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441.
A Geochemical Survey of Topsoil in the City of Oslo, Norway   总被引:9,自引:0,他引:9  
The city of Oslo is situated centrally in the Oslo-graben, which is a Permian rift basin consisting of different kinds of volcanic and sedimentary rocks. In the summer of 1998, approximately 300 samples of surface soil (2–3cm) were taken systematically, 1km–2. The investigated area covers about 500km2. Samples were dissolved in 7M HNO3 and analysed for 29 elements with ICP-AES, mercury with cold-vapour technique (CV-AAS) and arsenic and cadmium with a graphite furnace (GF-AAS). A factor analysis is frequently used to identify relationships among sets of interrelated variables. To describe the covariant relationships among the elements, a factor analysis has been completed. The first factor contains the elements Sc, Fe, Li, Co, Al, Cr, Be, K, Ni, V, Mg, Y, Ba, Zr, Mn and As (listed with decreasing communality). These elements are typical for the minerals in the area and most of these elements have a near normal distribution. Sources for this factor are probably geological. The second factor contains Cd, Hg, P, Zn, Cu, Ba and Pb. They have a log-normal distribution. Road traffic is probably one of the sources contributing to this factor. In Norway studded tyres are used frequently in the winter season which results in large amounts of road dust. Leaded petrol has been a major source for Pb but is not in use any more. Wear and tear of tyres and brakes contribute also to this factor. Other sources contributing to this factor are probably industry, rubbish incineration, crematoria and release of some of these elements from structural material by fire. Factors 3, 4 and 6 with elements such as Ca, Na, La, Ti and Sr probably have geological sources. They are associated with minerals like amphiboles, pyroxenes and feldspars and some of the elements are from sea aerosols. Factor 5 contains Mn, Cd, Zn, As and Pb. Manganese may be derived from many different sources such as rock weathering, windblown dust, agriculture and traffic. Since As and Mn are placed in both factor 1 and 5 they probably have both geological and anthropogenic sources. Concentrations of the elements in the second factor are much higher in the central parts of Oslo, than in the rest of Oslo. The median value of Hg in the centre is 0.48mgkg–1, which is 8 times higher than that in the rest of the city. Also, the other elements have much higher levels in the centre. The industrial district north-east of the centre also has high values. The distribution of arsenic is regular throughout the whole city, but has a slightly higher level in the centre. Norm values for contaminated land used by the Norwegian authorities are 2mg As kg–1 and 25mg Cr kg–1. Of 297 samples, 61% contain more than 25mg Cr kg–1 and 79% more than 3mg As kg–1, which is the detection limit of the analysis. These samples will therefore be regarded as contaminated. Factor analysis places these elements in the geological factor. The Norm value of zinc is 150mgkg–1, and 40% of the samples contain more than this. The Norm value of lead is 150mgkg–1, and 35% of the samples contain. Road traffic is probably the major source for these elements.  相似文献   
442.
湖南怀化地区96.7城市特大洪涝灾害成因分析   总被引:1,自引:1,他引:0  
湖南省怀化地区地形以山地为主,该地区1996年7月发生了城市特大洪涝灾害,本文概述了该地区96.7城市洪涝灾情,并以区域灾害系统论为指导,从孕灾环境、致害因子、承灾能力和人类活动的不利影响等方面,对这次灾害的成因进行了分析,认为其主要成因是:(1)易洪涝的山丘区环境;(2)96.7降雨强度大、覆盖面广、持续时间长的异常雨情和高洪峰水位、流量的异常水情;(3)城市防洪标准低、水利水电工程防洪效益差和抗洪害意识不强等原因造成的城市防洪能力低;(4)砍伐森林、人为侵占河道和大型水库超常规蓄水等人类活动造成的不利影响。  相似文献   
443.
我国城市地价评估模型及其空间分布规律研究   总被引:11,自引:0,他引:11  
本文以城市地价产生地区差异的理论分析为依据,提出了城市地价的主要影响因素、因子,并以城市土地批租资料为基础运用逐步回归分析方法建立城市地价评估模型。根据模型估测了我国517个城市1992年的地价水平,最后分析了我国城市地价空间分布的规律及其未来走势展望。  相似文献   
444.
ABSTRACT. Estimates of peak flows, with specified return periods, are needed in practice for the design of works that affect streams in forested areas. In the province of British Columbia (B.C.), Canada, the new Forest Practices Code specifies the 100-year instantaneous peak flow (Q100) for the design of bridges and culverts for stream crossings under forest roads; and many practitioners are engaged in making such estimates. The state of the art is still quite primitive, very similar to the state of urban hydrology 30 years ago, when popular estimating techniques were used with little consideration given to their applicability. Urban hydrology then evolved on a much more scientific basis, such that within about a 10-year period, standard approaches to design were developed. Forest hydrology should follow the same pattern, at least as far as estimating design flows is concerned. Popular present day design procedures include the rational method and other empirical approaches based on rainfall data, as use of the standard flood frequency approach is limited by the paucity of relevant flow data. Estimating procedures based on peak streamflow measurements and statistics are likely to evolve, and these will include distinctions for rain, snowmelt, and rain on snow floods. Guidelines will also be developed for selecting and applying appropriate procedures for particular areas.  相似文献   
445.
在对西藏雅鲁藏布板块缝合线西段北亚带达机翁蛇绿岩的地质构造、岩石组合等进行野外考察的基础上,首次对该蛇绿岩的主量元素、微量元素、REE及Sr、Pb、Nd同位素进行了较系统的测试分析和综合研究,并由此探讨了该蛇绿岩的构造环境。提出该蛇绿岩为新特提斯东段岛海格局中的岛派成国,为已消亡的中生代新特提斯洋岩石圈的残片。  相似文献   
446.
城市工业水污染控制模拟系统的模型体系   总被引:5,自引:0,他引:5       下载免费PDF全文
基于工业水污染与工业活动的规模和结构紧密相关的事实,通过分析城市工业水污染经济学特征,依据环境经济学原理,建立城市工业水污染物排放模型。并以决策模型为核心,将水污染排放模型。水环境质量模型以及水污染损失模型整合在系统中,构成城市工业水污染控制模拟系统的模型体系。最后,在分析了黄河流域典型城市-呼和浩特市的工业水污染状况的基础上,建立了符合该市工业水污染特征的模型体系。  相似文献   
447.
Integrated environmental assessment: an urban perspective   总被引:2,自引:0,他引:2  
1 IntroductionUrbanareasthroughouttheworldareincreasinglyafocusofenvironmentalconcern.Theyareplacesofintenseandgrowingeconomicactivity.Inresponse,urbanpopulationsaregrowingrapidly.Itisestimatedthat,by2000,morethanhalftheworld○spopulationwillliveintow…  相似文献   
448.
1 IntroductionIntegratedenvironmentalassessment(IEA)isafundamentalmeansforcomprehensiveenvironmentalmanagementandforcoordinatingtherelationshipbetweeneconomicdevelopmentandenvironmentalprotection.IEAaimstoidentifythemainenvironmentalproblemsinaregion…  相似文献   
449.
基于1990-2016年的统计数据,采用场理论研究世界煤炭资源流动的时空格局变化及其成因,揭示近30年来世界煤炭资源的流动状态及其演变过程。研究结果显示:(1)2016年世界煤炭的输出总量达12.25亿t,比1990年增加了10.13亿t,年均增长6.98%,其中澳大利亚、印尼和俄罗斯等是主要的煤炭输出国,印度、日本、中国和韩国是主要的煤炭输入国;(2)以场理论的位势、流场分布、流动迹线角度分析,世界煤炭资源的流动以北美洲、中南美洲和非洲为源流场,以欧洲及欧亚大陆、中东和亚太为汇流场,在澳大利亚—东亚、印尼—东亚/印度之间形成主要运输航线;(3)资源空间分布、供需匹配程度、空间距离、市场因素和国家政策等是煤炭资源流动的主要动因。研究发现:虽然中国煤炭储量丰富,但是煤炭消费数量庞大,仅可维持72年,必须重视煤炭的进口和储备工作。该研究对于中国科学制定产业政策具有重要价值。  相似文献   
450.
介绍呼和浩特市城市生活垃圾的管理体制和垃圾处理、处置的现状,分析了管理中存在的问题,并对今后的管理提出相关的解决措施和建议。  相似文献   
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