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A.?V.?SundalEmail author H.?Henriksen S.?E.?Lauritzen O.?Soldal T.?Strand V.?Valen 《Environmental Geology》2004,45(6):843-858
In 1996–1997, indoor radon values of more than 40,000 Bq/m3 and large seasonal and geographical variations in indoor air radon were reported from a residential area located on a highly permeable ice-marginal deposit. Geochemical analyses of bedrock, groundwater and sediments and comparisons between indoor radon values and soil radon values indicate that the indoor radon concentrations in this area are strongly affected by subterranean airflows caused by temperature differences between soil air and atmospheric air. The airflows concentrate the radon-laden soil air towards the topographic highest part of the deposit in winter and towards the topographic lowest part in summer. In areas where subterranean airflows are likely to occur, radon measurements performed both in summer and in winter provide the best estimate of annual average indoor radon concentrations, and assessments of indoor radon concentrations based on single soil gas measurements are not recommended. 相似文献
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Social Change, Ecology and Climate in 20th-Century Greenland 总被引：5，自引：1，他引：4
Two great transitions, from seal hunting to codfishing, then from cod fishing to shrimp, affectedpopulation centers of southwest Greenland during the20th century. These economic transitionsreflected large-scale shifts in the underlying marineecosystems, driven by interactions between climate andhuman resource use. The combination of climaticvariation and fishing pressure, for example, provedfatal to west Greenland's cod fishery. We examine thehistory of these transitions, using data down to thelevel of individual municipalities. At this level,the uneven social consequences of environmental changeshow clearly: some places gained, while others lost. Developments in 20th-century Greenland resemblepatterns of human-environment interactions in themedieval Norse settlements, suggesting some generalpropositions relevant to the human dimensions ofclimatic change. 相似文献
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Binyam L. Alemu Eyvind Aker Magnus Soldal Øistein Johnsen Per Aagaard 《Geophysical Prospecting》2013,61(1):235-250
The effect of sub‐core scale heterogeneity on fluid distribution pattern, and the electrical and acoustic properties of a typical reservoir rock was studied by performing drainage and imbibition flooding tests with CO2 and brine in a laboratory. Moderately layered Rothbach sandstone was used as a test specimen. Two core samples were drilled; one perpendicular and the other parallel to the layering to allow injection of fluids along and normal to the bedding plane. During the test 3D images of fluid distribution and saturation levels were mapped by an industrial X‐ray CT‐scanner together with simultaneous measurement of electrical resistivity, ultrasonic velocities as well as amplitudes. The results showed how the layering and the flooding direction influenced the fluid distribution pattern and the saturation level of the fluids. For a given fluid saturation level, the measured changes in the acoustic and electrical parameters were affected by both the fluid distribution pattern and the layering orientation relative to the measurement direction. The P‐wave amplitude and the electrical resistivity were more sensitive to small changes in the fluid distribution patterns than the P‐wave velocity. The change in amplitude was the most affected by the orientation of the layering and the resulting fluid distribution patterns. In some instances the change due to the fluid distribution pattern was higher than the variation caused by the change in CO2 saturation. As a result the Gassmann relation based on ‘uniform' or ‘patchy' saturation pattern was not suitable to predict the P‐wave velocity variation. Overall, the results demonstrate the importance of core‐imaging to improve our understanding of fluid distribution patterns and the associated effects on measured rock‐physics properties. 相似文献
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Towards a policy for sustainable use of groundwater by non-governmental organisations in Afghanistan
A 'first pass' groundwater management policy has been developed for use by non-governmental organisations (NGOs) in Afghanistan,
designed to prevent derogation of existing traditional water sources, aquifer over-abstraction and chemical deterioration
of soil and groundwater quality. Key elements include (1) continuing promotion of groundwater as a drinking water source,
(2) a presumption against use of motorised pumps to abstract groundwater for irrigation unless other options (surface water,
qanats) are not available, (3) the use of groundwater for irrigation as a temporary alternative to surface water (i.e. a strategy
for drought survival) rather than as a long-term development policy, (4) limiting groundwater abstraction to a long-term average
of 1 l s–1 km–2, (5) siting irrigation wells at least 500 m from other groundwater sources and (6) analysing irrigation groundwater for electrical
conductivity, sodium absorption ratio, boron and residual sodium carbonate alkalinity. Analyses of these parameters indicate
that groundwater from some areas is of dubious suitability for irrigation. In some villages and towns, groundwater contains
elevated nitrate and faecal bacteria concentrations, probably derived from latrines, sewage or animal wastes.
Electronic Publication 相似文献
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Geophysical surveys have been carried out in two fjord delta aquifers in western Norway. Geophysical methods comprised ground penetrating radar (GPR), shallow reflection seismic and resistivity measurements. The purpose of the investigations was to evaluate hydrogeological properties of the fjord delta aquifers with emphasis on the possibilities of abstracting saline groundwater for use in fish farming. At Sunndalsøra, reflection seismic was helpful in the mapping of the base of the aquifer. Resistivity profiles revealed both the spatial and seasonal variability of seawater intrusion. Penetration depths of ground penetrating radar (GPR-D) revealed the spatial variation of the boundary of the transition zone between saline and fresh groundwater. Maps of GPR-D can be used to indicate direction and magnitude of mean hydraulic gradients and thus to locate optimal sites for both fresh and saline groundwater abstraction.In fjord delta aquifers, both rivers and abandoned river channels constitute important groundwater divides. Optimal locations for saline groundwater abstraction wells are in areas separated from the rivers by abandoned river channels. In areas between the rivers and the abandoned river channels, groundwater abstraction will result in decreasing salinity of the water. 相似文献
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