玄武湖挺水植物区与敞水区浮游甲壳动物昼夜水平迁移初探

浮游甲壳动物昼夜垂直迁移(DVM)是深水湖泊中的一种常见的现象,在浅水湖泊中,没有明显的下层滞水层为浮游甲壳动物提供避护所,浮游甲壳动物的垂直迁移活动不明显。但浅水湖泊挺水植物的存在为浮游甲壳动物提供了区别于敞水带的生境,结合理化、浮游植物和鱼的因素,对浅水湖泊玄武湖挺水植物区与敞水区浮游甲壳动物的昼夜水平迁移进行了研究。结果得出：浅水湖泊玄武湖中理化环境（如温度、溶解氧和pH)在荷花区、敞水区、荷花区与敞水区的交界区差异不大,对浮游甲壳动物的昼夜水平迁移不起主导作用。荷花区的浮游植物在质量和数量上低于敞水区,浮游甲壳动物在夜间捕食压力小的情况下会向敞水区移动。敞水区、交界区浮游甲壳动物在白天被捕食的风险要大于荷花区,因而白天时间浮游甲壳动物会迁移到荷花区聚集.     

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.     

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。     

Understanding local community attitudes toward industrial development in the Great Barrier Reef region World Heritage Area: are environmental impacts perceived to overshadow economic benefits?

Conflicts between industrial development and environmental conservation can be particularly acute when such development occurs in the vicinity of World Heritage sites. A key example is the Great Barrier Reef World Heritage Area (GBRWHA) in northeastern Australia, where a 2012 review by the World Heritage Council found that rapid port development inshore of the coral reef posed significant risks to local marine ecosystems. Such instances pose pressing challenges for decision‐makers seeking to manage World Heritage sites for multiple values and needs, including those of key stakeholder groups, such as local communities. There is increasingly a societal expectation that public decision‐making takes into account local views and priorities, and that companies seek a ‘social license to operate’. This research explored local community attitudes toward port development associated with the export of liquefied natural gas (LNG) and coal through the GBRWHA. Using data drawn from a survey and interviews, the research examined how a range of geographical factors, including proximity to gas infrastructure and the perceived impacts and risks of development to the local community, economy and environment shape community perceptions of the industry. Findings suggest that local attitudes toward gas and coal terminal development inshore of the GBRWHA are shaped predominantly by community perceptions of environmental impacts and risks associated with such infrastructure, in contrast to a broader public narrative that focuses largely on economic benefits. A complex combination of other factors, including social impacts, personal environmental values, community trust in industry, and equity in decision‐making and distribution of the risks and benefits of industrial development also contribute. Placed in a broader, global context, the findings have important implications for public decision‐making processes in Australia and elsewhere as they suggest that, for local communities, the perceived impacts of gas development on the environment may overshadow the benefits of industry.     

海上平台采油工艺设计浅析

文章通过实例,简要阐述了滩海、浅海、深海三种开发模式的特点、主要工艺及其适用性。指出各自存在的问题,并提出相应的建议,为海上勘探开发提供借鉴。     

石油类污染物自然衰减能力现场试验验证研究

在北京地区某加油站开展的前期石油类污染物自然衰减现场试验的基础上,进一步开展了验证试验,结果表明本次试验得到的挥发性有机物(VOCs)变化趋势及O2、CO2含量沿土壤深度分布和前期试验结果呈现相同的规律,说明基于自然衰减法设计实施的加油站现场试验检测分析结果可靠,试验方法具有合理性、可操作性及可重复性.进一步的理论分析对前期试验结果进行了验证,得出以下结论:(1)通过氧平衡和碳平衡计算对加油站土壤内的自然衰减方式进行评价,验证了该加油站地下土壤中实际发生的微生物降解既有需氧降解也有厌氧降解;(2)利用有机物的一级衰减模型对该污染现场土壤中石油类污染物的降解速率和半衰期进行计算表明,2次试验计算得到的石油类污染物的半衰期基本一致,该污染现场石油类污染物的半衰期为50 d左右;(3)在此基础上,对该加油站包气带土壤的自然衰减能力和环境质量进行评价,2次试验结果均表明该污染现场在自然衰减的作用下已经不存在环境风险.     

生物柴油促进原油污染砂粒释放油

对4种生物柴油促进原油污染砂粒释放油的效果进行了研究,并探讨了菜籽生物柴油投加量和砂粒粒径对促进效果的影响。结果表明,菜籽生物柴油的促进效果最好,8 h释放量达到73%,废油脂生物柴油的效果最差,仅为52%;生物柴油的促进效果随着投加量的增大而升高,当投加量超过海水体积的5%时促进效果不再明显增加;在生物柴油作用下,小粒径砂粒上原油的释放效果优于大粒径砂粒。     

某矿区土壤和地下水重金属污染调查与评价

为了解湘南某矿区土壤和地下水重金属污染状况,对该矿区东河流域附近重金属污染源进行了调查,同时,对地下水和土壤样品进行了采样分析,结果表明：（1）该矿区东河流域附近的主要污染源有18个,其中有色金属选厂、尾矿库、采矿场和冶炼厂是排放重金属较多的污染源;（2）20个采样点中土壤重金属Pb、Cd、Zn、As和Hg大部分超过国家土壤环境质量标准（GB15618-1995）,综合污染指数P综〉1,该矿区主要的重金属污染元素为Cd、As和Hg,且土壤中Cd、Zn和As的含量两两之间存在着极显著的正线性相关关系;（3）重金属元素在土壤中的纵向迁移不明显,该矿区附近20个采样点的地下水并未受到污染,综合污染指数P综〈1。20个采样点地下水Pb、Cd、Zn、As、Hg浓度均能达到地下水质量标准（GB／T14848．9）中的Ⅲ类标准。     

实例分析卫生防护距离和大气环境防护距离设置条件

卫生防护距离、大气环境防护距离,其定义相近、设定途径相似,但两者又有不同。故在环境影响评价大气环境预测分析时对大气环境防护距离、卫生防护距离的概念极易混淆。本文以某县殡仪馆建设项目为例,详细分析建设项目设置防护距离的设置条件,帮助环评工作者理解防护距离设置原则,防止出现"在环境保护法规和导则要求下盲目划定、划大防护距离"的技术错误。