The environmental impacts of regional disparity in population and wealth distribution in Nigeria

The disparity in both population and wealth distribution in Nigeria by geo-political zones is well recognized. There is also the recognition that some of the environmental problems in certain sections of the country can be attributed to the imbalance in both population and wealth distribution. Hence the various agitations for environmental resource control in the country. What is lacking however is the research that shows the magnitude of the linkages between the disparity and the environmental degradation in regional context. This provides the basis for this research. To achieve the aim of the research, a STIRPAT model was employed as an analytical tool. The findings show that the southern geopolitical zones are generally more densely populated and wealthier than the northern zones. The south is also experiencing a higher degree of environmental resource degradation attributable to anthropogenic factors. Thus, there is congruence between population density, wealth distribution and environmental degradation in Nigeria. Therefore the achievement of sustainable environment and development in Nigeria requires deliberate policies to mitigate the impact of population concentration and wealth creation on the environment. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

H4SiW12O40/TiO2/beads光催化降解亚甲基蓝的研究

以钛酸四丁酯为原料,空心微珠为载体,采用溶胶-凝胶法制备TiO2/beads光催化剂载体,然后浸渍法制备出H4SiW12O40/TiO2/beads表面负载修饰型复合光催化剂,并运用SEM、XRD、FT-IR和DRS对催化剂进行表征和分析。研究了H4SiW12O40/TiO2/beads对亚甲基蓝降解的光催化活性,考察了光强度、pH值、曝气量、底物浓度和催化剂用量等对催化效率的影响。实验结果表明,在中性条件下,H4SiW12O40/TiO2/beads催化剂的投加量为0.25 g/L,浓度为7.5 mg/L的亚甲基蓝溶液在250 W的紫外灯和600 W的可见光灯下光照60 min降解率分别可达到94.5%和55%。     

Photocatalytic degradation of NOx in a pilot street canyon configuration using TiO2-mortar panels

Titanium dioxide is the most important photocatalysts used for purifying applications. If a TiO₂- containing material is left outdoors as a form of flat panels, it is activated by sunlight to remove harmful NOx gases during the day. The photocatalytic efficiency of a TiO₂-treated mortar for removal of NOx was investigated in the frame of this work. For this purpose a fully equipped monitoring system was designed at a pilot site. This system allows the in situ evaluation of the de-polluting properties of a photocatalytic material by taking into account the climatologic phenomena in street canyons, accurate measurements of pollution level and full registration of meteorological data The pilot site involved three artificial canyon streets, a pollution source, continuous NOx measurements inside the canyons and the source as well as background and meteorological measurements. Significant differences on the NOx concentration level were observed between the TiO₂ treated and the reference canyon. NOx values in TiO₂ canyon were 36.7 to 82.0% lower than the ones observed in the reference one. Data arising from this study could be used to assess the impact of the photocatalytic material on the purification of the urban environment.     

武汉市九峰城市森林保护区景观敏感度评价

为合理开展森林景观的规划与建设，应用RS和GIS技术，并结合小班调查，对武汉市九峰城市森林保护区的景观生态敏感度和景观视觉敏感度进行了研究。结果表明：在武汉市九峰城市森林保护区中，高生态敏感区面积占总面积的4.6％，主要包括荒山、废弃采石场和少量灌木林地，应尽快进行生态恢复。中生态敏感区面积占总面积的535％，主要为水域、农田、部分苗圃和建设用地，可重点开展森林植被恢复和景观建设。低生态敏感区面积占总面积的419％，主要是森林覆盖区域、部分苗圃和居民点，应重点加强保护。一级视觉敏感区主要分布在沿道路两侧坡度大于20°的近景带，应以保护和生态恢复措施为主。二级视觉敏感区主要是坡度较小的近景带和山体的中、远景带区域，可视性强，应重点开展景观改造。三级视觉敏感区主要是中、远景带中的平坦地带，包括农田、苗圃、居民点等半自然景观和人文景观，可在不影响整体风貌和视觉环境的前提下进行景观建设。四级视觉敏感区为不可见区域或低可见区域，坡度大，可及性差，不宜规划建设项目。     

Land Degradation Evaluation in North Hebei Province Based on Remote Sensing and GIS

Abstract

Land degradation is one of the serious environmental problems that can lead to poverty, and is especially prominent in eco-fragile areas in developing countries and increases the risk of environmental safety. North Hebei Province belongs to an ecologically fragile region in North China, which has great impact on the eco-safety of Beijing and Tianjin. Using Landsat TM data and GIS, this paper evaluates land degradation in North Hebei province of China from the the 1960's to 1987 and 2000. Land use/cover change pattern from 1987 to 2000, its regional difference and forest change characteristics will also be analyzed; soil erosion intensity and arable land suitability were also evaluated. Results revealed that land use/cover pattern in this study area did not change greatly from 1987 to 2000. The structure and function of regional land ecosystem was at a level of local improvement and integral deterioration. Land above medium soil erosion intensity reached 21 percent, which was also the area with a serious soil erosion and land degradation problem. Soil erosion and land degradation intensity of grassland was the biggest. For the present arable land, the proportion of high suitability was 13 percent.     

Dechlorination of carbon tetrachloride by the catalyzed Fe-Cu process

The electrochemical reduction characteristics of carbon tetrachloride (CT) were investigated using cyclic voltammetry in this study. In addition, the difference in reduction mechanisms of CT between Master Builders' iron and the catalyzed Fe-Cu process was discussed. The results showed that CT was reduced directly on the surface of copper rather than by atomic hydrogen produced at the cathode in the catalyzed Fe-Cu process. The reduction was realized largely by atomic hydrogen in Master Builders' iron. The entire CT in 350 ml aqueous solution with 320 mgL was reduced to trichloromethane and dichloromethane in 2.25 h when 100 g of scrap iron with FeCu ratio of 10:1 (ww) were used. Moreover, the reduction rate slowed with time. CT could be reduced at acidic, neutral and alkaline pH from solution by Fe-Cu bimetallic media, but the mechanisms were di?erent. The degradation rate was not significantly in?uenced by pH in the catalyzed Fe-Cu process; in Master Builders' iron it clearly increased with decreasing pH. The kinetics of the reductions followed pseudo-first order in both cases. Furthermore, the reductions under acidic conditions proceeded faster than that under the neutral and alkaline conditions. The catalyzed Fe-Cu process was superior to Master Builders' iron in treating CT-containing water and this advantage was particularly noticeable under alkaline conditions. The reduction was investigated in the cathode (Cu) and anode (Fe) compartments respectively, the results showed that the direct reduction pathway played an important role in the reduction by the catalyzed Fe-Cu process. The catalyzed Fe-Cu process is of practical value.     

Degradation of MTBE and TBA by a new isolate from MTBE-contaminated soil

Methyl ten-butyl ether （MTBE）, a gasoline additive, possesses serious problems to the environmental health. In the present study, a bacterial culture named A-3 which could effectively degrade MTBE was isolated from the MTBE contaminated soil. The isolate was identified as Chryseobacterium sp., a new species capable of degrading MTBE. In order to enhance its degradation ability, selected environment factors were investigated. The results showed that the optimal temperature was in the range of 25-30℃, the pH was 7.0, the inoculum size was 2 × 10^8 CFU/ml and the optimal concentration of MTBE was from 50 to 100 mg/L. The maximum MTBE utilization rate （Vmax） was 102 nmol MTBE/（mg cell protein.h）. Furthermore, it was found that the isolate could also degrade tert-butyl alcohol （TBA）. The degradation rates of TBA were much faster than those of MTBE. The additional TBA would lead to the decrease of the initial MTBE degradation rate and the inhibitory effect of TBA increased with the increase of TBA concentration. Similar protein profiles at least seven peptides were demonstrated after SDS-PAGE analysis of crude extracts obtained from the cells growing in MTBE and TBA culture.     

Effect of copper on the degradation of pesticides cypermethrin and cyhalothrin

The influence of coexisting copper (Cu) ion on the degradation of pesticides pyrethroid cypermethrin and cyhalothrin in soil and photodegradation in water system were studied.Serial concentrations of the pesticides with the addition of copper ion were spiked in the soil and incubated for a regular period of time,the analysis of the extracts from the soil was carried out using gas chromatography (GC).The photodegradation of pyrethroids in water system was conducted under UV irradiation.The effect of Cu~(2 ) on the pesticides degradation was measured with half life (t_(0.5)) of degradation.It was found that a negative correlation between the degradation of the pyrethroid pesticides in soil and Cu addition was observed.But Cu~(2 ) could accelerate photodegradation of the pyrethroids in water.The t_(0.5) for cyhalothrin extended from 6.7 to 6.8 d while for cypermethrin extended from 8.1 to 10.9 d with the presence of copper ion in soil.As for photodegradation,t_(0.5) for cyhalothrin reduced from 173.3 to 115.5 rain and for cypermethrin from 115.5 to 99.0 min.The results suggested that copper influenced the degradation of the pesticides in soil by affecting the activity of microorganisms.However, it had catalyst tendency for photodegradation in water system.The difference for the degradation efficiency of pyrethroid isomers in soil was also observed.Copper could obviously accelerate the degradation of some special isomers.     

Biodegradation of methyl parathion by Acinetobacter radioresistens USTB-04

Biodegradation of methyl parathion (MP),a widely used organophosphorus pesticide,was investigated using a newly isolated bacterium strain Acinetobacter radioresistens USTB-04.MP at an initial concentration of 1200 mg/L could be totally biodegraded by A.radioresistens USTB-04 as the sole carbon source less than 4 d in the presence of phosphate and urea as phosphorus and nitrogen sources,respectively.Biodegradation of MP was also achieved using cell-free extract of A.radioresistens USTB-04.MP at an initial concentration of 130 mg/L was completely biodegraded in 2 h in the presence of cell-free extract with a protein concentration of 148.0 mg/L,which was increased with the increase of pH from 5.0 to 8.0.Contrary to published reports,no intermediate or final degradation metabolites of MP could be observed.Thus we suggest that the cleavage of C--C bond on the benzene ring other than P-O bond may be the biodegradation pathway of MP by A.radioresistens USTB-04.     

电梯门机智能维护系统的研究进展

探讨了研发电梯门机智能维护系统的必要性和实际意义,介绍国外在门机智能维护领域的研究进展,从理论和技术方面论述该系统的整体流程和涉及到的重要模块和硬件平台,最后指出电梯门机智能维护系统主要的研究方向并建议国内学者对该系统进行更深入的研究。