排序方式： 共有11条查询结果，搜索用时 406 毫秒
1.
Hanne M. L. Kvitsand Mette Myrmel Liv Fiksdal Stein W. Østerhus 《Hydrogeology Journal》2017,25(5):1257-1269
Two case studies were carried out in central Norway in order to assess the performance of bank filtration systems in cold-climate fluvial aquifers relying on recharge from humic-rich surface waters with moderate microbial contamination. Three municipal wells and two surface-water sources at operative bank filtration systems were monitored for naturally occurring bacteriophages, fecal indicators, natural organic matter (NOM) and physico-chemical water quality parameters during a 4-month period. Aquifer passage effectively reduced the microorganism and NOM concentrations at both study sites. Bacteriophages were detected in 13 of 16 (81%) surface-water samples and in 4 of 24 (17%) well-water samples, and underwent 3 ± 0.3 log10 reduction after 50–80-m filtration and 20–30 days of subsurface passage. NOM reductions (color: 74–97%; dissolved organic carbon: 54–80%; very hydrophobic acids: 70%) were similar to those achieved by conventional water-treatment processes and no further treatment was needed. Both groundwater dilution and sediment filtration contributed to the hygienic water quality improvements, but sediment filtration appeared to be the most important process with regard to microbial and NOM reductions. A strengths-weaknesses-opportunities-threats analysis showed that bank filtration technology has a high potential as a pretreatment method for the provision of hygienically safe drinking water in Norway. 相似文献
2.
3.
Studies of the mid-Norwegian margin reveal that the Fennoscandian continental uplift represents a flexural intraplate deformation event separated in time and space from the regional syn-rift uplift associated with crustal breakup at the Plaeocene-Eocene transition. In the area 64–68°N, the uplift occurred from late Oligocene through Pliocene. During Late Pliocene and Pleistocene times the tectonic uplift was amplified by isostatic rebound in response to the Northern Hemisphere glaciation. The tectonic uplift component reaches 1 km in the northern part of the study area decreasing to the south. The shelf stratigraphy and sediment composition record the combined effects of tectonic uplift, eustatic sea level changes and Neogene climatic deterioration. The coeval uplift and climatic change may suggest causal relations. The resulting depositional model has three stages: (1) late Miocene ( 10.5-5.5 m.y.) increased continental erosion and deposition of prograding wedges most of which were later removed; (2) early-middle Pliocene (5.5-2.6 m.y.) development of extensive local ice-sheets reaching the coastline and deposition of the prominent, oldest Pliocene wedges; (3) Northern Hemisphere glaciation (2.6-0.01 m.y.) resulting in the younger wedges farther west covered by Quaternary deposits. The model is consistent with the development of landforms on the adjacent mainland. Both the tectonic and isostatic components of the Fennoscandian uplift appear to vary in magnitude along the uplift axis, however separation of the syn-rift plate boundary related uplift and the intraplate event support the Neogene age of the main Fennoscandian uplift. We document a correspondence between structural and physiographic margin segmentation and uplift magnitude and suggest that the intraplate deformation has a thermal origin. A hot-cold asthenosphere boundary beneath the Caledonide-Baltic Shield transition combined with pre-Tertiary relief at the base of the lithosphere might induce small-scale convection and preferential volume expansion beneath the observed elongate uplift. 相似文献
4.
Late Weichselian and Holocene sediment flux and sedimentation rates in a continental‐shelf trough, Andfjord, and its inshore continuation, Vågsfjord, North Norway, have been analysed. The study is based on sediment cores and high‐resolution acoustic data. Andfjord was deglaciated between 14.6 and 13 14C kyr BP (17.5 and 15.6 calibrated (cal.) kyr BP), the Vågsfjord basin before 12.5 14C kyr BP (14.7 cal. kyr BP), and the heads of the inner tributary fjords about 9.7 14C kyr BP (11.2 cal. kyr BP). In Andfjord, five seismostratigraphical units are correlated to a radiocarbon dated lithostratigraphy. Three seismostratigraphical units are recognised in Vågsfjord. A total volume of 23 km3 post‐glacial glacimarine and marine sediments was mapped in the study area, of which 80% are of Late Weichselian origin. Sedimentation rates in outer Andfjord indicate reduced sediment accumulation with increasing distance from the ice margin. The Late Weichselian sediment flux and sedimentation rates are significantly higher in Vågsfjord than Andfjord. Basin morphology, the position of the ice front and the timing of deglaciation are assumed to be the reasons for this. Late Weichselian sedimentation rates in Andfjord and Vågsfjord are comparable to modern subpolar glacimarine environments of Greenland, Baffin Island and Spitsbergen. Downwasting of the Fennoscandian Ice Sheet, and winnowing of the banks owing to the full introduction of the Norwegian Current, caused very high sedimentation rates in parts of the Andfjord trough at the Late Weichselian–Holocene boundary. Holocene sediment flux and sedimentation rates in Andfjord are about half the amount found in Vågsfjord, and about one‐tenth the amount of Late Weichselian values. A strong bottom current system, established at the Late Weichselian–Holocene boundary, caused erosion of the Late Weichselian sediments and an asymmetric Holocene sediment distribution. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
5.
Environmental Justice in Hamburg,Germany 总被引：1，自引：0，他引：1
This environmental justice study investigates whether disempowered segments of the population in Hamburg, Germany, namely, foreigners and the poor, reside disproportionately in neighborhoods that contain, have higher concentrations of, and are in closer proximity to facilities releasing toxic chemicals into the environment. Methods include choropleth mapping; comparisons of means, correlation, and ordinary least squares (OLS); and spatial econometric regression. The results provide evidence that toxic release facilities are disproportionately located within, and closer to, neighborhoods with comparatively higher proportions of foreigners and the poor as compared to those with higher proportions of German citizens and the non-poor. We speculate that the causes of this pattern of environmental inequity are similar to the causes scholars have proposed for comparable patterns observed in many U.S. cities, where marginalized immigrant or minority groups subject to discrimination in housing and employment have sought low-wage labor in industrial areas, whereas wealthier German citizens have settled in environmentally safer parts of the city. 相似文献
6.
Integrated acoustic and coring investigation of glacigenic deposits in Spitsbergen fjords 总被引：2，自引：0，他引：2
In many areas of Svalbard, the Neoglacial terminal deposits represent the Holocene glacial maximum. The glaciers began the retreat from their Neoglacial maximum positions around 1900 AD. Based on high resolution acoustic data and sediment cores, sedimentation patterns in four tidewater glacier-influenced inlets of the fjord Isfjorden (Tempelfjorden, Billefjorden, Yoldiabukta and Borebukta), Spitsbergen, were investigated. A model for sedimentation of tidewater glaciers in these High Arctic environments is proposed. Glacigenic deposits occur in proximal and distal basins. The proximal basins comprise morainal ridges and hummocky moraines, bounded by terminal moraines marking the maximum Neoglacial ice extent. The distal basins are characterized by debris lobes and draping stratified glacimarine sediments beyond, and to some extent beneath and above, the lobes. The debris lobe in Tempelfjorden is composed of massive clayey silt with scattered clasts. Distal glacimarine sediments comprise stratified clayey silt with low ice-rafted debris (IRD) content. The average sedimentation rate for the glacimarine sediments in Tempelfjorden is 17 mm/yr for the last ca. 130 years. It is suggested that the stratified sediments in Tempelfjorden are glacimarine varves. The high sedimentation rate and low IRD content are explained by input from rivers, in addition to sedimentation from suspension of glacial meltwater. The debris lobes in Borebukta are composed of massive clayey silt with high clast content. Distal glacimarine sediments in Yoldiabukta comprise clayey silt with high IRD content. The average sedimentation rate for these sediments is 0.6 mm/yr for the last 2300 years. 相似文献
7.
The effects of phase fractionation on the composition of oils, condensates and gases 总被引：1，自引：0，他引：1
The effects of phase fractionation on the composition of oils, condensates and gases have been studied in the laboratory by a differential evaporation experiment. The experiment was designed to simulate the behaviour of a single-charge petroleum during (upward) migration or in a reservoir undergoing uplift, scenarios thought to be typical for the Norwegian continental shelf. After each pressure reduction step, samples from all phases (oil, condensate, free and associated gas) were collected and analysed. The results show that, in general, small molecules are preferentially enriched in the gas phase, both at elevated pressure and temperature and under standard conditions (15°C, 1 bar). The solvent power of the gas phase for large molecules is drastically reduced at lower pressures (here below approx. 300 bar). Carbon isotope ratios of individual compound are not affected, while variations in isotope ratios of fractions can be explained by changes in the fraction compositions. Individual geochemical parameters behave as can be expected based on the molecular size and structure of the compounds involved. However, a generally valid, quantitative prediction of how geochemical parameters vary as a result of phase fractionation is very difficult, as this will depend not only on the pressure and temperature of fractionation, but also on the composition and amounts of the oil and gas that are involved. The observations from this study confirm the importance of phase fractionation as an important process to consider when interpreting geochemical data for both condensates and oils. 相似文献
8.
S. Chand J. Mienert K. Andreassen J. Knies L. Plassen B. Fotland 《Marine and Petroleum Geology》2008,25(7):625-636
The Barents Sea seabed exhibits an area of major glacial erosion exposing parts of the old hydrocarbon basins. In this region, we modelled the gas hydrate stability field in a 3D perspective, including the effects of higher order hydrocarbon gases. We used 3D seismic data to analyse the linkage between fluid-flow expressions and hydrate occurrences above old sedimentary basin systems and vertical faults. Pockmarks showed a relation to fault systems where some of them are directly connected to hydrocarbon bearing sedimentary formations. The influence of bottom water temperature, pore water salinity and geothermal gradient variation on gas hydrate stability zone (GHSZ) thickness is critically analysed in relation to both geological formations and salt tectonics. Our analysis suggests a highly variable GHSZ in the Barents Sea region controlled by local variations in the parameters of stability conditions. Recovery of gas-hydrate sample from the region and presence of gas-enhanced reflections below estimated BSR depths may indicate a prevalent gas-hydrate stable condition. 相似文献
9.
Liv Heinecke Steffen Mischke Karsten Adler Anja Barth Boris K. Biskaborn Birgit Plessen Ingmar Nitze Gerhard Kuhn Ilhomjon Rajabov Ulrike Herzschuh 《Journal of Paleolimnology》2017,58(3):317-334
We present results of analyses on a sediment core from Lake Karakul, located in the eastern Pamir Mountains, Tajikistan. The core spans the last ~29 cal ka. We investigated and assessed processes internal and external to the lake to infer changes in past moisture availability. Among the variables used to infer lake-external processes, high values of grain-size end-member (EM) 3 (wide grain-size distribution that reflects fluvial input) and high Sr/Rb and Zr/Rb ratios (coinciding with coarse grain sizes), are indicative of moister conditions. High values in EM1, EM2 (peaks of small grain sizes that reflect long-distance dust transport or fine, glacially derived clastic input) and TiO2 (terrigenous input) are thought to reflect greater influence of dry air masses, most likely of Westerly origin. High input of dust from distant sources, beginning before the Last Glacial Maximum (LGM) and continuing to the late glacial, reflects the influence of dry Westerlies, whereas peaks in fluvial input suggest increased moisture availability. The early to early-middle Holocene is characterised by coarse mean grain sizes, indicating constant, high fluvial input and moister conditions in the region. A steady increase in terrigenous dust and a decrease in fluvial input from 6.6 cal ka BP onwards points to the Westerlies as the predominant atmospheric circulation through to present, and marks a return to drier and even arid conditions in the area. Proxies for productivity (TOC, TOC/TN, TOC Br ), redox potential (Fe/Mn) and changes in the endogenic carbonate precipitation (TIC, δ18O Carb ) indicate changes within the lake. Low productivity characterised the lake from the late Pleistocene until 6.6 cal ka BP, and increased rapidly afterwards. Lake level remained low until the LGM, but water depth increased to a maximum during the late glacial and remained high into the early Holocene. Subsequently, the water level decreased to its present stage. Today the lake system is mainly climatically controlled, but the depositional regime is also driven by internal limnogeological processes. 相似文献
10.