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排序方式: 共有197条查询结果,搜索用时 203 毫秒
81.
澜沧江流域生态系统水源涵养功能研究 总被引:4,自引:0,他引:4
生态系统的水源涵养功能一直以来都是生态学和水文学研究的热点和难点问题。本文基于新开发的InVEST模型对澜沧江流域的水源涵养功能进行了研究,得出以下结果:(1)澜沧江流域年均供水7.24E+10 m3 y-1,其中干流贡献率为23.87%,而支流贡献率为76.13%,从上游至下游呈明显递增趋势。(2)草地生态系统和森林生态系统的水源涵养量贡献率共计达71.66%;对不同组成结构生态系统类型的水源涵养能力进行比较,阔叶林〉针阔混交林〉竹林〉针叶林〉灌木林〉草地。(3)澜沧江流域三分之二的水由占总面积40%的热点区域提供。研究为澜沧江流域水资源的有效管理提供一定依据。 相似文献
82.
Pham Tich Xuan Nguyen Van Pho O. L. Gas’kova S. B. Bortnikova 《Geochemistry International》2013,51(11):931-938
This study provides an assessment of the environmental impact of open pit mining operations at the Cay Cham titanomagnetite-ilmenite deposit (northern Vietnam). The results of surface water sampling indicate the formation of acid mine drainage and contamination of adjacent areas by heavy metals (Cu, Zn, Ni, and Mn). The acid mine drainage is produced by oxidation leaching of sulfide minerals associated with primary mineralization owing to the low neutralization potential of the natural waters in the humid environment of tropical rainforest. The study showed that alternating dry and wet seasons typical of this climatic region promote the generation of stored acidity leading to a sharp decrease in pH of drainage water during the wet season and result in the negative impacts of this mine on both flowing and stagnant surface waters. 相似文献
83.
Model experiments were performed on the solubility of sulfide ores from the Kyzyl-Tashtyg deposit in distilled water and fulvic-acid (FA) solutions of different concentrations. It has been established that the oxidation of sulfide minerals in ores under atmospheric conditions might produce acid drainage waters with toxic heavy metals (Cu, Zn, Cd). The influence of natural organic acids depends on the capability of ore and host rock to neutralize the acidity of solutions. If carbonate content is enough at the first stage, a considerable increase in the pH value of FA-free solutions ensures Fe and Cu removal into the solid phase, whereas the formation of metal fulvate complexes hinders this process. However, when the rocks exhaust their neutralizing potential, all the solutions remain acidic for > 100 days of leaching. In this case, FAs, on the contrary, inhibit the oxidation of the surface of sulfide minerals and reduce the removal of heavy metals into the solution. 相似文献
84.
SUN Haitao ZHONG Dakang ZHANG Simeng WANG Xingming.State Key Lab of Petroleum Resource Prospecting Faculty of Natural Resource Information Technology China University of Petroleum Beijing China.Exploration Development Research Institute of Dagang Oilfield Company PetroChina Tianjin China 《东北亚地学研究》2010,(1)
There are eighty sedimentary basins in five different types in African continent,i.e.craton sag basin,foreland basin,intermountain basin,passive margin basin and rift basin,which underwent the stress environment of stable depression-compression-extension.The first three types of basins had been intensely influenced by Hercynian and Alpine tectonic movement,while the later two types of basins always exist in a stable extension environment.Different basin evolution caused the obviously hydrocarbon distributio... 相似文献
85.
渤海湾盆地黄骅坳陷中北区新生代幕式沉降过程 总被引:4,自引:0,他引:4
黄骅坳陷中北区是位于渤海湾盆地中部的一个重要新生代构造单元.构造层序界面分析、同生断裂活动和盆地沉降史回剥分析表明该区经历了幕式沉降过程,沉降中心显示出规律性的迁移演化特征.馆陶组底界面为区域性裂后不整合界面,将研究区的演化划分为裂陷期和裂后期.在裂陷期的充填序列中,沙一段底界面为整个研究区都可以识别的显著的角度不整合界面,以此界面为界,盆地的裂陷期进一步划分为裂陷Ⅰ幕和裂陷Ⅱ幕.裂陷Ⅰ幕发育了Es3-Es2地层,断裂几何学和断裂的性质表明该幕构造活动为北西南东向伸展作用所致,而裂陷Ⅱ幕发育了Es1-Ed地层,为近南北向拉伸作用的结果.裂后期,从早到晚则表现为由稳定热沉降到加速沉降的过程.分析认为上述盆地的幕式沉降过程与区域应力场的转变密切相关,受控于周缘板块的动力学事件,尤其是晚始新世之后,太平洋板块对欧亚大陆向西的加速俯冲,促使了郯庐断裂右旋活动向南延伸和穿过黄骅坳陷的兰聊断裂北段的活化,形成了位于渤海海域的南北向伸展叠加区,从根本上改变了黄骅坳陷中北区应力场的分布,由此导致了盆地同裂陷阶段的幕式演化. 相似文献
86.
10-水锰矿是海洋成岩型铁锰结核和很多陆生锰矿的主要矿物,铜、镍等过渡金属元素对于10-水锰矿结构的稳定起着重要的作用,而对于碱金属元素钠离子在其中的地球化学行为则少有涉及.利用取自东太平洋海底的成岩型铁锰结核,借助化学方法,利用矿物学和晶体化学的理论对碱金属元素钠离子在成岩型铁锰结核中的存在状态以及对结核组成矿物10-水锰矿结构的影响进行了研究.结果显示,10-水锰矿中钠离子可以被弱酸析出并且会导致其结构的破坏,使得10-水锰矿转换成7-水锰矿;析出钠离子并且结晶状态变差的10-水锰矿吸附钠离子后,其结晶状态可明显好转并且部分非10相转化为10-水锰矿,但是这种结构的破坏在自然条件下不能完全恢复.因此,钠离子对于10-水锰矿结构的稳定性起着非常重要的作用. 相似文献
87.
88.
基于Applet-CORBA的空间物流信息平台体系 总被引:5,自引:0,他引:5
现代科学技术的迅速发展,尤其是信息技术的迅速发展,极大地促进了物流管理技术的发展。在供应链的“四流”,即物流、商流、资金流、信息流中,信息流提升到了前所未有的高度,信息获取和处理的实时性和准确性是物流管理成败的关键。本文首先简单介绍了物流管理技术、空间信息技术以及这两种技术集成的优势,然后结合当前分布计算技术中最具发展潜力的CORBA技术,设计了基于Applet-CORBA的空间物流信息平台,并对系统的体系结构进行了分析。 相似文献
89.
陈百明 《中国地理科学(英文版)》1997,(1)
I.MR.BROWN'SMAINOPINIONMr.LesterBrown,'presidentoftheWorldWatchinstituteintheU.S.A,publishedalongicicletitledas"WhowillfeedChina"in1994(Brown,1995),whicharousedgreatresponSeSfromhomeandabroadandattractedmuchattentionfromallsides.Theadnideasofthearticleincludethefollowingthreepoints:(1)ItisestimatedthatthepopulationofChinawillincrare490whitionfrom1990tO2030,uptol,600whition;thecultivatedlandofChinaisaffectedbythemedeAnzationoftheeconomy,andisevendisap~ng;inaddition,thepotentiality… 相似文献
90.
MEI Mingxiang MA Yongsheng GUO Qingyin Institute of Earth Sciences Natural Resources China University of Geosciences Beijing China Petrochemical Corporation 《《地质学报》英文版》2001,75(4):421-431
The Mesoproterozoic Wumishan Formation in the Jixian section of Tianjin is a succession of 3300-m-thick carbonate strata formed in a period of about 100 Ma (1310±20 Ma-1207±10 Ma). In this succession of strata, the carbonate metre-scale cyclic sequences belonging to peritidal type with an approximately symmetrical lithofacies-succession are best developed. The wide development of 1:4 stacking patterns shows that these metre-scale cyclic sequences are genetically related to the short-eccentricity cycles, which are called the Wumishan cyclothems that could truly represent sedimentary cycles. Generally, massive and thick-bedded calcareous dolomites and dolomitic limestones of stromatolite biostromes and thrombolite bioherms constitute the central part of the Wumishan cyclothems. The lower and upper parts consist of tidal flat dolostones, sandy-muddy dolostone and the top part is composed of lagoonal facies dolomitic shales with a paleosol cap. Therefore, an approximately symmetrical lithofacies-successio 相似文献