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Pneumatic Barrier
A pneumatic barrier is a method to contain oil spills. It is also called a bubble curtain. Air bubbling through a perforated pipe causes an upward water flow that slows the spread of oil. It can also be used to stop fish from entering polluted water. A further application of the pneumatic barrier is to decrease the salt-water exchange in navigation locks and prevent salt intrusion in rivers. . Pneumatic barriers are also known as air curtains. The pneumatic barrier is a (non-patented) invention of the Dutch engineer Johan van Veen from around 1940 . A pneumatic barrier is an ''active'' (as opposed to ''passive'') method of waterway oil spill control. (An example of a passive method would be a containment boom.) Method of operation The pneumatic barrier consists of a perforated pipe and a compressed air source. Air escaping from the pipe provides a "hump" of rising water and air which contains the oil spill. Anchors to keep the pipe in a particular spot are helpful. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pneumatic Barrier
A pneumatic barrier is a method to contain oil spills. It is also called a bubble curtain. Air bubbling through a perforated pipe causes an upward water flow that slows the spread of oil. It can also be used to stop fish from entering polluted water. A further application of the pneumatic barrier is to decrease the salt-water exchange in navigation locks and prevent salt intrusion in rivers. . Pneumatic barriers are also known as air curtains. The pneumatic barrier is a (non-patented) invention of the Dutch engineer Johan van Veen from around 1940 . A pneumatic barrier is an ''active'' (as opposed to ''passive'') method of waterway oil spill control. (An example of a passive method would be a containment boom.) Method of operation The pneumatic barrier consists of a perforated pipe and a compressed air source. Air escaping from the pipe provides a "hump" of rising water and air which contains the oil spill. Anchors to keep the pipe in a particular spot are helpful. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oil Spill
An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially the marine ecosystem, due to human activity, and is a form of pollution. The term is usually given to marine oil spills, where oil is released into the ocean or coastal waters, but spills may also occur on land. Oil spills may be due to releases of crude oil from tankers, offshore platforms, drilling rigs and wells, as well as spills of refined petroleum products (such as gasoline, diesel) and their by-products, heavier fuels used by large ships such as bunker fuel, or the spill of any oily refuse or waste oil. Oil spills penetrate into the structure of the plumage of birds and the fur of mammals, reducing its insulating ability, and making them more vulnerable to temperature fluctuations and much less buoyant in the water. Cleanup and recovery from an oil spill is difficult and depends upon many factors, including the type of oil spilled, the temperature of the water (affecting evapor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bubble Curtain
A bubble curtain is a system that produces bubbles in a deliberate arrangement in water. It is also called pneumatic barrier. The technique is based on bubbles of air (gas) being let out under the water surface, commonly on the bottom. When the bubbles rise they act as a barrier, a curtain, breaking the propagation of waves or the spreading of particles and other contaminants. Uses It can be used for the following purposes: * to reduce propagation of shock waves (e.g. acoustic waves from engines or pile driving, explosions etcetera), * to reduce liquid or debris floating on the surface from spreading * to prevent salt intrusion * to control the movements of fish * for decoration and airing in aquariums In June 2010, Okaloosa County, Florida used air bubble curtains to help protect their Destin Pass coastline from oil produced in the Gulf of Mexico by the Deepwater Horizon oil spill. They hoped to push oil up to the surface for booms and skimming boats to collect the oil. Bri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of living fish species are ray-finned fish, belonging to the class Actinopterygii, with around 99% of those being teleosts. The earliest organisms that can be classified as fish were soft-bodied chordates that first appeared during the Cambrian period. Although they lacked a true spine, they possessed notochords which allowed them to be more agile than their invertebrate counterparts. Fish would continue to evolve through the Paleozoic era, diversifying into a wide variety of forms. Many fish of the Paleozoic developed external armor that protected them from predators. The first fish with jaws appeared in the Silurian period, after which many (such as sharks) became formidable marine predators rather than just the prey of arthropods. Mos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Pollution
Water pollution (or aquatic pollution) is the contamination of water bodies, usually as a result of human activities, so that it negatively affects its uses. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and groundwater. Water pollution results when contaminants are introduced into these water bodies. Water pollution can be attributed to one of four sources: sewage discharges, industrial activities, agricultural activities, and urban runoff including stormwater. It can be grouped into surface water pollution (either fresh water pollution or marine pollution) or groundwater pollution. For example, releasing inadequately treated wastewater into natural waters can lead to degradation of these aquatic ecosystems. Water pollution can also lead to water-borne diseases for people using polluted water for drinking, bathing, washing or irrigation. Water pollution reduces the ability of the body of water to provide the ecosystem services (such as drinking water) that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johan Van Veen
Johan van Veen (Uithuizermeeden, 21 December 1893 – The Hague, 9 December 1959) was a Dutch hydraulic engineering, hydraulic engineer. He is considered the father of the Delta Works. Education Johan van Veen was the fifth child of seven in a farming family. He was the brother of Marie van Veen, married to the artist Johan Dijkstra (artist), Johan Dijkstra. In 1913, after high school graduation, he started his studies in Delft at the Technische Universiteit Delft, Technische Hoogeschool van Delft. He studied civil engineering. In 1919, he graduated as "ingenieur" (equivalent to M.Sc. in engineering). Provincial Water Authority Drenthe Van Veen worked as an engineer for the Drainage Department of the Provincial Water Authority of the Province of Drenthe. The task of this department was to develop plans to improve the drainage and road structure of the province. In turn, this would enlarge the agricultural yield and to transport the products in a more efficient way to the markets ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boom (containment)
A containment boom is a temporary floating barrier used to contain an oil spill. Booms are used to reduce the possibility of polluting shorelines and other resources, and to help make recovery easier. Booms help to concentrate oil in thicker surface layers so that skimmers, vacuums, or other collection methods can be used more effectively. They come in many shapes and sizes, with various levels of effectiveness in different types of water conditions. Often the first containment method to be used and the last equipment to be removed from the site of an oil spill, they are "the most commonly used and most environmentally acceptable response technique to clean up oil spills in the United States." Booms used in oil spills can be seen as they rest on the surface of the water, but can have between 45 and 120 cm (18 to 48 inches) of material that hangs beneath the surface. They are effective in calm water, but as wave height increases oil or other contaminants can easily wash ov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dead Zone (ecology)
Dead zones are hypoxic (low-oxygen) areas in the world's oceans and large lakes. Hypoxia occurs when dissolved oxygen (DO) concentration falls to or below 2 mg of O2/liter. When a body of water experiences hypoxic conditions, aquatic flora and fauna begin to change behavior in order to reach sections of water with higher oxygen levels. Once DO declines below 0.5 ml O2/liter in a body of water, mass mortality occurs. With such a low concentration of DO, these bodies of water fail to support the aquatic life living there. Historically, many of these sites were naturally occurring. However, in the 1970s, oceanographers began noting increased instances and expanses of dead zones. These occur near inhabited coastlines, where aquatic life is most concentrated. In March 2004, when the recently established UN Environment Programme published its first Global Environment Outlook Year Book (''GEO Year Book 2003''), it reported 146 dead zones in the world's oceans where marine life cou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eutrophication
Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phytoplankton productivity". Water bodies with very low nutrient levels are termed oligotrophic and those with moderate nutrient levels are termed mesotrophic. Advanced eutrophication may also be referred to as dystrophic and hypertrophic conditions. Eutrophication can affect freshwater or salt water systems. In freshwater ecosystems it is almost always caused by excess phosphorus. In coastal waters on the other hand, the main contributing nutrient is more likely to be nitrogen, or nitrogen and phosphorus together. This depends on the location and other factors. When occurring naturally, eutrophication is a very slow process in which nutrients, especially phosphorus compounds and organic matter, accumulate in water bodies. These nutrients deriv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cetacean Stranding
Cetacean stranding, commonly known as beaching, is a phenomenon in which whales and dolphins strand themselves on land, usually on a beach. Beached whales often die due to dehydration, collapsing under their own weight, or drowning when high tide covers the blowhole. Cetacean stranding has occurred since before recorded history. Several explanations for why cetaceans strand themselves have been proposed, including changes in water temperatures, peculiarities of whales' echolocation in certain surroundings, and geomagnetic disturbances, but none have so far been universally accepted as a definitive reason for the behavior. However, a link between the mass beaching of beaked whales and use of mid-frequency active sonar has been found. Subsequently, whales that die due to stranding can decay and bloat to the point where they can easily explode, causing gas and their internal organs to fly out. Species Every year, up to 2,000 animals beach themselves. Although the majority of s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluid Dynamics
In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids— liquids and gases. It has several subdisciplines, including ''aerodynamics'' (the study of air and other gases in motion) and hydrodynamics (the study of liquids in motion). Fluid dynamics has a wide range of applications, including calculating forces and moments on aircraft, determining the mass flow rate of petroleum through pipelines, predicting weather patterns, understanding nebulae in interstellar space and modelling fission weapon detonation. Fluid dynamics offers a systematic structure—which underlies these practical disciplines—that embraces empirical and semi-empirical laws derived from flow measurement and used to solve practical problems. The solution to a fluid dynamics problem typically involves the calculation of various properties of the fluid, such as flow velocity, pressure, density, and temperature, as functions of space and time. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
