Controlling geological and hydrogeological processes in an arsenic contaminated aquifer on the Red River flood plain,Vietnam   总被引：1，自引：0，他引：1  

Flemming Larsen  Nhan Quy Pham  Nhan Duc Dang  Dieke Postma  Søren Jessen  Viet Hung Pham  Thao Bach Nguyen  Huy Duc Trieu  Luu Thi Tran  Hoan Nguyen  Julie Chambon  Hoan Van Nguyen  Dang Hoang Ha  Nguyen Thi Hue  Mai Thanh Duc  Jens Christian Refsgaard 《Applied Geochemistry》2008

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武汉市区第四系含水层地下水有机污染敏感性研究   总被引：14，自引：0，他引：14  

王焰新  付素蓉等 《地球科学》2002,27(5):616-620

在详细调查武汉市水文地质条件和地下水污染现状的基础上，获得了高精度的武汉市水环境中微量有机污染物的组成数据。所检测出的有机组分达30余种，以苯及相关苯系物为主，污染程度较高的地下水主要分布在人口密集区和工业，商业区，应用改进的DRASTIC模型－地下水污染敏感性评价模型，在GIS平台上，编制了武汉市区地下水污染敏感性分区图。根据其评价结果，建议集中对那些敏感性相对较高的区域采取有效的环保措施，开发利用时应作出风险评价。  相似文献   

A method to estimate hydraulic conductivity while drilling     

Kurt I. Srensen  Flemming Effers  Esben Auken  Louise Pellerin 《Journal of Hydrology》2002,260(1-4):15-29

A field test and analysis method has been developed to estimate the vertical distribution of hydraulic conductivity in shallow unconsolidated aquifers. The field method uses fluid injection ports and pressure transducers in a hollow auger that measure the hydraulic head outside the auger at several distances from the injection point. A constant injection rate is maintained for a duration time sufficient for the system to become steady state. Exploiting the analogy between electrical resistivity in geophysics and hydraulic flow two methods are used to estimate conductivity with depth: a half-space model based on spherical flow from a point injection at each measurement site, and a one-dimensional inversion of an entire dataset.

The injection methodology, conducted in three separate drilling operations, was investigated for repeatability, reproducibility, linearity, and for different injection sources. Repeatability tests, conducted at 10 levels, demonstrated standard deviations of generally less than 10%. Reproducibility tests conducted in three, closely spaced drilling operations generally showed a standard deviation of less than 20%, which is probably due to lateral variations in hydraulic conductivity. Linearity tests, made to determine dependency on flow rates, showed no indication of a flow rate bias. In order to obtain estimates of the hydraulic conductivity by an independent means, a series of measurements were made by injecting water through screens installed at two separate depths in a monitoring pipe near the measurement site. These estimates differed from the corresponding estimates obtained by injection in the hollow auger by a factor of less than 3.5, which can be attributed to variations in geology and the inaccurate estimates of the distance between the measurement and the injection sites at depth.  相似文献   

Winter seabird distribution and abundance off south-western Greenland, 1999   总被引：3，自引：0，他引：3  

Flemming Ravn Merkel  ers Mosbech  David Boertmann  Louise Grøndahl 《Polar research》2002,21(1):17-36

South-western Greenland constitutes an internationally important wintering area for many seabird species. Several species of management concern have a predominantly near-coastal distribution, though available information about seabird numbers is mostly confined to offshore waters. Here we report on extensive aerial surveys conducted in March 1999, covering the coastal waters (up to 15-20 km from the mainland coast) and fjords of south-west Greenland. The most widespread and numerous species were estimated as 463 000 common eiders ( Somateria mollissima ), 153000 king eiders ( S. spectabilis ), 125000 thick-billed murres ( Uria lomvia ), 94 000 long-tailed ducks ( Clangula hyemails ), and 12 000 black guillemots ( Cepphus grylle ). A total of 19 bird species were recorded. The estimates for common eider and long-tailed duck approximately represent the entire winter population in south-western Greenland while estimates for the other species represent only an unknown proportion since their distribution continues further offshore. Waters around Nuuk and within the Julianehåbsbugten (Julianehåb Bay) area were identified as areas of high seabird density. A large proportion of the common eider population was aggregated in the fjord systems (22%), calling attention to the importance of fjords for this species. In contrast, pelagic seabird species appear to be absent from the fjords. The large winter population of common eider reveals the importance of south-western Greenland as a key wintering area for the eastern Canadian breeding population. The western Greenland breeding population is the only other contributor, probably amounting to no more than 15 000 pairs.  相似文献   

Imaging buried Quaternary valleys using the transient electromagnetic method   总被引：3，自引：0，他引：3  

Flemming Jrgensen  Peter B. E. Sandersen  Esben Auken 《Journal of Applied Geophysics》2003,53(4):199

Buried Quaternary valleys in Denmark are complex structures filled with various deposits consisting primarily of glacio-lacustrine clay, till and meltwater sand, and gravel. The valleys are important geophysical targets, because they often contain significant volumes of groundwater used for public water supply. About 700 km of buried valley structures have been imaged in the western part of Denmark by the transient electromagnetic (TEM) method. The ability to map the valleys depends primarily on valley geometry, infill architecture and the resistivity of the fill sediments as well as the substratum. One-dimensional (1-D) inversion models of the TEM soundings have been used to construct contour maps of 20 m average resistivities and depth to a good conductor, which provide images for geological interpretation. Images of buried valley morphology, fill properties, infill architecture, such as cut-and-fill structures, valley distribution and valley generations, are characterized for case studies from Hornsyld, Holstebro and the Vonsild/Agtrup areas of Denmark.  相似文献   

Response of the wadden sea to a rising sea level: a Predictive empirical model     

Burghard W. Flemming  Alexander BartholomÄ 《Ocean Dynamics》1997,49(2-3):343-353

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Corrigendum to “Deformation of polycrystalline iron up to 30 GPa and 1000 K” [Phys. Earth Planet Inter. 145 (2004) 239–251]     

Sbastien Merkel  Hans-Rudolf Wenk  Philippe Gillet  Ho-kwang Mao  Russell J. Hemley 《Physics of the Earth and Planetary Interiors》2005,150(4):351-352

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Uranium in groundwater of the Al-Batin Alluvial Fan aquifer,south Iraq     

Majid Alkinani  Wael Kanoua  Broder Merkel 《Environmental Earth Sciences》2016,75(10):869

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Hydraulic roughness over simple subaqueous dunes   总被引：2，自引：1，他引：1  

Jesper Bartholdy  Burg W. Flemming  Verner B. Ernstsen  Christian Winter  Alex Bartholom ä 《Geo-Marine Letters》2010,30(1):63-76

Detailed studies of flow over subaqueous dunes in laboratory flumes were used to suggest a virtual near-bed layer of twice the dune height in which the mean velocity is accelerated towards the crest by contraction. The mean flow velocity in this layer above the crest, transformed into friction velocity by means of the surface skin roughness, is shown to give values consistent with measured values. The resulting dimensionless shear stress due to skin friction is depth-independent, in contrast to that derived by means of often cited traditional methods. As a result of the relationship between dune height and the thickness of the near-bed layer, an expression for the expansion loss behind dunes was formulated and used to relate form resistance directly to dune height.  相似文献   

Vulnerability of groundwater in Quaternary aquifers to organic contaminants: a case study in Wuhan City,China   总被引：5，自引：0，他引：5  

Yanxin Wang  Broder J. Merkel  Yilian Li  Hui Ye  Surong Fu  Dana Ihm 《Environmental Geology》2007,53(3):479-484

More than 30 organic contaminants were detected in shallow groundwaters at Wuhan, the largest city in central China. Seriously contaminated groundwaters were from densely populated, industrial and commercial areas. Abnormal concentrations were found in groundwater from Hankou, downtown Wuhan: trimethylbenzene up to 29 μg/L, tetramethylbenzene up to 866 μg/L, and trichloroethene up to 9.5 μg/L. Benzene, Toluene, Ethylene and Xylene (BTEX) contamination of groundwater is serious and widespread at Wuhan, ranging between 0.14 and 25.0 μg/L. Considering the hydrogeological conditions of most Chinese cities, DRAMIC, a modified version of the widely used DRASTIC model, was proposed by the authors for assessing vulnerability of groundwater to contamination. The factors D, R, A and I in DRAMIC model are the same as in DRASTIC. The factor topography is ignored. The factor soil media is substituted by a new factor aquifer thickness (M) and the factor hydraulic conductivity of the aquifer by a new factor impact of contaminant (C). The equation for determining the DRAMIC Index is: DRAMIC = 5D _R + 3R _R + 4A _R + 2M _R + 5I _R + 1C _R. The calculated DRAMIC Index can be used to identify areas that are more likely to be susceptible to groundwater contamination relative to each other. The higher the DRAMIC Index is, the greater the groundwater pollution potential. Applying DRAMIC, a GIS-based vulnerability map for Wuhan city was prepared. Interestingly, places such as downtown Hankou, where enhanced concentrations of BTEX have been detected, correspond quite well with those with higher DRAMIC ratings.  相似文献