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991.
Qingrong Qian Motoi Machida Masami Aikawa Hideki Tatsumoto 《Journal of Material Cycles and Waste Management》2008,10(1):53-61
Activated carbons were prepared from cattle manure compost (CMC) by ZnCl2 activation with various ZnCl2/CMC mass ratios. Based on the N2 adsorption-desorption isotherms, mathematical models including the Dubinin-Radushkevich (DR) equation, the αs plot, and the Horvath-Kawazoe method were used to analyze the pore structural characteristics of the prepared activated carbons.
It was found that for carbons possessing both micro-and mesopores, the DR method provided a more accurate estimation than
the αs method for the extent of microporosity. The effect of the ZnCl2 impregnation ratio on the pore structure was discussed using the DR method. The results revealed that pore evolution involved
three distinct regions with increases in the amount of impregnated ZnCl2: raising the ZnCl2/CMC mass ratio from 0.00 to 0.50 resulted in a 19-fold increase in micropore volume (Vme
D) but caused no change in the mesopore volume (Vme
D); increasing the ZnCl2/CMC mass ratio from 0.50 to 1.00 led to an increment in Vmi
D of about 50% and in Vme
D of 170%; while raising the ratio from 1.50 to 2.50 caused a slight decrease in Vmi
D but a 200% increment in the value of Vme
D. 相似文献
992.
993.
郭英杰 《中国环境管理干部学院学报》2008,18(3)
从秦皇岛市海港区城市游憩绿地存在的空间分布不均匀、设计不完善、疏于管理、服务设施不足等问题出发,提出了从宏观调控、游憩绿地设计、管理、法制、可持续发展和建设投入角度发展海港区城市游憩绿地的对策,从而提高城市人居环境质量,充分发挥城市游憩绿地系统在整个城市绿地系统中的重要地位。 相似文献
994.
Yanhui Wang Pengtao Yu Wei Xiong Zhenxi Shen Mingchun Guo Zhongjie Shi Apeng Du Liangmin Wang 《Journal of the American Water Resources Association》2008,44(5):1086-1097
Abstract: The increase of coverage of forest/vegetation is imperative to improve the environment in dry‐land areas of China, especially for protecting soil against serious erosion and sandstorms. However, inherent severe water shortages, drought stresses, and increasing water use competition greatly restrict the reforestation. Notably, the water‐yield reduction after afforestation generates intense debate about the correct approach to afforestation and forest management in dry‐land areas. However, most studies on water‐yield reduction of forests have been at catchment scales, and there are few studies of the response of total evapotranspiration (ET) and its partitioning to vegetation structure change. This motivates us to learn the linkage between hydrological processes and vegetation structure in slope ecosystems. Therefore, an ecohydrological study was carried out by measuring the individual items of water balance on sloping plots covered by different vegetation types in the semiarid Liupan Mountains of northwest China. The ratio of precipitation consumed as ET was about 60% for grassland, 93% for shrubs, and >95% for forestland. Thus, the water yield was very low, site‐specific, and sensitive to vegetation change. Conversion of grassland to forest decreased the annual water yield from slope by 50‐100 mm. In certain periods, the plantations at lower slopes even consumed the runon from upper slopes. Reducing the density of forests and shrubs by thinning was not an efficient approach to minimize water use. Leaf area index was a better indicator than plant density to relate ET to vegetation structure and to evaluate the soil water carrying capacity for vegetation (i.e., the maximum amount of vegetation that can be supported by the available soil water for an extended time). Selecting proper vegetation types and plant species, based on site soil water condition, may be more effective than the forest density regulation to minimize water‐yield reduction by vegetation coverage increase and notably by reforestation. Finally, the focuses in future research to improve the forest‐water relations in dry‐land areas are recommended as follows: vegetation growth dynamics driven by environment especially water conditions, coupling of ecological and hydrological processes, further development of distributed ecohydrological models, quantitative relation of eco‐water quota of ecosystems with vegetation structures, multi‐scaled evaluation of soil water carrying capacity for vegetation, and the development of widely applicable decision support tools. 相似文献
995.
Bioaccumulation and physiological effects of tetrabromobisphenol A in coontail Ceratophyllum demersum L 总被引:2,自引:0,他引:2
Tetrabromobisphenol A (TBBPA) is one of the most widely used brominated flame retardants. In the present study, the accumulation of TBBPA and its consequent biological responses were examined in coontail (Ceratophyllum demersum L.) over 14 days' exposure. Most of the TBBPA was accumulated after 4d exposure and TBBPA concentration in plant increased with increasing TBBPA concentration in growth solution (R(2)=0.99). By using electron paramagnetic resonance (EPR), we found that the TBBPA exposure significantly increased total free radicals generation in the plants. A good positive relationship (R(2)=0.99) was found between the free radicals formation and accumulation level of TBBPA in plant. Lipid peroxidation was enhanced and chlorophyll content showed declined after TBBPA exposure. The activities of superoxide dismutase (SOD), peroxidase (POD), and the contents of glutathione were also detected. The results suggest that TBBPA accumulation in C. demersum induces oxidative stress and the level of tolerance depends on the antioxidative capacity of the plants. 相似文献
996.
997.
成都市生态城市建设的路径设计 总被引:5,自引:0,他引:5
文章结合成都市自然资源的优势和特点,依据生态原理的基本思想,从城市河流生态的保护与建设;成都绿化的生态建设与城市生态社区示范建设;城乡融合生态系统的基本设计;成都郊县市生态农业、生态聚落的建设和生态建设总体布局与功能分区等五个方面进行了具体的分析,提出了相关的设计路径和措施。 相似文献
998.
Evaluating Controlling Factors to Ali/(Ca + Mg) Molar Ratio in Acidic Soil Water, Southern and Southwestern China: Multivariate Approach 总被引:2,自引:0,他引:2
Guo JH Zhang XS Vogt RD Xiao JS Zhao DW Xiang RJ Luo JH 《Environmental monitoring and assessment》2007,129(1-3):321-329
Ali/(Ca + Mg) molar ratio in soil water has been used as an indicator to the effects of acid deposition on terrestrial ecosystems.
However, the main factors controlling this ratio have not been well documented in southern and southwestern China. In this
study, we presented the variation in inorganic aluminum (Ali) and Ali/(Ca + Mg) molar ratio in different sites and soil horizons based on two to three years monitoring data, and evaluated the
main factors controlling Ali/(Ca + Mg) molar ratio using principle component analysis (PCA) and partial least square (PLS) regression. Monitoring data
showed although Ali/(Ca + Mg) molar ratios in most soil water were lower than assumed critical 1.0, higher molar ratios were found in some soil
water at TSP and LXH site. Besides acid loading, both soil properties and soil water chemistry affected the value of Ali/(Ca + Mg) molar ratio in soil water. Partial least square (PLS) indicated that they had different relative importance in
different soil horizons. In A-horizon, soil aluminum saturation (AlS) had higher influence on Ali/(Ca + Mg) molar ratio than soil water chemistry did; higher soil aluminum saturation (AlS) led to higher Ali/(Ca + Mg) molar ratio in soil water. In the deeper horizons (i.e., B1-, B2- and BC-horizon), inorganic aluminum (Ali) in soil water had more and more important role in regulating Ali/(Ca + Mg) molar ratio. On regional scale, soil aluminum saturation (AlS) as well as cation exchange capacity (CEC) was the
dominant factor controlling Ali/(Ca + Mg) molar ratio. This should be paid enough attention on when making regional acid rain control policy in China. 相似文献
999.
Fourteen surface sediment samples were collected from Lanzhou Reach of Yellow River, China in July 2005. The concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs) were determined by gas chromatography equipped with a mass spectrometry detector (GC-MS). Total concentrations of the PAHs ranged from 464 to 2621 ng/g dry weight. Sediment samples with the highest PAH concentrations appeared at the downstream of Lanzhou City, where there was the biggest wastewater discharge pipeline from Lanzhou Oil Refinery Factory and Lanzhou Chemical Industry Company. Municipal sewage also contributed to the PAH contamination in the sediments. A correlation existed between the sediment organic carbon content (f(oc)) and the total PAH concentrations (r(2)=0.57), suggesting that sediment organic carbon content played an important role in controlling the PAHs levels in the sediments. According to the observed molecular indices, PAHs contamination in Lanzhou Reach of Yellow River originated both from the high-temperature pyrolytic processes and from the petrogenic source, showing a mixed PAH input pattern, which was also confirmed by the results of a principal component analysis (PCA). According to the numerical effect-based sediment quality guidelines (SQGs) of the United States, the levels of PAHs at most studied sites in Lanzhou Reach of Yellow River should not exert adverse biological effects. Although at some sites (such as S10, S12, etc.) one PAH may exceed the effects range low (ERL), individual PAH did not exceed the effects range median (ERM). The results indicated that sediments in all sites should have potential biological impact, but should have no impairment. 相似文献
1000.