Polycyclic aromatic hydrocarbon(PAH)-contaminated soils are usually complex and characterized by a lack of nutrition and soil salinization,resulting in difficulties in soil remediation.In this study,bioaugmentation wi...Polycyclic aromatic hydrocarbon(PAH)-contaminated soils are usually complex and characterized by a lack of nutrition and soil salinization,resulting in difficulties in soil remediation.In this study,bioaugmentation with a PAH-degrading Bacillus PheN7(BA)and low-dose persulfate oxidation(PS),along with natural biodegradation,were utilized to remediate alkaline PAH-contaminated soil.The soil used in the study had a pH of 9.35,and the total PAH content was 568.8±31.0 mg/kg dry soil.After 42 d of remediation,the degradation efficiency of PAHs was 96.72%and 93.88%using persulfate oxidation and bioaugmentation,respectively,whereas 38.66%of PAHs were degraded in natural attenuation(NA).Bacillus was the dominant genera throughout the process of bioremediation with the relative abundance of 79.3%on day 42 in the BA system,whereas,Alcanivorax was enriched and became the dominant genera in PS systems.In the meantime,PAH degradation genes were detected with remarkably higher level in the BA system than in PS system during the remediation.In addition to the degradation of contaminants,persulfate oxidation promotes microbial bioremediation efficiency mainly by lowering the pH to neutral and increasing the active phosphorus content in the soil.Microbial species and ecological niches were less reduced in the PS system than in the BA system.Collectively,persulfate oxidation had a better impact on the soil microbiome and is more suitable for long-term soil health than bioaugmentation through PheN7 addition.展开更多
The effect of W on the microstructure and the mechanical properties of ultrahigh strength low alloy steels was carried out. The microstructure of 30Cr3Si2Mn2NiMoNb and 30Cr3Si2Mn2NiMoNbW steels under quenched conditio...The effect of W on the microstructure and the mechanical properties of ultrahigh strength low alloy steels was carried out. The microstructure of 30Cr3Si2Mn2NiMoNb and 30Cr3Si2Mn2NiMoNbW steels under quenched conditions were investigated by metallographic microscope, scanning electron microscope （SEM）, X-ray diffrac- tion （XRD）, and transmission electron microscope （TEM）. Thermodynamic cal- culation was also conducted. The results showed that the addition of W made undissolved carbides more and finer, which exerted strong pinning force on migrat- ing packet boundary and improved tensile strength significantly. M6C particles in 30Cr3Si2Mn2NiMoNb steel were disappeared above 1193 K, while the M6C particles in 30Cr3Si2Mn2NiMoNbW steel were disappeared above 1253 K, the calculation results were in agreement with the experimental.展开更多
基金supported by the National Key Research and Development Program of China(Nos.2020YFC1808801,2020YFC1808805)the National Natural Science Foundation of China(Nos.41773082,41573065).
文摘Polycyclic aromatic hydrocarbon(PAH)-contaminated soils are usually complex and characterized by a lack of nutrition and soil salinization,resulting in difficulties in soil remediation.In this study,bioaugmentation with a PAH-degrading Bacillus PheN7(BA)and low-dose persulfate oxidation(PS),along with natural biodegradation,were utilized to remediate alkaline PAH-contaminated soil.The soil used in the study had a pH of 9.35,and the total PAH content was 568.8±31.0 mg/kg dry soil.After 42 d of remediation,the degradation efficiency of PAHs was 96.72%and 93.88%using persulfate oxidation and bioaugmentation,respectively,whereas 38.66%of PAHs were degraded in natural attenuation(NA).Bacillus was the dominant genera throughout the process of bioremediation with the relative abundance of 79.3%on day 42 in the BA system,whereas,Alcanivorax was enriched and became the dominant genera in PS systems.In the meantime,PAH degradation genes were detected with remarkably higher level in the BA system than in PS system during the remediation.In addition to the degradation of contaminants,persulfate oxidation promotes microbial bioremediation efficiency mainly by lowering the pH to neutral and increasing the active phosphorus content in the soil.Microbial species and ecological niches were less reduced in the PS system than in the BA system.Collectively,persulfate oxidation had a better impact on the soil microbiome and is more suitable for long-term soil health than bioaugmentation through PheN7 addition.
文摘The effect of W on the microstructure and the mechanical properties of ultrahigh strength low alloy steels was carried out. The microstructure of 30Cr3Si2Mn2NiMoNb and 30Cr3Si2Mn2NiMoNbW steels under quenched conditions were investigated by metallographic microscope, scanning electron microscope （SEM）, X-ray diffrac- tion （XRD）, and transmission electron microscope （TEM）. Thermodynamic cal- culation was also conducted. The results showed that the addition of W made undissolved carbides more and finer, which exerted strong pinning force on migrat- ing packet boundary and improved tensile strength significantly. M6C particles in 30Cr3Si2Mn2NiMoNb steel were disappeared above 1193 K, while the M6C particles in 30Cr3Si2Mn2NiMoNbW steel were disappeared above 1253 K, the calculation results were in agreement with the experimental.
