The combined application of mineral fertilizer and biochar significantly improves the passivation of heavy metal-contaminated soil,surpassing the effects of individual application.This study has reinforced the validat...The combined application of mineral fertilizer and biochar significantly improves the passivation of heavy metal-contaminated soil,surpassing the effects of individual application.This study has reinforced the validation of their passivation competence as soil remediation agents by examining the multifaceted role of potassium-silicon-calcium mineral fertilizer combined with rice husk-based biochar generated at different pyrolysis temperatures.The soil leaching column experiment,conducted based on the adsorption experiments,has facilitated our scrutiny of the passivation impacts of cadmium(Cd)and lead(Pb)when introducing different proportions of mineral fertilizers and biochar into the soil.These results indicate that biochar’s adsorption efficiency for Cd and Pb is significantly improved at escalated pyrolytic temperature conditions in a single solution.The biochar generated at 700℃(C700)renders adsorption effectiveness of approximately 84.24%for Cd and 99.74%for Pb.Biochar conspicuously registers superior adsorption efficiency towards Pb relative to Cd.The mineral fertilizer,which achieves an adsorption efficiency of 97.76%for Cd,is identified as the main adsorbent for Cd,although its competence is slightly lower compared to C700 for Pb adsorption.Within a complex solution,biochar and mineral fertilizer show reduced Cd and Pb adsorption levels compared to single solutions.There is a keen competition for adsorption surfaces witnessed between Cd and Pb,with Pb’s distribution coefficient(Kd)notably outpacing that of Cd.The isothermal adsorption analyses depict that the mineral fertilizer follows the Langmuir model for Cd adsorption,while C700 conveys the Freundlich model for Pb adsorption.The soil leaching column experiment’s results signify that the composite passivation agents significantly outperform the individual passivation agents in efficiency.The combined application of biochar and mineral fertilizer minimizes the cumulative leaching of Cd and Pb,with the optimal soil remedy proportion for heavy metal contamination being 7∶3.In practical application,mindful consideration should be accorded to the deployment ratios of different passivation agents.展开更多
The eastern foothills of the Helan Mountains in China are a typical mountainous region of soil and gravel,where gravel could affect the water movement process in the soil.This study focused on the effects of different...The eastern foothills of the Helan Mountains in China are a typical mountainous region of soil and gravel,where gravel could affect the water movement process in the soil.This study focused on the effects of different gravel contents on the water absorption characteristics and hydraulic parameters of stony soil.The stony soil samples were collected from the eastern foothills of the Helan Mountains in April 2023 and used as the experimental materials to conduct a one-dimensional horizontal soil column absorption experiment.Six experimental groups with gravel contents of 0%,10%,20%,30%,40%,and 50%were established to determine the saturated hydraulic conductivity(K_(s)),saturated water content(θ_(s)),initial water content(θ_(i)),and retention water content(θ_(r)),and explore the changes in the wetting front depth and cumulative absorption volume during the absorption experiment.The Philip model was used to fit the soil absorption process and determine the soil water absorption rate.Then the length of the characteristic wetting front depth,shape coefficient,empirical parameter,inverse intake suction and soil water suction were derived from the van Genuchten model.Finally,the hydraulic parameters mentioned above were used to fit the soil water characteristic curves,unsaturated hydraulic conductivity(K_(θ))and specific water capacity(C(h)).The results showed that the wetting front depth and cumulative absorption volume of each treatment gradually decreased with increasing gravel content.Compared with control check treatment with gravel content of 0%,soil water absorption rates in the treatments with gravel contents of 10%,20%,30%,40%,and 50%decreased by 11.47%,17.97%,25.24%,29.83%,and 42.45%,respectively.As the gravel content increased,inverse intake suction gradually increased,and shape coefficient,K_(s),θ_(s),andθ_(r)gradually decreased.For the same soil water content,soil water suction and K_(θ)gradually decreased with increasing gravel content.At the same soil water suction,C(h)decreased with increasing gravel content,and the water use efficiency worsened.Overall,the water holding capacity,hydraulic conductivity,and water use efficiency of stony soil in the eastern foothills of the Helan Mountains decreased with increasing gravel content.This study could provide data support for improving soil water use efficiency in the eastern foothills of the Helan Mountains and other similar rocky mountainous areas.展开更多
In order to understand the mechanism and regularity of the groundwater contamination from mine water of abandoned mines, experiments were conducted on an abandoned coal mine in Fuxin, a representative city with lots o...In order to understand the mechanism and regularity of the groundwater contamination from mine water of abandoned mines, experiments were conducted on an abandoned coal mine in Fuxin, a representative city with lots of mine water in northeast China. The groundwater pollution from different contaminants of coal-mining voids （total hardness, SO4^2-, CI^- and total Fe） and pollution factors transportation situation in the coal rock were simulated by soil column experiment under the conditions of mine water leaching and main water leaching （similar to rainwater leaching）, and the water-rock interaction mechanism was discussed during mine water infiltration through saturated coal rock by application of principle of mass conservation, based on physical properties of coal rock, as well as monitored chemical composition. The results show that, compared with the clear water leaching process, trends of change in pollutant concentrations presented different characteristics in the mine water leaching process. Groundwater is contaminated by the water rock interactions such as migration ＆ accumulation, adsorption ＆ transformation, dissolution ＆ desorption and ion exchange during the mine water permeation. The experiments also suggest that at first dissolution rate of some kinds of dissoluble salts is high, but it decreases with leaching time, even to zero during both the mine water leaching and main water leaching.展开更多
In order to better understand the soil moisture dynamics during a drying process, a soil column experiment is conducted in the laboratory, followed by the numerical modeling with consideration of the coupled liquid wa...In order to better understand the soil moisture dynamics during a drying process, a soil column experiment is conducted in the laboratory, followed by the numerical modeling with consideration of the coupled liquid water, water vapor and heat transport in the vadose zone. Results show that there are three distinct subzones above the water table according to the temporally dynamic variation of the water content profiles. Zone 1 sees a decrease in the water contents in the upper profiles （0 m-0.05 m） due to a negative net water flux in this zone where the upward isothermal water vapor flux becomes the main flow mechanism in the soils. Irl contrast, the water content within Zone 2 in the depth ranging from 0.05 m to 0.37 m sees an apparent increase over the, resulting from the positive net thermal water-vapor and isothermal liquid-water fluxes into this layer. Zone 3 （0.37 m-0.65 m） also sees an apparent decrease in the water content since the isothermal liquid water flux carries the liquid water either upward out of this region for vaporization or downward to the water table as a recharge to the groundwater.展开更多
基金supported by the National Natural Science Foundation of Sichuan Province(22NSFSC0191,22NSFSC3990)。
文摘The combined application of mineral fertilizer and biochar significantly improves the passivation of heavy metal-contaminated soil,surpassing the effects of individual application.This study has reinforced the validation of their passivation competence as soil remediation agents by examining the multifaceted role of potassium-silicon-calcium mineral fertilizer combined with rice husk-based biochar generated at different pyrolysis temperatures.The soil leaching column experiment,conducted based on the adsorption experiments,has facilitated our scrutiny of the passivation impacts of cadmium(Cd)and lead(Pb)when introducing different proportions of mineral fertilizers and biochar into the soil.These results indicate that biochar’s adsorption efficiency for Cd and Pb is significantly improved at escalated pyrolytic temperature conditions in a single solution.The biochar generated at 700℃(C700)renders adsorption effectiveness of approximately 84.24%for Cd and 99.74%for Pb.Biochar conspicuously registers superior adsorption efficiency towards Pb relative to Cd.The mineral fertilizer,which achieves an adsorption efficiency of 97.76%for Cd,is identified as the main adsorbent for Cd,although its competence is slightly lower compared to C700 for Pb adsorption.Within a complex solution,biochar and mineral fertilizer show reduced Cd and Pb adsorption levels compared to single solutions.There is a keen competition for adsorption surfaces witnessed between Cd and Pb,with Pb’s distribution coefficient(Kd)notably outpacing that of Cd.The isothermal adsorption analyses depict that the mineral fertilizer follows the Langmuir model for Cd adsorption,while C700 conveys the Freundlich model for Pb adsorption.The soil leaching column experiment’s results signify that the composite passivation agents significantly outperform the individual passivation agents in efficiency.The combined application of biochar and mineral fertilizer minimizes the cumulative leaching of Cd and Pb,with the optimal soil remedy proportion for heavy metal contamination being 7∶3.In practical application,mindful consideration should be accorded to the deployment ratios of different passivation agents.
基金funded by the National Natural Science Foundation of China(32360321)the Natural Science Foundation of Ningxia Hui Autonomous Region,China(2023AAC03046,2023AAC02018)the Ningxia Key Research and Development Project(2021BEG02011).
文摘The eastern foothills of the Helan Mountains in China are a typical mountainous region of soil and gravel,where gravel could affect the water movement process in the soil.This study focused on the effects of different gravel contents on the water absorption characteristics and hydraulic parameters of stony soil.The stony soil samples were collected from the eastern foothills of the Helan Mountains in April 2023 and used as the experimental materials to conduct a one-dimensional horizontal soil column absorption experiment.Six experimental groups with gravel contents of 0%,10%,20%,30%,40%,and 50%were established to determine the saturated hydraulic conductivity(K_(s)),saturated water content(θ_(s)),initial water content(θ_(i)),and retention water content(θ_(r)),and explore the changes in the wetting front depth and cumulative absorption volume during the absorption experiment.The Philip model was used to fit the soil absorption process and determine the soil water absorption rate.Then the length of the characteristic wetting front depth,shape coefficient,empirical parameter,inverse intake suction and soil water suction were derived from the van Genuchten model.Finally,the hydraulic parameters mentioned above were used to fit the soil water characteristic curves,unsaturated hydraulic conductivity(K_(θ))and specific water capacity(C(h)).The results showed that the wetting front depth and cumulative absorption volume of each treatment gradually decreased with increasing gravel content.Compared with control check treatment with gravel content of 0%,soil water absorption rates in the treatments with gravel contents of 10%,20%,30%,40%,and 50%decreased by 11.47%,17.97%,25.24%,29.83%,and 42.45%,respectively.As the gravel content increased,inverse intake suction gradually increased,and shape coefficient,K_(s),θ_(s),andθ_(r)gradually decreased.For the same soil water content,soil water suction and K_(θ)gradually decreased with increasing gravel content.At the same soil water suction,C(h)decreased with increasing gravel content,and the water use efficiency worsened.Overall,the water holding capacity,hydraulic conductivity,and water use efficiency of stony soil in the eastern foothills of the Helan Mountains decreased with increasing gravel content.This study could provide data support for improving soil water use efficiency in the eastern foothills of the Helan Mountains and other similar rocky mountainous areas.
基金the National Natural Science Foundation of China(50434020,50374042)Science & Technology Found of Liaoning Province(20022155)Specialized Research Fund for the Doctoral Program of Higher Education(20040147003)
文摘In order to understand the mechanism and regularity of the groundwater contamination from mine water of abandoned mines, experiments were conducted on an abandoned coal mine in Fuxin, a representative city with lots of mine water in northeast China. The groundwater pollution from different contaminants of coal-mining voids （total hardness, SO4^2-, CI^- and total Fe） and pollution factors transportation situation in the coal rock were simulated by soil column experiment under the conditions of mine water leaching and main water leaching （similar to rainwater leaching）, and the water-rock interaction mechanism was discussed during mine water infiltration through saturated coal rock by application of principle of mass conservation, based on physical properties of coal rock, as well as monitored chemical composition. The results show that, compared with the clear water leaching process, trends of change in pollutant concentrations presented different characteristics in the mine water leaching process. Groundwater is contaminated by the water rock interactions such as migration ＆ accumulation, adsorption ＆ transformation, dissolution ＆ desorption and ion exchange during the mine water permeation. The experiments also suggest that at first dissolution rate of some kinds of dissoluble salts is high, but it decreases with leaching time, even to zero during both the mine water leaching and main water leaching.
基金supported by the National Natural Science Foundation of China(Grant Nos.41172204,41102144)the Natural Science Foundation of Jiangsu Province of China(Grant Nos.BK2011110,BK2012814)
文摘In order to better understand the soil moisture dynamics during a drying process, a soil column experiment is conducted in the laboratory, followed by the numerical modeling with consideration of the coupled liquid water, water vapor and heat transport in the vadose zone. Results show that there are three distinct subzones above the water table according to the temporally dynamic variation of the water content profiles. Zone 1 sees a decrease in the water contents in the upper profiles （0 m-0.05 m） due to a negative net water flux in this zone where the upward isothermal water vapor flux becomes the main flow mechanism in the soils. Irl contrast, the water content within Zone 2 in the depth ranging from 0.05 m to 0.37 m sees an apparent increase over the, resulting from the positive net thermal water-vapor and isothermal liquid-water fluxes into this layer. Zone 3 （0.37 m-0.65 m） also sees an apparent decrease in the water content since the isothermal liquid water flux carries the liquid water either upward out of this region for vaporization or downward to the water table as a recharge to the groundwater.
