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排序方式: 共有411条查询结果,搜索用时 15 毫秒
371.
Ramster John; Daan Niels; Frid Chris; Megrey Bernard; Payne Andrew; Pepin Pierre 《ICES Journal of Marine Science》2003,60(6):1169-1171
Article 1 of the ICES Convention of 1964 sets out the fundamentalpurposes of the Council and includes as the third and finalpoint: "to publish or otherwise disseminate the results of researchand investigations carried out under its auspices or to encouragethe publication thereof". Publication and dissemination of informationabout the living resources and their environment have been atthe heart of ICES from the first 相似文献
372.
A field study was conducted to assess the potential use of metallothionein (MT) and stress proteins as biomarkers of trace metal exposure. Shore crabs (Carcinus maenas) were collected from five sites: three located in the metal-contaminated Fal estuary (Southwest England) and two control sites located on the south coast of England. Two methods for determining MT levels in crab midgut gland were compared. A direct method in which MT was quantified by spectrophotometric measurement of SH content, and an indirect method in which the metal content (Cu and Zn) of partially purified MT was measured. Stress protein levels (stress-70) were quantified in crab gills using an improved western blotting technique. Elevated Cu and Cd concentrations compared to values in control crabs were found in the midgut glands of crabs from the Fal estuary. No significant variation was seen in Zn concentrations among the five sites. The two techniques used for MT analysis yielded similar results. Metallothionein concentrations were slightly higher in crabs from Restronguet Creek (the most metal-contaminated site) than in crabs from the other four sites, however this difference was not significant (p > 0.05). Stress protein levels did not reflect the metal gradient. 相似文献
373.
374.
Application of Natural Attenuation to Ground Water Contaminated by Phenoxy Acid Herbicides at an Old Landfill in Sjoelund, Denmark 总被引:1,自引:0,他引:1
Nina Tuxen Palle Ejlskov Hans-Jørgen Albrechtsen Lotte A. Reitzel Jørn K. Pedersen Paul L. Bjerg 《Ground Water Monitoring & Remediation》2003,23(4):48-58
Investigations of geology, hydrogeology, and ground water chemistry in the aquifer downgradient from Sjoelund Landfill, Denmark, formed the basis for an evaluation of natural attenuation as a remediation technology for phenoxy acid herbicides at the site. Concentrations of phenoxy acids were up to 65 μg/L in the ground water, primarily 4-chlor-2-methylphenoxypropionic acid (MCPP) and 2,4-dichlorophenoxypropionic acid (dichlorprop). Mass removal of the phenoxy acids was shown within 50 to 100 m of the landfill by calculation of contaminant fluxes passing transects at three distances. There was accordance between increasing oxygen concentrations and decreasing phenoxy acid concentrations with distance from the landfill, indicating that aerobic degradation was a major mass removal process. Presence of high concentrations of putative anaerobic phenoxy acid metabolites suggested that anaerobic degradation was also occurring. Laboratory degradation experiments using sediment and ground water from the aquifer supported aerobic and anaerobic degradability of MCPP at the site. It was concluded that natural attenuation may be applicable as a remedy for the phenoxy acids at the Sjoelund Landfill site, although uncertainties related to calculations of chloride and phenoxy acid fluxes at a complex site and identification of specific in situ indicators were encountered. Thus, there is a pronounced need for development and broader experience with evaluation tools for natural attenuation of phenoxy acids, such as specific metabolites, changes in enantiomeric fractions, compound-specific stable carbon isotope ratios, or microbial fingerprints. 相似文献
375.
Charlotte B. Hasager Niels W. Nielsen Niels Otto Jensen Eva Boegh Jens H. Christensen Ebba Dellwik Henrik Soegaard 《Boundary-Layer Meteorology》2003,109(3):227-254
In numerical weather prediction, climate and hydrologicalmodelling, the grid cell size is typically larger than the horizontal length scales of variations in aerodynamicroughness, surface temperature and surface humidity. These local land cover variations give rise to sub-gridscale surface flux differences. Especially the roughness variations can give a significantly differentvalue between the equilibrium roughness in each of the patches as compared to the aggregated roughness value,the so-called effective roughness, for the grid cell. The effective roughness is a quantity that secures thephysics to be well-described in any large-scale model. A method of aggregating the roughness step changesin arbitrary real terrain has been applied in flat terrain (Denmark) where sub-grid scale vegetation-drivenroughness variations are a dominant characteristic of the landscape. The aggregation model is a physicaltwo-dimensional atmospheric flow model in the horizontal domain based on a linearized version of theNavier Stoke equation. The equations are solved by the Fast Fourier Transformation technique, hence the codeis very fast. The new effective roughness maps have been used in the HIgh Resolution Limited Area Model(HIRLAM) weather forecasting model and the weather prediction results are compared for a number of casesto synoptic and other observations with improved agreement above the predictions based on currentstandard input. Typical seasonal springtime bias on forecasted winds over land of +0.5 m s-1 and-0.2 m s-1 in coastal areas is reduced by use of the effective roughness maps. 相似文献
376.
377.
Landslide and Tsunami 21 November 2000 in Paatuut,West Greenland 总被引:1,自引:0,他引:1
Dahl-Jensen Trine Larsen Lotte Melchior Pedersen Stig A. Schack Pedersen Jerrik Jepsen Hans F. Pedersen Gunver Nielsen Tove Pedersen Asger Ken Von Platen-Hallermund Frants Weng Willy 《Natural Hazards》2004,31(1):277-287
A large landslide occurred November 21, 2000 at Paatuut, facing the Vaigat Strait onthe west coast of Greenland. 90 million m3 (260 million tons) of mainly basalticmaterial slid very rapidly (average velocity 140 km/h) down from 1,000–1,400 maltitude. Approximately 30 million m3 (87 million tons) entered the sea, creatinga tsunami with an run-up height of 50 m close to the landslide and 28 m at Qullissat,an abandoned mining town opposite Paatuut across the 20 km wide Vaigat strait. Theevent was recorded seismically, allowing the duration of the slide to be estimated tocirca 80 s and also allowing an estimate of the surface-wave magnitude of the slideof 2.3. Terrain models based on stereographic photographs before and after the slidemade it possible to determine the amount of material removed, and the manner ofre-deposition. Simple calculations of the tsunami travel times are in good correspondencewith the reports from the closest populated village, Saqqaq, 40 km from Paatuut, whererefracted energy from the tsunami destroyed a number of boats. Landslides are notuncommon in the area, due to the geology with dense basaltic rocks overlying poorlyconsolidated sedimentary rocks, but the size of the Paatuut slide is unusual. Based onthe observations it is likely at least 500 years since an event with a tsunami of similarproportions occurred. The triggering of the Paatuut slide is interpreted to be caused byweather conditions in the days prior to the slide, where re-freezing melt water inpre-existing cracks could have caused failure of the steep mountain side. 相似文献
378.
379.
We studied whether incorporation of terms for environmental factors (temperature, herring and 0-group cod) into the stock recruitment functions for the Barents Sea capelin ( Mallotus villosus ) would increase the ability to predict recruitment. We also investigated the effects of alternative estimates of the capelin spawning stock (SSB) and juvenile herring on model predictability. By using nonlinear regression, the modified Beverton–Holt and Ricker stock recruitment models were fitted to time series of capelin spawning stock, capelin recruitment, juvenile herring, 0-group cod and temperature from 1973 to 2000. The modified Beverton–Holt model with a term for juvenile herring fit capelin recruitment data well. Inclusion of terms for temperature and 0-group cod abundance did not significantly improve the model fit. The best model predicts an almost proportional relationship between the spawning stock and the capelin recruitment when the abundance of juvenile herring is high. 相似文献
380.
This work is a part of the TOR1 project (1996–1997) and is devoted to determining the lithospheric structure across the Sorgenfrei–Tornquist Zone in Northern Europe. For the first time in Europe, a very dense seismic broadband array has offered the possibility of determining very sharp lateral variations in the structure of the lithosphere at small scales using surface wave analysis. We measure phase velocities for Rayleigh waves with periods ranging between 10 and 100 s, both within arrays with apertures of 40–50 km (small compared to the wavelength), and along long profiles of at least 100 km. Dispersion curves are then inverted and shear-wave velocity models down to the depth of 200 km are proposed. We show that the Sorgenfrei–Tornquist Zone is a major tectonic feature within the whole lithosphere. North–east of this feature, in Sweden beneath the Baltic Shield, no lithosphere–asthenosphere boundary is observed to exist to depths of 200 km. South–west of the Sorgenfrei–Tornquist Zone, beneath Denmark, we find a lithospheric thickness of 120±20 km. The transition across the Sorgenfrei–Tornquist Zone is sharp and determined to be very steeply dipping to the south–west. We also demonstrate the existence of a sharp discontinuity between the lithospheres beneath Denmark (120±20 km thick) and beneath Germany (characterized by thicknesses of 50±10 km in the northernmost part and 100±20 km in the southwest). This discontinuity is most likely related to the Trans-European Fault at the surface. 相似文献