汉江水质优于长江的原因刍议

简述汉江水质总体优于长江水质这一自然现象，分析产生这一现象的原因。认为其原因极可能是由两江的地质构造、土壤化学成份、河道坡度、河面宽度等的不同而引起。人类可用环境水利工程改造河流，使河流自然地为人类“制造”洁净饮水，从而克服现有净化处理技术在净化微污染水方面的局限。     

县(市)域可持续发展的拓荒之作--评陈烈教授等新作《广州增城市域可持续发展研究》

陈烈教授是我国著名的区域可持续发展研究与规划专家，从80年代初期就开始关注县(市)域的发展研究与规划问题，在多年的实践中，摸索了一套比较系统的研究模式，并取得了丰硕的成果。尤其是在广东省，许多成果因与珠江三角洲的超常规发展相联系而载入史册，现在又走出省界和国门，在北部湾沿岸，在三湘四水之问，展露他的才华。     

我国湿地保护的法律思考

湿地是一种不同于陆地和海洋的特殊生态系统，具有重大的经济、生态和教育价值。长期以来，我国对湿地的价值认识不足，对湿地过度地开发利用，也未进行有效的保护，使之遭到了前所未有的破坏。我国对湿地保护的法律规范多散见于其他相关的法律法规之中。没有一部专门的法律规范对其进行调整，与我国严峻的湿地保护形势不相适应。本文针对我国湿地保护法律制度中存在的问题，提出了完善我国湿地保护的若干法律构想。     

承载力:从静态到动态的转变

承载力的概念来自于生态学领域。随着该概念应用范围的拓展，尤其在人类活动对环境影响中的应用，被赋予了不同的内涵，在国际学术界引起广泛的争议，不仅生物学家、生态学家对其提出质疑，而且生态经济学家和主流经济学家也在一些与之相关的观点上存在着严重的分歧。本文试图从承载力的起源、内涵的演变、存在的缺陷和定量的测度等方面对其进行刻划，同时揭示了国际上有关承载力研究的进展。     

试论我国煤矿区生态环境现状及综合整治战略

本文分析了我国煤矿区生态环境现状，并对之进行了分类，指出了当前我国煤矿区生态环境境保护工作中存在的主要问题，提出了我国煤矿区生态环境综合整治战略。     

广东省土地资源可持续利用评价研究

基于广东省城市化进程中土地资源利用之特点，利用熵权技术和线性加成技术建立了广东省土地资源可持续利用的评价体系，并对广东省1992～2002年期间土地利用的基本状况进行了实证分析，研究表明：广东省土地资源利用状况从总体上看是趋好的，在经历了1992～1995年的弱可持续之后，目前已进入良性发展阶段，其经济指标和社会指标均处于良好发展势头．但资源和环境指标在2000年后呈明显下滑趋势。这应该引起政府及有关部门高度重视。     

都市圈化:一种新型的中国城市化战略

在我国城市化的理论和实践基础上。提出了一个可持续的城市化模式——都市圈化。并对其内涵和外延进行归纳，进而将中国三大都市圈与日本的都市圈进行比较。结论是：中国沿海地区的都市圈化。既适应世界潮流，又符合中国国情。还能实现国家和区域的人口-经济-生态的平衡。都市圈化的推行。将在中国沿海地区形成以三大都市圈为核心的长达数千公里的人口高度聚集的沿海城镇密集地区。成为新时期我国国家竞争战略的支撑点。并将在一定程度上消弭城乡之闻、沿海与内地之闻的体制鸿沟和贫富鸿沟。     

可再生资源非线性收获的策略研究

本文运用非线性理论建立了可再生资源二次非线性收获的动力摸式。研究结果表明：为了保证可再生资源的可持缓利用、收获，必须把收获强度控制在一定的水平上，我们因此可以得到持续的最大产量。我们发现虽然对可再生资源的收获策略有线性和非线性之分，但是得到的可再生资源的最大持续收获量是相同的。因此，我们必须采用合理的可再生资源收获策略。避免可再生资源的过度利用和枯竭。我国可再生资源十分短缺，需正确处理好经济发展与可再生资源保护之问的关系，保护好我国珍贵的可再生资源对于我国的可持续发展具有重大的现实意义。     

大城市旧城住区可持续发展研讨会在武汉市召开

随着我国经济的飞速发展，城市化步伐不断加快，许多具有优秀历史建筑及文化遗产的大城市在发展过程中面临着严峻的考验，如何实现大城市旧城区的城市建设与历史文化遗产保护之间的协调和可持续发展越来越成为人们所关注的问题。为了探索如何进一步提高我国城市旧城住区规划与建设能力，保护历史文化遗产，改善社区弱势群体的居住环境质量，学习欧盟国家的先进经验，促进我国大城市旧城住区的可持续发展，     

推进我国可持续消费政策探析

2003年，我国的能源供应已全面吃紧，全国化学需氧量和二氧化硫排放量已超出环境容量，且二氧化硫排放量与国内生产总值显现出9％的同一增长速度。据估算，水污染造成的经济损失相当于GDP1．5％～3％，空气污染导致的公众健康和环境损害可能占GDP的7％。当前资源和环境的瓶颈约束加剧及现阶段我国经济持续高速增长态势使得经济增长方式上存在的高投入、高消耗、高排放、低效率等问题日益突显，可持续发展实现难度很大。     

Chemical pollution: Transfer of chemical elements to the aboverground phytomass of herbaceous plants

Changes in the species composition and a decrease in species diversity and total plant biomass along the gradient of soil pollution with heavy metals have been shown. Data on the concentrations of chemical elements (Zn, Cu, Cd, Pb, Co, Ni, Mn, Cr, and Fe) in the aboveground organs of herbaceous plants and the biomass of each species make it possible to estimate the role of higher producers in the incorporation of chemical elements into biogenic cycles in background zones and under conditions of chemical pollution. Plants of the composite family (Asteraceae) play the main role in accumulation of chemical elements. The results obtained indicate that natural ecosystems have mechanisms limiting excessive accumulation of chemical elements into the aboveground plant biomass.     

Chemical composition of water conditioned by crowdedMoina macrocopa (Crustacea: Cladocera)

The chemical composition of water conditioned by colonies ofMoina macrocopa and involved in the regulation of their life cycle was analyzed in comparison with water samples from natural water bodies. Dechlorinated tap water was used as the control medium. The results showed that metabolism of crustaceans leads to an increase in the concentrations of phosphorus and nitrogen in all forms, the appearance of protein and carbohydrate fractions, and changes in the composition of lipid fractions in the water conditioned by their colonies. The contents of all organic components are very low, which makes their identification difficult. Concentrations of substances identified in the conditioned water do not exceed those occurring in nature.     

Changes in the upper limits of tree species distribution in the Western Caucasus (Belaya River basin) related to recent climate warming

To estimate the response of tree vegetation to recent climate warming in the Western Caucasus, the population state of several tree species at the upper limit of their distribution has been estimated in three mountain massifs in the Belaya River basin. For this purpose, the average and maximum stem diameters, vitality, and age of trees have been determined in the transitional zone between middle-mountain and high-mountain beech-fir forests (1400–1700 m a.s.l.) and in crooked birch forests growing at the upper timberline (1810–2025 m). The upper limits of Acer platanoides, A. pseudoplatanus, Ulmus glabra, and Betula litwinowii have shown a tendency to rise. The upper limit of Abies nordmanniana has remained unchanged over the past few decades, which may be explained by a decrease in moisture supply during the warm season.     

石油短缺与中国经济安全

石油短缺已经成为引起中国能源危机最核心的问题,本文分析了中国石油短缺的背景及其影响因素,在实证分析的基础上,提出了“对石油依赖程度”这一概念。本文还把石油短缺与经济安全问题联系了起来,并提出了确保我国经济安全的具体对策。     

Performance studies of a low heat rejection engine operated on non-volatile vegetable oils with exhaust gas recirculation

During recent decades, considerable effort has been expended world-wide to reduce dependency on petroleum fuels for power generation and transportation through the search for suitable alternative fuels that are environmentally friendly. In this respect, vegetable oils are a promising alternative to diesel fuel. However, the high viscosity, poor volatility and cold flow characteristics of vegetable oils can cause some problems such as injector coking, severe engine deposits, filter gumming and piston ring sticking and thickening of lubrication from long-term use in diesel engines. These problems can be eliminated or minimised by transesterification of the vegetable oils to form monoesters. Although transesterification improves the fuel properties of vegetable oil, the viscosity and volatility of biodiesel are still worse than those of petroleum diesel fuel. The performance of a diesel engine with such biodiesel operation can be improved further with the concept of the low heat rejection (LHR) engine. In the LHR engine, combustion surfaces on the pistons, cylinder walls and valves can be coated with ceramic materials. The objective of this study was to apply the LHR engine concept for improving engine performance when either honge biodiesel, known as honge oil methyl ester (HOME), or neem biodiesel, known as neem oil methyl ester (NOME) oils was used as an alternative fuel. For this purpose, experiments were conducted on a single cylinder, four-stroke, direct injection, water-cooled compression ignition engine using diesel, HOME and NOME oils at different injection timings of 19, 23 and 27° before top dead centre (BTDC) with and without the induction of exhaust gas recirculation (EGR). The percentage of EGR was varied from 5 to 20% in steps of 5%. The results showed that specific fuel consumption and brake thermal efficiency were improved for both of the biodiesel fuels in the LHR engine. An EGR of 10% resulted in better performance with trade-off between oxides of nitrogen and hydrocarbons/carbon monoxide emissions and hence 10% EGR is taken as the best of the range from 5 to 20%. However, readings with other EGR ratios are not reported.     

Combustion and emission characteristics of a direct injection CI engine when operated on Marotti oil methyl ester and blends of Marotti oil methyl ester and diesel

This paper presents a feasibility study of Marotti oil biodiesel as an alternative to diesel fuel for a compression ignition engine. Marotti oil is inedible and available mainly in the state of Kerala. The oil is extracted from Marotti seeds. However, the high viscosity, poor volatility and cold flow characteristics of many vegetable oils in general, and Marotti oil in particular, can cause problems such as injector coking, severe engine deposits, filter gumming, piston ring sticking and thickening of lubrication from long-term use in diesel engines. These problems can be eliminated or minimised by transesterification of the vegetable oils to form monoesters. Although transesterification improves the fuel properties of vegetable oil, the viscosity and volatility of biodiesel are still worse than for petroleum diesel fuel. Subsequently, Marotti oil was converted into its methyl ester by the process of transesterification. The methyl ester was blended with diesel in various proportions to obtain different blends of Marotti oil with diesel. The performance, emission and combustion characteristics of Marotti methyl ester and its blends with diesel were studied and the results were compared with the base line data generated for diesel operation. Experiments were conducted using an injection timing of 23° before top dead centre (BTDC) and an injection pressure of 205 bar at various power outputs and at a constant rated speed of 1500 rpm. The engine manufacturer specifies an injection timing of 23° BTDC and injection pressure of 205 bar for the standard diesel fuel operation. The heat release rates, maximum rate of pressure rise, ignition delay and combustion duration for these fuel combinations were obtained.

From the results obtained, it was observed that the biodiesel produced from Marotti oil and its blends with diesel have slightly reduced brake thermal efficiency and increased smoke, hydrocarbon, carbon monoxide and reduced NO _x emissions compared with diesel-only operation. The investigation showed that the B20 biodiesel blend of Marotti oil with diesel produced better performance in terms of higher brake thermal efficiency, lower specific fuel consumption and comparatively lower emissions compared to the other blend ratios considered.     

基于知识的洞庭湖湿地遥感分类方法

湿地遥感影像分类是遥感研究的一大难题。分析洞庭湖不同湿地类型在遥感影像上的光谱曲线规律,利用两个季节的洞庭湖ETM数据,并辅助以物候特征和地面GIS信息,通过遥感软件Erdas Image的专家分类知识库建立决策树分类方法,结合研究区的DEM进行洞庭湖湿地的影像分类,通过专家分类器分层次实现了包括水体、泥沙滩地、防护林滩地、湖草、芦苇滩地和苔草滩地以及其他水体7种湿地类型的分类。相比传统分类方法,专家分类过程以规则为基础,可以同时利用多个条件进行分类,减少了数据处理时间,同时还提高了分类精度,最终得到试验区较为可靠的遥感分类图像。     

Risks of global warming on montane and subalpine forests in Switzerland – a modeling study

In this study, we assess the risks of global warming on distributions of individual tree species in Switzerland. Applying a spatially explicit model, tree occurrence is predicted as a function of high resolution and physiologically relevant biophysical variables. The study shows that warming only slightly alters the overall abundance of tree species. However, the preferred temperature regimes are unevenly distributed along an elevational gradient, and the sensitivity to temperature varies considerably between the species. As a result, major reorganizations of forests in montane and subalpine belts are expected, i.e., a segregation of the core distributions of Fagus sylvatica and Picea abies is observed. Tree distribution potentials near timberlines, however, remain roughly the same. Electronic Publication     

Combustion and emission characteristics of a direct injection,compression‐ignition engine when operated on Honge oil,HOME and blends of HOME and diesel

This paper reports the results of research conducted to study the fuel properties of Honge oil and blends of its ester and the subsequent testing of these oils in a four‐stroke, single cylinder, water‐cooled, direct injection, compression‐ignition (CI) engine. Experiments were conducted with injection timings of 19, 23 and 27° BTDC at various loads and at a constant rated speed of 1500?rev?min^?1. The performance and emission characteristics of Honge oil and Honge oil methyl ester (HOME) blended with diesel, to produce blends designated B20, B40 and B80, were studied. The heat release rates, maximum rate of pressure rise, ignition delay, and combustion duration for these fuel combinations were determined.