社会经济活动对太湖流域的生态影响分析

采用系统分析的方法,围绕社会经济压力、水体污染负荷以及水体环境状态3个方面,建立社会经济活动对太湖流域生态影响的评价指标体系,利用层次分析法计算各指标因子的权重.根据太湖流域2005和2006年的相关数据,以MATLAB为工具,运用模糊模式识别方法进行流域生态综合评价,分析社会经济活动对太湖流域的生态影响.研究结果表明,太湖流域的社会经济活动对湖泊生态的影响较大,除了点源污染以外,面源污染也是太湖流域生态环境问题的重要根源.     

景观生态学方法在规划环境影响评价中的应用 ——以大连森林公园东区规划环境影响评价为例

在综合考虑各种社会经济影响因素的基础上,从景观格局、景观功能、景观受胁迫性等3方面构建评价指标体系,并据此开展规划实施的景观生态影响综合评价.利用计算机模型模拟各种规划替代方案的景观格局动态,并通过分析景观格局指数的变化实现对规划替代方案的比选,建立起规划环评中景观生态学方法应用的技术框架,进而应用于大连森林公园东区建设规划环境影响评价.研究结果表明,规划的实施有利于区域景观格局和功能的改善,但会导致人类对景观干扰和胁迫加重.采用以旅游经济为主导型方案(替代方案1),景观破碎化趋势明显;以生态优先主导型方案(替代方案2),景观向整合集约化趋势发展.     

Energy dissipation, flow resistance and gas-liquid interfacial area in skimming flows on moderate-slope stepped spillways

With the re-evaluation and revision of a number of design floods, several embankment overtopping protection systems have been developed and a common technique is the construction of a stepped spillway on the downstream slope. For such moderate slope stepped channels, detailed air–water flow measurements were performed in a large facility with a focus on the rate of energy dissipation, flow resistance, air–water interfacial areas and re-aeration rates. Past and present experimental results showed a significant aeration of the flow. The median dimensionless residual head was about 3 × d_c for the 21.8° sloping chute and smaller than that for flatter slopes (θ = 3.4° and 15.9°). The flow resistance results yielded an equivalent Darcy friction factor of about 0.25 implying a larger flow resistance for the 21.8° slope angle than for smaller slope angles. The re-aeration rate was deduced from the integration of the mass transfer equation using measured air–water interfacial areas and air–water flow velocities. The results suggested an increasing re-aeration rate with increasing rate of energy dissipation. The stepped invert contributed to intense turbulence production, free-surface aeration and large interfacial areas. The experimental data showed however some distinctive seesaw pattern in the longitudinal distribution of air–water flow properties with a wave length of about two step cavities. While these may be caused by the interactions between successive adjacent step cavities and their interference with the free-surface, the existence of such “instabilities” implies that the traditional concept of normal flow might not exist in skimming flows above moderate-slope stepped spillways.     

宁夏地区二斑叶螨的寄主植物选择及其季节转移

采用田间系统观察和室内饲养方法,调查并发现宁夏引黄灌区和新垦区二斑叶螨（Tetranychus urticae Koch)为寄主植物88种,其中野生寄主植物59种,栽培寄主29种,垦前荒漠,半荒漠有适宜二斑叶螨生存和繁殖的寄主植物分布,用生命表方法研究了20种主要寄主植物对二斑叶螨实验种群净生殖率（R0)的营养效应,不同寄主植物随季节的变化其营养效应明显不同,对二斑叶螨在这些寄主植物间的季节转移规律研究表明,宁夏农田,以野荠菜Capsella bursa-pastoris,小旋花Calystegia hederacea,小蓟Cephalanoplos segetumji,苦苣菜Sonchus brachyotus,车前草Plantago asiatica,蚕豆Vicia foba,大豆Glycine max,玉米Zea mays等一起,构成了有利于二斑叶螨季节转移的寄主体系,分析认为,宁夏麦套玉米间作大豆的耕种模式是二斑叶螨大发生的主要原因之一。     

Statistical detection of multiscale landscape patterns

Detection of discontinuities in landscape patterns is a crucial problem both in ecology and in environmental sciences since they may indicate substantial scale changes in generating and maintaining processes of landscape patches. This paper presents a statistical procedure for detecting distinct scales of pattern for irregular patch mosaics using fractal analysis. The method suggested is based on a piecewise regression model given by fitting different regression lines to different ranges of patches ordered according to patch size (area). Proper shift-points, where discontinuities occur, are then identified by means of an iterative procedure. Further statistical tests are applied in order to verify the statistical significance of the best models selected. Compared to the method proposed by Krummel et al. (1987), the procedure described here is not influenced by subjective choices of initial parameters. The procedure was applied to landscape pattern analysis of irregular patch mosaics (CORINE biotopes) of a watershed within the Map of the Italian Nature Project. Results for three different CORINE patch types are herein presented revealing different scaling properties with special pattern organizations linked to ecological traits of vegetation communities and human disturbance.     

内蒙古沙地森林草原过渡带中沙地云彬种群动态

沙地云彬是我国内蒙东部沙地森林草原过渡带的特有濒危树种,沙地杉林是陆地上非常特殊的森林生态系统类型。本文研究了沙地云杉的种群动态,建立了沙地云杉种群生命表、年龄结构、存活曲线和生殖力表,同时研究了沙地云杉种群分布格局及增长动态,可为沙地治理和沙地森林生态系统研究提供科学依据。     

Share-Shift Analysis of Geo-Economic Pattern on Global Cereal Crops in Recent 50 Years

In recent 50 years, with the rapid development of international food trade, the geoeconomic pattern of cereal crops has changed tremendously which produced a significant impact on global food security. This paper attempted to analysis the production pattern and trade pattern of global cereals, especially three main crops of wheat, maize and rice by using the method of share-shift. Given the fact of almost every economic phenomenon is driven by their economic return behind them, this paper attempted to a further step into their economic pattern by examining their net trade flow. The results showed that from the view of production and trade, the geographic pattern of global cereals has changed greatly which can be described as developing countries has replaced developed countries and become the world’s biggest cereals production and trading area. But when moving to the net trade flow, it turns out to be another story that can depicted as the regional fixation features of economic returns which can be convinced from the labor division of global cereals trade, among which developed countries acts as net trade profit area while developing countries as net trade output area, and their gap between net export and net import has been widening from the view of evolution trend. So what we learn from the evolution of geoeconomic pattern on this topic is that our place in global cereals trade system, and therefore alert us to concern not only on the pattern transition but also the economic meaning behind it, only by doing so can we learn to plan our food future more wisely and effectively.     

江汉平原建设用地扩张的时空特征与驱动力分析

建设用地的迅速扩张已经成为当前中国土地利用变化的主要特征。以中国科学院土地利用数据库（基于1995、2000和2005TM影像）为基础,利用GIS空间叠加分析和缓冲区分析技术,提取建设用地变化及其空间分布信息,运用建设用地扩张速度和强度指数对江汉平原1995～2005年10 a来建设用地扩张的时空特征进行了研究。在此基础上,结合各县市的社会经济等信息,运用灰色关联分析,对建设用地扩张的驱动力进行探讨。结果显示：总体上江汉平原建设用地扩张速度呈现增大趋势,但各县市之间扩张差异显著;各县市建设用地扩张分布上呈现组团状特点;沿交通线扩张的特征较为突出,尤其是后一阶段增幅高于前一阶段,沿江扩张增幅明显;总人口的增长是江汉平原建设用地扩张最主要的驱动力;交通条件改善、经济发展与区域建设用地扩张也有明显的相关关系     

中国高新技术产业的地理格局与地理集中

与传统产业相比,高新技术产业对地理集中具有更加强烈的内在要求,这导致其地理格局与传统产业具有明显的差别。在产业集中指数等相关理论方法和实证分析的基础上,力图从地理学视角,结合高新技术产业的时间序列数据和2008年断面数据,从整体产业和分行业研究了高新技术产业地理格局和地理集中的现状和变动趋势。研究发现,我国高新技术产业高度集中在沿海省区和陕、川两省,省区间差距悬殊;高新技术产业产值份额同经济发展显著相关。时间序列分析表明：长时间尺度产业集中持续增强,近年来趋于稳定;地理格局逐渐清晰,核心省区凸显。不同行业由于产业性质、发展基础、资源需求和市场群体的差异,有其各自的集中态势和演变趋势。     

Cellular uptake and mutagenic potential of metal oxide nanoparticles in bacterial cells

Extensive production and consumption of nanomaterials such as ZnO and TiO₂ has increased their release and disposal into the environment. The accumulation of nanoparticles (NPs) in ecosystem is likely to pose threat to non-specific targets such as bacteria. The present study explored the effect of ZnO and TiO₂ NPs in a model bacterium, Salmonella typhimurium. The uptake of ZnO and TiO₂ bare NPs in nano range without agglomeration was observed in S. typhimurium. TEM analysis demonstrated the internalization and uniform distribution of NPs inside the cells. Flow cytometry data also demonstrates that both ZnO and TiO₂ NPs were significantly internalized in the S. typhimurium cells in a concentration dependent manner. A significant increase in uptake was observed in the S. typhimurium treated even with 8 and 80 ng mL⁻¹ of ZnO and TiO₂ NPs with S9 after 60 min, possibly the formation of micelles or protein coat facilitated entry of NPs. These NPs exhibited weak mutagenic potential in S. typhimurium strains TA98, TA1537 and Escherichia coli (WP2uvrA) of Ames test underscoring the possible carcinogenic potential similar to certain mutagenic chemicals. Our study reiterates the need for re-evaluating environmental toxicity of ZnO and TiO₂ NPs presumably considered safe in environment.