彗木相撞中的惯性引力波

苏梅克-列维9号彗星(SL9)与木星相撞后，在木星上观测到的以常速度(～450m／s)向外扩展的圆环意味着这是碰撞在木星大气中引起的线性波动．我们选取：非旋转、无粘性、密度分层、不可压缩的木星大气模型，而且木星大气以水平速度U=b az运动；给出初始扰动压力P(r；0)作为碰撞的初始条件，用流体力学方程组求解了彗木相撞中的惯性引力波．结果表明：当木星大气以速度U=U0(～170m／s)运动时，彗星碎片的大部分能量都用来产生内波，同时还得到彗星碎片的撞击深度H与水平相速Vp的关系式．当木星大气以速度为U=b az运动时，木星大气的扰动能量不再是在动能和势能间均分。     

Calculation of Ecological Footprint Based on Modified Method and Quantitative Analysis of Its Impact Factors ——A Case Study of Shanghai

1 Introduction The publication of UNDPI (The United Nation Devel- opment and Planning Indices) in May 1990 has brought about an on-going search for the system of “sustainable development”, which is also one of hot topics in China (Wackernagel et al., 1999; Vuuren and Smeets, 2000). Regretfully, the difficulty in quantifying sustainable de- velopment resulted in a slow progress in those researches. In the past a few years, however, ecological footprint (EF) analysis (Rees, 1992; Wackn…     

Discontinuous analysis of softening solids under impact loading

Softening solids are analysed under impact loading using a new numerical method which allows displacement discontinuities to propagate arbitrarily through a finite element mesh. The Dirac‐delta distributions that arise in the strain field of classical continuum theory in the presence of strain softening are interpreted as discontinuities in the displacement field. A new finite element procedure with Heaviside jumps added to the underlying displacement interpolation basis is able to capture displacement jumps independent of the spatial discretisation. The amplitudes of displacement jumps are represented by extra degrees of freedom at existing nodes. Numerical results for mode‐I and mode‐II failure due to impact loading are presented. The numerical results highlight the objectivity of the approach with respect to spatial discretisation under dynamic loading conditions. Copyright © 2001 John Wiley & Sons, Ltd.     

Degradation of High Mountain Ecosystems in Northern Europe

Data material of a long-term high mountain ecosystem research project was used to interpret the grazing impact of reindeers. In central Norway investigations were conducted to both, areas where reindeer grazing is excluded, and areas where intensive pasturing is present for a long period of time.The comparative analysis of grazing impact was based on similar environmental conditions. The results were transposed to northern Norway where dramatic overgrazing had been exceeding the carrying capacity. Using landscape ecological mappings, especially of vegetation and soils, the impact of reindeer grazing in different areas became obvious. Non-grazed lichen-dominated ecosystems of the snow-free locations functioned sensitively near the limit of organism survival. These localities were most influenced by grazing as they offer the winter forage to the reindeers. So, intensive grazing in central Norway led to landscape degradation by destruction of the vegetation and superinduced by soil erosion. Those features were comparable to the situation in northern Norway, where a broad-scale destruction of the environment combined with a depression of the altitudinal belts had occurred due to overgrazing. Functioning principles of intact high mountain systems were explained and used to interpret the environmental background for the understanding of degradation phenomena. Finally, the use of a new model calculating the carrying capacity of high mountain landscape was discussed.     

BOOK REVIEWS

Book Reviewed in this article: Main Street: Northeastern Oregon: The Founding and Development of Small Towns . Barbara Ruth Bailey . Food Politics: The Regional Conflict . David N. Balaam and Michael J. Carey , eds. The International Economy and Industrial Development: Trade and Investment in the Third World . R. Ballance , J. Ansari and H. Singer . Neighborhoods in Urban America . Ronald H. Bayor , ed. The English Heartland . By Robert Beckinsale and Monica Beckinsale . Regional Dimensions of Industrial Policy . Michael E. Bell and Paul S. Lande , eds. Tension Areas of the World . D. Gordon Bennett , ed. Latin America: an Introductory Survey . B. W. Blouet and O. M. Blouet , eds. Integration and Division: Geographical Perspectives on the Northern Ireland Problem . Frederick W. Boal and J. Neville H. Douglas , eds. Energy and Land Use . Robert W. Burchell and David Listokin , eds. Slopes and Weathering . Michael Clarke and John Small . Alaska's Rural Development . Peter G. Cornwall and Gerald Mc Beath , eds. The Politics of Park Design: A History of Urban Parks in America . Galen Cranz . World Congress on Land Policy, 1980, Proceedings . Matthew Cullen and Sharon Woolery , eds. Oregon Divided: A Regional Geography . Samuel N. Dicken and Emily F. Dicken . Urban Food Marketing and Third World Rural Development . T. Scarlett Epstein . South Africa: Spatial Frameworks for Development . T. J. D. Fair . Institutions and Geographical Patterns . Robin Flowerdew , ed. Industrialization of U.S. Agriculture, An Interpretive Atlas . Howard F. Gregor . Planning Theory: Prospects for the 1980s . Patsy Healy , Glen Mc Dougall and Michael J. Thomas , eds. Neighborhood Mobilization: Redevelopment and Response . Jeffrey R. Henig . The American Urban System: A Geographical Perspective . R. J. Johnston . Climate, History and the Modern World . Hubert H. Lamb . Climate and History: Studies in Past Climates and Their Impact on Man . T. M. L. Wigley , M. J. Ingram and G. Farmer . China: Railways and Agricultural Development, 1875–1935 . Ernest P. Liang . A Desirable Energy Future—A National Perspective . Robert S. Livingston , T. D. Anderson , T. M. Besmann , M. Olszewski , A. M. Perry , and C. D. West . Topothesia: Essays Presented to T. S. Ó Máille . B. S. Mac Aodha , ed. Transportation for the Poor: Research in Rural Mobility . Hal S. Maggied . Land Uses in American Cities . Harold M. Mayer and Charles R. Haves . Industrial Organisation and Location . Philip Mc Dermott and Michael Taylor . Human Adaptability: an Introduction to Ecological Anthropology . Emilio F. Moran . Regional Analysis and the New International Division of Labor . Frank Moulaert and Patricia W. Salinas , eds. The Nuclear War Atlas. Victoriaville, Quebec, Canada : Urbanization and Environmental Quality . Isao Orishimo . The Garden of Eden: The Botanic Garden and the Re-Creation of Paradise . John Prest . Earthfire, The Eruption of Mount St. Helens . Charles Rosenfeld and Robert Cooke . Contest for the South China Sea . Marwyn S. Samuels . The Future of the Wetlands: Assessing Visual-Cultural Values . Richard C. Smardon , ed. Tucson: the Life and Times of An American City. C. L. Sonnichsen . The Geography of Multinationals . Michael Taylor and Nigel Thrift , eds. Impact of Marine Pollution on Society . Virginia Tippie and Dana Kester . Reviving the Industrial City: the Politics of Urban Renewal in Lyon and Birmingham . Jerry A. Webman . Andean Reflections: Letters from Carl O. Sauer While on a South American Trip under a Grant from the Rockefeller Foundation, 1942 . Robert C. West , ed. Cartographic Drawing with Computers . P. Yoeli .     

Oil-spill fishery impact assessment model: Application to selected Georges Bank fish species

An oil-spill fishery impact assessment model composed of an oil-spill fates model, a shelf hydrodynamics model, an ichthyoplankton transport and fate model, and a fishery population model originally developed by Reed & Spaulding, has been improved and applied to the Georges Bank-Gulf of Maine region to assess the probable impact of oil spills on several key fisheries. The model addresses direct impacts of oil on the commercial fishery through hydrocarbon-induced egg and larval mortality. This early life stage hydrocarbon-induced mortality is estimated by assuming a toxicity threshold approach and by mapping the spatial/temporal interaction between the subsurface oil concentrations caused by the spill and the developing eggs and larvae. Model output is given in terms of differential catch, with a comparison made of hydrocarbon-impacted fisheries.Simulations of tanker and blowout spills at two separate locations for each season of the year in the Outer Continental Shelf lease areas have been completed for Atlantic herring, haddock, and Atlantic cod. Results to date suggest a complex interaction among spill location and timing, the spatial and temporal spawning distribution of the species, and the hydrodynamics of the area. The largest impacts occur for spring and winter spills.     

Mining threatens isolated indigenous peoples in the Brazilian Amazon

The largest concentration of isolated indigenous peoples in the world is in the indigenous lands of the Brazilian Legal Amazon. However, the right to self-isolation and the survival of these societies are at risk because powerful interests want to exploit the natural assets of their relatively untouched areas. These ambitions are reflected in a recent bill (PL191/2020), which proposes opening up indigenous lands to mining. We assess the threat imposed by mining to isolated peoples and the indigenous territories they occupy. Specifically, we cross data on mining requests received by the National Mining Agency with information on the distribution of isolated indigenous groups recorded by the Socio-Environmental Institute, in order to evaluate the number and aerial extent of requests for mineral prospecting and operation registered in indigenous lands with isolated groups. We also analyze whether mining requests are related to the presence of isolated groups, the state of knowledge about them, and the current existence of illegal mining operations. Our results indicate that, even though mining is not yet allowed in indigenous lands, mining companies are very active in the search for exploitable areas in these territories. If bill PL191/2020 passes, mining operations would affect more than 10 million hectares in 25 indigenous lands in the Legal Amazon region that are home to 43 isolated groups. We found that the situation is especially worrisome for 21 isolated groups whose lands concentrate 97% of all mining requests. Mineral-rich areas overlap remote areas where more indigenous peoples persist in isolation, so that mining requests are significantly related to the presence of isolated groups. Nonetheless, we show that companies are hesitant to invest in lands with well-known isolated groups that could impede the licensing process and pose reputational risks to the companies. Brazil’s mechanisms for environmental and indigenous protection have been dismantled by the current presidential administration and offer no guarantees for a safe coexistence between extractive operations and isolated peoples. Thus, the approval of bill PL191/2020 could lead to undesired contact and the extinction of a large number of unique peoples, societies and cultures.     

层析分析法在高速公路生态环境影响评价中的应用

通过介绍层次分析法的基本原理、步骤和计算方法,将层析分析法应用到高速公路生态环境影响评价研究中,以宝(鸡)天(水)高速公路为例,将此方法运用在公路生态环境影响评价的方案比选问题中进行分析.评价结果表明:层次分析法不仅是处理公路建设生态环境影响评价中方案比选问题的有效手段,而且提高了权重定量的理性成分,其评价结果与实际结果具有较好的一致性.最后论述层析分析法在高速公路生态环境评价中的优缺点,以此为今后高速公路生态环境影响评价研究提供参考依据.     

中国典型有机污染场地土层岩性和污染物特征分析

目前我国存在大量待修复场地,其分布具有一定的规律性和区域性,场地地层系统结构复杂、渗透性空间异质性显著,污染物种类复杂。总结场地典型土层结构和典型污染物有助于有针对性地开展修复技术的研发。为此,本文收集并整理了全国136处有机污染场地相关资料,对其地域性、地层及污染物特征总结如下:目前我国已经开展调查与修复的有机污染场地主要集中在京津冀和沪宁杭地区;有机污染场地土层基本都含有黏土等低渗透介质,而且都具有非均质性,其中67%场地土层有强非均质性;沪宁杭地区场地土层渗透性总体低于京津冀和辽中南地区,此外我国京津冀和辽中南地区场地调查深度(20.3 m)总体大于沪宁杭地区(12.8 m);我国有机污染场地地下水中最常见的有机污染物种类为氯代溶剂,依次为氯代烷烃类(场地数量占比84%)、氯代苯类(场地数量占比46%)和氯代烯烃类(场地数量占比33%);最常见的3种氯代溶剂依次为二氯乙烷、一氯苯和三氯甲烷。