This study explores the adaptation of microbial enzymatic techniques,which were originally developed to eliminate amino impurities in alcoholic beverages,for stabilizing strongly alkaline sodium-based dispersive soils...This study explores the adaptation of microbial enzymatic techniques,which were originally developed to eliminate amino impurities in alcoholic beverages,for stabilizing strongly alkaline sodium-based dispersive soils from check dams.Employing acid urease from Lactobacillus reuteri(L.reuteri)and a control group using soybean-derived urease,this research aimed to modify soil alkalinity through biomineralization.Ultraviolet(UV)mutagenesis optimized L.reuteri strains for biomass and activity.Solution experiments were conducted to assess the effects of pH,temperature,and storage duration on urease activity and to evaluate the calcium carbonate production and crystal morphology of the two ureases under varying calcium ion concentrations.Dispersivity identificationtests and tensile strength evaluations were conducted to analyze the disparities in the modifieddispersive soil treated with the two types of ureases.The results showed that soybean urease should be stored under low-temperature conditions and a neutral pH,whereas acid urease from L.reuteri can be stored at room temperature across a range of pH levels.Both urease treatments effectively reduced soil dispersivity and improved tensile strength significantly(up to 94%and 177%,respectively),with acid urease from L.reuteri resulting in superior soil strengthening and ammonia regulation.These findingssuggest that treating alkaline dispersive soils with acid urease is an efficientand eco-friendly method.展开更多
A novel method that combines reinforced enzyme-induced carbonate precipitation(REICP)was proposed to improve the mechanical properties of dispersive soil.Dispersive soils,which are highly susceptible to erosion caused...A novel method that combines reinforced enzyme-induced carbonate precipitation(REICP)was proposed to improve the mechanical properties of dispersive soil.Dispersive soils,which are highly susceptible to erosion caused by rainfall or seepage,pose significantenvironmental challenges.It is essential to focus on modifying dispersive soil using environmentally friendly methods.This study investigated the cohesion,internal friction angle,permeability,hydrostability test,and microstructure of dispersive soil treated with enzyme-induced carbonate precipitation(EICP)-MgCl2-xanthan gum(REICP),using statistical analysis.A series of laboratory experiments was conducted,including direct shear tests,permeability experiments,mud ball tests,simulated rainfall tests,Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),and scanning electron microscopy(SEM).The results showed that the combined treatment significantly enhanced the mechanical properties of dispersive soil.At the optimal ratio,cohesion increased by a factor of 2,and the permeability coefficientdecreased by approximately 1.7×10^(7)times.Additionally,the strength parameters gradually increased with curing time.Microstructural analyses indicated that calcite precipitation,pore filling,and ionic redistribution significantlyimproved the mechanical properties and hydrostability of the soil.Statistical analyses showed that EICP materials and xanthan gum increased soil cohesion,while magnesium chloride enhanced the internal friction angle and reduced porosity.This study integrates mechanical testing,statistical analysis,and microstructural evaluation to propose a sustainable and environmentally friendly method for improving dispersive soils.This approach reduces the use of chemical modifiers,minimizes environmental impacts,and demonstrates application potential in the stabilization of dispersive soils.展开更多
This study addresses the challenges posed by dispersive soil in various engineering fields,including hydraulic and agricultural engineering,by exploring the effects of physical adsorption on soil modification.The prim...This study addresses the challenges posed by dispersive soil in various engineering fields,including hydraulic and agricultural engineering,by exploring the effects of physical adsorption on soil modification.The primary objective is to identify an environmentally friendly stabilizer that can alleviate cracking and erosion resulting from soil dispersivity.Activated carbon(AC),known for its porous nature,was examined for its potential to enhance soil strength and erosion resistance.The charge neutralization process was evaluated by monitoring pH and conductivity,in addition to a comprehensive analysis of microscopic and mineral properties.The results show that high sodium levels or low clay contents result in the dispersive nature of soil in water.However,the incorporation of AC can transform such soil into a non-dispersive state.Moreover,both soil strength and erosion resistance exhibited enhancements with increasing AC content and curing duration.The incorporation of AC resulted in a maximum 5.6-fold increase in unconfined compressive strength and a 1.8-fold increase in tensile strength for dispersive soil.Notably,a significant correlation was observed during the curing phase among soil dispersivity,mechanical properties,and pH values.Microscopic analyses revealed that the porous structure of AC facilitated a filling effect and enhanced adsorption capacity,which contributed to improved soil characteristics and reduced dispersivity.The release of hydrogen ions and the formation of aggregates promote water stability.Validation tests conducted on dispersive soil from northern Shaanxi demonstrated the efficacy of physical adsorption using AC as a viable method for modifying dispersive soil in the water conservancy hub.展开更多
In order to research engineering geological properties of the soil in Zhenlai of western Jilin, especially the dispersivity of soil, the authors carried out the basic physicocbemical test and dispersivity identificati...In order to research engineering geological properties of the soil in Zhenlai of western Jilin, especially the dispersivity of soil, the authors carried out the basic physicocbemical test and dispersivity identification test. The results show that the dispersivity of the soil increases with the increase of depth within 0-30 cm （surface soil） ; it decreases as the depth increases within in 30-100 cm. Furthermore, the statistical analysis of the dispersivity indexes and physicochemical propertity indexes show that the DP is positively linear correlated with total soluble salt content, sodium ion content, ESP, pH and organic matter content. Meanwhile, it is negatively linear correlated with clay content, and the linear relationship is better. Through the study of the dispersion mechanism of soil samples, it can be concluded that sodium montmorillonite, higher percentage of exchangeable sodium and high pH are the main reasons for the dispersion of soils in western Jilin.展开更多
This paper presented the first part of the studies about the development of a tool for groundwater contamination prediction, conducted by the Laboratory of Sciences and Technology of Water (UAC/Benin). The investigati...This paper presented the first part of the studies about the development of a tool for groundwater contamination prediction, conducted by the Laboratory of Sciences and Technology of Water (UAC/Benin). The investigation made consisted in estimating the combined effect of retardation factor and biodegradation on migration processes of leachate, in the underlying soils of household waste dumpsites, without active safety barrier. Leachate infiltration tests for different initial conditions were made on soil columns and the breakthrough curves were traced for electrical conductivity, the 5 day biochemical oxygen demand (BOD5) and total kjeldahl nitrogen TKN. A mathematical migration model was developed and solved numerically by finite difference method and implemented with Matlab R2013a. Thus, the calibration of the model was made with electric conductivity data by determining the dispersion coefficient of the studied soils (D = 0.96 cm2/min). Simulations for model verification showed that the established model can perfectly predict the migration of biodegradable organic pollution (BOD5) but did not give conclusive results for the monitoring of nitrogenous organic matter (TKN). The influence of the retardation factor on the migration of biodegradable organic pollutants in soils was linear, while the biodegradation rate of the organic material on migration showed an exponential pattern.展开更多
Irrigation-induced soil erosion seriously affects the sustainability of irrigated agriculture. The effects of irrigation water quality and furrow gradient on runoff and soil loss were studied under simulated furrow ir...Irrigation-induced soil erosion seriously affects the sustainability of irrigated agriculture. The effects of irrigation water quality and furrow gradient on runoff and soil loss were studied under simulated furrow irrigation in laboratory using a soil collected from an experimental station of China Agricultural University, North China. The experimental treatments were different combinations of irrigation water salt concentrations of 5, 10, 20, and 30 mmol c L-1 , sodium adsorption ratios (SAR) of 0.5, 5.0, and 10.0 (mmol c L-1 ) 0.5 , and furrow gradients of 1%, 3%, and 5%, with distilled water for irrigation at 3 furrow gradients as controls. The experimental data indicated that total runoff amount, sediment concentration in runoff, and total soil loss amount generally decreased with increasing salt concentration in irrigation water but increased with its sodicity and furrow gradient. The effects of water quality and furrow gradient on soil loss were greater than those on runoff, and the increase of furrow gradient decreased the influence of water quality on soil loss. When the salt concentration increased from 5 to 30 mmol c L-1 at SAR of 10.0 (mmol c L-1 ) 0.5 , total runoff amount, sediment concentration, and total soil loss amount decreased by 3.89%, 52.1%, and 53.92%, and 10.57%, 38.86%, and 42.03% at the furrow gradients of 1% and 5%, respectively. However, they respectively increased by 3.37%, 45.34%, and 55.36%, and 3.86%, 10.77%, and 13.91% when SAR increased from 0.5 to 10.0 (mmol c L-1 ) 0.5 at the salt concentration of 5 mmol c L-1 . Irrigation water quality and furrow gradient should be comprehensively considered in the planning and management of furrow irrigation practices to decrease soil loss and improve water utilization efficiency.展开更多
Both physical and chemical processes affect the fate and transport of herbicides. It is useful to simulate these processes with computer programs to predict solute movement. Simulations were run with HYDRUS- 1 D to id...Both physical and chemical processes affect the fate and transport of herbicides. It is useful to simulate these processes with computer programs to predict solute movement. Simulations were run with HYDRUS- 1 D to identify the sorption and degradation parameters of atrazine through calibration from the breakthrough curves （BTCs）. Data from undisturbed and disturbed soil column experiments were compared and analyzed using the dual-porosity model. The study results show that the values of dispersivity are slightly lower in disturbed columns, suggesting that the more heterogeneous the structure is, the higher the dispersivity. Sorption parameters also show slight variability, which is attributed to the differences in soil properties, experimental conditions and methods, or other ecological factors. For both of the columns, the degradation rates were similar. Potassium bromide was used as a conservative non-reactive tracer to characterize the water movement in columns. Atrazine BTCs exhibited significant tailing and asymmetry, indicating non-equilibrium sorption during solute transport. The dual-porosity model was verified to best fit the BTCs of the column experiments. Greater or lesser concentration of atrazine spreading to the bottom of the columns indicated risk of groundwater contamination. Overall, HYDRUS-1D successfully simulated the atrazine transport in soil columns.展开更多
基金financiallysupported by the National Natural Science Foundation of China(Grant Nos.52079116,52108343,and 51579215).
文摘This study explores the adaptation of microbial enzymatic techniques,which were originally developed to eliminate amino impurities in alcoholic beverages,for stabilizing strongly alkaline sodium-based dispersive soils from check dams.Employing acid urease from Lactobacillus reuteri(L.reuteri)and a control group using soybean-derived urease,this research aimed to modify soil alkalinity through biomineralization.Ultraviolet(UV)mutagenesis optimized L.reuteri strains for biomass and activity.Solution experiments were conducted to assess the effects of pH,temperature,and storage duration on urease activity and to evaluate the calcium carbonate production and crystal morphology of the two ureases under varying calcium ion concentrations.Dispersivity identificationtests and tensile strength evaluations were conducted to analyze the disparities in the modifieddispersive soil treated with the two types of ureases.The results showed that soybean urease should be stored under low-temperature conditions and a neutral pH,whereas acid urease from L.reuteri can be stored at room temperature across a range of pH levels.Both urease treatments effectively reduced soil dispersivity and improved tensile strength significantly(up to 94%and 177%,respectively),with acid urease from L.reuteri resulting in superior soil strengthening and ammonia regulation.These findingssuggest that treating alkaline dispersive soils with acid urease is an efficientand eco-friendly method.
基金supported by the National Natural Science Foundation of China(Grant No.42407199)Heilongjiang Provincial Natural Science Foundation of China(Grant No.PL2024D003)the Fundamental Research Funds for the Central Universities(Grant No.2572023CT17).
文摘A novel method that combines reinforced enzyme-induced carbonate precipitation(REICP)was proposed to improve the mechanical properties of dispersive soil.Dispersive soils,which are highly susceptible to erosion caused by rainfall or seepage,pose significantenvironmental challenges.It is essential to focus on modifying dispersive soil using environmentally friendly methods.This study investigated the cohesion,internal friction angle,permeability,hydrostability test,and microstructure of dispersive soil treated with enzyme-induced carbonate precipitation(EICP)-MgCl2-xanthan gum(REICP),using statistical analysis.A series of laboratory experiments was conducted,including direct shear tests,permeability experiments,mud ball tests,simulated rainfall tests,Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),and scanning electron microscopy(SEM).The results showed that the combined treatment significantly enhanced the mechanical properties of dispersive soil.At the optimal ratio,cohesion increased by a factor of 2,and the permeability coefficientdecreased by approximately 1.7×10^(7)times.Additionally,the strength parameters gradually increased with curing time.Microstructural analyses indicated that calcite precipitation,pore filling,and ionic redistribution significantlyimproved the mechanical properties and hydrostability of the soil.Statistical analyses showed that EICP materials and xanthan gum increased soil cohesion,while magnesium chloride enhanced the internal friction angle and reduced porosity.This study integrates mechanical testing,statistical analysis,and microstructural evaluation to propose a sustainable and environmentally friendly method for improving dispersive soils.This approach reduces the use of chemical modifiers,minimizes environmental impacts,and demonstrates application potential in the stabilization of dispersive soils.
基金financially supported by the National Postdoctoral Program for Innovative Talents(Grant No.BX20200287)the National Natural Science Foundation of China(Grant Nos.52079116 and 52378322).
文摘This study addresses the challenges posed by dispersive soil in various engineering fields,including hydraulic and agricultural engineering,by exploring the effects of physical adsorption on soil modification.The primary objective is to identify an environmentally friendly stabilizer that can alleviate cracking and erosion resulting from soil dispersivity.Activated carbon(AC),known for its porous nature,was examined for its potential to enhance soil strength and erosion resistance.The charge neutralization process was evaluated by monitoring pH and conductivity,in addition to a comprehensive analysis of microscopic and mineral properties.The results show that high sodium levels or low clay contents result in the dispersive nature of soil in water.However,the incorporation of AC can transform such soil into a non-dispersive state.Moreover,both soil strength and erosion resistance exhibited enhancements with increasing AC content and curing duration.The incorporation of AC resulted in a maximum 5.6-fold increase in unconfined compressive strength and a 1.8-fold increase in tensile strength for dispersive soil.Notably,a significant correlation was observed during the curing phase among soil dispersivity,mechanical properties,and pH values.Microscopic analyses revealed that the porous structure of AC facilitated a filling effect and enhanced adsorption capacity,which contributed to improved soil characteristics and reduced dispersivity.The release of hydrogen ions and the formation of aggregates promote water stability.Validation tests conducted on dispersive soil from northern Shaanxi demonstrated the efficacy of physical adsorption using AC as a viable method for modifying dispersive soil in the water conservancy hub.
基金Project supported by Natural Science Foundation of China (No. 40672180)The Open Fund of Geological Disaster Prevention and Geology Environmental Protection of National Professional Laboratory of Chengdu University of Technology.(No. GZ2004 -08)International Cooperation Project of NSFC(No.40911120044)
文摘In order to research engineering geological properties of the soil in Zhenlai of western Jilin, especially the dispersivity of soil, the authors carried out the basic physicocbemical test and dispersivity identification test. The results show that the dispersivity of the soil increases with the increase of depth within 0-30 cm （surface soil） ; it decreases as the depth increases within in 30-100 cm. Furthermore, the statistical analysis of the dispersivity indexes and physicochemical propertity indexes show that the DP is positively linear correlated with total soluble salt content, sodium ion content, ESP, pH and organic matter content. Meanwhile, it is negatively linear correlated with clay content, and the linear relationship is better. Through the study of the dispersion mechanism of soil samples, it can be concluded that sodium montmorillonite, higher percentage of exchangeable sodium and high pH are the main reasons for the dispersion of soils in western Jilin.
基金The authors gratefully acknowledge the International Foundation for Science(IFS),Stockholm,for supporting the present work under the IFS Grant W/5840-1.
文摘This paper presented the first part of the studies about the development of a tool for groundwater contamination prediction, conducted by the Laboratory of Sciences and Technology of Water (UAC/Benin). The investigation made consisted in estimating the combined effect of retardation factor and biodegradation on migration processes of leachate, in the underlying soils of household waste dumpsites, without active safety barrier. Leachate infiltration tests for different initial conditions were made on soil columns and the breakthrough curves were traced for electrical conductivity, the 5 day biochemical oxygen demand (BOD5) and total kjeldahl nitrogen TKN. A mathematical migration model was developed and solved numerically by finite difference method and implemented with Matlab R2013a. Thus, the calibration of the model was made with electric conductivity data by determining the dispersion coefficient of the studied soils (D = 0.96 cm2/min). Simulations for model verification showed that the established model can perfectly predict the migration of biodegradable organic pollution (BOD5) but did not give conclusive results for the monitoring of nitrogenous organic matter (TKN). The influence of the retardation factor on the migration of biodegradable organic pollutants in soils was linear, while the biodegradation rate of the organic material on migration showed an exponential pattern.
基金Project supported by the State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau of China(No. 10501-169)the National Natural Science Foundation of China (No. 40635027)+1 种基金the National Hi-Tech Research and Development Program of China (No. 2006AA100205)the Program for Changjiang Scholars and Innovative ResearchTeam in University of China (No. IRT0657)
文摘Irrigation-induced soil erosion seriously affects the sustainability of irrigated agriculture. The effects of irrigation water quality and furrow gradient on runoff and soil loss were studied under simulated furrow irrigation in laboratory using a soil collected from an experimental station of China Agricultural University, North China. The experimental treatments were different combinations of irrigation water salt concentrations of 5, 10, 20, and 30 mmol c L-1 , sodium adsorption ratios (SAR) of 0.5, 5.0, and 10.0 (mmol c L-1 ) 0.5 , and furrow gradients of 1%, 3%, and 5%, with distilled water for irrigation at 3 furrow gradients as controls. The experimental data indicated that total runoff amount, sediment concentration in runoff, and total soil loss amount generally decreased with increasing salt concentration in irrigation water but increased with its sodicity and furrow gradient. The effects of water quality and furrow gradient on soil loss were greater than those on runoff, and the increase of furrow gradient decreased the influence of water quality on soil loss. When the salt concentration increased from 5 to 30 mmol c L-1 at SAR of 10.0 (mmol c L-1 ) 0.5 , total runoff amount, sediment concentration, and total soil loss amount decreased by 3.89%, 52.1%, and 53.92%, and 10.57%, 38.86%, and 42.03% at the furrow gradients of 1% and 5%, respectively. However, they respectively increased by 3.37%, 45.34%, and 55.36%, and 3.86%, 10.77%, and 13.91% when SAR increased from 0.5 to 10.0 (mmol c L-1 ) 0.5 at the salt concentration of 5 mmol c L-1 . Irrigation water quality and furrow gradient should be comprehensively considered in the planning and management of furrow irrigation practices to decrease soil loss and improve water utilization efficiency.
基金the China Harbor Engineering Company (CHEC) for providing financial support
文摘Both physical and chemical processes affect the fate and transport of herbicides. It is useful to simulate these processes with computer programs to predict solute movement. Simulations were run with HYDRUS- 1 D to identify the sorption and degradation parameters of atrazine through calibration from the breakthrough curves （BTCs）. Data from undisturbed and disturbed soil column experiments were compared and analyzed using the dual-porosity model. The study results show that the values of dispersivity are slightly lower in disturbed columns, suggesting that the more heterogeneous the structure is, the higher the dispersivity. Sorption parameters also show slight variability, which is attributed to the differences in soil properties, experimental conditions and methods, or other ecological factors. For both of the columns, the degradation rates were similar. Potassium bromide was used as a conservative non-reactive tracer to characterize the water movement in columns. Atrazine BTCs exhibited significant tailing and asymmetry, indicating non-equilibrium sorption during solute transport. The dual-porosity model was verified to best fit the BTCs of the column experiments. Greater or lesser concentration of atrazine spreading to the bottom of the columns indicated risk of groundwater contamination. Overall, HYDRUS-1D successfully simulated the atrazine transport in soil columns.
