血吸虫病的生态防治与抑螺防病林消除钉螺孳生环境机制   总被引：2，自引：0，他引：2  

费世民  周金星  张旭东  蒋俊明  陈秀明 《湿地科学与管理》2006,2(4):28-32

血吸虫病是发展中国家主要的寄生虫病之一,历史悠久,传播广泛,危害严重。研究表明,血吸虫是血吸虫病的病原体,哺乳类动物(终末宿主)和钉螺(中间宿主)是血吸虫的两个宿主。由于钉螺寄生终末宿主哺乳类动物种类多样,活动区域繁杂,人类难以控制,抑制中间寄主——钉螺的繁生便成了血吸虫病防治的有效对策。钉螺具有水陆两栖特性,其中卵的孵化、幼螺的生长发育离不开水。钉螺分布和数量受土壤和植被环境因素影响,并对栖息地具有严格的选择性。依据钉螺生物学和生态学特性,彭镇华和江泽慧提出通过林业生态工程对血吸虫病进行生态防治的思路——兴林抑螺。参照前人研究结果,综合分析了抑螺防病林改变钉螺孳生环境的机制:(1)在林木个体耗水、林分耗水、小流域耗水和林冠降低径流等方面,抑螺防病林降低了土壤水分含量,使得林地土壤水分无法满足钉螺的生长和发育条件;(2)从林木自身生物化学物质对钉螺外在生存和内部代谢环境影响角度,分析了林木自身代谢产物对抑制钉螺的生存和繁殖的作用及抑螺防病林抑制钉螺生存的生理生化机制。抑螺防病林除了具有抑制钉螺生长发育、控制血吸虫病的功能以外,还兼有人工林的多重效益。  相似文献   

Site Effects Study in the Serravalle Village (NE Italy) by Means of Spectral Ratios Analyses Relatively to Multiple Reference Sites     

Andrea Restivo  Carla Barnaba  Alberto Michelini 《Natural Hazards》2006,39(1):31-49

The area of Serravalle, sited in the northern part of the town of Vittorio Veneto (TV), NE Italy, has been the target of a seismic microzonation campaign. 10 seismic stations have been deployed for a 7 months period to record in continuous mode. Three stations were installed on bedrock outcrops and seven on sedimentary sites with variable cover thickness. Spectral analyses have been performed on the collected data-set using the Generalized Inversion Technique (GIT, e.g. Andrews, 1986). In particular, spectral ratios have been calculated for each station relatively to the average of the three reference, bedrock sites. The spectral ratios provide quantitative estimates of the seismic motion amplifications which occur in each of the monitored sites. Two sites show high values of amplification, 5 times larger than signal amplitude at the reference sites, in correspondence of well discernible peak frequencies of 5 Hz. Results for the other stations show smaller amounts of site amplification spreading over a broad range of frequencies. Sites where the highest amplifications were recorded all lie on the left bank of the Meschio River and in areas farther away from its outlet into the plain correlating with the presence of thick layers of Quaternary deposits.  相似文献   

Benthic foraminifers in upper Quaternary sediments of the southern Bering Sea: Distribution and paleoceanographic interpretations     

T. A. Khusid  I. A. Basov  S. A. Gorbarenko  M. P. Chekhovskaya 《Stratigraphy and Geological Correlation》2006,14(5):538-548

Composition and distribution of benthic foraminifers, being coupled with isotopic-geochemical data on Upper Pleistocene and Holocene sediments from the southern Bering Sea (Core GC-11; 53°31′ N, 178°51′E, water depth 3060 m), demonstrate variations in bottom water properties during the last 54 kyr. Their abundance increased to some extent during short periods corresponding to warm Dansgaard-Oeshger interstadials 14, 12, 8, and 2 of marine isotopic stages (MIS) 3 and 2. The first and second deglaciation phases separated by the Younger Dryas cooling episode are marked by significant abundance peaks of benthic foraminifers (an order magnitude higher than in the glacial period), although their share in community of benthic and planktonic foraminifers taken together decreases. Species typical of stable high-productivity areas gain the dominant position. A significant proportion of agglutinated species in the Holocene sediments is indicative of Ca ions deficiency that accelerates dissolution of carbonate tests up to their disappearance approximately 2.5–3 ka ago.  相似文献   

Temperature dependence of large-scale water-retention curves: a case study     

Hui-Hai Liu  G. S. Bodvarsson  J. H. Dane 《Hydrogeology Journal》2006,14(8):1403-1408

A local-scale model for temperature-dependence of water-retention curves may be applicable to large scales. Consideration of this temperature dependence is important for modeling unsaturated flow and transport in the subsurface in numerous cases. Although significant progress has been made in understanding and modeling this temperature effect, almost all the previous studies have been limited to small scales (on the order of several centimeters). Numerical experiments were used to investigate the possibility of extending a local-scale model for the temperature-dependence of water retention curves to large scales (on the order of meters). Temperature effects on large-scale hydraulic properties are of interest in many practical applications. Numerical experiment results indicate that the local-scale model can indeed be applicable to large-scale problems for special porous media with high air entry values. A typical porous medium of this kind is the porous tuff matrix in the unsaturated zone of Yucca Mountain, Nevada, the proposed geologic disposal site for national high-level nuclear wastes. Whether this finding can approximately hold for general cases needs to be investigated in future studies.  相似文献   

Basin-related effects on ground motion for earthquake scenarios in the Lower Rhine Embayment   总被引：1，自引：0，他引：1  

Michael Ewald  Heiner Igel  Klaus-Günter Hinzen  Frank Scherbaum 《Geophysical Journal International》2006,166(1):197-212

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H/V ratio: a tool for site effects evaluation. Results from 1-D noise simulations   总被引：9，自引：1，他引：9  

Sylvette Bonnefoy-Claudet  Cécile Cornou  Pierre-Yves Bard  Fabrice Cotton  Peter Moczo  Jozef Kristek  Donat Fäh 《Geophysical Journal International》2006,167(2):827-837

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油页岩综合利用对周围环境的影响——以抚顺矿区为例   总被引：3，自引：0，他引：3  

张丽萍曾荣树  徐文东金福杰 《中国煤田地质》2006,18(2):46-48,51

世界能源日益减少的局面为油页岩的开发应用带来广阔的前景，但油页岩工业所带来的环境影响亦不容忽视。以抚顺油页岩为例，从油页岩综合利用和油页岩工业对环境的影响等方面系统讨论了在我国发展油页岩工业时，如何本着节约能源、保护环境、实现可持续发展的观念，利用现有先进技术，科学发展油页岩工业，降低生产过程中的固、液、气污染物对环境的危害。  相似文献   

Early Estimation of Seismic Hazard for Strong Earthquakes in Taiwan   总被引：1，自引：0，他引：1  

Wen-Yu Jean  Yu-Wen Chang  Kuo-Liang Wen  Chin-Hsiung Loh 《Natural Hazards》2006,37(1-2):39-53

A shakemap system providing rapid estimates of strong ground shaking could be useful for emergency response providers in a damaging earthquake. A hybrid procedure, which combines site-dependent ground motion prediction models and the limited observations of the Real-Time Digital stream output system (RTD system operated by Central Weather Bureau, CWB), was set up to provide a high-resolution shakemap in a near-real-time manner after damaging earthquakes in Taiwan. One of the main factors that affect the result of ground motion prediction analysis is the existence of site effects. The purpose of this paper is to investigate the local site effects and their influence in the ground shaking and then establish an early estimation procedure of potential hazard for damaging earthquakes. Based on the attenuation law, the site effects of each TSMIP station are discussed in terms of a bias function that is site and intensity-level dependent function. The standard deviation of the site-dependent ground motion prediction model can be significantly reduced. The nonlinear behavior of ground soil is automatically taken into account in the intensity-level dependent bias function. Both the PGA and the spectral acceleration are studied in this study. Based on the RTD data, event correctors are calculated and applied to precisely estimate the shakemap of damaging earthquakes for emergency response.  相似文献   

MapGIS下空间数据库的建立及其典型问题研究   总被引：4，自引：0，他引：4  

李定平  胡光道  程路 《武汉大学学报(信息科学版)》2005,30(11):1029-1032

以云南省地质图、水文地质图空间数据库的建立为例,通过对空间数据库建设中资料准备、图形矢量化、空间数据处理及文件转换四个过程的分析,总结了在进行回溯型空间数据库建库过程中需要注意的一些典型问题,并提出了解决的办法。论述了在MapGIS下空间数据库建立过程中的一些技巧及经验。  相似文献   

高山峡谷区影响土壤测量找矿效果的元素表生活动特性研究   总被引：3，自引：0，他引：3  

马生明  朱立新等 《地质与勘探》2002,38(5):58-62

研究发现，高山峡谷区内土壤中元素的表生活动以表生富集作用为主，元素表征富集作用的程度、富集层位和粒级等受矿化作用和自然风化作用双重影响。非矿化地段土壤中元素的表生富集程度较矿化带处土壤中元素表生富集程度更强；矿化带处B层土壤比A层土壤中元素的富集强度稍大，元素明显地富集在粗粒级组分中；近矿（化）带的非矿化地段，A、B两层土壤仍受到矿化组分的影响，A层土壤比B层土壤受到的影响更加明显，粗粒级组分比细粒级组分反映敏感，C层土壤中元素在细粒级组分中轻微富集。根据本次研究结果，调整了高山峡谷区土壤测量工作方法，经试点测量验证，找矿效果良好。  相似文献