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361.
We report concurrent measurements of ocean currents and turbulence at two sites in the North Sea, one site at upwind of the FINO1 platform and the other 200-m downwind of the Alpha Ventus wind farm. At each site, mean currents, Reynolds stresses, turbulence intensity and production of turbulent kinetic energy are obtained from two bottom-mounted 5-beam Nortek Signature1000s, high-frequency Doppler current profiler, at a water depth of approximately 30 m. Measurements from the two sites are compared to statistically identify the effects of wind farm and waves on ocean current variability and the turbulent structure in the water column. Profiles of Reynolds stresses are found to be sensible to both environmental forcing and the wind farm wake-induced distortions in both boundary layers near the surface and the seabed. Production of turbulent kinetic energy and turbulence intensity exhibit approximately similar, but less pronounced, patterns in the presence of farm wake effects. 相似文献
362.
The Stern Review has played an enormous role in making the world of business aware of the challenge of long-term climate change. In order to make real progress on the basis of this awareness, it is important to pay attention to the difference between human suffering and losses of gross domestic product (GDP). The Review has compared climate change to experiences of suffering like World War I. That war, however, hardly affected global GDP. The long-term damages to be expected from business-as-usual greenhouse gas emissions include loss of the coastal cities of the world over the next millennia. This would be an act of unprecedented barbarism, regardless of whether it would slow down economic growth or perhaps even accelerate it. Business leaders worried about climate change need to pay attention to the tensions between ethical and economic concerns. Otherwise, a credibility crisis threatens global climate policy. An important step to establish the credibility needed for effective climate policy will be to gradually move towards a regime where emission permits are auctioned, not handed out as hidden subsidies. The revenues generated by permit auctions should be used to establish a global system of regional climate funds. 相似文献
363.
The formation of sub-seafloor gas hydrates in marine environments can be described as a coupled transport and thermodynamic process inside a host sediment matrix undergoing structural evolution. The transport processes are driven by the sedimentary load and induced overpressure gradients, controlled by sediment permeability. In order to accurately model the resulting fluid flow profile, the decrease of sediment permeability during hydrate precipitation has to be taken into account, which affects both the transport of solutes and sediment compaction. In this paper, we investigate how total hydrate abundance is affected by regions of low permeability which deflect the flow field in their vicinity. For this purpose, a two-dimensional numerical hydrate system model was set up which permits to quantify this effect in scenarios where changes in water depth cause lateral variations of the thickness of the hydrate stability field, as well as of hydrate saturation and sediment permeability. The microscopic structure of gas hydrate crystals in the host sediment matrix defines the evolution of the permeability reduction during hydrate formation. Grain-coating precipitates have a stronger tendency to clog flow paths through pore throats than do pore-filling precipitates. Our results clearly show that these pore-scale processes affect the large-scale flow field and hydrate abundance. The sensitivity depends on the model geometry and, for a 5° slope of the seafloor, 4.1% relative difference is predicted for the hydrate saturation according to different porosity-permeability relationships. 相似文献
364.
HydrIS:一个用于地下水管理的开放的GIS决策支持系统——以Morocco为例(英文) 总被引:1,自引:0,他引:1
A regional groundwater management system has been elaborated, integrating Relational Database Management System (RDBMS) and
various web services. It consists of web geospatial application so-called HydrIS ( Hydrogeological Information System) based
on Open Source components and technologies, leading to a feasible and low-cost solution. Therefore, HydrIS permits delivery
of data from a number of heterogeneous sources to standards supported by the Open Geospatial Consortium (OGC). The protocols
used for exchanging data are also derived from OGC standards, i.e., WMS (Web Mapping Service), WFS (Web Feature Service),
and WCS (Web Coverage Service). Finally, a geoportal was developed, which consists of client-applications that communicate
with different Web Services (WMS, WCS, and WFS) through http-requests.
A prototype for web-based GIS application was designed using the deegree Framework to provide systematic interfaces and functions.
This system was developed to demonstrate the value of making hydrogeological data more widely accessible through client/server
architecture. This experience and knowledge already gained in this project will be a source for technology transfer and policy
decisions. Otherwise, this will enable user groups to improve the management of their groundwater resources and contribute
to enhanced decision support capabilities.
相似文献
365.
Matthew B Sanders Marion Sebire Joachim Sturve Paul Christian Ioanna Katsiadaki Brett P Lyons Dave Sheahan Jason M Weeks Stephen W Feist 《Marine environmental research》2008,66(1):161-163
Effects of nanoparticles on aquatic organisms have been little studied to date and toxicological data are urgently needed for development of regulatory frameworks for these substances. Here, we report the findings of a study exposing sticklebacks to cadmium sulfide (CdS) as bulk material and quantum dots. Fish were exposed for 21 d in a flow through test system to 5, 50 or 500 microg l(-1) CdS nanoparticles (nCdS) coated in thiol terminated methyl polyethylene glycol (MPEG), bulk CdS or MPEG at 500 microg l(-1) (nominal concentrations). With the exception of the highest nCdS exposure, measured concentrations were approximately one order of magnitude below nominal. A single fish from each group (excluding MPEG) was examined using energy dispersive X-ray analysis (EDX) to localise cadmium, however, cadmium could not be detected in whole body sections. Elevated levels of oxidized glutathione were measured in the gills of fish exposed to 50 and 500 microg l(-1) nCdS. Induction of vitellogenin synthesis was not detected in any of the treatment groups. The number of males engaged in nest-building behaviour following exposure to 500 microg l(-1) nCdS was reduced and livers of 4/6 fish in the same treatment displayed hepatocellular nuclear pleomorphism. The results are discussed emphasising the fundamental importance of experimental design and the need to understand the behaviour of nanoparticles in the aqueous phase. 相似文献
366.
Joachim Gürtler 《Astronomische Nachrichten》1996,317(2):106-106