Quantifying air pollution attenuation within urban parks: an experimental approach in Shanghai, China

Parks with various types of vegetations played an important role in ameliorating air quality in urban areas. However, the attenuation effect of urban vegetation on levels of air pollution was rarely been experimentally estimated. This study, using seasonal monitoring data of total suspended particles (TSP), sulfur dioxide (SO(2)) and nitrogen dioxide (NO(2)) from six parks in Pudong District, Shanghai, China, demonstrated vegetations in parks can remove large amount of airborne pollutants. In addition, crown volume coverage (CVC) was introduced to characterize vegetation conditions in parks and a mixed-effects model indicated that CVC and the pollution diffusion distance were key predictors influencing pollutants removal rate. Therefore, it could be estimated by regression analysis that in summer, urban vegetations in Pudong District could contribute to 9.1% of TSP removal, 5.3% of SO(2) and 2.6% of NO(2). The results could be considered for a better park planning and improving air quality.     

Removal of 2-chlorophenol from water using rice-straw derived ash

Removal of 2-chlorophenol from water using rice-straw derived ash (RSDA) was evaluated in this study to compare with commercial activated carbon. RSDA was obtained by burning rice-straw at 400 °C and 700 °C for 1 h. This ash can provide a better adsorbent for 2-chlorophenol. The adsorption capacities of RSDA at 400 °C and 700 °C are 37 and 52 mg g?1 at pH 4, respectively, and decrease to 9.0 and 40 mg g?1 at pH 10. Adsorption of either neutral or anionic 2-cholorphenol by the RSDA are shown as L-shaped nonlinear isotherms, suggesting surface adsorption rather than partitioning is occurring. At higher-burning temperatures, the surface area, porosity, point of zero charge and aromaticity of the resultant RSDA increase, but the oxygen content and surface acidity decrease. The combined effects result in a higher 2-chlorophenol adsorption of RSDA at 700 °C, which shows a slight pH effect on the adsorption of 2-chlorophenol, due to the lower content of oxygen-containing functional groups. Oxygen-containing functional groups contribute to surface acidity and H-bonding sites for adsorbed water, which compromises the interaction between 2-chlorophenol and the adsorbents. Thus, it suggests that rice-straw derived carbon (RSDC) can be used as an effective low-cost substitute material for activated carbon for removal of chlorophenols from wastewater.     

pH对生物质同步水解产酸的影响

采用香蒲枯叶作为发酵基质,考察了水生生物质在培养温度为(25.0±0.5)℃、pH为6～12下的水解产酸情况.结果表明:(1)实验末期(30 d),不同pH下香蒲枯叶中半纤维素降解率为28％～60％,比纤维素(19％～42％)和木质素(1％～46％)高.(2)在同一发酵时间内,发酵液总有机碳(TOC)、还原糖浓度总体随...     

三峡工程蓄水后荆江河段河势变化及生态护岸研究

三峡工程蓄水以来,进入长江中下游河道的水沙过程发生明显改变,从而导致中下游河道尤其是荆江河段冲刷、崩塌,局部河段河势调整较为剧烈,并导致主流顶冲部位发生变化,可能会引起新的崩岸发生。分析了荆江河段河势变化特点,列举了各种传统护岸方法,分析了传统护岸的特点和适用性,针对传统护岸工程的不足,提出生态护岸理念,在满足整体性、稳定性、适应变形等要求下,采取工程措施与植物措施共同护岸,并为河道与河岸之间水分交换提供条件,建立了水生生态系统和陆地生态系统之间的联系,实现了河流原本完整的结构和作为生态廊道的功能,进而保证整个生态系统的稳定,有利于生态环境的保护和水土保持,实现生态理念,满足生态需要,达到人与自然和谐发展。     

鸭绿江口及毗邻浅海沉积物重金属的分布特征与风险评价

采用重金属的富集系数和多金属污染度分析鸭绿江口及毗邻浅海沉积物重金属的分布特征.结果表明:鸭绿江口及毗邻浅海沉积物Cu、Hg和Cd属于重要的污染因子;多金属污染度高强度分布区与高含沙量区存在对应关系,但对重金属富集影响更大的是人类活动.采用潜在生态风险指数法与生物效应阈值浓度法2种评价方法进行研究区的生态风险评价,结果...     

林火烈度评价及其空间异质性研究进展

回顾了林火烈度评价的方法,包括单因素评价、综合评价和遥感技术的应用等;综述了林火烈度空间异质性的最新研究进展;展望了林火烈度及其空间异质性研究的未来发展趋势。     

基于投入产出法的中国出口产品隐含碳测算

使用投入产出法,利用1999 -2008年中国海关货物出口商品分类数据,研究和测算了中国出口商品中的隐含碳.研究结果显示,中国是隐含碳的出口大国,出口贸易是中国CO2排放量逐年增长的重要原因.1999 - 2008年,我国出口产品中的隐含碳由1999年的3.8亿t上升至2008年的11.9亿t,在此期间,中国CO2年排放量的12％ -24％是因生产满足国际市场消费的产品而产生的.中国出口产品中的隐含碳主要集中在5大类行业,分别为:纺织业及服装鞋帽制造业、化学医药制造业、黑色及有色金属冶炼和压延加工业、通用及专用机械设备、电气机械及器材制造业.这5大类行业的出口产品中的隐含碳在中国出口产品的隐含碳总量中占到80％左右.中国出口产品隐含碳的主要流向是美国、欧盟和日本.在实证研究结果的基础上,本文认为国际社会应从生产者负责制和消费者负责制相结合的角度界定各国的碳排放责任和减排目标;同时建议我国应提高生产技术,降低产品的能源消耗强度,并限制能源密集型产业产品的出口.     

母亲,在太阳里

我最早的一张照片是站在母亲身旁照的。母亲抱着四弟,我穿着有褶皱的棉袍,一只袖口露着镯子,一只手搭在母亲的腿上,面部表情凝重而又满足,显得对母亲十分依恋。母亲穿着带有暗花的夹袍,留着披肩长发,面带微笑。幼年的我,脸庞十分像母亲。这张照片应拍摄于1944年早春,当时我三岁多。     

不同瓦斯压力下煤体力学特性试验研究

为研究瓦斯对煤体力学特性的影响,设计不同瓦斯压力条件下煤体单轴压缩试验,研究煤样力学参数及变形特征随瓦斯压力的变化趋势,探讨瓦斯对煤体力学性质的影响机制,得出单轴压缩下煤样力学参数,并记录煤样的破坏形态.研究结果表明:随瓦斯压力增大,应力-应变曲线压实阶段增大,弹性阶段缩小,失稳破坏后曲线缓慢下降,抗压强度和弹性模量单...     

Crystallization and Mechanical Properties of Recycled Poly(ethylene terephthalate) Toughened by Styrene–Ethylene/Butylenes–Styrene Elastomer

Recycled poly(ethylene terephthalate) (R-PET) was blended with 15–30 wt% of styrene–ethylene/butylenes–styrene (SEBS) block copolymer and maleic anhydride grafted SEBS (SEBS-g-MA). Effects of nucleation and toughening of the elastomers were evaluated systematically by study of morphology, crystallization, thermal and mechanical properties of the blend. The addition of 30 wt% SEBS promoted the formation of co-continuous structure of the blend and caused the fracture mechanism to change from strain softening to strain hardening. Addition of SEBS-g-MA resulted in significant modification of phase morphology and obviously improved the impact strength. The compatibilization reaction of PET with SEBS-g-MA accelerated the crystallization of PET and increased the crystallinity. The shifts in glass transition temperature of PET towards that of SEBS-g-MA and the higher modulus for R-PET/SEBS-g-MA (70/30) blend found by DMA are also indications of better interactions under the conditions of compatibilization and interpenetrating structure.