact of temperature-induced f...Sudden temperature drops cause soils in natural environments to freeze unidirectionally,resulting in soil expansion and deformation that can lead to damage to engineering structures.The impact of temperature-induced freezing on deformation and solute migration in saline soils,especially under extended freezing,is not well understood due to the lack of knowledge regarding the microscopic mechanisms involved.This study investigated the expansion,deformation,and water-salt migration in chlorinated saline soils,materials commonly used for canal foundations in cold and arid regions,under different roof temperatures and soil compaction levels through unidirectional freezing experiments.The microscopic structures of saline soils were observed using scanning electron microscopy(SEM)and optical microscopy.A quantitative analysis of the microstructural data was conducted before and after freezing to elucidate the microscopic mechanisms of water-salt migration and deformation.The results indicate that soil swelling is enhanced by elevated roof temperatures approaching the soil's freezing point and soil compaction,which prolongs the duration and accelerates the rate of water-salt migration.The unidirectional freezing altered the microstructure of saline soils due to the continuous temperature gradients,leading to four distinct zones:natural frozen zone,peak frozen zone,gradual frozen zone,and unfrozen zone,each exhibiting significant changes in pore types and fractal dimensions.Vacuum suction at the colder end of the soil structure facilitates the upward migration of salt and water,which subsequently undergoes crystallization.This process expands the internal pore structure and causes swelling.The findings provide a theoretical basis for understanding the evolution of soil microstructure in cold and arid regions and for the management of saline soil engineering.展开更多
A simplified analytical approach is proposed for predicting the load-displacement behavior of single piles in unsaturated soils considering the contribution from the nonlinear shear strength and soil stiffness influen...A simplified analytical approach is proposed for predicting the load-displacement behavior of single piles in unsaturated soils considering the contribution from the nonlinear shear strength and soil stiffness influenced by matric suction.This approach includes a Modified Load Transfer Model(MLTM)that can predict the nonlinear relationships between the shear stress and pile-soil relative displacement along the pile shaft,and between the pile base resistance and base settlement.The proposed model is also extended for pile groups to incorporate the interaction effects between individual piles.The analytical approach is validated through a comparative analysis with the measurements from two single pile tests and one pile group test.In addition,a finite element analysis using 3D modeling is carried out to investigate the behavior of pile groups in various unsaturated conditions.This is accomplished with a user-defined subroutine that is written and implemented in ABAQUS to simulate the nonlinear mechanical behavior of unsaturated soils.The predictions derived from the proposed analytical and numerical methods compare well with the measurements of a published experimental study.The proposed methodologies have the potential to be applied in geotechnical engineering practice for the rational design of single piles and pile groups in unsaturated soils.展开更多
Earthworms play a vital role in enhancing soil quality and structure in agricultural ecosystems.This study investigated the diversity of earthworm species found in banana and guava orchards in Nakhon Pathom,Thailand,w...Earthworms play a vital role in enhancing soil quality and structure in agricultural ecosystems.This study investigated the diversity of earthworm species found in banana and guava orchards in Nakhon Pathom,Thailand,where 166 samples were collected.The results showed that 56.63%of earthworms were in the adult stage.In the banana orchard,researchers identified two families and four species:from the family Megascolecidae,they found Amynthas alexandri,Metaphire posthuma,and Polypheretima elongata,along with one species from the family Moniligastridae,Drawida sp.In the guava orchard,two families and two species were identified:from the family Megascolecidae,Metaphire posthuma,and from the family Moniligastridae,Drawida sp.Fungi isolated from the intestines of earthworms,precisely the strains EW2,EW3,EW6,EW13,EW16,EW23,EW25,EW26,EW28,EW38,EW39,EW40,EW41,EW43,and EW44,have demonstrated the ability to produce cellulase.Among these,the fungus EW41 exhibited the highest cellulase activity,measuring 32.97 units per milliliter at an optimal temperature of 60℃ and a pH of 5.0.This study high-ranlightsthat most earthworm species in agricultural soils belong to the family Megascolecidae.Furthermore,earthwormsplay a crucial role in enhancing the chemical properties of the soil.The cellulolytic fungi present in earthworm intestinescontribute to the natural decomposition of organic matter,thereby promoting soil health by converting plant residuesinto nutrient-rich compost.These findings suggest promising applications of earthworm-associated fungi in sustainableagriculture and organic waste management.展开更多
Rubble deposits with a high concentration of rock debris were created after the powerful earthquakes in Jiuzhaigou.Because of the restricted soil resources,water leaks,and nutrient deficits,these deposits pose serious...Rubble deposits with a high concentration of rock debris were created after the powerful earthquakes in Jiuzhaigou.Because of the restricted soil resources,water leaks,and nutrient deficits,these deposits pose serious obstacles for vegetation regeneration.The purpose of this study was to investigate the main mechanisms controlling soil water retention and evaluate the effects of different amendments on the hydraulic characteristics and water-holding capacity of collapsed rubble soils.Finegrained soil,forest humus,crushed straw,and organic components that retain water were added to the altered soils to study the pore structure images and soil-water characteristic curves.Comparing understory humus to other supplements,the results showed a considerable increase in the soil's saturated and wilting water content.The saturated water content and wilting water content rose by 17.9%and 4.3%,respectively,when the percentage of understory soil reached 30%.Additionally,the enhanced soil's microporosity and total pore volume increased by 45.33%and 11.27%,respectively,according to nuclear magnetic imaging.It was shown that while clay particles and organic matter improved the soil's ability to adsorb water,they also increased the soil's total capacity to store water.Fine particulate matter did this by decreasing macropores and increasing capillary pores.These results offer an essential starting point for creating strategies for soil repair that would encourage the restoration of plants on slopes that have been damaged.展开更多
Plastic contamination has become a major environmental concern and impacts human health,and yet this is still a topic that remains largely understudied.Effects of macro-and microplastics on soil physical,chemical,and ...Plastic contamination has become a major environmental concern and impacts human health,and yet this is still a topic that remains largely understudied.Effects of macro-and microplastics on soil physical,chemical,and biological properties,including soil biota,are considered adverse for soils.Due to their small size and porous surface,microplastics can also be a new environmental concern because of their ability to act as carriers of contaminants or diseases.展开更多
Gassy soils are distributed in relatively shallow layers the Quaternary deposit in Hangzhou Bay area. The shallow gassy soils significantly affect the construction of underground projects. Proper characterization of s...Gassy soils are distributed in relatively shallow layers the Quaternary deposit in Hangzhou Bay area. The shallow gassy soils significantly affect the construction of underground projects. Proper characterization of spatial distribution of shallow gassy soils is indispensable prior to construction of underground projects in the area. Due to the costly conditions required in the site investigation for gassy soils, only a limited number of gas pressure data can be obtained in engineering practice, which leads to the uncertainty in characterizing spatial distribution of gassy soils. Determining the number of boreholes for investigating gassy soils and their corresponding locations is pivotal to reducing construction risk induced by gassy soils. However, this primarily relies on the engineering experience in the current site investigation practice. This study develops a probabilistic site investigation optimization method for planning investigation schemes (including the number and locations of boreholes) of gassy soils based on the conditional random field and Monte Carlo simulation. The proposed method aims to provide an optimal investigation scheme before the site investigation based on prior knowledge. Finally, the proposed approach is illustrated using a case study.展开更多
Heat transfers at the interface of adjacent saturated soil primarily through the soil particles and the water in the voids.The presence of water induces the contraction of heat flow lines at the interface,leading to t...Heat transfers at the interface of adjacent saturated soil primarily through the soil particles and the water in the voids.The presence of water induces the contraction of heat flow lines at the interface,leading to the emergence of the thermal contact resistance effect.In this paper,four thermal contact models were developed to predict the thermal contact resistance at the interface of multilayered saturated soils.Based on the theory of thermal-hydro-mechanical coupling,semi-analytical solutions of thermal consolidation subjected to time-dependent heating and loading were obtained by employing Laplace transform and its inverse transformation.Thermal consolidation characteristics of multilayered saturated soils under four different thermal contact models were discussed,and the effects of thermal resistance coefficient,partition thermal contact coefficient,and temperature amplitude on the thermal consolidation process were investigated.The outcomes indicate that the general thermal contact model results in the most pronounced thermal gradient at the interface,which can be degenerated to the other three thermal contact models.The perfect thermal contact model overestimates the deformation of the saturated soil during the thermal consolidation.Moreover,the effect of temperature on consolidation properties decreases gradually with increasing interfacial contact thermal resistance.展开更多
Nano zero-valent iron(nZVI)is widely used in soil remediation due to its high reactivity.However,the easy agglomeration,poor antioxidant ability and passivation layer of Fe-Cr coprecipitates of nZVI have limited its a...Nano zero-valent iron(nZVI)is widely used in soil remediation due to its high reactivity.However,the easy agglomeration,poor antioxidant ability and passivation layer of Fe-Cr coprecipitates of nZVI have limited its application scale in Cr-contaminated soil remediation,especially in high concentration of Cr-contaminated soil.Herein,we found that the carboxymethyl cellulose on nZVI particles could increase the zeta potential value of soil and change the phase of nZVI.Along with the presence of biochar,97.0%and 96.6%Cr immobilization efficiency through CMC-nZVI/BC were respectively achieved in high and low concentrations of Cr-contaminated soils after 90-days remediation.In addition,the immobilization efficiency of Cr(VI)only decreased by 5.1%through CMC-nZVI/BC treatment after 10 weeks aging in air,attributing to the strong antioxidation ability.As for the surrounding Crcontaminated groundwater,the Cr(VI)removal capacity of CMC-nZVI/BC was evaluated under different reaction conditions through column experiments and COMSOL Multiphysics.CMC-nZVI/BC could efficiently remove 85%of Cr(VI)in about 400 hr when the initial Cr(VI)concentration was 40 mg/L and the flow rate was 0.5 mL/min.This study demonstrates that uniformly dispersed CMC-nZVI/BC has an excellent remediation effect on different concentrations of Cr-contaminated soils.展开更多
Correctly tracking the evolution of spatial heterogeneity of local degree of saturation(Sr)in unsaturated soils is essential to explain the seepage phenomenon,which is crucial to assessing slope stability.Several meth...Correctly tracking the evolution of spatial heterogeneity of local degree of saturation(Sr)in unsaturated soils is essential to explain the seepage phenomenon,which is crucial to assessing slope stability.Several methods exist for quantifying the heterogeneity of local S_(r).However,a comprehensive comparison of these methods in terms of accuracy,relative advantages,and disadvantages is currently lacking.This paper presents a comparative analysis of local Sr obtained at multiple scales,ranging from the element scale to the slice,representative element volume(REV),pore,and voxel scales.The spatial heterogeneity of Sr in an unsaturated glass beads specimen at different matric suctions was visualised and quantified by multiscale X-ray micro-focus computed tomography image-based analysis methods.Local Sr obtained at different scales displayed a comparable trend along the sample depth,yet the REV-scale method showed a much scattered and discontinuous distribution.In contrast,the pore-scale method detected a distinct two-clustered,bimodal distribution of S_(r).The pore-scale method has the highest integrated resolution,as it has the highest spatial resolution(i.e.number of data points)and provides more information(i.e.number of extractable physical parameters).This method thus provides a more effective approach for tracking the spatial heterogeneity of S_(r).Based on this method,pore-scale water retention curves were determined,offering new quantitative means to characterise pore water heterogeneity and explainwater drainage processes such as hysteresis at the pore scale.展开更多
Utilizing the Discrete Element Method,this research studied the stiffness distribution of gap-graded soils by modifying the conventional static method.By acknowledging the inherent particle property disparity between ...Utilizing the Discrete Element Method,this research studied the stiffness distribution of gap-graded soils by modifying the conventional static method.By acknowledging the inherent particle property disparity between coarser and finer particles,this research differentiates the stiffness distribution of gap-graded soils from the perspective of contact and particle types.Results indicate that particle property disparity significantly influence the small-strain stiffness characteristics,consequently altering the overall stiffness distribution in gap-graded soil specimens.Specifically,with the equivalent coarser particle property,an increase in particle Young's modulus of finer particles results in an augmentation of small-strain stiffness values,alongside an increased stiffness distribution contribution from finer particles.Nevertheless,this study reveals that even with a higher particle Young's modulus of finer particles,the proportion of small-strain stiffness transferred by finer particles remains consistently lower than their volume fraction.Furthermore,the proportion of stiffness transferred by finer particles may fall below their contribution to stress transmission.This investigation accentuates the subtle yet significant effects of particle property variations on small strain stiffness and its subsequent distribution,providing a foundation for advancing the significance of particle property disparities in evaluating soil responses.展开更多
The main objectives of this study were to investigate the distribution features of the ^(210)Po in abiotic(water and bottom sediments)and biotic(zooplankton,mollusks,fish)components of the North Crimean Canal(NCC)aqua...The main objectives of this study were to investigate the distribution features of the ^(210)Po in abiotic(water and bottom sediments)and biotic(zooplankton,mollusks,fish)components of the North Crimean Canal(NCC)aquatic ecosystem and adjacent irrigated soils as well as assessment of the doses received by water organisms from α-radiation of absorbed ^(210)Po.The samples were processed using standard radiochemical methods accepted in international practice.The activity of ^(210)Po in the samples was measured using the alpha-spectrometric OCTETE Plus complex(ORTEC-AMETEK,USA).The measurement error did not exceed 20%.Activity concentration of ^(210)Po in the studied objects decreased in the following rank:suspended matter(73.6 Bq/kg d.w.)>soils(32.5 Bq/kg d.w.)≈bottom sediments(32.1 Bq/kg d.w.)>mollusks(23.4 Bq/kg w.w.)>fish(6.4 Bq/kg w.w.).The ^(210)Po distribution coefficient(K_(d))values in water between suspended matter and its dissolved parts varied within the 1.4×10^(4)-1.4×10^(5) L/kg range.The concentration factors(CF)of ^(210)Po for hydrobionts of the NCC were in the range 10^(3)-10^(4) L/kg.The calculated absorbed radiation doses from ^(210)Po alpha radiation for the hydrobionts of the North Crimean Canal were significantly below the recommended dose limits.展开更多
基金supported by grants funded by the Hong Kong Research Grants Council(Grant No.CRF/C6006-20G)a grant provided by the Joint NSFC/RGC Joint Research Scheme(Grant No.N_HKUST603/22)the Fundamental Research Funds for the Central Universities(Grant No.Z1090125018).
文摘The effectiveness of using vegetation to stabilise shallow soil slopes heavily depends on the survival of vegetation,yet the amplification of extreme events induced by climate change threatens the health of plants covering slopes.Hydrochar is an environmentally friendly soil amender that can achieve the potential benefits of promoting plant growth for slope stabilisation and facilitation of waste upcycling.The mechanism underlying the hydrochar effects on the mechanical behaviour of unsaturated soils remains unclear.This study investigated the influence of grass-derived hydrochar on the water retention,compressibility,and shear strength of a compacted siltyeclay sand.Soil microstructural changes due to hydrochar amendment were measured to explain the soilehydrochar hydromechanical interaction.The increase in suction resulted in a less significant increase in yield stress and a negligible reduction in compressibility of the hydrochar-amended soil compared with the unamended case.This phenomenon was observed because hydrochar addition reduced the large pores with diameters greater than the macropore peak of 60 mm due to pore filling by hydrochar particles,resulting in a less substantial volume contraction during drying.Hydrochar introduced more significant effects on the soil’s shear strength in an unsaturated state compared to a saturated case.Despite the similarity of the unsaturated amended soil with the critical-state friction angle to the saturated case,the former exhibited a greater shear strength because the hydrochar addition improved water retention capability.As a result,the degree of saturation and,hence,Bishop’s effective stress were higher than those for the unamended case for a given suction.
基金Technology Program of Jiaying University,No.2024KJZ01Open Funding of Guangdong Provincial Key Laboratory of Conservation and Precision Utilization of Characteristic Agricultural Resources in Mountainous Areas,No.2023JYKF08National Natural Science Foundation of China,No.42277442。
文摘The conversion of subtropical red soils into farmland involves complex transformations of iron oxides.Investigating iron mineralogy can enhance understanding of magnetic minerals in relation to soil formation on farmland in subtropical regions.In this study,we investigated the properties of iron oxide and its environmental implications in the farmland of Meizhou city,Guangdong province.The results showed that farmland soils had higher magnetism than the red soils developed from the same metamorphic rock.The red soils displayed significantly higher concentrations of goethite and hematite than the farmland soils.The dominant factor influencing the magnetic changes in farmland and red soils was the concentration of fine-grained ferromagnetic minerals.Red soil magnetism is an indicator of soil weathering intensity,whereas farmland soil magnetism is closely related to human cultivation activities.In contrast to the red soils,the farmland soils lacked the pronounced transformation of ferromagnetic minerals into hematite and goethite.A vigorous oxidation process catalyzes the transformation of strong magnetic minerals into significant amounts of hematite and goethite,which promotes the reduced magnetism of red soils.The conversion of red soils into farmland soils initially increased the accumulation of ferromagnetic materials due to cultivation processes.However,long-term cultivation led to the gradual loss of fine-grained ferromagnetic minerals,while goethite and lepidocrocite became the dominant magnetic mineral types.
基金funding support from the NSFC Key Projects of International Cooperation and Exchanges (Grant No.42020104006)the National Key Research and Development Program of China (Grant No.2023YFC3007001)the National Natural Science Foundation of China (Grant No.42307227).
文摘Water level fluctuations in the reservoir deteriorate soils and rocks on the bank landslides by drying-wetting(D-W)cycles,which results in a significant decrease in mechanical properties.A comprehensive understanding of deterioration mechanism of sliding-zone soils is of great significance for interpreting the deformation behavior of landslides.However,quantitative investigation on the deterioration characteristics of soils considering the structural evolution under D-W cycles is still limited.Here,we carry out a series of laboratory tests to characterize the multi-scale deterioration of sliding-zone soils and reveal the mechanism of shear strength decay under D-W cycles.Firstly,we describe the micropores into five grades by scanning electron microscope and observe a critical change in porosity after the first three cycles.We categorize the mesoscale cracks into five classes using digital photography and observe a stepwise increase in crack area ratio.Secondly,we propose a shear strength decay model based on fractal theory which is verified by the results of consolidated undrained triaxial tests.Cohesion and friction angle of sliding-zone soils are found to show different decay patterns resulting from the staged evolution of structure.Then,structural deterioration processes including cementation destruction,pores expansion,aggregations decomposition,and clusters assembly are considered to occur to decay the shear strength differently.Finally,a three-stage deterioration mechanism associated with four structural deterioration processes is revealed,which helps to better interpret the intrinsic mechanism of shear strength decay.These findings provide the theoretical basis for the further accurate evaluation of reservoir landslides stability under water level fluctuations.
基金supported by the National Natural Science Foundation of China(No.32171615)the National Key R&D Program of China(2019YFC1804102)。
文摘Agricultural soil is related to food security and human health,antibiotics and heavy metals(HMs),as two typical pollutants,possess a high coexistence rate in the environmental medium,which is extremely prone to inducing antibiotic-HMs combined pollution.Recently,frequent human activities have led to more prominent antibiotics-HMs combined contamination in agricultural soils,especially the production and spread of antibiotic resistance genes(ARGs),heavy metal resistance genes(MRGs),antibiotic resistant bacteria(ARB),and antibiotics-HMs complexes(AMCs),which seriously threaten soil ecology and human health.This review describes the main sources(Intrinsic and manmade sources),composite mechanisms(co-selective resistance,oxidative stress,and Joint toxicity mechanism),environmental fate and the potential risks(soil ecological and human health risks)of antibiotics and HMs in agricultural soils.Finally,the current effective source blocking,transmission control,and attenuation strategies are classified for discussion,such as the application of additives and barrier materials,as well as plant and animal remediation and bioremediation,etc.,pointing out that future research should focus on the whole chain process of“source-processterminal”,intending to provide a theoretical basis and decision-making reference for future research.
基金supported by the Open Fund of the Laboratory for Earth Surface Processes,Ministry of Education,Peking University,Beijing,China,and the Cultivation Fund Program for Excellent Dissertation in Fujian Normal University,China(No.LWPYS202315)the Research Start-up Fund of Fujian Normal University,China(No.Y0720304X13).
文摘Fifty agricultural soil samples collected from Fuzhou,southeast China,were first investigated for the occurrence,distribution,and potential risks of twelve organophosphate esters(OPEs).The total concentration of OPEs(ΣOPEs)in soil ranged from 1.33 to 96.5 ng/g dry weight(dw),with an average value of 17.1 ng/g dw.Especially,halogenated-OPEs were the predominant group with amean level of 9.75 ng/g dw,and tris(1-chloro-2-propyl)phosphate(TCIPP)was the most abundant OPEs,accounting for 51.1%ofΣOPEs.The concentrations of TCIPP andΣOPEs were found to be significantly higher(P<0.05)in soils of urban areas than those in suburban areas.In addition,the use of agricultural plastic films and total organic carbon had a positive effect on the occurrence of OPE in this study.The positive matrix factorization model suggested complex sources of OPEs in agricultural soils from Fuzhou.The ecological risk assessment demonstrated that tricresyl phosphate presented a medium risk to land-based organisms(0.1≤risk quotient<1.0).Nevertheless,the carcinogenic and noncarcinogenic risks for human exposure to OPEs through soil ingestion and dermal absorption were negligible.These findings would facilitate further investigations into the pollution management and risk control of OPEs.
基金supported by the Medical and Health Projects in Zhejiang Province(No.2022PY049)the Basic Scientific Research Project of Hangzhou Medical College(No.YS2021006)Key Discipline of Zhejiang Province in Public Health and Preventive Medicine(First Class,Category A),Hangzhou Medical College.
文摘Ubiquitous contamination of the soil environment with volatile organic compounds(VOCs)has raised considerable concerns.However,there is still limited comprehensive surveying of soil VOCs on a national scale.Herein,65 species of VOCswere simultaneously determined in surface soil samples collected from 63 chemical industrial parks(CIPs)across China.The results showed that the total VOC concentrations ranged from 7.15 to 1842 ng/g with a mean concentration of 326 ng/g(median:179 ng/g).Benzene homologs and halogenated hydrocarbons were identified as the dominant contaminant groups.Positive correlations between many VOC species indicated that these compounds probably originated from similar sources.Spatially,the hotspots of VOC pollution were located in eastern and southern China.Soils with higher clay content and a higher fraction of total organic carbon(TOC)content were significantly associated with higher soil VOC concentrations.Precipitation reduces the levels of highly water-soluble substances in surface soils.Both positive matrix factorization(PMF)and principal component analysis-multiple linear regression(PCA-MLR)identified a high proportion of industrial sources(PMF:59.2%and PCA-MLR:66.5%)and traffic emission sources(PMF:32.3%and PCA-MLR:33.5%).PMF,which had a higher R^(2) value(0.7892)than PCA-MLR(0.7683),was the preferred model for quantitative source analysis of soil VOCs.The health risk assessment indicated that the non-carcinogenic and carcinogenic risks of VOCs were at acceptable levels.Overall,this study provides valuable data on the occurrence of VOCs in soil from Chinese CIPs,which is essential for a comprehensive understanding of their environmental behavior.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.42307212 and 42177148)the Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(Grant No.SKLGME-JBGS2403)。
文摘Recently,Danziger et al.(2024)published a discussion on our paper(Zhang et al.,2023).In the discussed paper,seismic piezocone tests were conducted to characterize a granitic weathering profile.Pore pressure was measured at both the cone mid-face and the shoulder.The effects of penetrometer size and penetration rate were considered.The results of the study were presented as several updated soil behavior charts.In this reply,the issues raised during the discussion are addressed,including the geotechnical behavior and laboratory and in situ tests of weathered granite.The constructive feedback from the discussers not only enriches the research works of the studied soils but also enhances the understanding of weathering geomaterials.
基金Supported by National Key R&D Program of China during the 14 th Five-Year Plan Period"Development and Industrialization of New Green Value-Added Fertilizers"(2023YFD1700200).
文摘[Objectives]To investigate the performance of different efficiency-enhanced Diammonium phosphate(DAP)fertilizers in Xinjiang soils and identify new low-nutrient DAP formulations that promote maize growth in the region.[Methods]Using 64%DAP(additive-free high-nutrient fertilizer)as the control,it compared with low-nutrient fertilizers:57%DAP additive Formula A,57%DAP additive Formula B,57%DAP additive Formula C,57%DAP additive Formula D,57%DAP additive Formula E,and 57%DAP additive Formula F.By measuring maize growth morphology,physiological indicators,and biomass under different treatments,the measured parameters were evaluated using statistical methods such as regression analysis.[Results]The addition of enhancing additives can promote root development in maize plants and increase physiological indicators such as chlorophyll content and plant height.Low-nutrient DAP with additives shows a trend of being superior to high-nutrient DAP fertilizers in promoting maize growth.Different additive formulas exert varying effects on maize,with 57%DAP additive Formula A,57%DAP additive Formula E,and 57%DAP additive Formula F demonstrating positive effects on maize promotion.[Conclusions]This study provides practical guidance for DAP selection and application in Xinjiang maize cultivation while establishing a foundation for cutting-edge research on high-utilization,low-nutrient fertilizers in arid regions.
文摘This study aims to characterize the physical and mechanical properties of the soils from the Kenendé,Limbita 1,and Limbita 2 sites,located in the Dubréka prefecture,to develop a composite construction material based on soil and plant fibers that is more resistant to climatic and environmental conditions.To achieve this,soil samples were collected and subjected to various laboratory tests.The study assessed the physical and mechanical properties of these soils to develop a composite construction material incorporating soil and plant fibers.Laboratory tests revealed variations in water absorption capacity and compressive strength depending on the applied pressure(3,4,5 MPa)and the sample’s condition(dry or wet).After a 30-day maturation period,Kenendéexhibited a maximum dry-state strength of 2.66 MPa,while Limbita 1 and Limbita 2 recorded 0.95 MPa and 2.57 MPa,respectively.Soils compacted under high pressure demonstrated better performance,particularly in dry conditions.These results confirm the potential of the soils from the three sites for producing durable construction materials suitable for local climatic conditions,provided they undergo appropriate treatment and maturation,thereby contributing to sustainable construction in Guinea.
基金supported by the Open Fund of State Key Laboratory of Frozen Soil Engineering (Grant No.SKLFSE201806)the National Natural Science Foundation of China (Grant No.42177155).
文摘Sudden temperature drops cause soils in natural environments to freeze unidirectionally,resulting in soil expansion and deformation that can lead to damage to engineering structures.The impact of temperature-induced freezing on deformation and solute migration in saline soils,especially under extended freezing,is not well understood due to the lack of knowledge regarding the microscopic mechanisms involved.This study investigated the expansion,deformation,and water-salt migration in chlorinated saline soils,materials commonly used for canal foundations in cold and arid regions,under different roof temperatures and soil compaction levels through unidirectional freezing experiments.The microscopic structures of saline soils were observed using scanning electron microscopy(SEM)and optical microscopy.A quantitative analysis of the microstructural data was conducted before and after freezing to elucidate the microscopic mechanisms of water-salt migration and deformation.The results indicate that soil swelling is enhanced by elevated roof temperatures approaching the soil's freezing point and soil compaction,which prolongs the duration and accelerates the rate of water-salt migration.The unidirectional freezing altered the microstructure of saline soils due to the continuous temperature gradients,leading to four distinct zones:natural frozen zone,peak frozen zone,gradual frozen zone,and unfrozen zone,each exhibiting significant changes in pore types and fractal dimensions.Vacuum suction at the colder end of the soil structure facilitates the upward migration of salt and water,which subsequently undergoes crystallization.This process expands the internal pore structure and causes swelling.The findings provide a theoretical basis for understanding the evolution of soil microstructure in cold and arid regions and for the management of saline soil engineering.
基金financially supported by NSERC,CanadaDiscovery Grant 2020(Grant No.5808).
文摘A simplified analytical approach is proposed for predicting the load-displacement behavior of single piles in unsaturated soils considering the contribution from the nonlinear shear strength and soil stiffness influenced by matric suction.This approach includes a Modified Load Transfer Model(MLTM)that can predict the nonlinear relationships between the shear stress and pile-soil relative displacement along the pile shaft,and between the pile base resistance and base settlement.The proposed model is also extended for pile groups to incorporate the interaction effects between individual piles.The analytical approach is validated through a comparative analysis with the measurements from two single pile tests and one pile group test.In addition,a finite element analysis using 3D modeling is carried out to investigate the behavior of pile groups in various unsaturated conditions.This is accomplished with a user-defined subroutine that is written and implemented in ABAQUS to simulate the nonlinear mechanical behavior of unsaturated soils.The predictions derived from the proposed analytical and numerical methods compare well with the measurements of a published experimental study.The proposed methodologies have the potential to be applied in geotechnical engineering practice for the rational design of single piles and pile groups in unsaturated soils.
文摘Earthworms play a vital role in enhancing soil quality and structure in agricultural ecosystems.This study investigated the diversity of earthworm species found in banana and guava orchards in Nakhon Pathom,Thailand,where 166 samples were collected.The results showed that 56.63%of earthworms were in the adult stage.In the banana orchard,researchers identified two families and four species:from the family Megascolecidae,they found Amynthas alexandri,Metaphire posthuma,and Polypheretima elongata,along with one species from the family Moniligastridae,Drawida sp.In the guava orchard,two families and two species were identified:from the family Megascolecidae,Metaphire posthuma,and from the family Moniligastridae,Drawida sp.Fungi isolated from the intestines of earthworms,precisely the strains EW2,EW3,EW6,EW13,EW16,EW23,EW25,EW26,EW28,EW38,EW39,EW40,EW41,EW43,and EW44,have demonstrated the ability to produce cellulase.Among these,the fungus EW41 exhibited the highest cellulase activity,measuring 32.97 units per milliliter at an optimal temperature of 60℃ and a pH of 5.0.This study high-ranlightsthat most earthworm species in agricultural soils belong to the family Megascolecidae.Furthermore,earthwormsplay a crucial role in enhancing the chemical properties of the soil.The cellulolytic fungi present in earthworm intestinescontribute to the natural decomposition of organic matter,thereby promoting soil health by converting plant residuesinto nutrient-rich compost.These findings suggest promising applications of earthworm-associated fungi in sustainableagriculture and organic waste management.
基金jointly funded by the Sichuan Provincial Natural Science Foundation of China(Grant No.2023NSFSC0378)the Jiuzhaigou Lake Swamp and River Ecological Restoration Research Project(N5132112022000246)the Research base and Support provided by Jiuzhaigou Administration for this study。
文摘Rubble deposits with a high concentration of rock debris were created after the powerful earthquakes in Jiuzhaigou.Because of the restricted soil resources,water leaks,and nutrient deficits,these deposits pose serious obstacles for vegetation regeneration.The purpose of this study was to investigate the main mechanisms controlling soil water retention and evaluate the effects of different amendments on the hydraulic characteristics and water-holding capacity of collapsed rubble soils.Finegrained soil,forest humus,crushed straw,and organic components that retain water were added to the altered soils to study the pore structure images and soil-water characteristic curves.Comparing understory humus to other supplements,the results showed a considerable increase in the soil's saturated and wilting water content.The saturated water content and wilting water content rose by 17.9%and 4.3%,respectively,when the percentage of understory soil reached 30%.Additionally,the enhanced soil's microporosity and total pore volume increased by 45.33%and 11.27%,respectively,according to nuclear magnetic imaging.It was shown that while clay particles and organic matter improved the soil's ability to adsorb water,they also increased the soil's total capacity to store water.Fine particulate matter did this by decreasing macropores and increasing capillary pores.These results offer an essential starting point for creating strategies for soil repair that would encourage the restoration of plants on slopes that have been damaged.
基金funded by the research project Env Agro(No.XG-IDI24-05/04)of Universidade de Vigo(Spain)and Universidade do Minho(Portugal)the financial support of the Consellería de Cultura,Educación e Universidade,Xunta de Galicia(Spain)through the contract(No.ED431C2021/46-GCR)granted to the research group BV1 of Universidade de Vigo+3 种基金a postdoctoral fellowship(No.ED481B-2022081)funded by Xunta de Galiciaa pre-doctoral Formación de Profesorado Universitario contract(No.FPU19/03758)funded by the Ministry of Universities(Spanish Government)supported by a JdCi research contract(No.IJC2020044197-I)funded by MICIU/AEI/10.13039/501100011033 and European Union EU/PRTREuropean Cooperation in Science and Technology(COST)Action CA20101 Plastics Monitoring Detection Remediation Recovery—PRIORITY,supported by COST(www.cost.eu)。
文摘Plastic contamination has become a major environmental concern and impacts human health,and yet this is still a topic that remains largely understudied.Effects of macro-and microplastics on soil physical,chemical,and biological properties,including soil biota,are considered adverse for soils.Due to their small size and porous surface,microplastics can also be a new environmental concern because of their ability to act as carriers of contaminants or diseases.
文摘Gassy soils are distributed in relatively shallow layers the Quaternary deposit in Hangzhou Bay area. The shallow gassy soils significantly affect the construction of underground projects. Proper characterization of spatial distribution of shallow gassy soils is indispensable prior to construction of underground projects in the area. Due to the costly conditions required in the site investigation for gassy soils, only a limited number of gas pressure data can be obtained in engineering practice, which leads to the uncertainty in characterizing spatial distribution of gassy soils. Determining the number of boreholes for investigating gassy soils and their corresponding locations is pivotal to reducing construction risk induced by gassy soils. However, this primarily relies on the engineering experience in the current site investigation practice. This study develops a probabilistic site investigation optimization method for planning investigation schemes (including the number and locations of boreholes) of gassy soils based on the conditional random field and Monte Carlo simulation. The proposed method aims to provide an optimal investigation scheme before the site investigation based on prior knowledge. Finally, the proposed approach is illustrated using a case study.
基金Projects(U24B20113,42477162) supported by the National Natural Science Foundation of ChinaProject(2025C02228) supported by the Primary Research and Development Plan of Zhejiang Province,China。
文摘Heat transfers at the interface of adjacent saturated soil primarily through the soil particles and the water in the voids.The presence of water induces the contraction of heat flow lines at the interface,leading to the emergence of the thermal contact resistance effect.In this paper,four thermal contact models were developed to predict the thermal contact resistance at the interface of multilayered saturated soils.Based on the theory of thermal-hydro-mechanical coupling,semi-analytical solutions of thermal consolidation subjected to time-dependent heating and loading were obtained by employing Laplace transform and its inverse transformation.Thermal consolidation characteristics of multilayered saturated soils under four different thermal contact models were discussed,and the effects of thermal resistance coefficient,partition thermal contact coefficient,and temperature amplitude on the thermal consolidation process were investigated.The outcomes indicate that the general thermal contact model results in the most pronounced thermal gradient at the interface,which can be degenerated to the other three thermal contact models.The perfect thermal contact model overestimates the deformation of the saturated soil during the thermal consolidation.Moreover,the effect of temperature on consolidation properties decreases gradually with increasing interfacial contact thermal resistance.
基金supported by the National Key Research and Development Program of China(No.2020YFC1808701)the Fundamental Research Funds for the Central Universities(No.buctrc202232).
文摘Nano zero-valent iron(nZVI)is widely used in soil remediation due to its high reactivity.However,the easy agglomeration,poor antioxidant ability and passivation layer of Fe-Cr coprecipitates of nZVI have limited its application scale in Cr-contaminated soil remediation,especially in high concentration of Cr-contaminated soil.Herein,we found that the carboxymethyl cellulose on nZVI particles could increase the zeta potential value of soil and change the phase of nZVI.Along with the presence of biochar,97.0%and 96.6%Cr immobilization efficiency through CMC-nZVI/BC were respectively achieved in high and low concentrations of Cr-contaminated soils after 90-days remediation.In addition,the immobilization efficiency of Cr(VI)only decreased by 5.1%through CMC-nZVI/BC treatment after 10 weeks aging in air,attributing to the strong antioxidation ability.As for the surrounding Crcontaminated groundwater,the Cr(VI)removal capacity of CMC-nZVI/BC was evaluated under different reaction conditions through column experiments and COMSOL Multiphysics.CMC-nZVI/BC could efficiently remove 85%of Cr(VI)in about 400 hr when the initial Cr(VI)concentration was 40 mg/L and the flow rate was 0.5 mL/min.This study demonstrates that uniformly dispersed CMC-nZVI/BC has an excellent remediation effect on different concentrations of Cr-contaminated soils.
基金support provided by the research funds from the Hong Kong Research Grants Council(Grant Nos.16206623,N_HKUST603/22,and C6006-20G).
文摘Correctly tracking the evolution of spatial heterogeneity of local degree of saturation(Sr)in unsaturated soils is essential to explain the seepage phenomenon,which is crucial to assessing slope stability.Several methods exist for quantifying the heterogeneity of local S_(r).However,a comprehensive comparison of these methods in terms of accuracy,relative advantages,and disadvantages is currently lacking.This paper presents a comparative analysis of local Sr obtained at multiple scales,ranging from the element scale to the slice,representative element volume(REV),pore,and voxel scales.The spatial heterogeneity of Sr in an unsaturated glass beads specimen at different matric suctions was visualised and quantified by multiscale X-ray micro-focus computed tomography image-based analysis methods.Local Sr obtained at different scales displayed a comparable trend along the sample depth,yet the REV-scale method showed a much scattered and discontinuous distribution.In contrast,the pore-scale method detected a distinct two-clustered,bimodal distribution of S_(r).The pore-scale method has the highest integrated resolution,as it has the highest spatial resolution(i.e.number of data points)and provides more information(i.e.number of extractable physical parameters).This method thus provides a more effective approach for tracking the spatial heterogeneity of S_(r).Based on this method,pore-scale water retention curves were determined,offering new quantitative means to characterise pore water heterogeneity and explainwater drainage processes such as hysteresis at the pore scale.
基金Financial supports from the PolyU Distinguished Postdoctoral Fellowship Scheme are highly appreciatedsupported by the National Natural Science Foundation of China (Grant No.52201008)the Fundamental Research Funds for the Central Universities,the State Key Laboratory of Particle Detection and Electronics (Grant No.SKLPDE-KF-202311).
文摘Utilizing the Discrete Element Method,this research studied the stiffness distribution of gap-graded soils by modifying the conventional static method.By acknowledging the inherent particle property disparity between coarser and finer particles,this research differentiates the stiffness distribution of gap-graded soils from the perspective of contact and particle types.Results indicate that particle property disparity significantly influence the small-strain stiffness characteristics,consequently altering the overall stiffness distribution in gap-graded soil specimens.Specifically,with the equivalent coarser particle property,an increase in particle Young's modulus of finer particles results in an augmentation of small-strain stiffness values,alongside an increased stiffness distribution contribution from finer particles.Nevertheless,this study reveals that even with a higher particle Young's modulus of finer particles,the proportion of small-strain stiffness transferred by finer particles remains consistently lower than their volume fraction.Furthermore,the proportion of stiffness transferred by finer particles may fall below their contribution to stress transmission.This investigation accentuates the subtle yet significant effects of particle property variations on small strain stiffness and its subsequent distribution,providing a foundation for advancing the significance of particle property disparities in evaluating soil responses.
基金supported by the Russian Science Foundation,grant number 23-26-00128,“The role of the irrigation system of the North Crimean Canal in the transfer of long-lived radionuclides of Chernobyl origin,heavy metals,as well as hydrocarbons from the Dnieper water to irrigated farmlands of the Crimea.”。
文摘The main objectives of this study were to investigate the distribution features of the ^(210)Po in abiotic(water and bottom sediments)and biotic(zooplankton,mollusks,fish)components of the North Crimean Canal(NCC)aquatic ecosystem and adjacent irrigated soils as well as assessment of the doses received by water organisms from α-radiation of absorbed ^(210)Po.The samples were processed using standard radiochemical methods accepted in international practice.The activity of ^(210)Po in the samples was measured using the alpha-spectrometric OCTETE Plus complex(ORTEC-AMETEK,USA).The measurement error did not exceed 20%.Activity concentration of ^(210)Po in the studied objects decreased in the following rank:suspended matter(73.6 Bq/kg d.w.)>soils(32.5 Bq/kg d.w.)≈bottom sediments(32.1 Bq/kg d.w.)>mollusks(23.4 Bq/kg w.w.)>fish(6.4 Bq/kg w.w.).The ^(210)Po distribution coefficient(K_(d))values in water between suspended matter and its dissolved parts varied within the 1.4×10^(4)-1.4×10^(5) L/kg range.The concentration factors(CF)of ^(210)Po for hydrobionts of the NCC were in the range 10^(3)-10^(4) L/kg.The calculated absorbed radiation doses from ^(210)Po alpha radiation for the hydrobionts of the North Crimean Canal were significantly below the recommended dose limits.
