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21.
Radiocaesium isotopes, discharged into the North-east Irish Sea from the Sellafield (formerly Windscale) nuclear fuel reprocessing plant in Cumbria, have been employed as flow monitors to update and extend the record of coastal water movement from the Irish Sea to the Clyde Sea area and, further north, to Loch Etive. The temporal trends in radiocaesium levels have been used to determine the extent of water mixing en route and to define mean advection rates. Flow conditions from the Irish Sea have changed considerably since the mid-1970s, the residence time of northern Irish Sea waters being ~12 months during 1978–1980 inclusive. Average transport times of four and six months are estimated for the Sellafield to Clyde and Sellafield to Etive transects respectively. Sellafield 137Cs levels in seawater were diluted by factors of 27 and 50 respectively during current movement to the Clyde and Etive areas. The decrease in salinity-corrected 137Cs concentrations between the Clyde and Etive suggests that dilution by Atlantic water occurs, the latter mainly entering the Firth of Lorne from the west. The majority (~94%) of the radiocaesium supply to Loch Etive enters the Firth of Lorne via the portion of the coastal current circulating west of Islay, only ~6% arriving via the Sound of Jura. 相似文献
22.
倪万魁 《地球科学与环境学报》1996,(3)
本文根据大量的调查资料,采用多指标评判打分法对铜川市区滑坡逐一进行了危险性综合评价,旨在为该区滑坡的预测与防治提供可靠的依据。 相似文献
23.
24.
INTRODUCTIONTheSubeiShoalandtheChangjiangRiverestuarineareainthewestoftheHuanghaiandEastChinaSeasisoneofthemarginalseasintheworld ,wheresuspendedmatterisextremelyhigh .Here ,notonlyistheretheTaiwanWarmCurrentoneoftheKuroshio’sbranchesintheEastChinaSea,butalsotheHuanghaiCoastalCurrent,andChangjiangDilutedWater.Sothestrongmixingbetweenthecoastalandoffshorewaterscomplicatessuspendedmatterdistributioninthisarea.HowthesuspendedmatterdischargedfromtheChangjiangRiverandtheabandonedHuan… 相似文献
25.
26.
孙世春 《中国海洋湖沼学报》1995,(2)
Two nemerteans of the Zhoushan Islands, Paranemertes sinensis sp. nov. and P. peregrina, are reportedin this paper. P. sinensis sp. nov. has the body wall longitudinal musculature anteriorly divided,numerous eyes grouped into four clusters, two pairs of cephalic furrows, rhynchocoel 1/3 to 1/2 of fullbody length, cephalic glands well developed and posteriorly extending beyond the cerebral ganglia.precerebral septum absent, cerebral sense organs situated in front of brain, three pairs of nephridiopores,and 17-18 proboscis nerves. 相似文献
27.
This study presents a laboratory study of the following two aspects: (1) the influence of sea laver treatment acid on the
geoenvironmental properties of Ariake Sea tidal mud, and (2) the natural remediation effect on the sea laver treatment acid
contaminated Ariake Sea tidal mud caused by the upward seepage of pore water liquid in the mud. Firstly, the mechanisms of
the transport of sea laver treatment acid in the Ariake Sea tidal mud and the generation mechanisms of the upward seepage
flow in the Ariake Sea tidal mud are discussed. Secondly, a series of one-dimensional laboratory infiltration tests were carried
out to investigate the deterioration of the Ariake Sea tidal mud caused by the sea laver acid treatment practice. Test results
reveal that the acid treatment practice caused considerable change in the geochemical properties of the mud in terms of increase
in sulfide content and decrease in pH value. After the treatment by the sea laver treatment acid, the sulfide content of the
mud even exceeded the safe limit value for the benthos, which represents undesirable living condition for benthos. Thirdly,
series of laboratory fresh seawater infiltration tests for the deteriorated Iida site mud were conducted to illustrate this
natural remediation efficiency. It is found that with the infiltration of the fresh seawater, the sulfide content of the Iida
site mud was considerably reduced and pH value increased to an acceptable range for benthos living in the tidal flat mud.
With the increase in the infiltration time and the hydraulic gradient, the remediation efficiency could be increased. 相似文献
28.
The Dead Sea Basin is the lowest point on earth and is tectonically subsiding. During the Holocene Period the climate became much drier with increasing evaporation whereby initially lacustrine sediments were deposited from the non-marine brines, giving a multi-layered stratigraphy of lime carbonate and halite sediments. The lime carbonate sediments are comprised of laminated, clay to silt sized, clastic sediments (calcite) and authigenic aragonite and gypsum. The halite commonly appears as rock salt. Chemical industries, based on harvesting the salts from the Dead Sea, have developed on both the Israeli and the Jordanian sides of the basin. The lime carbonate soils are used for dike construction, and these soils, together with significant salt layers, are encountered in the foundations of structures, dikes, and tailings dams, requiring definition of their geotechnical properties. Use of standard soil mechanics definitions and testing approaches for the lime carbonates have been found inapplicable, particularly in view of their exceptionally high saline content, and it has been necessary to develop new concepts. The rock salt is encountered at shallow depths, with unit weights considerably lower than those usually discussed in the literature, and with correspondingly different mechanical properties. The geotechnical properties of these soils, and approaches used to define them, are discussed in the paper. 相似文献
29.
30.
Gary Bridge 《Geoforum》2008,39(4):1570-1584
This paper explores the radical possibilities of pragmatism for geography using the illustration of arguments concerning a renewed (urban) public realm through the exchange of validity claims in communication. Pressing further the pragmatist possibilities of Habermas’s idea of communicative action it draws on John Dewey’s work, and a range of contemporary pragmatist philosophers, to consider human communicability in its widest sense. This is then explored using an example of the spatiality and performativity of body-minds in a range of communicative spaces of the city. Then the paper moves on to consider the radical implications of pragmatism for geography in general in terms of body-mind/environment relations; a transactional view of space; experience, rationality and radical democracy. 相似文献