Dust emissions from smelters, as a major contributor to heavy metal contamination in soils, could severely influence soil quality. Downwind surface soils within 1.5 km of a zinc smelter, which was active for 10 years ...Dust emissions from smelters, as a major contributor to heavy metal contamination in soils, could severely influence soil quality. Downwind surface soils within 1.5 km of a zinc smelter, which was active for 10 years but ceased in 2000, in Magu Town, Cuizhou Province, China were selected to examine Pb, Zn, and Cd concentrations and their fractionation along a distance gradient from a zinc smelter, and to study the possible effects of Pb, Zn, and Cd accumulation on soil microorganisms by comparing with a reference soil located at a downwind distance of 10 km from the zinc smelter. Soils within 1.5 km of the zinc smelter accumulated high levels of heavy metals Zn （508 mg kg^-1）, Pb （95.6 mg kg^-1）, and Cd （5.98 mg kg^-1） with low ratios of Zn/Cd （59.1-115） and Pb/Cd （12.4-23.4）. Composite pollution indices （CPIs） of surface soils （2.52-15.2） were 3 to 13 times higher than the reference soils. In metal accumulated soils, exchangeable plus carbonate-bound fractions accounted for more than 10% of the total Zn, Pb, and Cd. The saturation degree of metals （SDM） in soils within 1.5 km of the smelter （averaging 1.25） was six times higher than that of the reference soils （0.209）. A smaller soil microbial biomass was found more frequently in metal accumulated soils （85.1-438 μg C g^-1） than in reference soils （497 μg C g^-1）, and a negative correlation （P 〈 0.01） of soil microbial biomass carbon to organic carbon ratio （Cmic/Corg） with SDM was observed. Microbial consumption of carbon sources was more rapid in contaminated soils than in reference soils, and a shift in the substrate utilization pattern was apparent and was negatively correlated with SDM （R = -0.773, P 〈 0.01）. Consequently, dust deposited Pb, Zn, and Cd in soils from zinc smelting were readily mobilized, and were detrimental to soil quality mainly in respect of microbial biomass .展开更多
Ultrasonic extraction （UE） was employed for the extraction of bamboo leaf polysaccharides （BLP）. The influential parameters of UE procedure including extraction time, ultrasonic power and solid/liquid ratio were o...Ultrasonic extraction （UE） was employed for the extraction of bamboo leaf polysaccharides （BLP）. The influential parameters of UE procedure including extraction time, ultrasonic power and solid/liquid ratio were optimized by orthogonal experiments. DEAE-cellulose col- umn chromatography was applied to purify BLP and then the radical scavenging activity of BLP was also evaluated. Optimal extraction con- ditions were： extraction time .of 15 min, ultrasonic power of 300 W, and solid/liquid ratio of 1：15. Four kinds of polysaccharides were obtained by DEAE-cellulose colunm chromatography; the maximum superoxide radical scavenging rate （20.4%） of BLP was inferior to that of vitamin C （Vc, the control） and the hydroxyl radical scavenging rate （50%） was equivalent to that of Vc.展开更多
为了提高双孢蘑菇多糖的提取得率和效率,并研究双孢蘑菇多糖的组分,在考察了单因素水料比、超声功率、超声时间对双孢蘑菇子实体多糖提取得率影响的基础上,采用Box-Behnken响应面设计法,建立了3个影响因素与双孢蘑菇子实体多糖提取得率...为了提高双孢蘑菇多糖的提取得率和效率,并研究双孢蘑菇多糖的组分,在考察了单因素水料比、超声功率、超声时间对双孢蘑菇子实体多糖提取得率影响的基础上,采用Box-Behnken响应面设计法,建立了3个影响因素与双孢蘑菇子实体多糖提取得率的回归方程,优化提取工艺。同时利用DEAE Sepharose F F阴离子层析法对多糖进行了分离。Design Expert软件分析结果表明:在水料比36∶1、超声功率594 W、超声时间17 min的优化工艺条件下,双孢蘑菇子实体多糖的提取得率可高达6.63%。分离出2个多糖组分,分子量分别为2.75×105和1.4×104。通过响应面法设计结合超声波辅助提取能提高提取效率、缩短提取时间和保护有效成分,具有一定实际应用价值。DEAE Sepharose F F层析柱对双孢蘑菇多糖具有良好的分离效果。展开更多
基金Project supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (No.KZCX2-105)the "Light in Western China" Program of the Chinese Academy of Sciences and Guizhou Province, and the National Natural Science Foundation of China (No.40473049)
文摘Dust emissions from smelters, as a major contributor to heavy metal contamination in soils, could severely influence soil quality. Downwind surface soils within 1.5 km of a zinc smelter, which was active for 10 years but ceased in 2000, in Magu Town, Cuizhou Province, China were selected to examine Pb, Zn, and Cd concentrations and their fractionation along a distance gradient from a zinc smelter, and to study the possible effects of Pb, Zn, and Cd accumulation on soil microorganisms by comparing with a reference soil located at a downwind distance of 10 km from the zinc smelter. Soils within 1.5 km of the zinc smelter accumulated high levels of heavy metals Zn （508 mg kg^-1）, Pb （95.6 mg kg^-1）, and Cd （5.98 mg kg^-1） with low ratios of Zn/Cd （59.1-115） and Pb/Cd （12.4-23.4）. Composite pollution indices （CPIs） of surface soils （2.52-15.2） were 3 to 13 times higher than the reference soils. In metal accumulated soils, exchangeable plus carbonate-bound fractions accounted for more than 10% of the total Zn, Pb, and Cd. The saturation degree of metals （SDM） in soils within 1.5 km of the smelter （averaging 1.25） was six times higher than that of the reference soils （0.209）. A smaller soil microbial biomass was found more frequently in metal accumulated soils （85.1-438 μg C g^-1） than in reference soils （497 μg C g^-1）, and a negative correlation （P 〈 0.01） of soil microbial biomass carbon to organic carbon ratio （Cmic/Corg） with SDM was observed. Microbial consumption of carbon sources was more rapid in contaminated soils than in reference soils, and a shift in the substrate utilization pattern was apparent and was negatively correlated with SDM （R = -0.773, P 〈 0.01）. Consequently, dust deposited Pb, Zn, and Cd in soils from zinc smelting were readily mobilized, and were detrimental to soil quality mainly in respect of microbial biomass .
文摘Ultrasonic extraction （UE） was employed for the extraction of bamboo leaf polysaccharides （BLP）. The influential parameters of UE procedure including extraction time, ultrasonic power and solid/liquid ratio were optimized by orthogonal experiments. DEAE-cellulose col- umn chromatography was applied to purify BLP and then the radical scavenging activity of BLP was also evaluated. Optimal extraction con- ditions were： extraction time .of 15 min, ultrasonic power of 300 W, and solid/liquid ratio of 1：15. Four kinds of polysaccharides were obtained by DEAE-cellulose colunm chromatography; the maximum superoxide radical scavenging rate （20.4%） of BLP was inferior to that of vitamin C （Vc, the control） and the hydroxyl radical scavenging rate （50%） was equivalent to that of Vc.
文摘为了提高双孢蘑菇多糖的提取得率和效率,并研究双孢蘑菇多糖的组分,在考察了单因素水料比、超声功率、超声时间对双孢蘑菇子实体多糖提取得率影响的基础上,采用Box-Behnken响应面设计法,建立了3个影响因素与双孢蘑菇子实体多糖提取得率的回归方程,优化提取工艺。同时利用DEAE Sepharose F F阴离子层析法对多糖进行了分离。Design Expert软件分析结果表明:在水料比36∶1、超声功率594 W、超声时间17 min的优化工艺条件下,双孢蘑菇子实体多糖的提取得率可高达6.63%。分离出2个多糖组分,分子量分别为2.75×105和1.4×104。通过响应面法设计结合超声波辅助提取能提高提取效率、缩短提取时间和保护有效成分,具有一定实际应用价值。DEAE Sepharose F F层析柱对双孢蘑菇多糖具有良好的分离效果。
