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Bjørn Kløve Hanne Margrethe Lund Kvitsand Tarja Pitkänen Maria J. Gunnarsdottir Sylvi Gaut Sigurdur M. Gardarsson Pekka M. Rossi Ilkka Miettinen 《Hydrogeology Journal》2017,25(4):1033-1044
The characteristics of groundwater systems and groundwater contamination in Finland, Norway and Iceland are presented, as they relate to outbreaks of disease. Disparities among the Nordic countries in the approach to providing safe drinking water from groundwater are discussed, and recommendations are given for the future. Groundwater recharge is typically high in autumn or winter months or after snowmelt in the coldest regions. Most inland aquifers are unconfined and therefore vulnerable to pollution, but they are often without much anthropogenic influence and the water quality is good. In coastal zones, previously emplaced marine sediments may confine and protect aquifers to some extent. However, the water quality in these aquifers is highly variable, as the coastal regions are also most influenced by agriculture, sea-water intrusion and urban settlements resulting in challenging conditions for water abstraction and supply. Groundwater is typically extracted from Quaternary deposits for small and medium municipalities, from bedrock for single households, and from surface water for the largest cities, except for Iceland, which relies almost entirely on groundwater for public supply. Managed aquifer recharge, with or without prior water treatment, is widely used in Finland to extend present groundwater resources. Especially at small utilities, groundwater is often supplied without treatment. Despite generally good water quality, microbial contamination has occurred, principally by norovirus and Campylobacter, with larger outbreaks resulting from sewage contamination, cross-connections into drinking water supplies, heavy rainfall events, and ingress of polluted surface water to groundwater. 相似文献
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Partial melting experiments on a San Carlos peridotite were done in a Walker type multi-anvil press at pressures from 5 to
12.5 GPa. Experiments were done in the presence of a COH-fluid and at oxygen fugacity controlled by the Fe–FeO buffer. Olivine,
clinopyroxene, garnet and orthopyroxene are stable in all but the highest temperature 10 GPa experiments where olivine and
garnet coexist, and the highest temperature 5 GPa experiments where olivine is the single crystalline phase. The solidus at
5 GPa was found to be at approximately 1,200°C and the liquidus was estimated to be at 1,325°C, which is ∼500°C lower than
has been reported for dry melting of peridotite. The aluminum concentration of the melts decreases with increasing melt fraction
and decreases also with increasing pressure. At 5 GPa the melts have a CaO/Al2O3-ratio of 0.85–1.0, which is similar to that of undepleted komatiites; major element concentrations are also identical to
those of undepleted komatiites such as the Munro komatiites. At 10 and 12.5 GPa the partial melts have CaO/Al2O3-ratios above 1.5 and major element composition almost identical to aluminum depleted komatiites such as the Barberton komatiites.
We therefore conclude that in the presence of a reducing COH-fluid both aluminum-depleted and -undepleted komatiites could
have formed at temperatures much lower than generally accepted. 相似文献
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An analytical model of a soil layer resting on a halfspace with vertically propagating shear waves is studied under a harmonic excitation on the surface. The soil is treated as a Kelvin-Voigt continuum, using the one-dimensional wave equation. The material parameters can be strain dependent. A hyperbolic model proposed by Hardin & Drnevich is used for describing the nonlinear stress-strain relationship. Based on this, a solution to a problem where thirty thousand people were jumping to the rhythm of rock music on the field in a stadium is given. The soil stratum is a 5–60m thick uniform soft high-plastic clay. The particle velocity was estimated to range from 22·5 mm/s to 45 mm/s in the first overtone. These velocity values exceeded the critical value, of 20 mm/s, of the German building code DIN 4150 which may explain the occurence of damages. 相似文献
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Bjoern Sundquist Ilmari Haapala Jens Morten Hansen Geir Hestmark Sigurdur Steinthorsson 《《幕》》2008,31(1):185-192
The Nordic countries of Denmark, Finland, Iceland, Norway, and Sweden have been closely connected for many centuries, not least from a geological point of view. Scientific cooperation as well as contentions have been common. The earliest known records of ＂geological＂ treatises are from the 16th century, but especially in the 18th century, when the natural sciences flourished all over Europe, Nordic scholars were in the forefront in geochemistry, mineralogy, and paleontology. This was also the century when ＂geology＂ started to be taught at the universities, and science academies were founded in Norden, adding greatly to ＂geological＂ studies. In the 19th century, like in so many other countries, national geological survey organizations and geological societies were founded. In Norden, geological research has long traditions within mineralogy and ore geology, paleontology and stratigraphy, tectonics and structural geology. During the last century, focus has turned also to Quaternary and glacial geology, igneous and metamorphic petrology, geochemistry, micropaleontology, petroleum geology, sedimentology, marine geology, geophysics, geochronology, and research related to geothermal energy and deposition of radioactive waste products. In many of these research areas, Nordic geoscientists have contributed greatly over the years to the development of the science of geology. 相似文献
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Oxygen fugacity control in piston-cylinder experiments 总被引：1，自引：1，他引：0
The main goal of this study was to develop and test a capsule assembly for use in piston-cylinder experiments where oxygen fugacity could be controlled in the vicinity of the QFM buffer without H2O loss or carbon contamination of the sample material. The assembly consists of an outer Pt-capsule containing a solid buffer (Ni–NiO or Co–CoO) plus H2O and an inner AuPd-capsule, containing the sample, H2O and a Pt-wire. No H2O loss is observed from the sample, even after 48 h, but a slight increase in H2O content is found in longer runs due to oxygen and hydrogen diffusion into the AuPd-capsule. Oxygen fugacity of runs in equilibrium with the Ni–NiO (NNO) and Co–CoO (CoCO) buffers was measured by analyzing Fe dissolved in the Pt-wire and in the AuPd-capsule. The second method gives values that are in good agreement with established buffer values, whereas results from the first method are one half to one log units higher than the established values. 相似文献