Environmental Pollution

Environmental Pollution

Table of Contents

1. Pollution (definition)

2. Water Pollution

3. Thermal Pollution

4. Land Pollution

5. Pestiside Pollution

6. Radiation Pollution

7. Noise Pollution

8. Air Pollution

Pollution - Environmental pollution is any discharge of material or energy into water, land, or air that causes or may cause acute (short-term) or chronic (long-term) detriment to the Earth's ecological balance or that lowers the quality of life. Pollutants may cause primary damage, with direct identifiable impact on the environment, or secondary damage in the form of minor perturbations in the delicate balance of the biological food web that are detectable only over long time periods.

Until relatively recently in humanity's history, where pollution has existed, it has been primarily a local problem. The industrialization of society, the introduction of motorized vehicles, and the explosion of the human population, however, have caused an exponential growth in the production of goods and services. Coupled with this growth has been a tremendous increase in waste by-products. The indiscriminate discharge of untreated industrial and domestic wastes into waterways, the spewing of thousands of tons of particulates and airborne gases into the atmosphere, the "throwaway" attitude toward solid wastes, and the use of newly developed chemicals without considering potential consequences have resulted in major environmental disasters, including the formation of smog in the Los Angeles area since the late 1940s and the pollution of large areas of the Mediterranean Sea. Technology has begun to solve some pollution problems (see pollution control), and public awareness of the extent of pollution will eventually force governments to undertake more effective environmental planning and adopt more effective antipollution measures.

Different Types of Pollution

 WATER POLLUTION

Water pollution is the introduction into fresh or ocean waters of chemical, physical, or biological material that degrades the quality of the water and affects the organisms living in it. This process ranges from simple addition of dissolved or suspended solids to discharge of the most insidious and persistent toxic pollutants (such as pesticides, heavy metals, and nondegradable, bioaccumulative, chemical compounds).

Conventional
Conventional or classical pollutants are generally associated with the direct input of (mainly human) waste products. Rapid urbanization and rapid population increase have produced sewage problems because treatment facilities have not kept pace with need. Untreated and partially treated sewage from municipal wastewater systems and septic tanks in unsewered areas contribute significant quantities of nutrients, suspended solids, dissolved solids, oil, metals (arsenic, mercury, chromium, lead, iron, and manganese), and biodegradable organic carbon to the water environment.

Conventional pollutants may cause a myriad of water pollution problems. Excess suspended solids block out energy from the Sun and thus affect the carbon dioxide-oxygen conversion process, which is vital to the maintenance of the biological food chain. Also, high concentrations of suspended solids silt up rivers and navigational channels, necessitating frequent dredging. Excess dissolved solids make the water undesirable for drinking and for crop irrigation.

Although essential to the aquatic habitat, nutrients such as nitrogen and phosphorus may also cause overfertilization and accelerate the natural aging process (eutrophication) of lakes. This acceleration in turn produces an overgrowth of aquatic vegetation, massive algal blooms, and an overall shift in the biologic community--from low productivity with many diverse species to high productivity with large numbers of a few species of a less desirable nature. Bacterial action oxidizes biodegradable organic carbon and consumes dissolved oxygen in the water. In extreme cases where the organic-carbon loading is high, oxygen consumption may lead to an oxygen depression: (less than 2 mg/l compared with 5 to 7 mg/l for a healthy stream) is sufficient to cause a fish kill and seriously to disrupt the growth of associated organisms that require oxygen to survive.

Nonconventional

The nonconventional pollutants include dissolved and particulate forms of metals, both toxic and nontoxic, and degradable and persistent organic carbon compounds discharged into water as a by-product of industry or as an integral part of marketable products. More than 13,000 oil spills of varying magnitude occur in the United States each year. Thousands of environmentally untested chemicals are routinely discharged into waterways; an estimated 400 to 500 new compounds are marketed each year. In addition, coal strip mining releases acid wastes that despoil the surrounding waterways. Nonconventional pollutants vary from biologically inert materials such as clay and iron residues to the most toxic and insidious materials such as halogenated hydrocarbons (DDT, kepone, mirex, and polychlorinated biphenyls--PCB). The latter group may produce damage ranging from acute biological effects (complete sterilization of stretches of waterways) to chronic sublethal effects that may go undetected for years. The chronic low-level pollutants are proving to be the most difficult to correct and abate because of their ubiquitous nature and chemical stability.

THERMAL POLLUTION

Thermal pollution is the discharge of waste heat via energy dissipation into cooling water and subsequently into nearby waterways. The major sources of thermal pollution are fossil-fuel and nuclear electric-power generating facilities and, to a lesser degree, cooling operations associated with industrial manufacturing, such as steel foundries, other primary-metal manufacturers, and chemical and petrochemical producers.

The discharge temperatures from electric-power plants generally range from 5 to 11 C degrees (9 to 20 F degrees) above ambient water temperatures. An estimated 90% of all water consumption, excluding agricultural uses, is for cooling or energy dissipation.

 The discharge of heated water into a waterway often causes ecologic imbalance, sometimes resulting in major fish kills near the discharge source. The increased temperature accelerates chemical-biological processes and decreases the ability of the water to hold dissolved oxygen. Thermal changes affect the aquatic system by limiting or changing the type of fish and aquatic biota able to grow or reproduce in the waters. Thus rapid and dramatic changes in biologic communities often occur in the vicinity of heated discharges.

LAND POLLUTION

Land pollution is the degradation of the Earth's land surface through misuse of the soil by poor agricultural practices, mineral exploitation, industrial waste dumping, and indiscriminate disposal of urban wastes.

Soil Misuse
Soil erosion--a result of poor agricultural practices--removes rich humus topsoil developed over many years through vegetative decay and microbial degradation and thus strips the land of valuable nutrients for crop growth. Strip mining for minerals and coal lays waste thousands of acres of land each year, denuding the Earth and subjecting the mined area to widespread erosion problems. The increases in urbanization due to population pressure presents additional soil-erosion problems; sediment loads in nearby streams may increase as much as 500 to 1,000 times over that recorded in nearby undeveloped stretches of stream. Soil erosion not only despoils the Earth for farming and other uses, but also increases the suspended-solids load of the waterway. This increase interferes with the ecological habitat and poses silting problems in navigation channels, inhibiting the commercial use of these waters.

Solid Waste

In the United States in 1988 municipal wastes alone--that is, the solid wastes sent by households, business, and municipalities to local landfills and other waste-disposal facilities--equaled 163 million metric tons (1980 million U.S. tons), or 18 k (40lb) per person, according to figures released by the Environmental Protection Agency. Additional solid wastes accumulate from mining, industrial production, and agriculture. Although municipal wastes are the most obvious, the accumulations of other types of wastes are the most obvious, the accumulations of other types of waste are far greater, in many instances are more difficult to dispose of, and present greater environmental hazards.

The most common and convenient method of disposing of municipal solid wastes is in the sanitary landfill. The open dump, once a common eyesore in towns across the United States, attracted populations of rodents and other pests and often emitted hideous odors; it is now illegal. Sanitary landfills provide better aesthetic control and should be odor-free. Often, however, industrial wastes of unknown content are commingled with domestic wastes. Groundwater infiltration and contamination of water supplies with toxic chemicals have recently led to more active control of landfills and industrial waste disposal. Careful management of sanitary landfills, such as providing for leachate and runoff treatment as well as daily coverage with topsoil, has alleviated most of the problems of open dumping. In many areas, however, space for landfills is running out and alternatives must be found.

Recycling of materials is practical to some extent for much municipal and some industrial wastes, and a small but growing proportion of solid wastes is being recycled. When wastes are commingled, however, recovery becomes difficult and expensive. New processes of sorting ferrous and nonferrous metals, paper, glass, and plastics have been developed, and many communities with recycling programs now require refuse separation. Crucial issues in recycling are devising better processing methods, inventing new products for the recycled materials, and finding new markets for them.

Incineration is another method for disposing of solid wastes. Advanced incinerators use solid wastes as fuel, burning quantities of refuse and utilizing the resultant heat to make steam for electricity generation. Wastes must be burned at very high temperatures, and incinerator exhausts must be equipped with sophisticated scrubbers and other devices for removing dioxins and other toxic pollutants. Problems remain, however: incinerator ash contains high ratios of heavy metals, becoming a hazardous waste in itself, and high-efficiency incinerators may discourage the use of recycling and other waste-reduction methods.

Composting is increasingly used to treat some agricultural wastes, as well as such municipal wastes as leaves and brush. Composting systems can produce usable soil conditioners, or humus, within a few months (see compost).

PESTICIDE POLLUTION

Pesticides are organic and inorganic chemicals originally invented and first used effectively to better the human environment by controlling undesirable life forms such as bacteria, pests, and foraging insects. Their effectiveness, however, has caused considerable pollution. The persistent, or hard, pesticides, which are relatively inert and nondegradable by chemical or biologic activity, are also bioaccumulative; that is, they are retained within the body of the consuming organism and are concentrated with each ensuing level of the biologic food chain. For example, DDT provides an excellent example of cumulative pesticide effects. (Although DDT use has been banned in the United States since 1972, it is still a popular pesticide in much of the rest of the world.) DDT may be applied to an area so that the levels in the surrounding environment are less than one part per billion. As bacteria or other microscopic organisms ingest and retain the pesticide, the concentration may increase several hundred- to a thousandfold. Concentration continues as these organisms are ingested by higher forms of life--algae, fish, shellfish, birds, or humans. The resultant concentration in the higher life forms may reach levels of thousands to millions of parts per billion.

Many pesticides are nondiscriminatory; that is, they are not specific for a particular plant or organism. A dramatic example of this effect is DDE (a product of the breakdown of DDT), which effectively inhibits the ability of birds to provide sufficient calcium deposits for their eggs, producing fragile shells and a high percentage of nested eggs that break prematurely. Another reported side effect of pesticides is their effect on the nervous system of animals and fish; they can cause instability, disorientation, and, in some cases, death. These examples are generally a result of relatively high body residuals producing acute (short-term) readily recordable results.

The long-term (chronic) effects of persistent pesticides are virtually unknown, but many scientists believe they are as much an environmental hazard as are the acute effects. Nonpersistent (readily degradable) pesticides or substitutes, insect sterilization techniques, hormone homologues that check or interfere with maturation stages, and introduction of animals that prey on the pests present a potentially brighter picture for pest control with significantly reduced environmental consequences.

RADIATION POLLUTION

Radiation pollution is any form of ionizing or nonionizing radiation that results from human activities. The most well-known radiation results from the detonation of nuclear devices and the controlled release of energy by nuclear-power generating plants (see nuclear energy). Other sources of radiation include spent-fuel reprocessing plants, by-products of mining operations, and experimental research laboratories. Increased exposure to medical X rays and to radiation emissions from microwave ovens and other household appliances, although of considerably less magnitude, all constitute sources of environmental radiation.

Public concern over the release of radiation into the environment greatly increased following the disclosure of possible harmful effects to the public from nuclear weapons testing, the accident (1979) at the Three Mile Island nuclear-power generating plant near Harrisburg, Pa., and the catastrophic 1986 explosion at Chernobyl, a Soviet nuclear power plant. In the late 1980s, revelations of major pollution problems at U.S. nuclear weapons reactors raised apprehensions even higher.

The environmental effects of exposure to high-level ionizing radiation have been extensively documented through postwar studies on individuals who were exposed to nuclear radiation in Japan. Some forms of cancer show up immediately, but latent maladies of radiation poisoning have been recorded from 10 to 30 years after exposure. The effects of exposure to low-level radiation are not yet known. A major concern about this type of exposure is the potential for genetic damage.

Radioactive nuclear wastes cannot be treated by conventional chemical methods and must be stored in heavily shielded containers in areas remote from biological habitats. The safest of storage sites currently used are impervious deep caves or abandoned salt mines. Most radioactive wastes, however, have half-lives of hundreds to thousands of years, and to date no storage method has been found that is absolutely infallible.

NOISE POLLUTION

Noise pollution has a relatively recent origin. It is a composite of sounds generated by human activities ranging from blasting stereo systems to the roar of supersonic transport jets. Although the frequency (pitch) of noise may be of major importance, most noise sources are measured in terms of intensity, or strength of the sound field. The standard unit, one decibel (dB), is the amount of sound that is just audible to the average human. The decibel scale is somewhat misleading because it is logarithmic rather than linear; for example, a noise source measuring 70 dB is 10 times as loud as a source measuring 60 dB and 100 times as loud as a source reading 50 dB. Noise may be generally associated with industrial society, where heavy machinery, motor vehicles, and aircraft have become everyday items. Noise pollution is more intense in the work environment than in the general environment, although ambient noise increased an average of one dB per year during the 1980s. The average background noise in a typical home today is between 40 and 50 decibels. Some examples of high-level sources in the environment are heavy trucks (90 dB at 15 m/50 ft), freight trains (75 dB at 15 m/50 ft), and air conditioning (60 dB at 6 m/20 ft).

The most readily measurable physiological effect of noise pollution is damage to hearing, which may be either temporary or permanent and may cause disruption of normal activities or just general annoyance. The effect is variable, depending upon individual susceptibility, duration of exposure, nature of noise (loudness), and time distribution of exposure (such as steady or intermittent). On the average an individual will experience a threshold shift (a shift in an individual's upper limit of sound detectability) when exposed to noise levels of 75 to 80 dB for several hours. This shift will last only several hours once the source of noise pollution is removed. A second physiologically important level is the threshold of pain, at which even short-term exposure will cause physical pain (130 to 140 dB). Any noise sustained at this level will cause a permanent threshold shift or permanent partial hearing loss. At the uppermost level of noise (greater than 150 dB), even a single short-term blast may cause traumatic hearing loss and physical damage inside the ear.

Although little hard information is available on the psychological side effects of increased noise levels, many researchers attribute increased irritability, lower productivity, decreased tolerance levels, increased incidence of ulcers, migraine headaches, fatigue, and allergic responses to continued exposures to high-level noises in the workplace and the general environment.

AIR POLLUTION

Air pollution is the accumulation in the atmosphere of substances that, in sufficient concentrations, endanger human health or produce other measured effects on living matter and other materials. Among the major sources of pollution are power and heat generation, the burning of solid wastes, industrial processes, and, especially, transportation. The six major types of pollutants are carbon monoxide, hydrocarbons, nitrogen oxides, particulates, sulfur dioxide, and photochemical oxidants.

Local and Regional
Smog has seriously affected more persons than any other type of air pollution. It can be loosely defined as a multisource, widespread air pollution that occurs in the air of cities. Smog, a contraction of the words smoke and fog, has been caused throughout recorded history by water condensing on smoke particles, usually from burning coal. The infamous London fogs--about 4,000 deaths were attributed to the severe fog of 1952--were smog of this type. Another type, ice fog, occurs only at high latitudes and extremely low temperatures and is a combination of smoke particles and ice crystals.

As a coal economy has gradually been replaced by a petroleum economy, photochemical smog has become predominant in many cities. Its unpleasant properties result from the irradiation by sunlight of hydrocarbons (primarily unburned gasoline emitted by automobiles and other combustion sources) and other pollutants in the air. Irradiation produces a long series of photochemical reactions (see photochemistry). The products of the reactions include organic particles, ozone, aldehydes, ketones, peroxyacetyl nitrate, and organic acids and other oxidants. Sulfur dioxide, which is always present to some extent, oxidizes and hydrates to form sulfuric acid and becomes part of the particulate matter. Furthermore, automobiles are polluters even in the absence of photochemical reactions. They are responsible for much of the particulate material in the air; they also emit carbon monoxide, one of the most toxic constituents of smog.

All types of smog decrease visibility and, with the possible exception of ice fog, are irritating to the respiratory system. Statistical studies indicate that smog is a contributor to malignancies of many types. Photochemical smog produces eye irritation and lacrimation and causes severe damage to many types of vegetation, including important crops. Acute effects include an increased mortality rate, especially among persons suffering from respiratory and coronary ailments. Air pollution also has a deleterious effect on works of art (see art conservation and restoration).

Air pollution on a regional scale is in part the result of local air pollution--including that produced by individual sources, such as automobiles--that has spread out to encompass areas of many thousands of square kilometers. Meteorological conditions and landforms can greatly influence air-pollution concentrations at any given place, especially locally and regionally. For example, cities located in bowls or valleys over which atmospheric inversions form and act as imperfect lids are especially likely to suffer from incidences of severe smog. Oxides of sulfur and nitrogen, carried long distances by the atmosphere and then precipitated in solution as acid rain, can cause serious damage to vegetation, waterways, and buildings.

Global

Humans also pollute the atmosphere on a global scale, although until the early 1970s little attention was paid to the possible deleterious effects of such pollution. Measurements in Hawaii suggest that the concentration of carbon dioxide in the atmosphere is increasing at a rate of about 0.2% every year. The effect of this increase may be to alter the Earth's climate by increasing the average global temperature. Certain pollutants decrease the concentration of ozone occurring naturally in the stratosphere, which in turn increases the amount of ultraviolet radiation reaching the Earth's surface. Such radiation may damage vegetation and increase the incidence of skin cancer. Examples of stratospheric contaminants include nitrogen oxides emitted by supersonic aircraft and chlorofluorocarbons used as refrigerants and aerosol-can propellants. The chlorofluorocarbons reach the stratosphere by upward mixing from the lower parts of the atmosphere (see ozone layer). It is believed that these chemicals are responsible for the noticeable loss of ozone over the polar regions that has occurred in the 1980s.

Special thanks to the ©1998 Environmental Protection Agency for allowing us to post this on our web site.

Petroleum

---

Petroleum is a naturally occurring liquid oil normally found in deposits beneath the surface of the earth. It is a type of oil composed of rock minerals, making it different from other kinds of oils that come from plants and animals (such as vegetable oil, animal fat, or essential oils). The word petroleum comes from the Latin words petra (rock) and oleum (oil), and so literally means rock oil. Despite this, petroleum is an organic compound, formed from the remains of microorganisms living millions of years ago. It is one of the three main fossil fuels, along with coal and natural gas.

Petroleum Economy

Petroleum, like all fossil fuels, primarily consists of a complex mixture of molecules called hydrocarbons (molecules containing both hydrogen and carbon). When it comes out of the ground, it is known as crude oil, and it may have various gases, solids, and trace minerals mixed in with it. Through refinement processes, a variety of consumer products can be made from petroleum. Most of these are fuels: gasoline, jet fuel, diesel fuel, kerosene, and propane are common examples. It is also used to make asphalt and lubricant grease, and it is a raw material for synthetic chemicals. Chemicals and materials derived from petroleum products include plastics, pesticides, fertilizers, paints, solvents, refrigerants, cleaning fluids, detergents, antifreeze, and synthetic fibers.

The modern petroleum industry began in 1859 in Pennsylvania, when a man named Edwin L. Drake constructed the first oil well, a facility for extracting petroleum from natural deposits. Since then, petroleum has become a valuable commodity in industrialized parts of the world, and oil companies actively search for petroleum deposits and build large oilextraction facilities. Several deposits exist in the United States. However, around 1960 oil production in the country began to decline as oil in the deposits was being used up and fewer new deposits were being discovered. Demand for petroleum products continued to increase, and as a result the United States came to rely more and more on oil imported from other countries. In 2001 the amount of petroleum extracted from deposits in the United States was estimated to be only one-third of the amount demanded by U.S. consumers. A similar pattern exists in other industrialized countries, and some, like Japan and Germany, import almost all of the oil they use.

TEN LARGEST OIL SPILLS IN HISTORY (BY VOLUME)

Location	Date	Amount Spilled
SOURCE: Oil Spill Intelligence Report (1999). International Oil Spill Statistics: 1998. New York: Aspen Publishers. Available from www.aspenpublishers.com/environment.asp
1. Sea Island Installations, Persian Gulf, Kuwait	January 26, 1991	240,000,000 gallons (816,327 tons)
2. Ixtoc I exploratory well, Bahia del Campeche, Mexico	June 3, 1979	140,000,000 gallons (476,190 tons)
3. Production well, Fergana Valley, Uzbekistan	March 2, 1992	88,000,000 gallons (299,320 tons)
4. Nowruz No. 3 well, Persian Gulf, Nowruz Field, Iran	February 4, 1983	80,000,000 gallons (272,109 tons)
5. Tanker Castillo de Bellver , Table Bay, South Africa	August 6, 1983	78,500,000 gallons (267,007 tons)
6. Tanker Amoco Cadiz , off Portsall, Brittany, France	March 16, 1978	68,668,000 gallons (233,565 tons)
7. Tanker Odyssey , North Atlantic Ocean, off St. John's, Newfoundland, Canada	November 10, 1988	43,100,000 gallons (146,600 tons)
8. Tanker Atlantic Empress , Caribbean Sea, Trinidad and Tobago	July 19, 1979	42,704,000 gallons (145,252 tons)
9. Tanker Haven , Genoa, Italy	April 11, 1991	42,000,000 gallons (142,857 tons)
10. Production well D-103, 800 km southeast of Tripoli, Libya	August 1, 1980	42,000,000 gallons (142,857 tons)

However, on a per capita basis, the consumption in these countries is nowhere near the consumption in the United States.

The United States and Canada are unique in that, on average, an individual in these countries consumes about twice as much petroleum product as do individuals in most other industrialized nations. People in the United States and Canada rely more on personal vehicles for their transportation and tend to drive greater distances, making petroleum their major source of energy. In the United States, about two-thirds of the petroleum consumed is transportation fuel, and two-thirds of that (45% of the total) is gasoline for cars and trucks. About 40 percent of the energy used in the United States every year comes from petroleum.

Foreign Oil Dependence

Political leaders in the United States have long been gravely concerned about the country's growing dependence on foreign oil, which in many ways puts the country at the mercy of foreign governments, some of them hostile to the United States. The greatest production of crude oil in the world is in the Persian Gulf region of the Middle East, where about 65 percent of the world's known petroleum deposits are located. About half of U.S. imports come from members of the Organization of the Petroleum Exporting Countries (OPEC), a group of countries encompassing the Persian Gulf and certain parts of Africa and South America. Events in these often volatile regions can have a huge impact on oil prices in the United States and worldwide, and because of the crucial role oil plays in U.S. society any change in the price can precipitate uncontrollable shifts in the country's economy (see chart "World Oil Price 1970-2000"). The most famous example of this is the Arab Oil Embargo of 1973 to 1974, when U.S. support for Israel in a conflict in the Middle East led to a decision by OPEC to impose steep price increases on the sale of oil to the United States. One response by the U.S. government has been the establishment of the Strategic Petroleum Reserve, an emergency stockpile designed to sustain the country's oil needs for approximately three months in the event of a complete cutoff of imports. There is little doubt, however, that dependence on foreign oil is both a political liability for the United States as well as a risk to national security.

Workers using water hoses to clean oil from a beach following a spill. (

United States Environmental Protection Agency. Reproduced by permission.

)

Environmental Pollution

Petroleum-derived contaminants constitute one of the most prevalent sources of environmental degradation in the industrialized world. In large concentrations, the hydrocarbon molecules that make up crude oil and petroleum products are highly toxic to many organisms, including humans. Petroleum also contains trace amounts of sulfur and nitrogen compounds, which are dangerous by themselves and can react with the environment to produce secondary poisonous chemicals. The dominance of petroleum products in the United States and the world economy creates the conditions for distributing large amounts of these toxins into populated areas and ecosystems around the globe.

Smoke is pouring from a refinery burnoff vent. (

© Royalty-Free/Corbis. Reproduced by permission.

)

Oil Spills

Perhaps the most visible source of petroleum pollution are the catastrophic oil-tanker spills—like the 1989 Exxon Valdez spill in Prince William Sound, Alaska—that make news headlines and provide disheartening pictures of oilcoated shorelines and dead or oiled birds and sea animals. These spills occur during the transportation of crude oil from exporting to importing nations. Crude oil travels for long distances by either ocean tanker or land pipeline, and both methods are prone to accidents. Oil may also spill at the site where it is extracted, as in the case of a blowout like the Ixtoc I exploratory well in 1979 (see table "Ten Largest Oil Spills in History"). A blowout is one of the major risks of drilling for oil. It occurs when gas trapped inside the deposit is at such a high pressure that oil suddenly erupts out of the drill shaft in a geyser.

Accidents with tankers, pipelines, and oil wells release massive quantities of petroleum into land and marine ecosystems in a concentrated form. The ecological impacts of large spills like these have only been studied for a very

World Oil Price 1970-2000 (

World Oil Market and Price Chronologies DOE Energy Information Administration ; originally published by the Department of Energy's Office of the Strategic Petroleum Reserve, Analysis Division

)

few cases, and it is not possible to say which have been the most environmentally damaging accidents in history. A large oil spill in the open ocean may do less harm to marine organisms than a small spill near the shore. The Exxon Valdez disaster created a huge ecological disaster not because of the volume of oil spilled (eleven million gallons) but because of the amount of shoreline affected, the sensitivity and abundance of organisms in the area, and the physical characteristics of the Prince William Sound, which helped to amplify the damage. The Exxon Valdez spill sparked the most comprehensive and costly cleanup effort ever attempted, and called more public attention to oil accidents than ever before. Scientific studies of the effects of oil in Prince William Sound are ongoing, and the number of tanker accidents worldwide has decreased significantly since the time of the Valdez spill, due to stricter regulations and such required improvements in vessel design as double-hull construction.

Nonpoint Sources

Spills from tankers, pipelines, and oil wells are examples of point sources of pollution, where the origin of the contaminants is a single identifiable point. They also represent catastrophic releases of a large volume of pollutants in a short period of time. But the majority of pollution from oil is from nonpoint sources, where small amounts coming from many different places over a long period of time add up to large-scale effects. Seventy percent of the oil released by human activity into oceans worldwide is a result of small spills during petroleum consumption. These minor unreported spills can include routine discharges of fuel from commercial vessels or leakage from recreational boats. However, in North America, the majority of the release originates on land. Oil tends to collect in hazardous concentrations in the stream of wastewater coming out of cities and other populated areas. Runoff from asphalt-covered roads and parking lots enters storm drains, streams, and lakes and eventually travels to the ocean, affecting all of the ecosystems through which it passes. As cities grow, more and more people use petroleum products—lubricants, solvents, oil-based paint, and, above all, gasoline—and these are often improperly disposed of down drains and sewage pipes. Industrial plants also produce small, chronic spills that aren't noticed individually, but add up over time and enter waterways.

Taken together, land-based river and urban runoff sources constitute over half of the petroleum pollution introduced to North American coastal waters due to human activity, and 20 percent of the petroleum pollution introduced to ocean waters worldwide. When wastewater from these sources enters the marine environment it is usually by means of an estuary, an area where freshwater from land mixes with seawater. Estuaries are especially critical habitats for a variety of plants and animals, and are among the ecosystems most sensitive to pollutants.

Petroleum-Contaminated Soil

Not all oil released from land sources is quickly washed away to sea, however. Pipeline and oil-well accidents, unregulated industrial waste, and leaking underground storage tanks can all permanently contaminate large areas of soil, making them economically useless as well as dangerous to the health of organisms living in and around them. Removing or treating soil contaminated by petroleum is especially urgent because the hydrocarbons can leach into the underlying groundwater and move into human residential areas. The engineering field of bioremediation has emerged in recent decades as a response to this threat. In bioremediation, bacteria that feed on hydrocarbons and transform them into carbon dioxide can be applied to an affected area. Bioremediation has in many cases made cleaning up petroleum-contaminated sites a profitable real-estate investment for land developers.

Air Pollution

The U.S. Environmental Protection Agency (EPA) designates six criteria pollutants for determining air quality. These are: carbon monoxide (CO), nitrogen oxides (NO and/or NO ₂ , usually referred to as NO _x ), sulfur dioxide (SO ₂ ), ground-level ozone (O ₃ ), particulate matter (including things like soot, dust, asbestos fibers, pesticides, and metals), and lead (Pb). Petroleum-fueled vehicles, engines, and industrial processes directly produce the vast majority of CO and NO _x in the atmosphere. They are also the principal source of gaseous hydrocarbons (also called volatile organic compounds, or VOCs), which combine with NO _x in sunlight to create O ₃ . Ozone, while important for blocking ultraviolet rays in the upper atmosphere, is also a key component of urban smog and creates human health problems when present in the lower atmosphere. Sulfur dioxide is a trace component of crude oil, and can cause acid rain when released into the air at oil refineries or petroleum power plants. Particulate matter is directly emitted in vehicle exhaust and can also form from the reaction of exhaust gases with water vapor and sunlight. Finally, leaded gasoline is a huge contributor of lead to the atmosphere, and the use of unleaded gasoline has decreased lead concentrations dramatically. The EPA and the World Bank are working to encourage the phaseout of leaded gasoline worldwide.

Petroleum-fueled transportation and coal-burning power plants are considered the chief causes of global warming. Excess amounts of carbon dioxide, methane, and NO _x , among other gases, trap heat in the atmosphere and create the greenhouse effect. Carbon dioxide (CO ₂ ) is a main constituent of petroleum fuel exhaust, even though it is not toxic and therefore not classified as a pollutant. About one-third of the CO ₂ emitted into the atmosphere every year comes from vehicle exhaust. Methane (NH ₃ ), although usually associated with natural gas, is also emitted whenever crude oil is extracted, transported, refined, or stored.

The Future of Petroleum

The world's reliance on petroleum is expected to grow, despite widespread environmental, economic, and political consequences. The U.S. oil extraction industry continues to aggressively search for new oil deposits and lobby the federal government to open up restricted areas to drilling. The Arctic National Wildlife Refuge in Alaska has been on the oil industry agenda for several decades, creating a long-standing environmental controversy. Advances in oil well technology have allowed extraction in the deep ocean beyond the continental shelf, but these have not been enough to reverse the trend of declining production in the United States.

There are many compelling reasons to decrease society's dependence on petroleum for energy, and the most obvious place to begin is in the transportation sector. Energy-efficient engines and hybrid gas/electric cars can help to reduce some of the need for oil, providing higher gas mileage and less demand. A variety of alternative fuels have also been developed, such as ethanol, biodiesel (made from vegetable oil), and hydrogen. Each of these would produce little or no exhaust pollutants or greenhouse gases, and each derives from plentiful renewable resources. The United States is now in fact actively researching hydrogen as a viable alternative to gasoline, and the hydrogen fuel cell as a substitute for the internal combustion engine.

Petroleum is a useful chemical substance for many important purposes. But it is also a nonrenewable resource with a highly toxic composition, and it poses significant problems when used in huge volumes throughout the industrialized world.

SEE ALSO A IR P OLLUTION ; A RCTIC N ATIONAL W ILDLIFE R EFUGE ; C OAL ;  
D ISASTERS: O IL S PILLS ; E CONOMICS ; E LECTRIC P OWER ; E NERGY ; 
F OSSIL F UELS ; G LOBAL W ARMING ; O ZONE ; NO _x ; 
R ENEWABLE E NERGY ; S ULFUR D IOXIDE ;  
U NDERGROUND S TORAGE T ANKS ; V EHICULAR P OLLUTION .

Bibliography

Oil Spill Intelligence Report. (1997). Oil Spills from Vessels (1960–1995): An International Historical Perspective. New York: Aspen Publishers.

Internet Resources

Committee on Oil in the Sea, National Research Council. (2003). Oil in the Sea III: Inputs, Fates, and Effects. Washington, D.C.: The National Academies Press. Available from http://www.nap.edu/catalog/10388.html .

Energy Information Administration. "Official Energy Statistics from the U.S. Government." Available from http://www.eia.doe.gov .

Exxon Valdez Oil Spill Trustee Council. "Restoring the Resources Injured by the Exxon Valdez Oil Spill and Understanding Environmental Change in the Northern Gulf of Alaska." Available from http://www.oilspill.state.ak.us .

National Biodiesel Board. "Need a Fill Up?" Available from http://www.biodiesel.org .

National Ethanol Vehicle Coalition. "National Ethanol Vehicle Coalition and E85." Available from http://www.e85fuel.com .

National Oceanic and Atmospheric Administration. "Office of Response and Restoration, National Ocean Service." Available from http://response.restoration.noaa.gov .

Schlumberger Excellence in Educational Development (SEED) Science Center. "Science Lab: Oil Well Blowout Simulator." Available from http://www.slb.com/seed/en/lab/blowout .

Trench, Cheryl J. (2001). "Oil Market Basics." Washington, D.C.: Energy Information Administration. Available from http://www.eia.doe.gov .

U.S. Department of Energy. "Energy Efficiency and Renewable Energy." Available from http://www.eere.energy.gov .

U.S. Department of Energy. "Fossil.energy.gov: A U.S. Department of Energy Web Site." Available from http://www.fossil.energy.gov .

U.S. Department of Energy. "Fossil Fuels: An Energy Education Website." Available from http://www.fossil.energy.gov/education .

U.S. Environmental Protection Agency. (1995). Profile of the Petroleum Refining Industry. Washington, D.C.: U.S. Government Printing Office. Available from http://www.epa.gov .

U.S. Environmental Protection Agency. (1999). Profile of the Oil and Gas Extraction Industry. Washington, D.C.: U.S. Government Printing Office. Available from http://www.epa.gov .

U.S. Environmental Protection Agency. "Air Quality Where You Live." Available from http://www.epa.gov/air/urbanair/index.html .

U.S. Geological Survey. Available from http://www.usgs.gov .

U.S. Geological Survey. (1997). "Bioremediation: Nature's Way to a Cleaner Environment." Available from http://water.usgs.gov/wid/html/bioremed.html .

Adrian MacDonald

OIL SEEPS

Almost half (45%) of the petroleum entering the marine environment is from natural seeps rather than anthropogenic sources. At seeps, oil and gas bubble out of cracks in the seabed creating special environments in which new organisms grow. These organisms survive through chemosynthesis rather than photosynthesis. They live in total darkness, more than four hundred meters below sea level, but survive by feeding directly off the hydrocarbons present in seeps or by eating carbon compounds resulting from chemosynthetic bacterial degradation of seep oil. Since 1984 oceanographers have discovered chemosynthetic communities of clams, mussels, tubeworms, bacterial mats, and other organisms on the seafloor of the Gulf of Mexico. United States Department of the Interior regulations protect these chemosynthetic communities from damage due to oil and gas drilling activities.

Read more: Petroleum - water, effects, environmental, disasters, pollutants, United States, history, causes, impact, EPA, soil, chemicals, industrial, liquid, wells, toxic, world, human, power http://www.pollutionissues.com/Na-Ph/Petroleum.html#ixzz1WlXPoHQO

SHIVA - DHYAN SLOK {SRI SHIV MAHIMA,SRI SHIV TANDAV STOTTRAM}.

Tortoise enters temple - Tv9

ganapati maha sloka

Sankata Nasana Ganapati Stotram Devotional Song - Narada Purana

How the Brain Stores Information for Short Periods of Time

The cells of several neural circuits store information by maintaining a persistent level of activity: A short-lived stimulus triggers the activity of neurons, and this activity is then maintained for several seconds. (Credit: Image courtesy of Albert-Ludwigs-Universität Freiburg)

Science Daily  — Freiburg biologist Dr. Aristides Arrenberg and his American colleagues studied mechanisms used by the brain to store information for a short period of time. The cells of several neural circuits store information by maintaining a persistent level of activity: A short-lived stimulus triggers the activity of neurons, and this activity is then maintained for several seconds. The mechanisms of this information storage have not yet been sufficiently described, although this phenomenon occurs in very many areas of the brain.

The persistent activity in the neural integrator for eye positions is never perfect, as the eyes gradually drift back to their point of rest after a saccade. The authors thus had the possibility of measuring the dynamics of the system during spontaneous eye movements in the dark and testing the model without the measurements being distorted by saccade commands or visual feedback.

The authors of the study, now published in the journal Nature Neuroscience, investigated the persistent activity in a hindbrain circuit responsible for eye movements in zebrafish larvae. This circuit, the so-called oculomotor system, gives the command for rapid eye movement by way of special nerve cells that produce a short-lived succession of action potentials. On the one hand, this "burst of fire" reaches the neurons responsible for movement in the eyes and triggers a "saccade," a rapid movement of the eye. On the other hand, it is also transmitted to a second cell population, the so-called neural integrator for eye movements, where the speed signal is integrated mathematically and a position signal is created. This signal is then transmitted to the motor neurons, thus producing -- in fish as well as in humans -- a stable eye position following the rapid eye movement. The neural integrator keeps up this signal for several seconds, until a new saccade is initiated.

The authors discovered that, contrary to previous belief, the cells of the neural integrator for eye movements do not constitute a homogeneous population and that existing models for explaining persistent activity in the oculomotor system will have to be reconsidered. The scientists demonstrated that the integrator neurons do not posses a uniform dynamics and that the neurons are distributed in the hindbrain with the help of their integrator time constants.

These findings provide new evidence on the organization and functioning of circuits with persistent activity and suggest a potential explanation for their low susceptibility to failure. The study is an important milestone in the quest of network neuroscience to explain the functioning of local circuits and thus close the gap between the functioning of a single neuron and the production of behavior.

How coming home changes a soldier's brain

 Psychology & Psychiatry 

The part of the brain that regulates fear normalises 18 months after a soldier returns home, a study found. Credit: The U.S. Army

Soldiers returning from combat have heightened activity in the part of the brain that regulates fear but this usually normalises after around 18 months, a study has found.

The amygdala, the tiny part of the brain that modulates fear, arousal and facial recognition, tends to be overactive in soldiers who have recently returned from deployment, causing increased irritability and heightened sensitivity to perceived threats.

To find out whether these changes were permanent or not, Dutch researchers conducted a series of experiments on 23 combat soldiers who had been deployed for four months to Afghanistan. A group of 16 non-deployed soldiers participated as a control.

The subjects underwent a brain MRI scan while being shown images of angry and fearful faces and were asked to match them with other face images. The tests were done before deployment, shortly after deployment and again a year and a half later.

“Across investigations, amygdala reactivity in the combat group followed a pattern of increased activity shortly after deployment and normalisation at the long-term,” the researchers wrote in their paper, which was published in the journal Molecular Psychiatry Professor Alexander McFarlane, head of the University of Adelaide Centre for Traumatic Stress Studies, said the study was interesting but that it was important to remember that not every returning soldier has the same recovery trajectory.

“And this may have relevance for police where they don’t get removed from the danger, they have constant and ongoing danger,” he said.

“There are certain people in policing roles who have not dissimilar levels of stress but it’s not like they are going through a deployment cycle. It keeps going.”

Professor Peter Warfe, director of the Centre for Military and Veterans' Health at the University of Queensland said the study provided some comforting conclusions.

“It’s reassuring to some extent that [amygdala function] appears to return to normal in this small group of people, presumably none of which were suffering post traumatic stress disorder,” he said.

“What [a return to normal amygdala function] means is a little unclear in terms of their psychological function, their day-to-day physical function and mental capacity,” he said.

“And this study involved small numbers, so I’d be cautious in drawing a broad conclusion,” he said. 

---

This story is published courtesy of the The Conversation (under Creative Commons-Attribution/No derivatives).

Source: The Conversation

"How coming home changes a soldier's brain." August 31st, 2011. http://medicalxpress.com/news/2011-08-home-soldierbrain.html

Posted by
Robert Karl Stonjek

Hubble Movies Provide Unprecedented View of Supersonic Jets from Young Stars

The glowing, clumpy streams of material shown in these NASA/ESA Hubble Space Telescope images are the signposts of star birth. Ejected episodically by young stars like cannon salvos, the blobby material zips along at more than 700 000 kilometres per hour. The speedy jets are confined to narrow beams by the powerful stellar magnetic field. Called Herbig-Haro or HH objects, these outflows have a bumpy ride through space. When fast-moving blobs collide with slower-moving gas, bow shocks arise as the material heats up. Bow shocks are glowing waves of material similar to waves produced by the bow of a ship ploughing through water. In HH 2, at lower right, several bow shocks can be seen where several fast-moving clumps have bunched up like cars in a traffic jam. In HH 34, at lower left, a grouping of merged bow shocks reveals regions that brighten and fade over time as the heated material cools where the shocks intersect. In HH 47, at top, the blobs of material look like a string of cars on a crowded motorway, which ends in a chain-reaction accident. The smash up creates the bow shock, left. These images are part of a series of time-lapse movies astronomers have made showing the outflows’ motion over time. The movies were stitched together from images taken over a 14-year period by Hubble’s Wide Field Planetary Camera 2. Hubble followed the jets over three epochs: HH 2 from 1994, 1997, and 2007; HH 34 from 1994, 1998, and 2007; and HH 47 from 1994, 1999, and 2008. The outflows are roughly 1350 light-years from Earth. HH 34 and HH 2 reside near the Orion Nebula, in the northern sky. HH 47 is located in the southern constellation of Vela. (Credit: NASA, ESA, and P. Hartigan (Rice University))

Science Daily — Stars aren't shy about sending out birth announcements. They fire off energetic jets of glowing gas travelling at supersonic speeds in opposite directions through space. Although astronomers have looked at still pictures of stellar jets for decades, now they can watch movies, thanks to the NASA/ESA Hubble Space Telescope.

An international team of scientists led by astronomer Patrick Hartigan of Rice University in Houston, USA, has collected enough high-resolution Hubble images over a 14-year period to stitch together time-lapse movies of young jets ejected from three stars.

The moving pictures offer a unique view of stellar phenomena that move and change over just a few years. Most astronomical processes change over timescales that are much longer than a human lifetime.

The movies reveal the motion of the speedy outflows as they tear through the interstellar environments. Never-before-seen details in the jets' structure include knots of gas brightening and dimming and collisions between fast-moving and slow-moving material, creating glowing arrowhead features. These phenomena are providing clues about the final stages of a star's birth, offering a peek at how the Sun behaved 4.5 billion years ago.

"For the first time we can actually observe how these jets interact with their surroundings by watching these time-lapse movies," said Hartigan. "Those interactions tell us how young stars influence the environments out of which they form. With movies like these, we can now compare observations of jets with those produced by computer simulations and laboratory experiments to see which aspects of the interactions we understand and which we don't understand."

Hartigan's team's results appear in the 20 July 2011 issue of the Astrophysical Journal.

Jets are an active, short-lived phase of star formation, lasting only about 100 000 years. They are called Herbig-Haro (HH) objects, named after George Herbig and Guillermo Haro, who studied the outflows in the 1950s. Astronomers still don't know what role jets play in the star formation process or exactly how the star unleashes them.

A star forms from a collapsing cloud of cold hydrogen gas. As the star grows, it gravitationally attracts more matter, creating a large spinning disc of gas and dust around it. Eventually, planets may arise within the disc as dust clumps together.

The disc material gradually spirals onto the star and escapes as high velocity jets along the star's axis of spin. The speedy jets are confined to narrow beams by the star's powerful magnetic field. The jet phase stops when the disc runs out of material, usually a few million years after the star's birth.

Hartigan and his colleagues used Hubble's Wide Field Planetary Camera 2 to study jets HH 1, HH 2, HH 34, HH 46, and HH 47. HH 1-HH 2 and HH 46-HH 47 are pairs of jets emanating in opposite directions from single stars. Hubble followed the jets over three epochs: HH 1 and HH 2 in 1994, 1997, and 2007; HH 34 in 1994, 1998, and 2007; and HH 46 and HH 47 in 1994, 1999, and 2008. The jets are roughly ten times the width of the Solar System and zip along at more than 700 000 kilometres per hour.

All of the outflows are roughly 1350 light-years from Earth. HH 34, HH 1, and HH 2 reside near the Orion Nebula, in the northern sky. HH 46 and HH 47 are in the southern constellation of Vela (The Sails).

Computer software has woven together these observations, taken over many years, and generated movies that show continuous motion. The movies support previous observations which revealed that the twin jets are not ejected in a steady stream, like water flowing from a garden hose. Instead, they are launched sporadically in clumps. The beaded-jet structure might be like a "ticker tape," recording episodes when material fell onto the star.

The movies show that the clumpy gas in the jets is moving at different speeds like traffic on a motorway. When fast-moving blobs collide with gas in the slow lane, bow shocks arise as the material heats up. Bow shocks are glowing waves of material similar to waves produced by the bow of a ship ploughing through water. In HH 2, for example, several bow shocks can be seen where several fast-moving clumps have bunched up like cars in a traffic jam. In another jet, HH 34, a grouping of merged bow shocks reveals regions that brighten and fade over time as the heated material cools where the shocks intersect.

In other areas of the jets, bow shocks form from encounters with the surrounding dense gas cloud. In HH 1 a bow shock appears at the top of the jet as it grazes the edge of a dense gas cloud. New glowing knots of material also appear. These knots may represent gas from the cloud being swept up by the jet, just as a swift-flowing river pulls along mud from the shoreline.

The movies also provide evidence that the inherent clumpy nature of the jets begins near the newborn stars. In HH 34 Hartigan traced a glowing knot to within about 14 billion kilometres of the star.

"Taken together, our results paint a picture of jets as remarkably diverse objects that undergo highly structured interactions between material within the outflow and between the jet and the surrounding gas," Hartigan explained. "This contrasts with the bulk of the existing simulations which depict jets as smooth systems."

The details revealed by Hubble were so complex that Hartigan consulted with experts in fluid dynamics from Los Alamos National Laboratory in New Mexico, the UK Atomic Weapons Establishment, and General Atomics in San Diego, California, as well as computer specialists from the University of Rochester in New York. Motivated by the Hubble results, Hartigan's team is now conducting laboratory experiments at the Omega Laser facility in New York to understand how supersonic jets interact with their environment.

"The fluid dynamicists immediately picked up on an aspect of the physics that astronomers typically overlook, and that led to a different interpretation for some of the features we were seeing," Hartigan explains. "The scientists from each discipline bring their own unique perspectives to the project, and having that range of expertise has proved invaluable for learning about this critical phase of stellar evolution."

[1] The international team of astronomers in this study consists of Patrick Hartigan (Rice University, Texas, USA), Adam Frank (University of Rochester, New York, USA); John Foster (Atomic Weapons Establishment, Aldermaston, UK); Paula Rosen (Atomic Weapons Establishment, Aldermaston, UK); Bernie Wilde (Los Alamos National Laboratory, New Mexico, USA); Rob Coker (Los Alamos National Laboratory, New Mexico, USA); Melissa Douglas (Los Alamos National Laboratory, New Mexico, USA); Brent Blue (General Atomics, San Diego, California, USA) and Freddy Hansen (General Atomics, San Diego, California, USA).

Videos 

Stellar jet HH 47

This video shows the evolution over time of Herbig-Haro object HH 47, a jet expelled from a newborn star in the southern constellation of Vela. The video was made by stitching together observations of HH 47 made in 1994, 1999 and 2008.

Credit:

NASA, ESA, P. Hartigan (Rice University), G. Bacon (STScI)

Bow shock in stellar jet HH 47

This video shows a close-up of a bow shock in Herbig-Haro object HH 47, a jet expelled from a newborn star in the southern constellation of Vela. Bow shocks like this are similar to the bow wave caused by a boat moving through water. They are produced by fast-moving material from the star colliding with slower-moving material.

The video was made by stitching together observations of HH 47 made in 1994, 1999 and 2008.

Credit:

NASA, ESA, P. Hartigan (Rice University), G. Bacon (STScI)

Bow shock in stellar jet HH 34

This video shows a close-up of a bow shock in Herbig-Haro object HH 34, a jet expelled from a newborn star in the constellation of Orion. Bow shocks like this are similar to the bow wave caused by a boat moving through water. They are produced by fast-moving material from the star colliding with slower-moving material.

The video was made by stitching together observations of HH 34 made in 1994, 1998 and 2007.

Credit:

NASA, ESA, P. Hartigan (Rice University), G. Bacon (STScI)

Tiny Oxygen Generators Boost Effectiveness of Anticancer Treatment

Researchers have created and tested a miniature device, seen here, that can be implanted in tumors to generate oxygen, boosting the killing power of radiation and chemotherapy. The technology is designed to treat solid tumors that are hypoxic at the center, meaning the core contains low oxygen levels. The device (right) fits inside a tube (left) that can then be inserted into a tumor with a biopsy needle. (Credit: Birck Nanotechnology Center, Purdue University)

Science Daily  — Researchers have created and tested miniature devices that are implanted in tumors to generate oxygen, boosting the killing power of radiation and chemotherapy.

"This is not good because radiation therapy needs oxygen to be effective," said Babak Ziaie, a Purdue University professor of electrical and computer engineering and biomedical engineering. "So the hypoxic areas are hard to kill. Pancreatic and cervical cancers are notoriously hypoxic. If you generate oxygen you can increase the effectiveness of radiation therapy and also chemotherapy."

The technology is designed to treat solid tumors that are hypoxic at the center, meaning the core contains low oxygen levels.

The new "implantable micro oxygen generator" is an electronic device that receives ultrasound signals and uses the energy to generate a small voltage to separate oxygen and hydrogen from water ╨ a chemical operation called water electrolysis.

"We are putting these devices inside tumors and then exposing the tumors to ultrasound," Ziaie said. "The ultrasound energy powers the device, generating oxygen.

The devices were created at the Birck Nanotechnology Center in the university's Discovery Park. Purdue researchers are working with Song-Chu (Arthur) Ko, an assistant professor of clinical radiation oncology at the Indiana University School of Medicine.

Researchers have tested the devices in pancreatic tumors implanted in mice, showing they generated oxygen and shrunk tumors faster than tumors without the devices. The devices are slightly less than one centimeter long and are inserted into tumors with a hypodermic biopsy needle.

"Most of us have been touched by cancer in one way or another," Ziaie said. "My father is a cancer survivor, and he went through many rounds of very painful chemotherapy. This is a new technology that has the potential to improve the effectiveness of such therapy."

Findings are detailed in a research paper appearing online this month in Transactions on Biomedical Engineering. The paper was written by research assistant professor Teimour Maleki, doctoral students Ning Cao and Seung Hyun Song, Ko and Ziaie.

"The implantable mini oxygen generator project is one of 11 projects the Alfred Mann Institute for Biomedical Development at Purdue University (AMIPurdue) has sponsored," Ziaie said. "AMIPurdue has been instrumental in providing the development funding of roughly $500,000 on this project. And beyond funding, the AMIPurdue team has also helped us with market research, physician feedback, industry input, as well as intellectual property and regulatory strategy. We have been able to accomplish a great deal in a short time due to the collaborative effort with AMIPurdue."

A patent application has been filed for the design.

Future work may focus on redesigning the device to make it more practical for manufacturing and clinical trials.

'Gene Overdose' Causes Extreme Thinness

Artist's rendering of chromosomes. Researchers have identified that duplication of a part of chromosome 16 is associated with being underweight. (Credit: © Sebastian Kaulitzki / Fotolia)

Science Daily  — Scientists have discovered a genetic cause of extreme thinness for the first time, in a study published August 30 in the journal Nature. The research shows that people with extra copies of certain genes are much more likely to be very skinny. In one in 2000 people, part of chromosome 16 is duplicated, making men 23 times and women five times more likely to be underweight.

In a study examining the DNA of over 95,000 people, researchers at Imperial College London and the University of Lausanne have identified that duplication of a part of chromosome 16 is associated with being underweight, defined as a a body mass index below 18.5. Half of all children with the duplication in the study have been diagnosed with a 'failure to thrive', meaning that their rate of weight gain is significantly lower than normal. A quarter of people with the duplication have microcephaly, a condition in which the head and brain are abnormally small, which is associated with neurological defects and shorter life expectancy. Last year, the same researchers discovered that people with a missing copy of these genes are 43 times more likely to be morbidly obese.

Each person normally has a copy of each chromosome from each parent, so we have two copies of each gene. But sometimes sections of a chromosome can be duplicated or deleted, resulting in an abnormal 'dosage' of genes.

Professor Philippe Froguel, from the School of Public Health at Imperial College London, who led the study, said: "The dogma is that we have two copies of each gene, but this isn't really true. The genome is full of holes where genes are lost, and in other places we have extra copies of genes. In many cases, duplications and deletions have no effect, but occasionally they can lead to disease.

"So far, we have discovered a large number of genetic changes that lead to obesity. It seems that we have plenty of systems that increase appetite since eating is so important -- you can suppress one and nothing happens. This is the first genetic cause of extreme thinness that has been identified.

"One reason this is important is that it shows that failure to thrive in childhood can be genetically driven. If a child is not eating, it's not necessarily the parents' fault.

"It's also the first example of a deletion and a duplication of one part of the genome having opposite effects. At the moment we don't know anything about the genes in this region. If we can work out why gene duplication in this region causes thinness, it might throw up new potential treatments for obesity and appetite disorders. We now plan to sequence these genes and find out what they do, so we can get an idea of which ones are involved in regulating appetite."

The part of chromosome 16 identified in the study contains 28 genes. Duplications in this region have previously been linked with schizophrenia, and deletions with autism.

The study was funded by the Medical Research Council, the Wellcome Trust, and other sources.