Strategies to combat desertification for the twenty-first century in China

SUMMARY

During the past half century, China has experienced increasingly severe land degradation, soil erosion, and desert expansion. Desertification is affecting one third of China's total territory and the annual accelerating rate of desertification spread is as high as 2460 km² in China. In 1996, China developed a National Action Programme to Combat Desertification (NAP), which is aimed to apply new legal measures and technical approaches to slow down desertification processes and achieve a long-term goal — control desertification and alleviate poverty through continuous efforts to fight against desertification, stabilize mobile dunes, revegetate degraded rangeland and control soil erosion in arid, semi-arid, and dry sub-humid areas. The long-term and integrated strategies of China's NAP result in encouragement of social participation, legal institutional guarantees, policy making, and establishment of demonstrations/pilot projects to combat desertification at both national and provincial level.     

Similarities and differences of metal distributions in the tissues of molluscs by using multivariate analyses

Multivariate analysis including correlation, multiple stepwise linear regression, and cluster analyses were applied to investigate the heavy metal concentrations (Cd, Cu, Fe, Ni, Pb, and Zn) in the different parts of bivalves and gastropods. It was also aimed to distinguish statistically the differences between the marine bivalves and the gastropods with regards to the accumulation of heavy metals in the different tissues. The different parts of four species of bivalves and four species of gastropods were obtained and analyzed for heavy metals. The multivariate analyses were then applied on the data. From the multivariate analyses conducted, there were correlations found between the soft tissues of bivalves and gastropods, but none was found between the shells and the soft tissues of most of the molluscs (except for Cerithidea obtusa and Puglina cochlidium). The significant correlations (P < 0.05) found between the soft tissues were further complemented by the multiple stepwise linear regressions where heavy metals in the total soft tissues were influenced by the accumulation in the different types of soft tissues. The present study found that the distributions of heavy metals in the different parts of molluscs were related to their feeding habits and living habitats. The statistical approaches proposed in this study are recommended for use in biomonitoring studies, since multivariate analyses can reduce the cost and time involved in identifying an effective tissue to monitor the heavy metal(s) bioavailability and contamination in tropical coastal waters.     

Cu-Mn-Ce ternary mixed-oxide catalysts for catalytic combustion of toluene

Cu–Mn, Cu–Mn–Ce, and Cu–Ce mixed-oxide catalysts were prepared by a citric acid sol–gel method and then characterized by XRD, BET, H_2-TPR and XPS analyses. Their catalytic properties were investigated in the toluene combustion reaction. Results showed that the Cu–Mn–Ce ternary mixed-oxide catalyst with 1:2:4 mole ratios had the highest catalytic activity, and 99% toluene conversion was achieved at temperatures below 220°C. In the Cu–Mn–Ce catalyst, a portion of Cu and Mn species entered into the Ce O_2 fluorite lattice, which led to the formation of a ceria-based solid solution. Excess Cu and Mn oxides existed on the surface of the ceria-based solid solution. The coexistence of Cu–Mn mixed oxides and the ceria-based solid solution resulted in a better synergetic interaction than the Cu–Mn and Cu–Ce catalysts, which promoted catalyst reducibility, increased oxygen mobility, and enhanced the formation of abundant active oxygen species.     

独立学院教学中的四忌

独立学院的学生与母体高校学生相比有一定的特殊性。独立学院的教学如若完全沿用母体高校的方法和要求，势必会出现一些问题和矛盾。为此，在独立学院教学中，教师应注意四忌。     

高铁酸盐氧化絮凝去除含油污水中的油

油田产出的油、水经分离后会产生大量的含油污水,选用高铁酸钾对污水进行处理已成为人们关注的一个问题。用荧光比色法测定非均相固-液悬浮体系中油含量的实验证明:(1)高铁酸盐在含油污水中的初始反应速度快,可将大部分有机物氧化;(2)氧化法处理含油污水受多种因素的影响;(3)高铁直接氧化和芬顿氧化法均可比较彻底地处理油田含油污水。用高铁氧化法处理含油污水技术上很有发展前景,各种浓度的污水经处理后都可达到国家排放标准。     

Seasonal Variation of Chemical Composition in Fine Particles at Gosan, Korea

PM_2.5 aerosol samples were collected at Gosan in Jeju Island during six intensive measurement periods between November 2001 and August 2003. In order to investigate the chemical composition of fine particles, major ion components, trace elements, and elemental and organic carbon were analyzed. Quite different seasonal characteristic in the chemical composition of fine particles was observed. The concentration of most secondary aerosol components showed a summer minimum and a winter maximum with higher correlation between them at Gosan. This fact clearly reveals the possibility of long-range transport of such pollutants in winter. On the other hand, OC and EC had the highest concentration and good correlation with ion components, such as K⁺, Ca²⁺ in fall. It means that biomass burning could significantly influence the ambient fine carbonaceous particulate in fall, which was primarily long-range transported.     

参数化绘图系统的开发与应用

探讨了参数化绘图系统开发的基本算法、功能和要求及开发步骤,简单介绍了国内外参数化CAD的应用情况。     

UASB处理离子交换树脂生产废水的试验研究

本研究主要介绍，尝试采用UASB（Upflow Anaerobic Sludge Bed）反应器厌氧工艺处理某离子交换树脂生产废水试验。研究表明，在中温（37℃±1）环境下，容积负荷在6．0-7．0kgCODcr·m^-3·d^-1时，CODcr去除率维持在80％左右，运行稳定。本试验取得的试验效果，为以后的利用厌氧技术处理离子交换树脂生产废水提供了重要依据。     

催化臭氧氧化法处理甲醛废水

用异丙醇钛盐表面改性法制备TiO2／SiO2催化剂，对甲醛废水进行催化臭氧氧化处理。通过比表面积的BET测定法、X射线衍射和拉曼光谱等分析方法对TiO2／SiO2催化剂进行了表征，考察了TiO2／SiO2催化剂加入量、臭氧流量及溶液pH等因素对甲醛催化臭氧氧化效果的影响。实验结果表明，在SiO2表面，TiO2微晶粒子以锐钛矿型高度分散；在甲醛质量浓度700mg／L、COD1000mg／L、TiO2／SiO2催化剂加入量2．0g、臭氧流量2．5mg／min、溶液pH8．5的条件下，催化臭氧氧化反应30min后，甲醛质量浓度由700mg／L降至39mg／L，COD去除率认到87．5％．