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971.
The problem of the diversity of the geochemical types of carbon dioxide waters (CDW) in petrografically and mineralogically uniform crystalline rock masses is solved with allowance made for the effect of different boundary conditions (physicochemical parameters) on the geochemical effect of interaction in the rock–water system. The formation of the entire geochemical spectrum of CDW in crystalline rock masses is shown to be explicable on the basis of a model of interaction in granite–water systems at different mass ratios of reacting rock (S) and water (L), different temperatures T, and equilibrium concentrations of dissolved CO2 (P
CO2). 相似文献
972.
Analysis is given of the modern approaches and methods used to assess the quality of bottom deposits based on the conditions of bacterio- and zoobenthos communities. The structural characteristics of bacterio- and zoobenthos communities of small rivers in the Upper Volga basin are studied. The type of substrate is shown to have appreciable effect on the quantitative characteristics of both the communities. The analysis of these data is used to create a generalized classification of the quality of bottom deposits and assess the extent of their pollution in the examined water bodies. 相似文献
973.
It is shown that large-size zooplankton can be used as a natural filter in flow-through plants for reducing the trophic status of water bodies and improve water transparency. Experiments in Chistye Prudy pond in the period of blue-green algae blooming show large-size zooplankton to reduce phytoplankton biomass in the pond throughout the period of phytoplankton growth. Daphnia magna specimens (with a biomass of 92 to 3450 mg/l) in lothic ecosystems are found to reduce the biomass of dominating Anabaena spirodes blue-green algae when this biomass attains its maximum. 相似文献
974.
The growth, maximum lateral extent and deglaciation of the last British Ice Sheet (BIS) has been reconstructed using sediment, faunal and stable isotope methods from a sedimentary record recovered from the Barra Fan, north-west Scotland. During a phase of ice sheet expansion postdating the early "warmth" of Marine Isotope Stage 3 (MIS 3), ice rafting events, operating with a cyclicity of approximately 1500 years, are interspersed between warm, carbonate-rich interstadials operating with a strong Dansgaard-Oeschger (D-O) cyclicity. The data suggest that the BIS expanded westwards to the outer continental shelf break shortly after 30 Ky BP (before present) and remained there until about 15 Ky BP. Within MIS 2, as the ice sheet grew to its maximum extent, the pronounced periodicities which characterize MIS 3 are lost from the record. The exact timing of the Last Glacial Maximum is difficult to define in this record; but maxima in Neogloboquadrina pachyderma (sinistral) Ø18 O are observed between 21-17 Ky BP. A massive discharge of ice-rafted detritus, coincident with Heinrich event 1, is observed at about 16 Ky BP. Deglaciation of the margin is complete by about 15 Ky BP and surface waters warm rapidly after this date. 相似文献
975.
The sea lochs (fjords) of north-west Scotland are located in a region of Europe particularly well situated to monitor changes in westerly air streams. The moisture transported in these air streams has a profound effect on regional precipitation, freshwater run-off and, in turn, sea loch circulation. The gentle slope of the regional salinity:δ18 O mixing-line, defined as 0.18 ‰ per salinity unit, suggests that the temperature: δ18 O relationship may be readily resolved in these coastal waters. Deep-water renewal events, both observed and predicted from empirical models, in the bottom-waters of Loch Etive provide an opportunity to assess the temperature, salinity and δ18 O relationship. Predicted changes in δ18 Ocalcite as a function of changing salinity (ΔS) and changing temperature (ΔT) during deep-water renewal events suggest that >80% fall above analytical detection limits. The theoretical likelihood of recording such renewal events in the "palaeoclimate" record appears to be promising, but temperature and salinity change during renewal events may have either sign. Scottish fjords, because of the relatively small impact which salinity has on δ18 Owater , may provide useful study sites in palaeoclimate research, particularly where palaeotemperature is the primary record of interest. 相似文献
976.
Determination of the influence zone for surface wave paths 总被引:6,自引:1,他引:6
977.
978.
979.
980.
Shear wave statics using receiver functions 总被引:1,自引:0,他引:1