Bauxite residue is an alkaline waste material in the process of alumina production due to its characteristics of higher salinity and alkalinity,which results in environmental issues and extremely restricts the sustain...Bauxite residue is an alkaline waste material in the process of alumina production due to its characteristics of higher salinity and alkalinity,which results in environmental issues and extremely restricts the sustainable development of alumina industries.In this work,we conduct a column experiment to study the effects of two amendments on aggregate stability and variations in alkaline minerals of bauxite residue.The two amendments are phosphogypsum(PG)and phosphogypsum and vermicompost(PVC).The dominant fraction in aggregate is 1–0.25 mm in diameter on the surface,which takes up 39.34%,39.38%,and 44.51%for CK,PG,and PVC,respectively.Additions of PG and PVC decreased pH,EC,ESP,exchangeable Na^+concentration and the percentage of alkaline minerals,and then increased exchangeable Ca^2+concentration in bauxite residue.There was significant positive correlation between pH and exchangeable Na^+concentration,the percentage of cancrinite,tricalcium aluminate and calcite;while negative correlation was found in pH value versus exchangeable Ca^2+concentration.Theses findings confirmed that additions of phosphogypsum and vermicompost have a stimulative effect on aggregate stability in bauxite residue.In particular,amendment neutralization(phosphogypsum+vermicompost)in column represents an advantage for large-scale simulation of vegetation rehabilitate in bauxite residue disposal areas.展开更多
A column experiment was conducted to investigate the effect of phosphogypsum(PG)on the salinealkalinity,and aggregate stability of bauxite residue.Results showed that:with increasing leaching time,the concentrations o...A column experiment was conducted to investigate the effect of phosphogypsum(PG)on the salinealkalinity,and aggregate stability of bauxite residue.Results showed that:with increasing leaching time,the concentrations of saline−alkali ions decreased while the SO_(4)^(2-)concentration increased in bauxite residue leachate;compared with CK(control group)treatment,pH,electric conductivity(EC),exchangeable sodium percentage(ESP),sodium absorption ratio(SAR),and exchangeable Na+content of bauxite residue were reduced following PG treatment;average particle sizes in aggregates following CK and PG treatments were determined to be 155 and 193 nm,respectively.SR-μCT test results also confirmed that bauxite residue following PG treatment acquired larger aggregates and larger pore diameter.These results indicate that the PG treatment could significantly modulate the saline-alkalinity,and simultaneously enhance aggregate stability of bauxite residue,which provides a facile approach to reclaim bauxite residue disposal areas.展开更多
Revegetation on bauxite residue disposal areas is the most promising strategy to reduce its potential ecological risk during stacking or disposing.Migration of salt ions in bauxite residue is one of the major issues t...Revegetation on bauxite residue disposal areas is the most promising strategy to reduce its potential ecological risk during stacking or disposing.Migration of salt ions in bauxite residue is one of the major issues to stimulate soil formation to support plant growth.21 residue samples were collected and the related parameters including exchangeable cations,soluble ions,total salt,pH,electrical conductivity(EC)and exchangeable sodium percentage(ESP)were selected to evaluate alkalization and salinization of bauxite residue.High levels of ions,cation exchange capacity(TOC),total salt,exchangeable sodium percentage(ESP)and cation exchange capacity(CEC)in bauxite residue were detected with greater coefficient of variation(CV),which indicated that distribution characteristics of salt ions varied significantly.The percentage of sulfate-chloride-soda type in the residues accounted for 71.43%.The mean value of pH was 10.10,whilst mean value of ESP was 52.05%.It indicated that the residues in this case study belonged to sulfate-chloride-soda saline and alkaline soil.The research results could provide theoretical basis for soil formation in bauxite residue.展开更多
Vegetation encroachment occurred in bauxite residue disposal area(BRDA)following natural weathering processes,whilst the typical indicators of soil formation are still uncertain.Residue samples were collected from the...Vegetation encroachment occurred in bauxite residue disposal area(BRDA)following natural weathering processes,whilst the typical indicators of soil formation are still uncertain.Residue samples were collected from the BRDA in Central China,and related physical,chemical and biological indicators of bauxite residue with different storage years were determined.The indicators of soil formation in bauxite residue were selected using principal component analysis,factor analysis,and comprehensive evaluation to establish soil quality diagnostic index model on disposal areas.Following natural weathering processes,the texture of bauxite residue changed from silty loam to sandy loam.The pH and EC decreased,whilst porosity,nutrient element content and microbial biomass increased.The identified minimum data set(MDS)included available phosphorus(AP),moisture content(MC),C/N,sand content,total nitrogen(TN),microbial biomass carbon(MBC),and pH.The soil quality index of bauxite residue increased,and the relative soil quality index decreased from 1.89 to 0.15,which indicated that natural weathering had a significant effect on improveing the quality of bauxite residue and forming a new soil-like matrix.The diagnostic model of bauxite residue was established to provide data support for the regeneration on disposal area.展开更多
目的观察三种全麻方式对老年患者手术后早期认知功能的影响。方法采用双盲随机原则将114例老年手术患者随机分为异丙酚、地佐辛静脉组(P组)、七氟烷与异丙酚、静吸复合组(SP组)和七氟烷吸入麻醉组(S组),比较3组不同时间简易精神状态量表...目的观察三种全麻方式对老年患者手术后早期认知功能的影响。方法采用双盲随机原则将114例老年手术患者随机分为异丙酚、地佐辛静脉组(P组)、七氟烷与异丙酚、静吸复合组(SP组)和七氟烷吸入麻醉组(S组),比较3组不同时间简易精神状态量表(MMSE)评分、不同时间认知功能障碍发生及手术前后白细胞介素(IL)-1β、IL-6水平变化情况。结果 3组出麻醉恢复室和术后1 d MMSE评分均显著低于术前1 d(P<0.05);3组不同时间MMSE评分差异显著(P>0.05);3组均为出麻醉恢复室时认知功能障碍发生率最高,之后逐渐下降,至术后3、7 d明显降低(P<0.05);3组不同时间认知功能障碍发生率差异不显著(P>0.05);3组术后1 d IL-1β、IL-6水平与术前1 d比较均显著升高(P<0.05);3组术前1 d、术后1 d IL-1β、IL-6水平差异不显著(P>0.05)。结论老年患者全麻术后出麻醉恢复室时和术后1 d认知功能均受到明显影响,至术后3~7 d基本恢复,三种全麻方式对认知功能的影响基本相同,术后IL-1β和IL-6水平升高可能与术后早期认知功能障碍的发生有紧密联系。展开更多
基金Projects(41701587,41877511)supported by the National Natural Science Foundation of China
文摘Bauxite residue is an alkaline waste material in the process of alumina production due to its characteristics of higher salinity and alkalinity,which results in environmental issues and extremely restricts the sustainable development of alumina industries.In this work,we conduct a column experiment to study the effects of two amendments on aggregate stability and variations in alkaline minerals of bauxite residue.The two amendments are phosphogypsum(PG)and phosphogypsum and vermicompost(PVC).The dominant fraction in aggregate is 1–0.25 mm in diameter on the surface,which takes up 39.34%,39.38%,and 44.51%for CK,PG,and PVC,respectively.Additions of PG and PVC decreased pH,EC,ESP,exchangeable Na^+concentration and the percentage of alkaline minerals,and then increased exchangeable Ca^2+concentration in bauxite residue.There was significant positive correlation between pH and exchangeable Na^+concentration,the percentage of cancrinite,tricalcium aluminate and calcite;while negative correlation was found in pH value versus exchangeable Ca^2+concentration.Theses findings confirmed that additions of phosphogypsum and vermicompost have a stimulative effect on aggregate stability in bauxite residue.In particular,amendment neutralization(phosphogypsum+vermicompost)in column represents an advantage for large-scale simulation of vegetation rehabilitate in bauxite residue disposal areas.
基金the financial supports from the National Natural Science Foundation of China(Nos.42030711,41877511).
文摘A column experiment was conducted to investigate the effect of phosphogypsum(PG)on the salinealkalinity,and aggregate stability of bauxite residue.Results showed that:with increasing leaching time,the concentrations of saline−alkali ions decreased while the SO_(4)^(2-)concentration increased in bauxite residue leachate;compared with CK(control group)treatment,pH,electric conductivity(EC),exchangeable sodium percentage(ESP),sodium absorption ratio(SAR),and exchangeable Na+content of bauxite residue were reduced following PG treatment;average particle sizes in aggregates following CK and PG treatments were determined to be 155 and 193 nm,respectively.SR-μCT test results also confirmed that bauxite residue following PG treatment acquired larger aggregates and larger pore diameter.These results indicate that the PG treatment could significantly modulate the saline-alkalinity,and simultaneously enhance aggregate stability of bauxite residue,which provides a facile approach to reclaim bauxite residue disposal areas.
基金Project(41701587)supported by the National Natural Science Foundation of ChinaProject(PM-zx703-201803-057)supported by Basic Scientific Research Business of Central Institutes of Environmental Protection,China
文摘Revegetation on bauxite residue disposal areas is the most promising strategy to reduce its potential ecological risk during stacking or disposing.Migration of salt ions in bauxite residue is one of the major issues to stimulate soil formation to support plant growth.21 residue samples were collected and the related parameters including exchangeable cations,soluble ions,total salt,pH,electrical conductivity(EC)and exchangeable sodium percentage(ESP)were selected to evaluate alkalization and salinization of bauxite residue.High levels of ions,cation exchange capacity(TOC),total salt,exchangeable sodium percentage(ESP)and cation exchange capacity(CEC)in bauxite residue were detected with greater coefficient of variation(CV),which indicated that distribution characteristics of salt ions varied significantly.The percentage of sulfate-chloride-soda type in the residues accounted for 71.43%.The mean value of pH was 10.10,whilst mean value of ESP was 52.05%.It indicated that the residues in this case study belonged to sulfate-chloride-soda saline and alkaline soil.The research results could provide theoretical basis for soil formation in bauxite residue.
基金Projects(41877551,41842020)supported by the National Natural Science Foundation of China
文摘Vegetation encroachment occurred in bauxite residue disposal area(BRDA)following natural weathering processes,whilst the typical indicators of soil formation are still uncertain.Residue samples were collected from the BRDA in Central China,and related physical,chemical and biological indicators of bauxite residue with different storage years were determined.The indicators of soil formation in bauxite residue were selected using principal component analysis,factor analysis,and comprehensive evaluation to establish soil quality diagnostic index model on disposal areas.Following natural weathering processes,the texture of bauxite residue changed from silty loam to sandy loam.The pH and EC decreased,whilst porosity,nutrient element content and microbial biomass increased.The identified minimum data set(MDS)included available phosphorus(AP),moisture content(MC),C/N,sand content,total nitrogen(TN),microbial biomass carbon(MBC),and pH.The soil quality index of bauxite residue increased,and the relative soil quality index decreased from 1.89 to 0.15,which indicated that natural weathering had a significant effect on improveing the quality of bauxite residue and forming a new soil-like matrix.The diagnostic model of bauxite residue was established to provide data support for the regeneration on disposal area.
文摘目的观察三种全麻方式对老年患者手术后早期认知功能的影响。方法采用双盲随机原则将114例老年手术患者随机分为异丙酚、地佐辛静脉组(P组)、七氟烷与异丙酚、静吸复合组(SP组)和七氟烷吸入麻醉组(S组),比较3组不同时间简易精神状态量表(MMSE)评分、不同时间认知功能障碍发生及手术前后白细胞介素(IL)-1β、IL-6水平变化情况。结果 3组出麻醉恢复室和术后1 d MMSE评分均显著低于术前1 d(P<0.05);3组不同时间MMSE评分差异显著(P>0.05);3组均为出麻醉恢复室时认知功能障碍发生率最高,之后逐渐下降,至术后3、7 d明显降低(P<0.05);3组不同时间认知功能障碍发生率差异不显著(P>0.05);3组术后1 d IL-1β、IL-6水平与术前1 d比较均显著升高(P<0.05);3组术前1 d、术后1 d IL-1β、IL-6水平差异不显著(P>0.05)。结论老年患者全麻术后出麻醉恢复室时和术后1 d认知功能均受到明显影响,至术后3~7 d基本恢复,三种全麻方式对认知功能的影响基本相同,术后IL-1β和IL-6水平升高可能与术后早期认知功能障碍的发生有紧密联系。
