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The transport and sedimentation of copper in the Glomma estuary, SE Norway during a period of 90% reduction in the industrial input of Cu, was studied from sediment trap material and compared to samples of the bottom sediments. Traps were deployed at four stations for several monthly periods during 1990, 1994 and 1995. Trapped material was analysed for suspended particulate matter (SPM), total organic carbon (TOC) and nitrogen (TN), Cu, and Al. Only about 10% of the Cu from the river is trapped in the estuary. Still there was a moderate but significant reduction in Cu concentration in the trap SPM from 1990 to 1994, reflecting the industrial reductions, but only if excluding summer samples apparently influenced by antifouling Cu from boat paint. Settling matter therefore seems appropriate and sensitive for monitoring changes in the Cu load. The results supported the view that TOC is the main carrier of Cu to the sediments. 相似文献
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Inga?BerreEmail author Kenneth?Hvistendal?Karlsen Knut-Andreas?Lie Jostein?R.?Natvig 《Computational Geosciences》2005,9(4):179-201
We continue the work that was initiated in (K. H. Karlsen, K.-A. Lie, and N. H. Risebro. A fast marching method for reservoir
simulation. Comp. Geo., 4(2) (2000)185–206) on a marching method for simulating two-phase incompressible immiscible flow of water and oil in a porous
medium. We first present an alternative derivation of the marching method that reveals a strong connection to modern streamline
methods. Then, through the study of three numerical test cases we present two deficiencies: (i) the original marching algorithm
does not always compute the correct solution of the underlying difference equations, and (ii) the method gives largely inaccurate
arrival times in the presence of large jumps within the upwind difference stencil. As a remedy of the first problem, we present
a new advancing-front method, which is faster than the original marching method and guarantees a correct solution of the underlying
discrete linear system. To cure the second problem, we present two adaptive strategies that avoid the use of finite-difference
stencils containing large jumps in the arrival times. The original marching method was introduced as a fast tool for simulating
two-phase flow scenarios in heterogeneous formations. The new advancing-front method has limited applicability in this respect,
but may rather be used as a fast and relatively accurate method for computing arrival times and derived quantities in heterogeneous
media. 相似文献
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Jostein R. Natvig Knut&#x;Andreas Lie Birgitte Eikemo Inga Berre 《Advances in water resources》2007,30(12):2424-2438
We consider a discontinuous Galerkin scheme for computing transport in heterogeneous media. An efficient solution of the resulting linear system of equations is possible by taking advantage of a priori knowledge of the direction of flow. By arranging the elements in a suitable sequence, one does not need to assemble the full system and may compute the solution in an element-by-element fashion. We demonstrate this procedure on boundary-value problems for tracer transport and time-of-flight. 相似文献
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Willem G.M. van der Bilt Jostein Bakke Kristian Vasskog Torgeir Røthe Eivind W. N. Støren 《Geology Today》2016,32(6):213-218
Glaciers show a sensitive and rapid response to climate shifts. Associated changes in ice extent drive variations in the production of rock flour, the suspended product of glacial erosion. These glacigenic sediments may accumulate in downstream lakes, continuously recording glacier history. Consequently, the lacustrine sediment records of such glacier‐fed lakes represent valuable palaeoenvironmental archives that help constrain past climate variability. In this paper, we discuss the multi‐disciplinary methodological toolbox that is applied to fingerprint a glacier signal from such lake sediments. Special emphasis is placed on dating methods, which transform stratigraphical data into climate time series, allowing us to distinguish leads and lags between archives. We also elaborate on techniques that are used to validate sediment‐based glacier signals and resolve their climate signature. Finally, we conclude with a brief outlook on new research avenues such as proxy data–climate model comparisons. 相似文献
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Mathias Trachsel Bjørn Christian Kvisvik Pål Ringkjøb Nielsen Jostein Bakke Atle Nesje 《Journal of Paleolimnology》2013,50(4):583-592
Reflectance spectroscopy in the visible spectrum (VIS-RS) is a method that has been successfully applied for inferring organic content of sediments. In this study, we test the applicability of VIS-RS to lake sediments in Norway. On the one hand we use conventional, established algorithms for inferring organic content of sediments, on the other hand we test the potential of multivariate calibration techniques to infer organic content. For absolute quantification of organic content, conventional Corg measurements are needed when using conventional algorithms as well as when employing multivariate calibration techniques. Both, conventional algorithms and multivariate calibrations, result in estimates of organic content closely mirroring loss-on-ignition measurements. When using multivariate calibration techniques, a conventional Corg measurement every 5 cm is sufficient to obtain estimates of organic matter that are more accurate than those obtained by means of conventional algorithms. Therefore, the potential of multivariate calibration techniques and VIS-RS to substitute measurements of more time consuming and costly sediment parameters (e.g. clay minerals) should be tested. 相似文献
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Henrik Løseth Jansen Svein Olaf Dahl Henriette Linge Jostein Bakke Pål Ringkjøb Nielsen Bjørn Christian Kvisvik 《Boreas: An International Journal of Quaternary Research》2023,52(2):168-193
Continuous glacier margin and equilibrium-line altitude fluctuations of a former glacier on central Andøya, northern Norway, are reconstructed during the Lateglacial based on moraines and AMS 14C-dated sediments from the distal glacier-fed lake Ner-Finnkongdalsvatnet. The results indicate that a valley glacier occupied the entire valley during the Last Glacial Maximum (before 21 970±620 cal. a BP). The glacier remained large throughout the early Lateglacial until a significant glacier retreat took place about 14 300±330 cal. a BP. Major advances occurred during the Older Dryas (OD) and during the Younger Dryas (YD), while minor advances are suggested to have taken place during the Intra Allerød Cold Period and the Late Allerød Cooling. Additionally, three smaller glacier retreats/re-advances within the YD are suggested to have taken place, the latter being the largest. The glacier re-formations/advances during the Lateglacial are consistent with increases in temperature, and they are thus suggested to be the result of increased winter precipitation. Comparing the results with relevant glacier and sea-surface temperature records, a south–north migration of storm tracks may have occurred between 12 100–11 810±220 cal. a BP. The high temporal resolution of local glacier activity in Finnkongdalen improves our understanding of the climate forcing of the regional glacier fluctuations of the northwestern sector of the Scandinavian Ice Sheet during the Skarpnes- (OD) and Tromsø-Lyngen (YD) re-advances. 相似文献
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The applied context of this paper is the exploration for petroleum resources, like petroleum accumulations in different deposits, where the most promising deposits are likely to be drilled first, based on some size indicators, so-called creaming. The paper explores creaming models in the context of sampling with probabilities in proportion to size, for which a lognormal size distribution has nice analytical features. It departs from the traditional paradigm in petroleum resource assessment. Instead of conceiving a finite population being depleted over time in a decaying fashion with respect to size, the situation is studied within the framework of independent observations (infinite population) and an exploration maturity-dependent creaming factor. The theoretical and practical consequences for inference on the parent population and the probabilities and expectations linked to future discoveries are studied. The theory applies to the issue of remaining sizes of petroleum resources to be found within different future discovery horizons on the mature part of the Norwegian Continental Shelf. The aim is to obtain reasonable and useful predictions, and not to provide the best possible explanation of the exploratory behavior itself. 相似文献