Investigation on flood event variations at space and time scales in the Huaihe River Basin of China using flood behavior classification

Journal of Geographical Sciences - Flood is one of the severest natural disasters in the world and has caused enormous causalities and property losses. Previous studies usually focus on flood...     

Distribution of heavy metals in urban soils – a case study of Danang-Hoian Area (Vietnam)

 This work is part of a research study which is intended to study the degree of anthropogenic influences of the trace metal distribution of soils from Danang-Hoian area (Vietnam). Cu, Ni, Zn and Zr show significant effects in most of the cultivated soil categories, especially in the industrial soils. Extremely high levels of Pb (up to 742 μg/g) are observed in the industrial soil category, which shows an enrichment factor 114 as compared to rural soils. Cd shows only a relative local enrichment with the maximum level of 4.6 μg/g in urban soils. Sequential extraction was performed in selected samples to evaluate the geochemical trace metals. The result indicates that Zn and Cr are mainly found in the crystal and amorphous Fe oxide bounded forms. The contents of Cr in these fractions comprise more than 94% of total extractable Cr. In the case of Zn, 85% of total extractable Zn is in fractions F_V and F_VI. Cu is mainly found in the organic fraction at an average of 39.3% of total extractable content. On the other hand, heavy metal contents show an increasing tendency in the fine fraction (silt and clay). Received: 4 February 1998 · Accepted: 26 November 1998     

旅游对目的地社会文化影响的研究进展

旅游发展使旅游目的地社会生活的各个方面都发生了变化, 这个问题从20 世纪60 年代 开始就引起了国外学者的关注, 并作为热点问题持续至今。本文结合人类学家的部分研究成果, 从国内外相关研究的成果数量、研究内容和研究方法入手, 系统总结了当前国内外关于旅游对目 的地社会文化影响研究在理论、观点、方法、实践、模型等方面取得的最新进展, 指出了当前该领 域研究中的薄弱环节和我国学者在研究中出现的主要问题： 实证研究较多, 理论总结少; 定性方 法多, 定量测算少; 研究观点的片面性; 研究指标各异, 可比性不强。从长远的角度看, 研究成果和 实际发展管理的紧密结合、研究技术的突破和理论体系的确立、多学科融合综合研究将成为这个 领域的主要发展方向。     

论太湖平原洪涝灾害与水利工程问题和发展趋势

在分析研究太湖流域洪涝灾害成因及以围圩、筑堤、建闸为特点的圩区经济基础上,论述了近几十年来流域下垫面变化对流域水情的影响。总结了近40年来流域水利工程规划设计的经验与不足之处;展望了未来几十年流域水情变化发展趋势,特别是全球海平面上升对流域洪水蓄、泄方面的重大影响。指出在流域十大骨干水利工程的基础上,今后流域中新建骨干工程的关键目标是提高长江南岸、杭州湾北岸闭闸时段的排洪能力及建设吴淞挡潮闸,从而大幅度提高各潮周期内黄浦江净泄洪量;同时运用非工程措施,确保与充分利用区内洪水调蓄能力。     

胶州湾扇贝养殖对海域环境影响的初步研究

在2004年11月17日对胶州湾西部扇贝养殖区及周围海区进行的综合海洋环境调查的基础上,分析了胶州湾秋季扇贝养殖区与非养殖区的海洋环境状况,初步探讨了扇贝养殖在收获期对养殖区环境的影响。胶州湾养殖区表层水中COD和无机营养盐含量,除了NO2 -N的变化不明显外,均高于非养殖区的值。养殖区底层水中溶解氧含量和表层沉积物中硫化物的含量均明显超标。因此,肢州湾的扇贝养殖在收获期对环境的影响也是综合性的,且养殖海域的环境同时受陆源、水动力状况及养殖活动的综合影响。     

Estimations of climate change impacts on crop production in the Republic of Moldova

Statistical methods for assessing crop sensitivity and vulnerability to climate change in Moldova were demonstrated and the following procedures were discussed: (1) projections of likely agroclimatic change; (2) assessments of crop sensitivity to climate change; and (3) assessments of the impact of climate change on crops. In order to predict the future agroclimate, key meteorological variables were transformed statistically to correspond to changes in plants' heat and water supply characteristics. Sensitivity of crop production was examined for corn and winter wheat. By combining the agroclimatic changes with crop response, possible impacts have been estimated and form a basis for possible adaptation strategies. It was shown that regional climate change can result in elevated aridity of Moldova's territory, especially during periods of crop growth. Cultivation of cereal crops in new agroclimatic conditions without adaptation measures will negatively affect yields, especially of winter wheat, whose yield decrease may be 18–39% by 2020s and 22–50% by 2050s. Corn yields may increase by 0–3% and 1–6%, respectively. As an example of adaptation, it is shown that the use of an increased number of late hybrids results in a 25–35% increase in corn yields. This revised version was published online in July 2006 with corrections to the Cover Date.     

前寒武纪突发事件与小行星/彗星碰撞的联系——地球科学中灾变观的重现

包括地外事件在内的地球中阵发性的意义重新引起了１８世纪均变论与灾变论之间的论争。看来有些前寒武纪构造热事件可能关系到和代表着大直径（Ｄｐ１０ｋｍ）抛射物大型撞击的最终效果。特别是，影响到构造上活动、地热上活跃的即硅镁壳下厚度小于２０ｋｍ的地区，可望引发区域性及全球性的亚岩石圈扰动、岩浆突发作用和大岩浆省的形成。对地壳活动带大型撞击的结果可能难以与完全由内因触发的事件相区别，因为①由撞击反应的地幔绝热熔融形成的、热传导能够广泛的再结晶和有关的变形覆盖初始冲击变质效应；②隆起地区的剥蚀、埋没和俯冲可能使初始撞击效应广泛消失。因此最终的，包括滑塌堆积、混杂堆积、浊积沉积、微波陨石（ｍｉｃｒｏｔｅｘｔｉｔｅ）及微晶柱（ｍｉｃｒｏｃｒｙｓｔｉｔｅ）（气化小行星和标准物质的球粒冷凝液）与地球化学异常一起提供了揭示前寒武纪撞击史的钥匙。主要撞击事件撞击期的论据可从保存的撞击标志、岩墙群、火山岩序列及碱性侵入岩的同位素年龄值分布直方图的热峰值的比较中获取。文章对前寒武纪地壳记录中这些事件标志的确认有两个前途：①用西澳具有保存良好的太古宇至新元古界（２１５～１Ｇａ）的约２０００ｋｍ２的Ｐｉｌｂａｒａ克拉通地区为例进行区域研?