Superior trichloroethylene removal from water by sulfide-modified nanoscale zero-valent iron/graphene aerogel composite

Sulfide-modified nanoscale zero-valent iron (S-nZVI) is a promising material for removal of organic pollutants from water, but S-nZVI nanoparticles (NPs) easily agglomerate and have poor contact with organic contaminants. Herein, we propose a new S-nZVI/graphene aerogel (S-nZVI/GA) composite which exhibits superior removal capability for trichloroethylene (TCE) from water. Three-dimensional porous graphene aerogel (GA) can improve the efficiency of electron transport, enhance the adsorption of organic pollutants and restrain the agglomeration of the core-shell S-nZVI NPs. The TCE removal rates of FeS, nZVI, GA and S-nZVI were 27.8%, 42%, 63% and 75% in 2?hr, respectively. Furthermore, TCE was completely removed within 50?min by S-nZVI/GA. The TCE removal rate increased with increasing pH and temperature, and TCE removal followed the pseudo-first-order kinetic model. The results demonstrate the great potential of S-nZVI/GA composite as a low-cost, easily separated and superior monolithic adsorbent for removal of organic pollutants.     

微波法磷改性斜发沸石的结构及水中除砷的研究

采用固固相、固液相同晶取代对斜发沸石进行微波法磷改性，并对改性前后的矿样采用化学分析，XRD，^31P MAS NMR等手段表征。结果表明，虽然微波磷改性不能改变沸石单斜晶系的主体骨架结构，但由于脱Al，脱Si和P同晶取代，使晶胞体积收缩，结晶度下降，比表面积、孔体积明显减小，骨架中Si和Al的键合方式发生变化，有四配位硅的Si—O—P结构出现，该结构是沸石阴离子交换的结构基础。沸石去除水中砷的结果表明，改性前，沸石去除水中砷的能力很小，属表面物理吸附，改性后，沸石去除水中砷的能力明显增强，属阴离子交换。而且水介质的酸度和同晶取代方法对沸石除砷都有明显影响。     

Determination and analysis of sorption of 137Cs to soils in Hong Kong reservoir

Soils from a local reservoir had been analyzed for their physical and chemical properties, distribution coefficients Kd and sorption rates for 137Cs. It was found that soils in Hong Kong were relatively low in organic matter and more acidic than those in some other countries. In sorption experiments, the rates of decrease in water activity concentration were initially very high, higher for larger mass of soils added, and then slowed down. The larger the mass, the shorter was the time for equilibrium. Three isotherms had been obtained by varying one of the three parameters (initial water activity concentration, slurry ratio and particle size) at a time. For constant initial water activity concentration and random sizes, percent sorption increased with slurry ratio. For soils of constant mass and random sizes. percent sorption decreased with increasing initial water activity concentration. For constant initial water activity concentration and slurry ratio, percent sorption increased with decreasing size of soil particles. A simple logistic model was developed to explain some of the findings.     

黄土高塬沟壑区植被恢复对不同地貌部位土壤可蚀性的影响

通过采集不同地貌部位（塬面、塬坡和沟坡）各土地利用（农地、草地、灌木地和林地）坡面土壤和根系样品,采用综合土壤可蚀性指数（CSEI）评价了植被恢复对土壤可蚀性的影响。结果表明：（1）不同地貌部位的CSEI差异显著,沟坡CSEI较塬坡和塬面分别增加8.1%和77.7%。（2）塬面草地、灌木地和林地的CSEI较农地分别降低21.1%、29.2%和28.8%;而塬坡和沟坡林地CSEI均低于其他土地利用。（3）CSEI与粘粒含量、砂粒含量、毛管孔隙度、根重密度、根平均直径、根长密度及根表面积密度均呈极显著负相关,而与粉粒含量和土壤容重呈显著正相关关系;粉粒含量、土壤容重和根重密度是影响CSEI的关键因素,其中粉粒含量对CSEI的直接影响最大,而根重密度通过直接或间接作用对CSEI产生负相关影响。建议在塬面上以灌木作为植被恢复模式的首选,而在塬坡和沟坡上选择以乔木为优势群落的恢复模式对水土流失的控制更为有效。     

Land use change and soil carbon sequestration in China: Where does it pay to conserve?

Regional Environmental Change - This paper estimates the impact of land use change on soil organic carbon (SOC) sequestration in China from 1985 to 2005 using a nationwide, georeferenced database...     

豆腐柴叶蛋白营养及安全性研究

对以豆腐柴（Ｐｒｅｍｎａｍｉｃｒｏｐｈｅｌａ）叶为原料制作的叶“豆腐”的营养价值及安全性进行综合评价，为我国资源植物豆腐柴叶的开发提供可行性参考．     

Causes of the elevated nitrate aerosol levels during episodic days in Taichung urban area,Taiwan

The purpose of this study is to explore the possible reasons accounting for elevated nitrate aerosol levels during high particulate days (HPD) in Taichung urban area of central Taiwan. To achieve this goal, simultaneous measurements of particulate and gaseous pollutants were carried out from September 2004 to April 2005 using an annular denuder system (ADS). The formation rate of NO₂ to nitrate aerosol, calculated using the relevant chemical reactions, was employed to interpret enhanced nitrate aerosol concentrations during HPD. The observations showed that nitrate concentration during HPD was 14 times higher than that during low particulate days (LPD). The average formation rate during HPD was 4.0% h^?1, which was 3.1 times higher than that during LPD. The quantitative analysis showed that the formation rate was mainly influenced by temperature and relative humidity. Lower temperature and higher relative humidity led much nitrate aerosol formation in HPD. Moreover, the residence time analysis of air masses staying over the studied area showed that the slow-motion air retained high nitrate concentrations due to more nitrate aerosol converted from the precursors in NOx-rich areas.     

Effects of ethylene biosynthesis and signaling on oxidative stress and antioxidant defense system in Nelumbo nucifera G. under cadmium exposure

Environmental Science and Pollution Research - Water contamination with cadmium (Cd) is a global environmental problem and its remediation becomes urgent. Phytoremediation using ornamental plants...     

ZnAlFe类水滑石的制备及其吸磷性能的研究

用共沉淀法制备了系列锌铝铁类水滑石(LDH)并考察了LDH的吸磷性能.结果表明,n(Zn)∶n(A1)∶n(Fe)=2∶0.2∶0.8时,LDH对磷酸根的吸附能力最好.温度为30℃,初始pH值为6时,磷饱和吸附容量达51.81 mg/g.吸附前后LDH的XRD和FT-IR分析表明,LDH主要通过表面吸附、离子交换以及形成Zn3(PO4)2·4H2O层来实现磷酸根的去除.     

基于国际化大都市建设的西安产业结构优化研究

运用多元回归模型、产业结构偏离度模型和产业结构层次系数,对西安产业结构贡献度及合理化和高级化程度进行了定量分析,并将其与北京、上海的产业结构进行横向比较.结果表明,西安市经济总量不大,经济增长主要依靠第三产业;产业结构合理化趋势明显,产业结构高级化程度呈稳步上升态势,但与国际大都市仍存在较大差距.据此,提出产业结构优化调控对策.