长江中游水生生物多样性保护面临的威胁和压力

长江中游地区作为世界上最大的淡水生态区之一,生物多样性保护具有非常特殊的地位和作用。分析了长江中游地区生物多样性保护面临的主要威胁与压力,认为生境破碎萎缩、资源不合理开发利用、水环境污染、外来物种入侵等是生物多样性面临的主要威胁,而传统方式下的经济增长、土地利用粗放、人口增长与贫困、政策与管理等方面存在的问题将是生物多样性保护面临的主要压力。     

Ecosystem services assessments in local municipal decision making in South Africa: justification for the use of a business-based approach

The ecosystem services (ES) concept is being increasingly incorporated into environmental policy formulation and management approaches. The Corporate Ecosystem Services Review (ESR) is a framework used to assess the dependence and impact that a business has on ES. The success of the corporate experience of ES assessment provides an opportunity for adaption for local authority decision making. In this paper, the ESR tool was adapted to the South African setting at a local government level, and tested at two sites in the Msunduzi Municipality, KwaZulu-Natal. In testing the tool and gathering feedback from key stakeholders, it was found that there are both opportunities and challenges to this approach. Overall, however, it provides an opportunity for the systematic inclusion of ES assessment into existing regulatory frameworks for land-use planning and Integrated Environmental Management, whether in a strategic application, at a broader spatial (municipal) scale or in a specific locale within the municipality.     

三峡库区消落带水淹初期主要优势草本植物生态位变化特征

根据三峡库区初期水位涨落情况,以空间代替时间法,连续两年对典型消落带区域地上植被进行调查,通过计算生态位宽度和生态位重叠来分析不同水淹时间下优势草本植物生态位的变化特征。结果表明,一年水淹区段在未水淹时,植物生态位宽度普遍较窄,此时生态位明显特化,而第二年水淹极大的增加了适应干湿变化的物种的优势度。水淹前生态位重叠值大于0.5的只有12对,小于0.2种对为189对,其中生态位重叠值为零的为103对;水淹后生态位重叠值大于0.5的有24对,小于0.2种对为53对,其中生态位重叠值为零的为6对,说明生境由干燥到湿润的变化,对湿润环境相对适应的物种存活,优势植物生态位重叠明显增加。经两年水淹区段中,第一年以毛马唐的生态位宽度最高,其余17种物种生态位宽度小于0.2的物种占优势物种的61%,第二年以雾水葛和鳢肠的生态位宽度较大,其余15种物种生态位宽度小于0.2的物种占优势物种的50%,共同出现的物种仅有8种。生态位重叠值大于0.5的种对由5对上升到17对,生态位重叠值为零的种对由10对减低到2对,说明连续水淹产生更加均一的生境类型,对资源要求相似的物种是增加的。     

土地利用生态服务价值指标体系评估结果比较研究

生态系统服务价值评估越来越受到学术界关注。针对当前生态服务价值评估方法、指标体系和评估效果较多的实践,通过文献归纳,对国内外土地利用生态服务价值评价方法、指标体系及其系数进行了梳理、分类和评价,将指标体系分为Costanza和谢高地两大类,并将谢高地指标体系分为价值当量、价值系数和区域修正。以辽宁省2005、2010年土地利用数据为案例,运用Costanza价值系数、谢高地两个版本价值当量、两个版本价值系数的区域修正,分别核算了案例区生态系统服务价值及变化,并比较评价结果。研究得出Costanza价值系数应用于中国实践时评估结果显得偏低,谢高地2002版的价值当量和2002版的价值系数区域修正结果最接近平均值,相对较为可取,2007版的价值系数区域修正评估结果也较为接近均值但略低,2007版的价值当量评估结果总体偏高。研究结果有利于指导土地利用生态服务价值评估指标体系选取。     

江苏省沿江开发区空间分工、制造业集聚与转移

基于新经济地理学相关理论,针对江苏省沿江开发战略实施以后,制造业空间可能存在的变动,在整理和分析调查问卷资料的基础上,选择专业化指数和基尼系数2种方法来定量分析江苏省21个沿江省级以上开发区空间分工、制造业集聚和转移态势。结果表明：（1）2002~2006年江南沿江开发区通过向江北沿江开发区转移部分传统产业,逐渐形成了江南沿江技术/资本密集型制造业“中心”和江北沿江劳动密集型制造业“外围”的空间分工格局;（2）江南沿江开发区内部、江北沿江开发区内部尚未形成良好的分工关系;（3）受开发区发展阶段、区域产业政策、本地化资源供给和市场需求等因素影响,并未发现理论预期的普遍存在的产业集聚现象,仅纺织服装、石化、电力、塑料橡胶等产业呈现集中趋势.     

Determinants for cassava production expansion in the semi-arid zone of West Africa

The study focuses on evaluating factors that farmers consider relevant in adopting cassava production in five semi-arid zone of West African countries. The study is based on primary data randomly collected as part of collaborative study of cassava in semiarid zones of Africa (COSCASSA) village level survey from five West African countries namely: Nigeria, Ghana, Chad, Niger and Burkina Faso. This study models effects of farm, farmer and technology specific factors on the decision of semi arid farmers to adopt cassava into their farming system. By way of threshold decision models—Probit and Logit models, the estimation of each country and the pooled data adoption models reveal different adoption models for the countries considered. For each country, different variables appeared as major adoption shifters. Comparatively, the adoption models for Nigeria and whole region appear to have the highest significance variables, being seven in number. This is followed by Chad (6), Ghana (4), and Burkina Faso and Niger with three each. For the variables considered, distance to nearby urban market appears a major adoption shifter in all the country, except for Niger. This is closely followed by contact with extension, variety, pest/disease resistance and livestock feeds, which appear significant in four of the countries. Membership of cooperative societies appears as the least adoption predictor, which is only significant in Chad republic. The study therefore recognizes the importance of varietial characteristics and farmers’ characteristics in acceptance of cassava as a major root tuber crop in the semi arid region of West Africa. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

Acid generation upon thermal concentration of natural water: The critical water content and the effects of ionic composition

Thermal evaporation of a variety of simulated pore waters from the region of Yucca Mountain, Nevada, produced acidic liquids and gases during the final stages of evaporation. Several simulated pore waters were prepared and then thermally distilled in order to collect and analyze fractions of the evolved vapor. In some cases, distillates collected towards the end of the distillation were highly acidic; in other cases the pH of the distillate remained comparatively unchanged during the course of the distillation. The results suggest that the pH values of the later fractions are determined by the initial composition of the water. Acid production stems from the hydrolysis of magnesium ions, especially at near dryness. Near the end of the distillation, magnesium nitrate and magnesium chloride begin to lose water of hydration, greatly accelerating their thermal decomposition to form acid. Acid formation is promoted further when precipitated calcium carbonate is removed. Specifically, calcium chloride-rich pore waters containing moderate (10–20 ppm) levels of magnesium and nitrate and low levels of bicarbonate produced mixtures of nitric and hydrochloric acid, resulting in a precipitous drop in pH to values of 1 or lower after about 95% of the original volume was distilled. Waters with either low or moderate magnesium content coupled with high levels of bicarbonate produced slightly basic fractions (pH 7–9). If calcium was present in excess of bicarbonate, waters containing moderate levels of magnesium produced acid even in the presence of bicarbonate, due to the precipitation of calcium carbonate. Other salts such as halite and anhydrite promote the segregation of acidic vapors from residual basic solids. The concomitant release of wet acid gas has implications for the integrity of the alloys under consideration for containers at the Yucca Mountain nuclear waste repository. Condensed acid gases at very low pH, especially mixtures of nitric and hydrochloric acid, are capable of corroding even alloys, such as nickel-based Alloy 22, which are considered to be corrosion-resistant under milder conditions.     

湖岸缓冲带反硝化作用的研究进展

反硝化作用是湖岸缓冲带去除硝酸盐的重要途径。湖岸缓冲带是联系陆地与湖泊生态系的纽带,不仅为许多动植物提供适宜生境,而且通过反硝化作用能去除地下水中的硝酸盐,提高湖泊水质。概述不同检测反硝化速率的方法,并对比各种方法的优点与缺点。阐述反硝化作用的影响因素：厌氧环境、有机碳、湖岸坡度、缓冲带坡度、pH与温度、硝酸盐浓度。介绍反硝化速率模型的研究开发状况。最后,提出了目前国内外反硝化研究中存在的不足及发展方向。     

渗滤液污染包气带中铁的形态变化

从渗滤液场龄和包气带岩性两方面出发,研究了新、老渗滤液对亚粘土和细砂包气带环境中Fe的含量及存在形态的影响。结果表明：新、老渗滤液分别能使细砂包气带介质中除残渣态以外Fe的含量增加16.68%或降低13.82%。亚粘土比细砂作为包气带介质更能缓冲渗滤液对介质中Fe的影响程度,其受影响范围在包气带0～20 cm深度处。当亚粘土为介质的包气带被新渗滤液污染后,其表层介质中碳酸盐结合态Fe的含量会增加15倍之多,为缓冲渗滤液Fe的污染做出了巨大贡献,但这部分Fe的存在也是潜在的二次污染源,在环境pH急剧变化的情况下,它可能会引起地下水高铁污染。     

昌吉市高新技术产业开发区循环经济模式探索及研究

传统开发区内,资源的流动是一些相互不发生关系的线性物质流的叠加,出入系统的物质流远远大于内部交互的物质流,因而造成经济活动的＂高开采、低利用、高排放＂特征,即＂大量生产、大量消费和大量废弃＂[1]。而发展循环经济,是我国贯彻落实科学发展观、建设资源节约型和环境友好型社会的重大战略选择[。2]目前新型开发区产业发展,则要求按照循环经济的理念,积极探索发展循环经济之路。本文以昌吉市高新技术产业开发区为例,研究其循环经济模式,为其他开发区设计和发展提供有益的经验和建议。