One of the research hotspots in geotechnical engineering is the solidification of problematic soil foundations. However, the traditional materials, such as Portland cement, lime, and various types of chemical solution...One of the research hotspots in geotechnical engineering is the solidification of problematic soil foundations. However, the traditional materials, such as Portland cement, lime, and various types of chemical solutions, typically cause CO_(2) emissions and environmental pollution. Geopolymer is a newly proposed method for soil solidification, offering an environmentally friendly and effective solution. Given that soils typically consist of diverse compositions, an optimal soil stabilization technique should be versatile enough to be applied across various soil types, ensuring consistent strength outcomes with minimal variations among different soil compositions. In this study, three commonly used geopolymers(fly ash, ground granulated blast-furnace slag, and metakaolin) were utilized to stabilize silt, loess, silica sand, calcareous sand, and gravel, representing a diverse range of soils. The mechanical properties and microstructures of both geopolymers and geopolymerstabilized soils were analyzed. The findings indicated that the strength of stabilized coarse cohesionless soils was primarily influenced by the mechanical properties of the geopolymers themselves, with minimal impact from the inherent properties of the soil. However, the effectiveness of stabilizing cohesive soil may show significant discrepancies compared to the mechanical properties of geopolymer materials when certain types of geopolymers, like metakaolin, are employed. Higher strength is typically achieved through a denser structure(with fewer pores) and the presence of products with a higher degree of polymerization. Additionally, ground granulated blast-furnace slag exhibited excellent stability and superior strength when compared to other types of geopolymers. The present research establishes a basis for selecting geopolymers to stabilize a range of soils, including those with non-uniform compositions and diverse components.展开更多
Soil greenhouse gas(GHG)emissions contribute profoundly to global warming;however,how plant detritus input alters GHG emissions is poorly understood.Here,we used detritus input and removal treatments(i.e.,DIRT:control...Soil greenhouse gas(GHG)emissions contribute profoundly to global warming;however,how plant detritus input alters GHG emissions is poorly understood.Here,we used detritus input and removal treatments(i.e.,DIRT:control,CK;double litter,DL;no roots with double litter,NRDL;no litter,NL;no roots,NR;no roots and no litter,NRNL)to assess the effects of litter and root inputs on soil CO_(2),CH_(4),and N_(2)O fluxes in soils in a coniferous(Pinus yunnanensis)and a broad-leaf forest(Quercus pannosa)in a subalpine region in southwestern China.Litter addition increased CO_(2) emissions on average 22.22%,but did not significantly alter CH_(4) uptake and N_(2)O emission compared to the CK.Litter removal(NL and NRNL)significantly reduced CO_(2) emissions on average 30.22%and N_(2)O emissions on average 31.16%from both forest soils,but did not significantly affect soil CH_(4) uptake.Root removal(NR and NRNL)generally decreased these three soil GHG fluxes.Changes inβ-1,4-glucosidase(BG)involved in C and phospholipid fatty acid(PLFAs)biomass were projected to influence CO_(2) emissions,while soil microclimates(temperature and moisture)combined with BG activity mainly regulated CH_(4) uptake.Alterations in dissolved organic nitrogen,microbial biomass nitrogen and BG were mainly responsible for changes in N_(2)O emissions.Interestingly,coniferous forest soil seemed to promote CH_(4) uptake more than the broad-leaf forest soil,but CO_(2) and N_(2)O fluxes were not significantly affected by the forest types.As expected,litter addition significantly increased the warming potential,while litter removal relatively lowered it.These findings revealed the divergent roles of plant detritus input and forest type in shaping soil GHG fluxes,thereby providing insights into forest management and predicting contributions of subalpine forests to global warming.展开更多
To investigate the influencesof non-plastic silt and soil aging on the re-liquefaction resistance of sands,a series of undrained triaxial tests was performed on sand-silt mixtures with finescontent ranging from 0%to 1...To investigate the influencesof non-plastic silt and soil aging on the re-liquefaction resistance of sands,a series of undrained triaxial tests was performed on sand-silt mixtures with finescontent ranging from 0%to 100%,as well as on undisturbed and reconstituted non-plastic sandy soils retrieved from earth structures with a history of earthquake-induced damage.The specimens on sand-silt mixtures were produced under an initial degree of compaction of 95%.In these tests,liquefaction histories were applied three times to a single specimen under the same cyclic stress ratio after the respective consolidation stages with the measurements of the shear wave velocities.The following conclusions can be obtained from the test results:(1)The liquefaction resistance obtained in the firstto third cyclicloading stages decreased initially with increasing finescontent up to about 45%,while it increased afterward.Therefore,the susceptibility of sands containing a relatively large amount of non-plastic silt to reliquefaction may be more significantthan that of clean sands;(2)The liquefaction resistance and the shear wave velocity decreased significantlyduring the second cyclic-loading stage and after the second consolidation,respectively,despite an increase in the specimen density caused by the first liquefaction history,while they increased in the third stage.The possible reason for this change would be the disturbance of soil structures due to liquefaction,which may be partially evaluated by the volumetric strain during the respective consolidation stages,and the stress-induced anisotropy formed in the previous liquefaction stage;and(3)The liquefaction resistance and the shear wave velocity of the undisturbed specimens,which were measured in the firstto third stages,were larger than those of the reconstituted ones due to the aging effects,respectively.That is,the aging effects may not necessarily be eliminated by the subsequent liquefaction history and may remain partially in some cases.展开更多
Ten physical and environmental variables collected from an on-the-go soil sensor at two field sites (MF3E and MF11S) in Mississippi, USA, were analyzed to assess soil variability and the interrelationships among the m...Ten physical and environmental variables collected from an on-the-go soil sensor at two field sites (MF3E and MF11S) in Mississippi, USA, were analyzed to assess soil variability and the interrelationships among the measurements. At MF3E, moderate variability was observed in apparent electrical conductivity shallow (ECas), slope, and ECa ratio measurements, with coefficients of variation ranging from 20% to 27%. In contrast, MF11S exhibited higher variability, particularly in ECas and ECad (deep) measurements, which exceeded 30% in their coefficient of variation values, indicating significant differences in soil composition and moisture content. Correlation analysis revealed strong positive relationships between the near-infrared-to-red ratio and red reflectance (r = 0.897***) soil values at MF3E. MF11S demonstrated a strong negative correlation between ECas and ECad readings with the x-coordinate (r ***). Scatter plots and fitted models illustrated the complexity of relationships, with many showing nonlinear trends. These findings emphasize the need for continuous monitoring and advanced modeling to understand the dynamic nature of soil properties and their implications for agricultural practices. Future research should explore the underlying mechanisms driving variability in the soil characteristics to enhance soil management strategies at the study sites.展开更多
Black soils represent only one-sixth of the global arable land area but play an important role in maintaining world food security due to their high fertility and gigantic potential for food production.With the ongoing...Black soils represent only one-sixth of the global arable land area but play an important role in maintaining world food security due to their high fertility and gigantic potential for food production.With the ongoing intensification of agricultural practices and negative natural factors,black soils are confronting enhanced degradation.The holistic overview of black soil degradation and the underlying mechanisms for soil health improvement will be key for agricultural sustainability and food security.In this review,the current status and driving factors of soil degradation in the four major black soil regions of the world are summarized,and effective measures for black soil conservation are proposed.The Northeast Plain of China is the research hotspot with 41.5%of the published studies related to black soil degradation,despite its relatively short history of agricultural reclamation,followed by the East European Plain(28.3%),the Great Plains of North America(20.7%),and the Pampas of South American(7.9%).Among the main types of soil degradation,soil erosion and soil fertility decline(especially organic matter loss)have been reported as the most common problems,with 27.6%and 39.4%of the published studies,respectively.In addition to the natural influences of climate and topography,human activities have been reported to have great influences on the degradation of black soils globally.Unsustainable farming practices and excess in agrochemical applications are common factors reported to accelerate the degradation process and threaten the sustainable use of black soils.Global efforts for black soil conservation and utilization should focus on standardizing evaluation criteria including real-time monitoring and the measures of prevention and restoration for sustainable management.International cooperation in technology and policy is crucial for overcoming the challenges and thus achieving the protection,sustainable use,and management of global black soil resources.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
Pyrrolizidine alkaloids(PAs)and their N-oxides(PANOs)are phytotoxins produced by various plant species and have been emerged as environmental pollutants.The sorption/desorption behaviors of PAs/PANOs in soil are cruci...Pyrrolizidine alkaloids(PAs)and their N-oxides(PANOs)are phytotoxins produced by various plant species and have been emerged as environmental pollutants.The sorption/desorption behaviors of PAs/PANOs in soil are crucial due to the horizontal transfer of these natural products from PA-producing plants to soil and subsequently absorbed by plant roots.This study firstly investigated the sorption/desorption behaviors of PAs/PANOs in tea plantation soils with distinct characteristics.Sorption amounts for seneciphylline(Sp)and seneciphylline-N-oxide(SpNO)in three acidic soils ranged from 2.9 to 5.9μg/g and 1.7 to 2.8μg/g,respectively.Desorption percentages for Sp and SpNO were from 22.2%to 30.5%and 36.1%to 43.9%.In the mixed PAs/PANOs systems,stronger sorption of PAs over PANOs was occurred in tested soils.Additionally,the Freundlich models more precisely described the sorption/desorption isotherms.Cation exchange capacity,sand content and total nitrogen were identified as major influencing factors by linear regression models.Overall,the soils exhibiting higher sorption capacities for compounds with greater hydrophobicity.PANOs were more likely to migrate within soils and be absorbed by tea plants.It contributes to the understanding of environmental fate of PAs/PANOs in tea plantations and provides basic data and clues for the development of PAs/PANOs reduction technology.展开更多
Arsenic(As)pollution in soils is a pervasive environmental issue.Biochar immobilization offers a promising solution for addressing soil As contamination.The efficiency of biochar in immobilizing As in soils primarily ...Arsenic(As)pollution in soils is a pervasive environmental issue.Biochar immobilization offers a promising solution for addressing soil As contamination.The efficiency of biochar in immobilizing As in soils primarily hinges on the characteristics of both the soil and the biochar.However,the influence of a specific property on As immobilization varies among different studies,and the development and application of arsenic passivation materials based on biochar often rely on empirical knowledge.To enhance immobilization efficiency and reduce labor and time costs,a machine learning(ML)model was employed to predict As immobilization efficiency before biochar application.In this study,we collected a dataset comprising 182 data points on As immobilization efficiency from 17 publications to construct three ML models.The results demonstrated that the random forest(RF)model outperformed gradient boost regression tree and support vector regression models in predictive performance.Relative importance analysis and partial dependence plots based on the RF model were conducted to identify the most crucial factors influencing As immobilization.These findings highlighted the significant roles of biochar application time and biochar pH in As immobilization efficiency in soils.Furthermore,the study revealed that Fe-modified biochar exhibited a substantial improvement in As immobilization.These insights can facilitate targeted biochar property design and optimization of biochar application conditions to enhance As immobilization efficiency.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
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
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
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
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
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
Coal power plants annually generate quantities of byproducts that release environmentally hazardous heavy metals like Cd and Pb.Understanding the behavior and spatiotemporal impacts on soils of these releases is cruci...Coal power plants annually generate quantities of byproducts that release environmentally hazardous heavy metals like Cd and Pb.Understanding the behavior and spatiotemporal impacts on soils of these releases is crucial for pollution control.This study investigated the concentrations and isotope ratios of Cd/Pb in combustion byproducts,depositions and soils collected froma coal-fired power plant or its surrounding area.The pulverized fuel ash(PFA)and desulfurized gypsum(DG)exhibited heavier Cd isotopes withΔ^(114)Cd values of 0.304‰and 0.269‰,respectively,while bottom ash(BA)showed lighter Cd isotopes(Δ^(114)CdBA-coal=–0.078‰),compared to feed coal.We proposed a two-stage condensation process that governs the distribution of Cd/Pb,including accumulation on PFA and DG within electrostatic precipitators and desulfurization unit,as well as condensation onto fine particles upon release from the stack.Emissions from combustion and large-scale transport make a significant contribution to deposition,while the dispersion of Cd/Pb in deposition is primarily influenced by the prevailing wind patterns.However,the distribution of Cd/Pb in soils not only exhibit predominant wind control but is also potentially influenced by the resuspension of long-term storage byproducts.The power plant significantly contributes to soil in the NW–N–NE directions,even at a considerable distance(66%–79%),demonstrating its pervasive impact on remote regions along these orientations.Additionally,based on the vertical behavior in the profile,we have identified that Cd tends to migrate downward through leaching,while variations in Pb respond to the historical progression of dust removal.展开更多
Expansive soils, prone to being influenced by the environmental conditions, undergo expansion when water is introduced and shrinkage upon drying. This persistent volumetric fluctuation can induce differential movement...Expansive soils, prone to being influenced by the environmental conditions, undergo expansion when water is introduced and shrinkage upon drying. This persistent volumetric fluctuation can induce differential movements and result in cracking of structures erected upon them. The present research focuses on characterizing the behavior of pavements erected on expansive clays subjected to swelling and shrinkage cycles. Direct shear tests and oedometer tests were conducted in the laboratory on samples of expansive soils undergoing swelling-shrinkage cycles. The experimental data reveal a significant decrease in shear strength, evidenced by a reduction in shear parameters (internal friction angle, cohesion) and a decrease in the modulus of elasticity as the number of cycles increases. A numerical model based on the finite element method was developed to simulate the behavior of a pavement on an expansive clay substrate. The model results indicate an increase in total displacements with the increase in the number of shrinkage-swelling cycles, demonstrating a progressive degradation of the soil’s mechanical behavior. This study contributes to a better understanding of the complex phenomena governing the behavior of expansive soils and serves as a foundation for developing effective management and mitigation strategies for road infrastructures.展开更多
Background Organic selenium(Se)has gained recognition in poultry nutrition as a feed additive to boost production and Se deposition in eggs and tissues,owing to its high bioavailability,efficient tissue accumulation a...Background Organic selenium(Se)has gained recognition in poultry nutrition as a feed additive to boost production and Se deposition in eggs and tissues,owing to its high bioavailability,efficient tissue accumulation and minimal toxicity.Selenium-enriched yeast(SeY)is a well-established source,while selenium-enriched lactobacilli(SeL),a newer alternative,offers the added benefits of probiotics.This study examined the effects of SeY and SeL on egg quality,antioxidant capacity,Se deposition,and gut health in laying hens.After a two-week pre-treatment with a Sedeficient diet(SeD),450 Hy-Line Brown laying hens(30-week-old)were assigned into five dietary groups with six replicates of 15 hens each.The groups included a SeD,SeD supplemented with 1.5 mg Se/kg from SeY(SeY15),or 1.5,3.0,and 6.0 mg Se/kg from SeL(SeL15,SeL30,SeL60).The feeding trial lasted for 12 weeks.Results SeY15 and SeL15 improved the feed-to-egg ratio(P<0.05)in the latter stages.Haugh units were significantly increased(P<0.05)in the SeY15 and SeL30 groups,while darker yolk color(P<0.05)was observed in the SeY15,SeL15,and SeL60 groups.All Se-supplemented diets increased Se content in whole eggs,albumen,and yolk(P<0.05),while SeL groups showed a dose-dependent effect.Antioxidant enzyme activities increased,and MDA content decreased in the serum(P<0.05),with SeY15 showing the highest GSH-Px levels(P<0.05).SeL60 increased serum alkaline phosphatase and aspartate transaminase,and distorted the liver architecture(P<0.05).Se-diets reduced concentrations of reactive oxygen species(ROS)in the ileum and liver(P<0.05).SeL15 improved the ileal villus height-tocrypt depth ratio(P<0.05).SeY15 and/or SeL15 up-regulated TXNRD1 and SEPHS1 mRNA while down-regulating SCLY expression in the liver.SeY15 altered ileal microbiota by increasing both beneficial and pathogenic bacteria,whereas SeL15 predominantly boosted beneficial bacteria.Conclusion SeL integrates the antioxidant properties of organic Se with the probiotic benefits on gut health,resulting in a performance-enhancing effect comparable to that of SeY.However,high SeL level(6.0 mg Se/kg)compromised productivity and metabolic functions while enhancing Se deposition.展开更多
Evaluation of hydromechanical shear behavior of unsaturated soils is still a challenging issue. The time and cost needed for conducting precise experimental investigation on shear behavior of unsaturated soils have en...Evaluation of hydromechanical shear behavior of unsaturated soils is still a challenging issue. The time and cost needed for conducting precise experimental investigation on shear behavior of unsaturated soils have encouraged several investigators to develop analytical, empirical, or semi-empirical models for predicting the shear behavior of unsaturated soils. However, most of the previously proposed models are for specimens subjected to the isotropic state of stress, without considering the effect of initial shear stress. In this study, a hydromechanical constitutive model is proposed for unsaturated collapsible soils during shearing, with consideration of the effect of the initial shear stress. The model implements an effective stress-based disturbed state concept (DSC) to predict the stress-strain behavior of the soil. Accordingly, material/state variables were defined for both the start of the shearing stage and the critical state of the soil. A series of laboratory tests was performed using a fully automated unsaturated triaxial device to verify the proposed model. The experimental program included 23 suction-controlled unsaturated triaxial shear tests on reconstituted specimens of Gorgan clayey loess wetted to different levels of suctions under both isotropic and anisotropic stress states. The results show excellent agreement between the prediction by the proposed model and the experimental results.展开更多
This work focused on determining the physico-chemical characteristics (pH, carbon and nitrogen) and trace metal elements (TMEs) content (As, Sb, Cd, Hg, Ni, Pb, Cr, Zn) of soils in the Brazzaville city. Soil samples w...This work focused on determining the physico-chemical characteristics (pH, carbon and nitrogen) and trace metal elements (TMEs) content (As, Sb, Cd, Hg, Ni, Pb, Cr, Zn) of soils in the Brazzaville city. Soil samples were taken from a depth of 0 to 20 cm using a hand auger on both banks of five tributaries of the Congo River (Djoué, Mfilou, Mfoa, Tsiémé, Djiri) that flow through the city of Brazzaville. 90 sampling points were defined, with 3 points 250 m apart on the banks and located, for each river, at three sites: upstream, midstream and downstream. Finally, 15 composite samples representative of the study area were taken. The average pH values of the water varied between 6.5 and 7.5. These pH values show that the soils studied are neutral. Total carbon content varied between 0.7% (Djiri) and 1.6% (Djoué). Total nitrogen content ranged from 0.08% (Djiri) to 0.12% (Djoué). TMEs contents varied from 0.5 to 1.8 mg/kg for Sb, from 0.5 to 2.5 mg/kg for As, from 0.1 to 0.18 mg/kg for Cd, from 4.2 to 11.3 mg/kg for Cr, from 0.07 to 0.27 mg/kg for Hg, from 0.7 to 2.4 mg/kg for Ni, from 0 to 158 mg/kg for Pb and from 16 to 105 mg/kg for Zn. The lowest TMEs levels were observed in the soils of the Djiri river, while the highest levels were observed in the soils of the Djoué and Tsiémé rivers. The ANOVA and Bonferroni test did not show significant differences in the means of the parameters measured (p > 0.05). The TMEs levels were below the accepted standards (NF U44-041), with the exception of Pb, which had high levels downstream of the Djoué. According to the pollution index values calculated using soil TME content, the soils on the banks of the Djoué river are considered polluted, while those on the banks of the Tsiémé river are moderately polluted, those on the banks of the Mfoa and Mfilou rivers are slightly polluted, and the soils on the banks of Djiri river are unpolluted.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
基金supported by the National Natural Science Foundation of China (Grant No.52308352)the Jiangxi Provincial Natural Science Foundation (Grant Nos.20242BAB25299,20232BAB214082)。
文摘One of the research hotspots in geotechnical engineering is the solidification of problematic soil foundations. However, the traditional materials, such as Portland cement, lime, and various types of chemical solutions, typically cause CO_(2) emissions and environmental pollution. Geopolymer is a newly proposed method for soil solidification, offering an environmentally friendly and effective solution. Given that soils typically consist of diverse compositions, an optimal soil stabilization technique should be versatile enough to be applied across various soil types, ensuring consistent strength outcomes with minimal variations among different soil compositions. In this study, three commonly used geopolymers(fly ash, ground granulated blast-furnace slag, and metakaolin) were utilized to stabilize silt, loess, silica sand, calcareous sand, and gravel, representing a diverse range of soils. The mechanical properties and microstructures of both geopolymers and geopolymerstabilized soils were analyzed. The findings indicated that the strength of stabilized coarse cohesionless soils was primarily influenced by the mechanical properties of the geopolymers themselves, with minimal impact from the inherent properties of the soil. However, the effectiveness of stabilizing cohesive soil may show significant discrepancies compared to the mechanical properties of geopolymer materials when certain types of geopolymers, like metakaolin, are employed. Higher strength is typically achieved through a denser structure(with fewer pores) and the presence of products with a higher degree of polymerization. Additionally, ground granulated blast-furnace slag exhibited excellent stability and superior strength when compared to other types of geopolymers. The present research establishes a basis for selecting geopolymers to stabilize a range of soils, including those with non-uniform compositions and diverse components.
基金supported by the National Natural Science Foundation of China(32130069)the National Key Research and Development Program of China(2024YFF1306700)the Scientific Research Foundation of Education Department of Yunnan Province(2024Y004).
文摘Soil greenhouse gas(GHG)emissions contribute profoundly to global warming;however,how plant detritus input alters GHG emissions is poorly understood.Here,we used detritus input and removal treatments(i.e.,DIRT:control,CK;double litter,DL;no roots with double litter,NRDL;no litter,NL;no roots,NR;no roots and no litter,NRNL)to assess the effects of litter and root inputs on soil CO_(2),CH_(4),and N_(2)O fluxes in soils in a coniferous(Pinus yunnanensis)and a broad-leaf forest(Quercus pannosa)in a subalpine region in southwestern China.Litter addition increased CO_(2) emissions on average 22.22%,but did not significantly alter CH_(4) uptake and N_(2)O emission compared to the CK.Litter removal(NL and NRNL)significantly reduced CO_(2) emissions on average 30.22%and N_(2)O emissions on average 31.16%from both forest soils,but did not significantly affect soil CH_(4) uptake.Root removal(NR and NRNL)generally decreased these three soil GHG fluxes.Changes inβ-1,4-glucosidase(BG)involved in C and phospholipid fatty acid(PLFAs)biomass were projected to influence CO_(2) emissions,while soil microclimates(temperature and moisture)combined with BG activity mainly regulated CH_(4) uptake.Alterations in dissolved organic nitrogen,microbial biomass nitrogen and BG were mainly responsible for changes in N_(2)O emissions.Interestingly,coniferous forest soil seemed to promote CH_(4) uptake more than the broad-leaf forest soil,but CO_(2) and N_(2)O fluxes were not significantly affected by the forest types.As expected,litter addition significantly increased the warming potential,while litter removal relatively lowered it.These findings revealed the divergent roles of plant detritus input and forest type in shaping soil GHG fluxes,thereby providing insights into forest management and predicting contributions of subalpine forests to global warming.
基金supported by JSPS KAKENHI(Grant Nos.JP22K04305 and JP19K15083).
文摘To investigate the influencesof non-plastic silt and soil aging on the re-liquefaction resistance of sands,a series of undrained triaxial tests was performed on sand-silt mixtures with finescontent ranging from 0%to 100%,as well as on undisturbed and reconstituted non-plastic sandy soils retrieved from earth structures with a history of earthquake-induced damage.The specimens on sand-silt mixtures were produced under an initial degree of compaction of 95%.In these tests,liquefaction histories were applied three times to a single specimen under the same cyclic stress ratio after the respective consolidation stages with the measurements of the shear wave velocities.The following conclusions can be obtained from the test results:(1)The liquefaction resistance obtained in the firstto third cyclicloading stages decreased initially with increasing finescontent up to about 45%,while it increased afterward.Therefore,the susceptibility of sands containing a relatively large amount of non-plastic silt to reliquefaction may be more significantthan that of clean sands;(2)The liquefaction resistance and the shear wave velocity decreased significantlyduring the second cyclic-loading stage and after the second consolidation,respectively,despite an increase in the specimen density caused by the first liquefaction history,while they increased in the third stage.The possible reason for this change would be the disturbance of soil structures due to liquefaction,which may be partially evaluated by the volumetric strain during the respective consolidation stages,and the stress-induced anisotropy formed in the previous liquefaction stage;and(3)The liquefaction resistance and the shear wave velocity of the undisturbed specimens,which were measured in the firstto third stages,were larger than those of the reconstituted ones due to the aging effects,respectively.That is,the aging effects may not necessarily be eliminated by the subsequent liquefaction history and may remain partially in some cases.
文摘Ten physical and environmental variables collected from an on-the-go soil sensor at two field sites (MF3E and MF11S) in Mississippi, USA, were analyzed to assess soil variability and the interrelationships among the measurements. At MF3E, moderate variability was observed in apparent electrical conductivity shallow (ECas), slope, and ECa ratio measurements, with coefficients of variation ranging from 20% to 27%. In contrast, MF11S exhibited higher variability, particularly in ECas and ECad (deep) measurements, which exceeded 30% in their coefficient of variation values, indicating significant differences in soil composition and moisture content. Correlation analysis revealed strong positive relationships between the near-infrared-to-red ratio and red reflectance (r = 0.897***) soil values at MF3E. MF11S demonstrated a strong negative correlation between ECas and ECad readings with the x-coordinate (r ***). Scatter plots and fitted models illustrated the complexity of relationships, with many showing nonlinear trends. These findings emphasize the need for continuous monitoring and advanced modeling to understand the dynamic nature of soil properties and their implications for agricultural practices. Future research should explore the underlying mechanisms driving variability in the soil characteristics to enhance soil management strategies at the study sites.
基金funded by the Science and Technology Plan for the Belt and Road Innovation Cooperation Project of Jiangsu Province,China(No.BZ2023003)the National Key Research and Development Program of China(No.2021YFD1500202)+2 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA28010100)the“14th Five-Year Plan”Self-Deployment Project of the Institute of Soil Science,Chinese Academy of Sciences(No.ISSAS2418)the National Natural Science Foundation of China(No.42107334)。
文摘Black soils represent only one-sixth of the global arable land area but play an important role in maintaining world food security due to their high fertility and gigantic potential for food production.With the ongoing intensification of agricultural practices and negative natural factors,black soils are confronting enhanced degradation.The holistic overview of black soil degradation and the underlying mechanisms for soil health improvement will be key for agricultural sustainability and food security.In this review,the current status and driving factors of soil degradation in the four major black soil regions of the world are summarized,and effective measures for black soil conservation are proposed.The Northeast Plain of China is the research hotspot with 41.5%of the published studies related to black soil degradation,despite its relatively short history of agricultural reclamation,followed by the East European Plain(28.3%),the Great Plains of North America(20.7%),and the Pampas of South American(7.9%).Among the main types of soil degradation,soil erosion and soil fertility decline(especially organic matter loss)have been reported as the most common problems,with 27.6%and 39.4%of the published studies,respectively.In addition to the natural influences of climate and topography,human activities have been reported to have great influences on the degradation of black soils globally.Unsustainable farming practices and excess in agrochemical applications are common factors reported to accelerate the degradation process and threaten the sustainable use of black soils.Global efforts for black soil conservation and utilization should focus on standardizing evaluation criteria including real-time monitoring and the measures of prevention and restoration for sustainable management.International cooperation in technology and policy is crucial for overcoming the challenges and thus achieving the protection,sustainable use,and management of global black soil resources.
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 earmarked fund for the Modern Agro-Industry Technology Research System (No.CARS-19)the Innovative Research Team in Chinese Academy of Agricultural Sciences (No.CAAS ASTIP-2014-TRICAAS).
文摘Pyrrolizidine alkaloids(PAs)and their N-oxides(PANOs)are phytotoxins produced by various plant species and have been emerged as environmental pollutants.The sorption/desorption behaviors of PAs/PANOs in soil are crucial due to the horizontal transfer of these natural products from PA-producing plants to soil and subsequently absorbed by plant roots.This study firstly investigated the sorption/desorption behaviors of PAs/PANOs in tea plantation soils with distinct characteristics.Sorption amounts for seneciphylline(Sp)and seneciphylline-N-oxide(SpNO)in three acidic soils ranged from 2.9 to 5.9μg/g and 1.7 to 2.8μg/g,respectively.Desorption percentages for Sp and SpNO were from 22.2%to 30.5%and 36.1%to 43.9%.In the mixed PAs/PANOs systems,stronger sorption of PAs over PANOs was occurred in tested soils.Additionally,the Freundlich models more precisely described the sorption/desorption isotherms.Cation exchange capacity,sand content and total nitrogen were identified as major influencing factors by linear regression models.Overall,the soils exhibiting higher sorption capacities for compounds with greater hydrophobicity.PANOs were more likely to migrate within soils and be absorbed by tea plants.It contributes to the understanding of environmental fate of PAs/PANOs in tea plantations and provides basic data and clues for the development of PAs/PANOs reduction technology.
基金supported by the National Key Research and Development Program of China(No.2020YFC1808701).
文摘Arsenic(As)pollution in soils is a pervasive environmental issue.Biochar immobilization offers a promising solution for addressing soil As contamination.The efficiency of biochar in immobilizing As in soils primarily hinges on the characteristics of both the soil and the biochar.However,the influence of a specific property on As immobilization varies among different studies,and the development and application of arsenic passivation materials based on biochar often rely on empirical knowledge.To enhance immobilization efficiency and reduce labor and time costs,a machine learning(ML)model was employed to predict As immobilization efficiency before biochar application.In this study,we collected a dataset comprising 182 data points on As immobilization efficiency from 17 publications to construct three ML models.The results demonstrated that the random forest(RF)model outperformed gradient boost regression tree and support vector regression models in predictive performance.Relative importance analysis and partial dependence plots based on the RF model were conducted to identify the most crucial factors influencing As immobilization.These findings highlighted the significant roles of biochar application time and biochar pH in As immobilization efficiency in soils.Furthermore,the study revealed that Fe-modified biochar exhibited a substantial improvement in As immobilization.These insights can facilitate targeted biochar property design and optimization of biochar application conditions to enhance As immobilization efficiency.
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 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 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supported by the National Natural Science Foundation of China(No.42025705)the Construction Project of Modern Agricultural Science and Technology Innovation Alliance of Guangdong Province,China(No.2023KJ112)+1 种基金the National Natural Science Foundation of China(Nos.41977291 and 42177242)the GDAS’Project of Science and Technology Development,China(No.2019GDASYL-0103048).
文摘Coal power plants annually generate quantities of byproducts that release environmentally hazardous heavy metals like Cd and Pb.Understanding the behavior and spatiotemporal impacts on soils of these releases is crucial for pollution control.This study investigated the concentrations and isotope ratios of Cd/Pb in combustion byproducts,depositions and soils collected froma coal-fired power plant or its surrounding area.The pulverized fuel ash(PFA)and desulfurized gypsum(DG)exhibited heavier Cd isotopes withΔ^(114)Cd values of 0.304‰and 0.269‰,respectively,while bottom ash(BA)showed lighter Cd isotopes(Δ^(114)CdBA-coal=–0.078‰),compared to feed coal.We proposed a two-stage condensation process that governs the distribution of Cd/Pb,including accumulation on PFA and DG within electrostatic precipitators and desulfurization unit,as well as condensation onto fine particles upon release from the stack.Emissions from combustion and large-scale transport make a significant contribution to deposition,while the dispersion of Cd/Pb in deposition is primarily influenced by the prevailing wind patterns.However,the distribution of Cd/Pb in soils not only exhibit predominant wind control but is also potentially influenced by the resuspension of long-term storage byproducts.The power plant significantly contributes to soil in the NW–N–NE directions,even at a considerable distance(66%–79%),demonstrating its pervasive impact on remote regions along these orientations.Additionally,based on the vertical behavior in the profile,we have identified that Cd tends to migrate downward through leaching,while variations in Pb respond to the historical progression of dust removal.
文摘Expansive soils, prone to being influenced by the environmental conditions, undergo expansion when water is introduced and shrinkage upon drying. This persistent volumetric fluctuation can induce differential movements and result in cracking of structures erected upon them. The present research focuses on characterizing the behavior of pavements erected on expansive clays subjected to swelling and shrinkage cycles. Direct shear tests and oedometer tests were conducted in the laboratory on samples of expansive soils undergoing swelling-shrinkage cycles. The experimental data reveal a significant decrease in shear strength, evidenced by a reduction in shear parameters (internal friction angle, cohesion) and a decrease in the modulus of elasticity as the number of cycles increases. A numerical model based on the finite element method was developed to simulate the behavior of a pavement on an expansive clay substrate. The model results indicate an increase in total displacements with the increase in the number of shrinkage-swelling cycles, demonstrating a progressive degradation of the soil’s mechanical behavior. This study contributes to a better understanding of the complex phenomena governing the behavior of expansive soils and serves as a foundation for developing effective management and mitigation strategies for road infrastructures.
基金supported by the National Natural Science Foundation of China(32302774)Beijing Innovation Consortium of Agriculture Research System(BAIC04)+1 种基金China Agriculture Research System(CARS-40)the Agricultural Science and Technology Innovation Program of the Feed Research Institute of the Chinese Academy of Agricultural Sciences(CAASIFR-ZDRW202402).
文摘Background Organic selenium(Se)has gained recognition in poultry nutrition as a feed additive to boost production and Se deposition in eggs and tissues,owing to its high bioavailability,efficient tissue accumulation and minimal toxicity.Selenium-enriched yeast(SeY)is a well-established source,while selenium-enriched lactobacilli(SeL),a newer alternative,offers the added benefits of probiotics.This study examined the effects of SeY and SeL on egg quality,antioxidant capacity,Se deposition,and gut health in laying hens.After a two-week pre-treatment with a Sedeficient diet(SeD),450 Hy-Line Brown laying hens(30-week-old)were assigned into five dietary groups with six replicates of 15 hens each.The groups included a SeD,SeD supplemented with 1.5 mg Se/kg from SeY(SeY15),or 1.5,3.0,and 6.0 mg Se/kg from SeL(SeL15,SeL30,SeL60).The feeding trial lasted for 12 weeks.Results SeY15 and SeL15 improved the feed-to-egg ratio(P<0.05)in the latter stages.Haugh units were significantly increased(P<0.05)in the SeY15 and SeL30 groups,while darker yolk color(P<0.05)was observed in the SeY15,SeL15,and SeL60 groups.All Se-supplemented diets increased Se content in whole eggs,albumen,and yolk(P<0.05),while SeL groups showed a dose-dependent effect.Antioxidant enzyme activities increased,and MDA content decreased in the serum(P<0.05),with SeY15 showing the highest GSH-Px levels(P<0.05).SeL60 increased serum alkaline phosphatase and aspartate transaminase,and distorted the liver architecture(P<0.05).Se-diets reduced concentrations of reactive oxygen species(ROS)in the ileum and liver(P<0.05).SeL15 improved the ileal villus height-tocrypt depth ratio(P<0.05).SeY15 and/or SeL15 up-regulated TXNRD1 and SEPHS1 mRNA while down-regulating SCLY expression in the liver.SeY15 altered ileal microbiota by increasing both beneficial and pathogenic bacteria,whereas SeL15 predominantly boosted beneficial bacteria.Conclusion SeL integrates the antioxidant properties of organic Se with the probiotic benefits on gut health,resulting in a performance-enhancing effect comparable to that of SeY.However,high SeL level(6.0 mg Se/kg)compromised productivity and metabolic functions while enhancing Se deposition.
文摘Evaluation of hydromechanical shear behavior of unsaturated soils is still a challenging issue. The time and cost needed for conducting precise experimental investigation on shear behavior of unsaturated soils have encouraged several investigators to develop analytical, empirical, or semi-empirical models for predicting the shear behavior of unsaturated soils. However, most of the previously proposed models are for specimens subjected to the isotropic state of stress, without considering the effect of initial shear stress. In this study, a hydromechanical constitutive model is proposed for unsaturated collapsible soils during shearing, with consideration of the effect of the initial shear stress. The model implements an effective stress-based disturbed state concept (DSC) to predict the stress-strain behavior of the soil. Accordingly, material/state variables were defined for both the start of the shearing stage and the critical state of the soil. A series of laboratory tests was performed using a fully automated unsaturated triaxial device to verify the proposed model. The experimental program included 23 suction-controlled unsaturated triaxial shear tests on reconstituted specimens of Gorgan clayey loess wetted to different levels of suctions under both isotropic and anisotropic stress states. The results show excellent agreement between the prediction by the proposed model and the experimental results.
文摘This work focused on determining the physico-chemical characteristics (pH, carbon and nitrogen) and trace metal elements (TMEs) content (As, Sb, Cd, Hg, Ni, Pb, Cr, Zn) of soils in the Brazzaville city. Soil samples were taken from a depth of 0 to 20 cm using a hand auger on both banks of five tributaries of the Congo River (Djoué, Mfilou, Mfoa, Tsiémé, Djiri) that flow through the city of Brazzaville. 90 sampling points were defined, with 3 points 250 m apart on the banks and located, for each river, at three sites: upstream, midstream and downstream. Finally, 15 composite samples representative of the study area were taken. The average pH values of the water varied between 6.5 and 7.5. These pH values show that the soils studied are neutral. Total carbon content varied between 0.7% (Djiri) and 1.6% (Djoué). Total nitrogen content ranged from 0.08% (Djiri) to 0.12% (Djoué). TMEs contents varied from 0.5 to 1.8 mg/kg for Sb, from 0.5 to 2.5 mg/kg for As, from 0.1 to 0.18 mg/kg for Cd, from 4.2 to 11.3 mg/kg for Cr, from 0.07 to 0.27 mg/kg for Hg, from 0.7 to 2.4 mg/kg for Ni, from 0 to 158 mg/kg for Pb and from 16 to 105 mg/kg for Zn. The lowest TMEs levels were observed in the soils of the Djiri river, while the highest levels were observed in the soils of the Djoué and Tsiémé rivers. The ANOVA and Bonferroni test did not show significant differences in the means of the parameters measured (p > 0.05). The TMEs levels were below the accepted standards (NF U44-041), with the exception of Pb, which had high levels downstream of the Djoué. According to the pollution index values calculated using soil TME content, the soils on the banks of the Djoué river are considered polluted, while those on the banks of the Tsiémé river are moderately polluted, those on the banks of the Mfoa and Mfilou rivers are slightly polluted, and the soils on the banks of Djiri river are unpolluted.
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.
