Community structure and elevational diversity patterns of soil Acidobacteria

Acidobacteria is one of the most dominant and abundant phyla in soil,and was believed to have a wide range of metabolic and genetic functions. Relatively little is known about its community structure and elevational diversity patterns. We selected four elevation gradients from 1000 to 2800 m with typical vegetation types of the northern slope of Shennongjia Mountain in central China. The vegetation types were evergreen broadleaved forest,deciduous broadleaved forest,coniferous forest and sub-alpine shrubs. We analyzed the soil acidobacterial community composition,elevational patterns and the relationship between Acidobacteria subdivisions and soil enzyme activities by using the 16 S rRNA meta-sequencing technique and multivariate statistical analysis. The result found that 19 known subdivisions as well as an unclassified phylotype were presented in these forest sites,and Subdivision 6 has the highest number of detectable operational taxonomic units(OTUs). A significant single peak distribution pattern(P 0.05) between the OTU number and the elevation was observed. The Jaccard and Bray–Curtis index analysis showed that the soil Acidobacteria compositional similarity significantly decreased(P 0.01) with the increase in elevation distance. Mantel test analysis showed the most of the soil Acidobacteria subdivisions had the significant relationship(P 0.01) with different soil enzymes. Therefore,soil Acidobacteria may be involved in different ecosystem functions in global elemental cycles. Partial Mantel tests and CCA analysis showed that soil pH,soil temperature and plant diversity may be the key factors in shaping the soil Acidobacterial community structure.     

生态经济城市建设的SWOT分析与策略研究——以粤北山区韶关市为研究样本

生态经济城市通过城市生态、经济与社会系统的动态协调,形成一个生态高度有效保护、经济良性高效发展、人与自然和谐相处的整体功能系统,代表了现代和未来城市发展的方向.作为全国首批六个生态文明建设试点地区之一和广东省的生态发展区,韶关市加快生态经济城市建设符合这一发展潮流和趋势.根据SWOT分析方法,对韶关市生态经济城市建设面临的优势、劣势、机遇和挑战进行分析,不仅为韶关生态经济城市建设提供策略依据,而且为其它类似地区的生态经济城市建设提供借鉴.     

Prediction of vortex height from mechanical mixing in metal matrix nanocomposite processing by means of dimensional analysis and scaling

Mechanical mixing can be used for initial dispersion and distribution of nanoparticle agglomerates in metal matrix nanocomposite (MMNC) fabrication. As vortex height increases, flow is enhanced as well as the risk of oxidate melt contamination. The goal of this study was to examine and predict vortex height using dimensional analysis while varying fluid and the angular speed of a pitched square-blade impeller. An equation proposed by Markopoulos et al. was verified for the present experimental conditions. The relevant dimensionless numbers were the Reynolds (Re), Froude (Fr) and Galilei (Ga) numbers. A modified Fr was defined (Fr*) including the shaft and blade angles of the impeller. Experiments allowed calculation of the dimensionless numbers. Two fluids, water and 50 vol% aqueous glycerine, were used. Angular clockwise speed varied from 200 to 900 rpm in 100 rpm increments. Vortex height was measured in lateral view digital images. Correlations of the dimensionless numbers yielded, first, a linear relationship of the product of dimensionless vortex height (H) and specific gravity (ρ*) with respect to Fr*. A polynomial relationship was found between H and ReFr* for each fluid. The polynomial coefficients, in turn, follow a power law behavior with respect to Ga. This allows a prediction of vortex height in other Newtonian fluids that satisfy the single-phase isothermal flow condition. Perhaps, molten aluminum used in MMNC fabrication, can be analyzed based on a simple, room temperature, low cost transparent fluid system. For the experimental conditions in this study, the equation proposed by Markopoulos et al. was valid. The predicting methodology was verified with experimental results using 25 vol% aqueous glycerine, resulting in an absolute percent error of 5.29%, comparable and lower than an error of 9.12% obtained by predicting vortex height with Markopoulos’ equation.     

基于GIS的煤矿区景观格局时空变化分析——以呼伦贝尔市某煤矿为例

在GIS平台和Fragstats 4．1软件的支持下,本文以1989年和1999年的TM影像,2012年的资源三号卫星影像为数据源,利用景观／斑块类型面积、斑块所占景观面积的比例、斑块密度、最大斑块指数、总边缘长度、边缘密度、香农多样性指数、蔓延度指数等景观特征指标,对呼伦贝尔市某煤矿区的景观特征动态变化进行分析。结果显示：该煤矿区20多年来景观格局有了很大变化,景观类型由1989年的水域、草地、未利用地为主导变为2012年以未利用地、草地、耕地为主导,其中因人类工业活动和人工复垦导致工矿景观、道路景观、林地景观和耕地景观面积增加,而原来占绝对优势的水域景观面积则大幅减小。     

北京地区冬夏季持续性雾-霾发生的环境气象条件对比分析

在北京地区,除冬季供暖期外盛夏也是雾-霾天气的高发季节,与我国南方不同.使用微波辐射仪、风廓线和常规气象探测资料、NCEP再分析资料以及大气成分观测结果,通过对比分析揭示了冬、夏季持续6 d的2个雾-霾过程形成和维持机制的异同.冬季雾-霾过程出现在高空西北气流、低层多短波活动的背景下,其形成和维持的主要机制是边界层内始终有逆温层、地面弱风场、底层湿度逐渐增大.逆温层昼高夜低、湿度昼小夜大是影响PM2.5质量浓度和能见度日变化的重要环境因子.在雾-霾天气持续期间地面弱风场能够维持主要源于冷空气势力弱、常不能影响到地面.此外,入夜后地面迅速辐射降温、边界层上层有暖平流以及空气过山后下沉增温在逆温层的形成中起了关键作用.然而,对于夏季持续性雾-霾天气,气溶胶区域输送、环境大气保持对流性稳定、空气的高饱和度是其发生的重要条件.在副热带高压长时间控制下对流层低层盛行偏南风,北京的PM2.5质量浓度随着偏南风风速增大升高.对流层底层系统性偏南风与北京附近的山谷风共同构成了从北京以南气溶胶累积地向北输送的机制.夏季雾-霾过程低层没有逆温,但是北京上空一直维持超过200 J·kG-1的对流抑制能量,它同样限制了污染物的垂直扩散.夏季自由对流高度也存在昼夜变化,其对PM2.5浓度和能见度的作用与逆温层高度升降相同.因此,冬、夏个例分别代表了2种不同类型的持续性雾-霾过程,导致差异的根本原因在于大气环流型.     

普兰店市土地利用景观格局及其生态环境效应研究

基于研究区2010年的土地利用图形数据,选用生态意义较明确的景观特征指数,定量分析了普兰店市景观空间格局及其生态环境效应.结果表明：（1）普兰店市旱地景观面积最大、分布最广,其面积比例为47.1％,林地景观的面积比例也较大,草地和沼泽地的面积比例较小.平均斑块面积0.82 km2/个,景观多样性指数为1.35,优势度指数为0.73,均匀度指数为0.62;（2）大部分旱地景观分布在普兰店市南部,林地景观大多分布在北方.城乡用地、水田则相对集中分布在南部沿海地区;（3）普兰店市的生态环境指数为0.40,生态环境质量总体一般.     

利用SPAMS研究华北乡村站点(曲周)夏季大气单颗粒物老化与混合状态

利用单颗粒气溶胶飞行时间质谱(SPAMS)于2013年6月30日~7月8日对华北地区乡村站点曲周大气单颗粒粒径及其化学组成进行了在线测量,共采集到同时含有正负离子谱图的颗粒230 152个,其粒径主要集中在0.2~2.0μm.结果表明,该地区的大气颗粒物主要分为8类:元素碳(EC,55.5%)、有机碳(OC,10.7%)、钠,钾等碱金属颗粒(alkalis,17.4%)、其他金属颗粒(other metals,1.7%)、富铁颗粒(Fe-rich,6.3%)、富铅颗粒物(Pb-rich,3.1%)、沙尘颗粒(dust,4.8%),other颗粒(0.8%),观测得到的8类气溶胶颗粒中绝大部分包含46NO-2、62NO-3、80SO-3、96SO-4、97HSO-4等二次组分离子,说明这些颗粒都经历了不同的老化过程或与二次组分进行了不同程度的混合.从气溶胶类型的谱分布看,各类型颗粒数浓度峰值基本出现在700~800 nm之间,dust、Fe颗粒主要集中在粗粒径段,EC颗粒子类研究表明随着表面不断吸附NH+4、NO-3、SO2-4等二次组分,EC颗粒逐步演化成老化程度较低的NO-3吸附型EC(ECN)和严重老化的SO2-4吸附型EC(ECS)混合态,两者日变化呈现明显的负相关性,也可能随着二次有机物在EC表面吸附,形成OC/EC混合态.     

基于安全度与运营格局的油库选址优先级评价方法研究

从安全性和运营角度对油库选址的影响因素及评价指标分析对油库的安全稳定及有效运营具有重要的意义。该文选取与安全和运营有关的人口企业数量、安全管理能力、消防设施规划、地形地质条件、铁路公路数量、市场投资收益、政策支持情况等影响因子进行重要性及合理程度分析,综合运用安全度与运营格局影响因素多元耦合关系,构建了油库区安全与运营评价体系,改进了原有的模糊层次法评价模型,并对某油库区安全度与运营格局进行了评估验证。结果表明:利用改进模糊层次法能够较好地评价不同地址的优先级,评价模型具有一定应用性,能够对不同地址的特点及评价权重进行有效分析,可见油库选址优先级评价方法是实用且有效的。该研究方法及结果可以为油库区地址的优选提供一定参考与建议。     

Assessing Impacts of Typhoons and the Chi-Chi Earthquake on Chenyulan Watershed Landscape Pattern in Central Taiwan Using Landscape Metrics

The Chi-Chi earthquake (M_L = 7.3) occurred in the central part of Taiwan on September 21, 1999. After the earthquake, typhoons Xangsane and Toraji produced heavy rainfall that fell across the eastern and central parts of Taiwan on November 2000 and July 2001. This study uses remote sensing data, landscape metrics, multivariate statistical analysis, and spatial autocorrelation to assess how earthquake and typhoons affect landscape patterns. It addresses variations of the Chenyulan watershed in Nantou County, near the earthquake’s epicenter and crossed by Typhoon Toraji. The subsequent disturbances have gradually changed landscape of the Chenyulan watershed. Disturbances of various types, sizes, and intensities, following various tracks, have various effects on the landscape patterns and variations of the Chenyulan watershed. The landscape metrics that are obtained by multivariate statistical analyses showed that the disturbances produced variously fragmented patches, interspersed with other patches and isolated from patches of the same type across the entire Chenyulan watershed. The disturbances also affected the isolation, size, and shape-complexity of patches at the landscape and class levels. The disturbances at the class level more strongly affected spatial variations in the landscape as well as patterns of grasslands and bare land, than variations in the watershed farmland and forest. Moreover, the earthquake with high magnitude was a starter to create these landscape variations in space in the Chenyulan watershed. The cumulative impacts of the disturbances on the watershed landscape pattern had existed, especially landslides and grassland in the study area, but were not always evident in space and time in landscape and other class levels.     

高职院校试行"综合导师制"的教育教学实践研究

结合学院迎接人才培养工作水平评估和学院“迎评促建”工作的要求,凸现高职教育“以就业为导向”的办学要求,在环境工程系推行了“综合导师制”。意在充分发挥专业老师在教书育人、专业辅导、大学生人生规划和就业素质提高上的优势,积极构建环境工程系全员育人、全程育人、全方位育人的工作格局,建立一种师生互动的新型教育教学关系。