南极菲尔德斯半岛土壤氮循环微生物类群数量与功能活性的初步研究

南极乔治王岛南端的菲尔德斯半岛被认为是研究南极生态与生物资源的理想之地。本研究从该半岛全岛范围采集了3类不同类型的土壤样品,采用传统最大或然法(MPN)对其所含氮循环各类群微生物的总量进行了测定,同时利用常规Griess试剂、纳氏试剂等显色法初步估算了各菌群的功能活性强度,并结合土壤理化性质和采样点生态等进行了初步分析。目的是对该半岛土壤氮循环微生物进行先期初步了解,为进一步深入研究它们的其他特性奠定基础。结果表明:13个土样中所含氮循环微生物总量趋势为氨化菌反硝化菌硝化菌和固氮菌(活菌数),除极个别样品外均具有不同程度的硝化、反硝化、氨化活性。其中,所有土壤样品均具有比较高的氨化菌含量及氨化活性强度;丘陵山坡土壤的反硝化菌含量与反硝化活性强度要高于动、植物区土壤(极个别样品除外);动物区和植物区土壤的硝化菌含量较少,但硝化活性强度较高,预示着可能存在高效功能菌株;而丘陵山坡土壤的硝化菌含量及硝化活性强度则表现得高低不一。本结果为进一步深入研究该地区氮循环微生物提供了前期参考。     

Temporal and spatial variation of fish assemblages in Dianshan Lake,Shanghai, China

Using multi-mesh gillnets and trawls, the fish communities in Dianshan Lake at 6 stations from Oct. 2009 to Jul. 2010 were investigated seasonally to reveal the biodiversity and its spatial and temporal distribution patterns. The long-term changes in their structural characteristics were then analyzed to identify the main infl uencing factors and several measures for lake restoration were put forward. Thirty six species, belonging to 9 family and 30 genera, were collected, amongst which, the order Cypriniformes accounted for 61.1% of the total species number. In terms of importance value, Cypriniformes was the predominant group, Coilia nasus the dominant species, while Cyprinus carpio and Rhinogobius giurinus were the subdominant taxa. The community types did not differ among stations, but between seasons. There were no significant differences between seasons and among stations in species diversity, but richness differed both spatially and seasonally. Along with the process of eutrophication and the drastic reduction of the area colonized by macrophytes from 1959 to 2009–2010, the fish diversity declined markedly, and species numbers of herbivores and piscivores declined proportionately more than those of invertivores, omnivores, and planktivores. The decline of potamophilus and river-lake migratory fish was more marked than those of sedentary, river-sea migratory, and estuarine fishes. Eutrophication concomitant with sharp reduction of macrophyte area and overfishing may be the main reasons for the decline in fish diversity in Dianshan Lake.     

THE STATUS OF GEOGRAPHY IN GRADUATE URBAN AFFAIRS PROGRAMS

Literature on the theoretical foundations of urban affairs emphasizes that the field is interdisciplinary in nature. The urban perspectives of the traditional social sciences, which include geography, should each constitute a significant component within an urban affairs program. However, the results of a recent survey indicate that geography is not represented in graduate urban affairs programs nearly to the extent of the other social sciences. The discrepancies between the interdisciplinary claims of the theoretical literature and the survey results are demonstrated in this article, followed by several hypotheses regarding possible causes of this situation.     

非Dedekind完备的序拓扑向量空间中集值映射的一类扩张

在泛函分析中有着重要作用的Hahn-Banach扩张定理及其很多推广定理的条件都要求值域空间是Dedekind完备的,这是一个非常强的条件,因而在一定程度上局限了这些扩张定理的应用。主要考虑弱化这些定理的条件,讨论当值域空间是由锥引人序的非Dedekind完备的序拓扑向量空间时,一类集值映射的扩张。     

近30年天津滨海新区湿地景观格局遥感监测分析

在GIS和FRAGSTATS软件支持下,结合景观格局数量分析方法,利用1979-2008年间共6期TM遥感影像与非遥感数据,对天津滨海新区近30年的湿地景观空间格局进行了动态分析。结果表明,滨海新区湿地(以人工湿地为主),1979-2004年滨海新区湿地总面积变化不大,但各类型间转换较大,主要是自然湿地转变为人工湿地,沼泽湿地几近消失。2006-2008年,由于城市建设大量滨海滩涂湿地被围填占用,到2009年5月自然海岸线的90%以上被占用。景观破碎度增加,湿地斑块数量从137个增加到704个,同时造成平均斑块面积下降。驱动力分析表明,降雨量减少的同时,年平均气温上升是主要的自然驱动因素。和自然因素相比,人类干扰为主要人文驱动因素,表现在水产养殖为主的农业经济活动、城市建设用地占用和围海造地等方面。目前,滨海新区几乎没有自然湿地生态系统,破碎化和人工化是该区域湿地的主要特征。     

水平层状介质中双侧向测井资料的迭代Tikhonov正则化反演

根据非线性反演理论与Morozov偏差原理研究建立从双侧向测井(DLL)资料中同时重构地层原状电阻率、侵入带电阻率、侵入半径、层界面位置以及井眼泥浆电阻率的迭代正则化算法.首先利用Tikhonov正则化反演理论将双侧向测井资料的反演问题转化为含有稳定泛函的非线性目标函数的极小化问题,并利用Gauss-Newton算法确定极小化解.为得到稳定的反演结果并有效实现测井资料的最佳拟合,在迭代过程中将Morozov偏差原理和Cholesky分解技术相结合,建立了一套后验选择正则化因子的方法.最后通过理论模型和大庆油田实际测井资料的处理结果,验证了该算法能够取得更为满意的反演效果.     

Abiotic,residual and functional components of landforms

The concept of functional ecogeomorphology developed originally from the study of fluvial systems represents an insightful framework for describing landforms as structures adjusting to external physical forces, and also as functional components contributing to the complex play of interactions and reciprocal adjustments between biotic and abiotic elements of ecosystems. In this commentary we propose to extend the model of functional ecogeomorphology by classifying landforms in three fundamental components: abiotic, residual and functional. The various possible combinations of these three components are presented and discussed in the scope of evolutionary geomorphology. Copyright © 2010 John Wiley & Sons, Ltd.     

跨国公司功能区位实证研究

随着交通通讯技术的发展,跨国公司在东道国内部实现功能空间分离.伴随中国渐进式的改革开放进程,全球500 强跨国公司逐步在中国实现地理扩张和功能扩张.本文基于1979-2008 年电子信息和医药化工产业的全球500 强跨国公司在华投资数据研究跨国公司功能区位.研究表明,跨国公司倾向于在已有投资的城市追加投资,不同功能呈现一定差异性地理分布,但功能之间共聚趋势明显.区域性总部和商务功能聚集在一线城市,生产功能布局于省会和一线城市周边地区,研发功能追随生产功能.条件逻辑模型分析表明,跨国公司功能区位存在显著的公司内集聚、跨公司集聚、来源国集聚以及跨功能共聚现象.市场潜力及城市行政地位也是吸引跨国公司投资的重要因素.随着全方位开放格局形成,集聚效应较制度优势更为重要.跨国公司分支机构地理集聚提升一线城市的功能,强化顶级城市的领导力和聚集力.跨国公司的功能片段化布局既依托我国的城市等级体系,又在一定程度上重塑我国城市空间结构,促进城市体系按价值链等级进行专业化分工并推动区域协作.