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The Domingos Petrolini Swamp, located on the Southern Coastal Plain of Rio Grande do Sul, near the town of Rio Grande, constitutes an ample holocene lagoonal deposit. Events related to the holocene transgression and their diverse phases of glacial-eustatic ocillations were found through palynological analysis. Bases on these palynological data, four distinct phases to the paleoenvironmental evolution of the ecosystem were identified. It has also shown a transgressive restricted marine sequence on the base , which suggests the existence of a coastal brackish lagoon or a marisme type of environment. Later, there was a gradation for continentality conditions along with a scarce pollinical record. The third phase is characterized by the presence of marine components and halophyte vegetation, showing another transgressive event in that place. Lastly, the end of direct marine influence over the swamp was recorded and also the vegetation development as it appears these days. 相似文献
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Pu Wang R. Kahawita Professor of Mechanics Lenzhou University Lanzhou China. Professor of Civil Ensineering Ecole Polytechnique de Montreal Canada. 《国际泥沙研究》1990,(1)
I. INTRODUCTIONNumerical models of estuaries incorporating simulation of the density induced circulation are consideredimPOrtant tools in the assessment of their dispersive characteristics. Most models to date have used finite difference approximations to the governing equations (see for example thericke and Hogan, 1977, Blumberg,1 977, Perrels and Karelse, 1978). A numeriCal model of estuarine circulation using a SADI (Spline Alternating Direction implicit) procedure together with a… 相似文献
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I. ISTIARTO W.H. GRAF Res. Asst. Lab. de recherches hydrauliques Ecole Polytechnique Federale Lausanne Switzerland. E-mail: adhy.kurniawan@epfl.ch or istiarto@tsipil.ugm.ac.id Prof Lab. de recherches hydrauliques Ecole Polytechnique Federal 《国际泥沙研究》2001,(4)
1 INTRODUCTION'LOcal scour around a pier is a result of the interatiOn amongst the pier, the aPproach flow and theerodible bed. The Presence of a pier results in a stagnation pressure build-up in front of the pier and athree-dimensional tUrbulent flow echaracterized by the downward flow ahead of the pier and the so-called horseshoe vortex along the base of the Pier forms itself The flow modifies the erothe bed inthe vicinity of the pier when local scour takes place (Graf and AJhnakar l… 相似文献
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The dynamic headspace titration of the volatile constituents of the black truffle(Tuber Melanosporum)isplanned to be carried out with the new gas chromatographic device DCI using Tenax trapping.In thispaper the necessary optimization of the experimental factors which influence the desorption of thevolatiles from the sample and the adsorption on the trap is carried out by experimental design.The studyof the isoresponse curves makes it possible to determine the optimum conditions for a rapid titration ofhighest sensitivity and reproducibility,avoiding water trapping. 相似文献
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Andreas MALCHEREK Research Engineer Federal Waterways Engineering Research Institute 《国际泥沙研究》1997,(3)
LINTRODUCTIONThesimulationofmorphodynamicsinestUariesandcoastalareasisbecauseofitSeconomicalmeritageononehandandofitSscientificcomplexityontheOtheranoutStalldingfieldofresearchanddeVelopment.TheFederalWaterwaysEngineeringandResearchinstitote(BAW)isthecentraladvisoryinstitutefortheGermanwaterwayauthority.ItisthereforereSPonsibletoprovidethescientificsuPPOrtforoptimalsedimentmanagemelltproceduresforWatCrwaymaill~ce.ThehydredynndcSystemanalysisisthemainaPProachtosupportengineeringd… 相似文献
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越来越多的野外观测和实验数据表明,气相对成矿元素的迁移和富集具有不可忽视的作用。由高温火山气体形成的升华壳和凝结水中富集多种岩浆组分和成矿金属;中低温的地热田水蒸气中也检测到成矿元素;某些斑岩型铜-金矿床的富气体包裹体比共存的盐水包裹体更富集Cu和Au。金属呈简单氯化物或氟化物、硫化物、含氧酸及原子迁移的理论假设低估了400℃以下气体搬运成矿金属的能力,而必须考虑溶剂化作用(水合作用),有关银、金、铜、锡、钼、钨在水热气相中的溶解度实验证实了这一点,基于实验数据的热力学模拟计算表明,水热气相可运移足够的成矿金属以形成具有经济价值的浅成热液型和斑岩型矿床。此外,实验也证实砷和硼从液相分配至气相中也与水合作用有关,其气液相间的分配系数随温度和水蒸气的压力增大而增强。无疑地,成矿金属被水热气相搬运的理论对理解金属矿床的形成机理和发展诸如深穿透地球化学的地球气找矿方法具有重要意义。 相似文献
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