秸秆深还（Deep application of straw, DAS）是指将玉米秸秆施入土壤亚表层（20～40cm），可以解决秸秆焚烧的问题，同时提高土壤肥力、蓄水能力和作物产量。本文采集了吉林农业大学试验站玉米连作耕地试验田中的秸秆深还土壤和未秸秆...秸秆深还（Deep application of straw, DAS）是指将玉米秸秆施入土壤亚表层（20～40cm），可以解决秸秆焚烧的问题，同时提高土壤肥力、蓄水能力和作物产量。本文采集了吉林农业大学试验站玉米连作耕地试验田中的秸秆深还土壤和未秸秆深还土壤，采用湿筛法将其分为〉2mm、2～0．25mm、0．25～0．053mm和〈0．053mm 4个粒级，定性分析提取胡敏酸（HA），通过元素组成、红外光谱和差热分析研究了秸秆深还对黑土各粒级团聚体中HA结构特征的影响。结果表明：黑土团聚体中的优势粒级为2—0．25mm粒级，优势粒级的团聚体含量和有机碳含量均是表层较亚表层低，DAS有利于优势粒级团聚体的形成，促使优势粒级团聚体中有机碳增多；与亚表层相比，表层各粒级团聚体HA的缩合度、氧化度和热稳定性普遍较低，脂族碳／羧基碳和脂族碳／芳香碳较高；DAS促使土壤表层和亚表层各粒级团聚体中HA的缩合度、氧化度和热稳定性下降，其中表层HA的缩合度降低更明显；而亚表层氧化度和热稳定性的降低幅度较大。表层中HA的分子结构较亚表层的简单、年轻，秸秆深还促使土壤中有机碳含量增加，HA的结构简单化、年轻化。展开更多
秸秆还田主要是覆盖和表层浅施,存在着影响种子发芽生长、土壤升温慢和病虫害增加等问题。秸秆深还（corn stover deep incorporation,CSDI）是指将玉米秸秆施入土壤亚表层（20~40 cm）,不仅能解决秸秆焚烧的问题,还能达到保碳、蓄水、...秸秆还田主要是覆盖和表层浅施,存在着影响种子发芽生长、土壤升温慢和病虫害增加等问题。秸秆深还（corn stover deep incorporation,CSDI）是指将玉米秸秆施入土壤亚表层（20~40 cm）,不仅能解决秸秆焚烧的问题,还能达到保碳、蓄水、培肥、稳产的目的,使秸秆还田得到改善。虽对秸秆深还后胡敏素（Hu）的结构性质有一些研究,但是对秸秆深还后土壤团聚体中Hu的变化还未见报道。探究秸秆深还对土壤腐殖质的影响,可以为如何提高土地肥力、如何利用秸秆深还创建合理耕层提供理论依据。本试验采集于吉林农业大学试验站玉米连作耕地试验田,采用湿筛法将其分为〉2 mm、2~0.25 mm、0.25~0.053 mm和〈0.053 mm 4个粒级并提取Hu,通过元素组成、红外光谱和差热分析研究秸秆深还对团聚体中Hu结构特征的影响。结果表明：用此方法制备的黑土Hu的平均含碳量为721 g kg-1;H/C的平均值为0.776;Hu的缩合度高于相应的HA;秸秆深还促使土壤表层和亚表层团聚体中Hu的氧化度降低,脂族链烃减少,活性结构增多,稳定性降低,Hu的结构趋于简单化、年轻化。展开更多
To identify and apportion the sources of the ambient PM2.5 in the urban area of Hangzhou, China, PM2.s samples were collected at three sites in the city from April 2004 to March 2005. Water-soluble ions, metal element...To identify and apportion the sources of the ambient PM2.5 in the urban area of Hangzhou, China, PM2.s samples were collected at three sites in the city from April 2004 to March 2005. Water-soluble ions, metal elements, and total carbon （TC） in PM2.s samples were analyzed. The results indicated that the 24-h mean concentrations of PM2.5 ranged from 17.1 to 267.0 μg/m^3, with an annual average value of 108.2 μg/m^3. Moreover, the seasonal mean values for PM2.5 in spring, summer, autumn, and winter were 116, 73.1, 114.2, and 136.0μg/m^3, respectively. According to the Chinese ambient quality standard, at least 70% of the monitoring data exceeded the limit value. The total contribution of water-soluble ions, including F^-, CI^-, NO3^-, SO4^2- , NH4^＋, K^＋, and Na^＋, to PM2.5 mass varied from 32.3% to 36.7%. SO4^2- , NO3^-, and NH4^＋ were the main constituents of the ions, with contributions to PM2.5 varying from 14.1% to 14.7%, 6.0% to 7.89;, and 6.4% to 7.7%, respectively. In addition, the annual mean mass fraction of TC in PM2.5 was 27.8%. The annual average total contribution of the group of elements of Zn, Pb, Cu, Mn, Cr, Ni, Se, Mo, Cd, Sb, and Ag to the aerosol was in the range of 1.7-2.0%. Furthermore, positive matrix factorization was applied to analyze the PM2.5 data collected from the central area, and five factors were identified. The factor contributions to PM2.5 mass were 12.8%, 31.9%, 10.1%, 17.2%, and 27.9%, respectively. Iron/steel manufacturing and secondary aerosol were the main sources for the fine particles. These findings may have significance for controlling the atmospheric contamination in the city.展开更多
建立一种简便快速、灵敏准确、无损的检验橡胶鞋底物证的分析方法,为侦查破案提供线索、指明方向,为证实犯罪提供科学的依据。利用能量色散型X射线荧光光谱仪,电压为45 k V,电流为40μA,功率为1.8 k W,样品量为1.5 cm×1.5 cm,测试...建立一种简便快速、灵敏准确、无损的检验橡胶鞋底物证的分析方法,为侦查破案提供线索、指明方向,为证实犯罪提供科学的依据。利用能量色散型X射线荧光光谱仪,电压为45 k V,电流为40μA,功率为1.8 k W,样品量为1.5 cm×1.5 cm,测试时间60 s。对不同品牌、不同种类的40个橡胶鞋底样品中的无机元素进行定性和半定量分析,并考查了该方法的重现性。依据样品中所含元素的种类及含量的不同,可以对不同品牌、同一品牌不同种类的橡胶鞋底样品进行区分。同时,利用SPSS聚类分析-重心法作为类间定义距离,对橡胶鞋底样品进行分类,样品的聚类效果很好。试验结果表明:利用该方法检验橡胶鞋底样品简便快速、结果准确可靠、重现性好、无需制样且无损检材,可用于公安机关实际办案。展开更多
Particulate pollution is a serious health problem throughout the world, exacerbating a wide range of respiratory and vascular illnesses in urban areas. Urban plants play an important role in reducing particulate pollu...Particulate pollution is a serious health problem throughout the world, exacerbating a wide range of respiratory and vascular illnesses in urban areas. Urban plants play an important role in reducing particulate pollution. Physicochemical characteristics of ambient particles settling upon leaf surfaces of eleven roadside plants at four sites of Beijing were studies. Results showed that density of particles on the leaf surfaces greatly varied with plant species and traffic condition. Fraxinus chiuensis, Sophora japonica Ailanthus altissima, Syringa oblata and Prunus persica, had larger densities of particles among the tall species. Due to resuspension of road dust, the densities of particles of Euonymus japonicns and Parthenocissus quinquefolia with low sampling height were 2-35 times to other taller tree species. For test plant species, micro-roughness of leaf surfaces and density of particles showed a close correlation. In general, the larger micro-roughness of leaf surfaces is, the larger density of particles is. Particles settling upon leaf surfaces were dominantly PM30 （particulate matter less than 10 μm in aerodynamic diameter; 98.4%） and PM2.5 （particulate matter less than 2.5 μm in aerodynamic diameter; 64.2%） which were closely relative to human health. Constant elements of particles were C, O, K, Ca, Si, Al, Mg, Na, Fe, S, Cl and minerals with higher content were SiO2, CaCO3, CaMg（CO3）2, NaCI and 2CASO4. H2O, SiO2. CaCO3 and CaMg（CO3）2 mainly came from resuspension of road dust. 2CaSO4. H2O was produced by the reaction between CaCO3 derived from earth dust or industrial emission and SO2, H2SO4 or sulfate. NaCl was derived from sea salt.展开更多
文摘秸秆还田主要是覆盖和表层浅施,存在着影响种子发芽生长、土壤升温慢和病虫害增加等问题。秸秆深还（corn stover deep incorporation,CSDI）是指将玉米秸秆施入土壤亚表层（20~40 cm）,不仅能解决秸秆焚烧的问题,还能达到保碳、蓄水、培肥、稳产的目的,使秸秆还田得到改善。虽对秸秆深还后胡敏素（Hu）的结构性质有一些研究,但是对秸秆深还后土壤团聚体中Hu的变化还未见报道。探究秸秆深还对土壤腐殖质的影响,可以为如何提高土地肥力、如何利用秸秆深还创建合理耕层提供理论依据。本试验采集于吉林农业大学试验站玉米连作耕地试验田,采用湿筛法将其分为〉2 mm、2~0.25 mm、0.25~0.053 mm和〈0.053 mm 4个粒级并提取Hu,通过元素组成、红外光谱和差热分析研究秸秆深还对团聚体中Hu结构特征的影响。结果表明：用此方法制备的黑土Hu的平均含碳量为721 g kg-1;H/C的平均值为0.776;Hu的缩合度高于相应的HA;秸秆深还促使土壤表层和亚表层团聚体中Hu的氧化度降低,脂族链烃减少,活性结构增多,稳定性降低,Hu的结构趋于简单化、年轻化。
基金financially supported by the National Natural Science Foundation of China(41073019)
文摘To identify and apportion the sources of the ambient PM2.5 in the urban area of Hangzhou, China, PM2.s samples were collected at three sites in the city from April 2004 to March 2005. Water-soluble ions, metal elements, and total carbon （TC） in PM2.s samples were analyzed. The results indicated that the 24-h mean concentrations of PM2.5 ranged from 17.1 to 267.0 μg/m^3, with an annual average value of 108.2 μg/m^3. Moreover, the seasonal mean values for PM2.5 in spring, summer, autumn, and winter were 116, 73.1, 114.2, and 136.0μg/m^3, respectively. According to the Chinese ambient quality standard, at least 70% of the monitoring data exceeded the limit value. The total contribution of water-soluble ions, including F^-, CI^-, NO3^-, SO4^2- , NH4^＋, K^＋, and Na^＋, to PM2.5 mass varied from 32.3% to 36.7%. SO4^2- , NO3^-, and NH4^＋ were the main constituents of the ions, with contributions to PM2.5 varying from 14.1% to 14.7%, 6.0% to 7.89;, and 6.4% to 7.7%, respectively. In addition, the annual mean mass fraction of TC in PM2.5 was 27.8%. The annual average total contribution of the group of elements of Zn, Pb, Cu, Mn, Cr, Ni, Se, Mo, Cd, Sb, and Ag to the aerosol was in the range of 1.7-2.0%. Furthermore, positive matrix factorization was applied to analyze the PM2.5 data collected from the central area, and five factors were identified. The factor contributions to PM2.5 mass were 12.8%, 31.9%, 10.1%, 17.2%, and 27.9%, respectively. Iron/steel manufacturing and secondary aerosol were the main sources for the fine particles. These findings may have significance for controlling the atmospheric contamination in the city.
文摘建立一种简便快速、灵敏准确、无损的检验橡胶鞋底物证的分析方法,为侦查破案提供线索、指明方向,为证实犯罪提供科学的依据。利用能量色散型X射线荧光光谱仪,电压为45 k V,电流为40μA,功率为1.8 k W,样品量为1.5 cm×1.5 cm,测试时间60 s。对不同品牌、不同种类的40个橡胶鞋底样品中的无机元素进行定性和半定量分析,并考查了该方法的重现性。依据样品中所含元素的种类及含量的不同,可以对不同品牌、同一品牌不同种类的橡胶鞋底样品进行区分。同时,利用SPSS聚类分析-重心法作为类间定义距离,对橡胶鞋底样品进行分类,样品的聚类效果很好。试验结果表明:利用该方法检验橡胶鞋底样品简便快速、结果准确可靠、重现性好、无需制样且无损检材,可用于公安机关实际办案。
基金The National Natural Science Foundation of China (No. 30570338) the Natural Science Foundation of Beijing (No. 6053026) andthe Ministry of Education, China(No. 20040027020).
文摘Particulate pollution is a serious health problem throughout the world, exacerbating a wide range of respiratory and vascular illnesses in urban areas. Urban plants play an important role in reducing particulate pollution. Physicochemical characteristics of ambient particles settling upon leaf surfaces of eleven roadside plants at four sites of Beijing were studies. Results showed that density of particles on the leaf surfaces greatly varied with plant species and traffic condition. Fraxinus chiuensis, Sophora japonica Ailanthus altissima, Syringa oblata and Prunus persica, had larger densities of particles among the tall species. Due to resuspension of road dust, the densities of particles of Euonymus japonicns and Parthenocissus quinquefolia with low sampling height were 2-35 times to other taller tree species. For test plant species, micro-roughness of leaf surfaces and density of particles showed a close correlation. In general, the larger micro-roughness of leaf surfaces is, the larger density of particles is. Particles settling upon leaf surfaces were dominantly PM30 （particulate matter less than 10 μm in aerodynamic diameter; 98.4%） and PM2.5 （particulate matter less than 2.5 μm in aerodynamic diameter; 64.2%） which were closely relative to human health. Constant elements of particles were C, O, K, Ca, Si, Al, Mg, Na, Fe, S, Cl and minerals with higher content were SiO2, CaCO3, CaMg（CO3）2, NaCI and 2CASO4. H2O, SiO2. CaCO3 and CaMg（CO3）2 mainly came from resuspension of road dust. 2CaSO4. H2O was produced by the reaction between CaCO3 derived from earth dust or industrial emission and SO2, H2SO4 or sulfate. NaCl was derived from sea salt.
