NAME: MOHD SABRI B. CHE NOH
I/D: D20061026409
PROGRAM: SCIENCE EDUCATION (PHYSICS)
COURSE: ENVIRONMENTAL SCIENCE (TSE2013)
LECTURE GROUP: H (TUESDAY 5.00PM-7.00PM)
LECTURER: ASSOCIATE PROFESSOR DR. NUR TJAHJADI
Environmental dilemmas is similar to the problem or issues that has occurred in our environment. It can divide into four major problem which are population, food shortage, energy and also pollution.
POPULATION
One of the environmental dilemmas or problem is about the population. A population can be defined as a group of individuals of the same species inhabiting an area. Different population of the same species have specific characteristics that distinguish them from one another. In this subtopic me will discuss about the human population growth. There are some important way in which population differ include:
For most of human history, up to around 10 thousand years ago (generally accepted by science, although some place the time a few thousand years earlier), Earth's human population remained stabilized at around 8 to 10 million. Since then it has grown, at varying rates, to reach its present level of over 6,200 million (6.2 billion). This growth started when people began to grow crops and domesticate animals, which initiated the change from a hunter/gatherer subsistence (natural food supply) to a technology-driven food supply (agriculture). We note that about 620 (or more) humans are alive today (most supported by agricultural technology) for every one human who was supported by the natural food supply of early non-technological Earth.
In 2005, world population reached an all- time high of nearly 6.5 billion. By the year 2025 it could reach nearly 8 billion and could be expanding about 100 million a year. Ninety percent of this growth take place in the poorer nations.
Population Size Year Time Required to Double
1 billion 1850 All of human history
2 billion 1930 80 years
4 billion 1975 45 years
8 billion 2025 50 years
The more recent "explosive" growth, which causes serious human population problems and environmental problems, is due to much more than just advances in agricultural technology. Among other factors is the decrease in the death rate due to advances in medicine and sanitation.
So, what will happen to our environment when overpopulation occurs.
As a conclusion, the growth population rate increase is determine by subtracting the numbers of individuals leaving the population either by emigration or death from the numbers entering by immigration or birth.
Earth's present human population is over 6,200 million
FOOD SHORTAGE
According to the International Monetary Fund, over the past 12 months global food prices have increased on average by more than 40%. Most experts believe that there is no single driver behind this unprecedented rise in the cost of foodstuffs, but rather that numerous factors threaten the food security and well being of millions of people, particularly the poorest of the poor in the developing world.
Factors cited by experts include, the increased demand for food commodities from developing countries (as a result of population increases and increased consumption of meat), the production of crops for bio-fuels, increased costs of transportation, fuel and fertilizer due to the increasing cost of oil, a weakening U.S. currency which increases the effective cost for commodities purchased with dollars, and recurring natural disasters such as drought and flooding.
ENERGY
Many nations count on coal, oil and natural gas to supply most of their energy needs, but reliance on fossil fuels presents a big problem. Fossil fuels are a finite resource. Eventually, the world will run out of fossil fuels, or it will become too expensive to retrieve those that remain. Fossil fuels also causes air, water and soil pollution, and produce greenhouse gases that contribute to global warming.
Fossil Fuels - These constitute the main forms of energy used worldwide. They are formed over a period of millions of years by the decomposition of animals and plants. As such they are not renewable as it would take too long to for them to form again. They generally consist of carbon, sulphur and hydrogen and therefore upon combustion form carbon dioxide, sulphur dioxide and water vapour (h2o). While the latter is relatively harmless the previous two are responsible for global warming and acid rain.
The United States is a highly developed and industrialized society. We use a lot of energy - in our homes, in businesses, in industry, and for traveling between all these different places.The industrial sector uses about one-third of the total energy. The residential and commercial sectors combined use even more than this - 40 percent of all energy. These two sectors include all types of buildings, such as houses, offices, stores, restaurants, and places of worship. Energy used for transportation accounts for more than a quarter of all energy.
POLLUTION
A variety of environmental problems now affect our entire world. As globalization continues and the earth's natural processes transform local problems into international issues, few societies are being left untouched by major environmental problems. Some of the largest problems now affecting the world are Acid Rain, Air Pollution, Global Warming, Hazardous Waste, Ozone Depletion, Smog, Water Pollution, Overpopulation, and Rain Forest Destruction.
Every environmental problem has causes, numerous effects, and most importantly, a solution. There are several example discussing major environmental problem.
AIR POLUTION
Every day, the average person inhales about 20,000 liters of air. Every time we breathe, we risk inhaling dangerous chemicals that have found their way into the air. Air pollution includes all contaminants found in the atmosphere. These dangerous substances can be either in the form of gases or particles. Air pollution can be found both outdoors and indoors. Pollutants can be trapped inside buildings, causing indoor pollution that lasts for a long time.
The sources of air pollution are both natural and human-based. As one might expect, humans have been producing increasing amounts of pollution as time has progressed, and they now account for the majority of pollutants released into the air. Air pollution has been a problem throughout history.
The effects of air pollution are diverse and numerous. Air pollution can have serious consequences for the health of human beings, and also severely affects natural ecosystems. Because it is located in the atmosphere, air pollution is able to travel easily. As a result, air pollution is a global problem and has been the subject of global cooperation and conflict.
Some areas now suffer more than others from air pollution. Cities with large numbers of automobiles or those that use great quantities of coal often suffer most severely from problems of air pollution.
CAUSES
There are many different chemical substances that contribute to air pollution. These chemicals come from a variety of sources. Among the many types of air pollutants are nitrogen oxides, carbon monoxides, and organic compounds that can evaporate and enter the atmosphere.
Air pollutants have sources that are both natural and human. Now, humans contribute substantially more to the air pollution problem. Forest fires, volcanic eruptions, wind erosion, pollen dispersal, evaporation of organic compounds, and natural radioactivity are all among the natural causes of air pollution.
Usually, natural air pollution does not occur in abundance in particular locations. The pollution is spread around throughout the world, and as a result, poses little threat to the health of people and ecosystems.
Though some pollution comes from these natural sources, most pollution is the result of human activity. The biggest causes are the operation of fossil fuel-burning power plants and automobiles that combust fuel. Combined, these two sources are responsible for about 90% of all air pollution in the United States.
EFFECT
Air pollution is responsible for major health effects. Every year, the health of countless people is ruined or endangered by air pollution. Many different chemicals in the air affect the human body in negative ways. Just how sick people will get depends on what chemicals they are exposed to, in what concentrations, and for how long.
Studies have estimated that the number of people killed annually in the US alone could be over 50,000. Older people are highly vulnerable to diseases induced by air pollution. Those with heart or lung disorders are under additional risk. Children and infants are also at serious risk. Because people are exposed to so many potentially dangerous pollutants, it is often hard to know exactly which pollutants are responsible for causing sickness. Also, because a mixture of different pollutants can intensify sickness, it is often difficult to isolate those pollutants that are at fault.
Many diseases could be caused by air pollution without their becoming apparent for a long time. Diseases such as bronchitis, lung cancer, and heart disease may all eventually appear in people exposed to air pollution. Air pollutants such as ozone, nitrogen oxides, and sulfur dioxide also have harmful effects on natural ecosystems. They can kill plants and trees by destroying their leaves, and can kill animals, especially fish in highly polluted rivers.
SOLUTIONS
Air pollution has many disastrous effects that need to be curbed. In order to accomplish this, governments, scientists and environmentalists are using or testing a variety of methods aimed at reducing pollution.
There are two main types of pollution control. Input control involves preventing a problem before it occurs, or at least limiting the effects the process will produce. Five major input control methods exist. People may try to restrict population growth, use less energy, improve energy efficiency, reduce waste, and move to non-polluting renewable forms of energy production. Also, automobile-produced pollution can be decreased with highly beneficial results.
Output control, the opposite method, seeks to fix the problems caused by air pollution. This usually means cleaning up an area that has been damaged by pollution. Input controls are usually more effective than output controls. Output controls are also more expensive, making them less desirable to tax payers and polluting industries.
Current air pollution control efforts are not all highly effective. In wealthier countries, industries are often able to shift to methods that decrease air pollution. In the United States, for example, air pollution control laws have been successful in stopping air pollution levels from rising. However, in developing countries and even in countries where pollution is strictly regulated, much more needs to be done.
OZONE DEPLITION
The ozone layer protects the Earth from the ultraviolet rays sent down by the sun. If the ozone layer is depleted by human action, the effects on the planet could be catastrophic.
Ozone is present in the stratosphere. The stratosphere reaches 30 miles above the Earth, and at the very top it contains ozone. The suns rays are absorbed by the ozone in the stratosphere and thus do not reach the Earth.
Ozone is a bluish gas that is formed by three atoms of oxygen. The form of oxygen that humans breathe in consists of two oxygen atoms, O2. When found on the surface of the planet, ozone is considered a dangerous pollutant and is one substance responsible for producing the greenhouse effect.
The highest regions of the stratosphere contain about 90% of all ozone.
In recent years, the ozone layer has been the subject of much discussion. And rightly so, because the ozone layer protects both plant and animal life on the planet.
The fact that the ozone layer was being depleted was discovered in the mid-1980s. The main cause of this is the release of CFCs, chlorofluorocarbons.
Antarctica was an early victim of ozone destruction. A massive hole in the ozone layer right above Antarctica now threatens not only that continent, but many others that could be the victims of Antarctica's melting icecaps. In the future, the ozone problem will have to be solved so that the protective layer can be conserved.
CAUSES
Only a few factors combine to create the problem of ozone layer depletion. The production and emission of CFCs, chlorofluorocarbons, is by far the leading cause.
Many countries have called for the end of CFC production because only a few produce the chemical. However, those industries that do use CFCs do not want to discontinue usage of this highly valuable industrial chemical.
CFCs are used in industry in a variety of ways and have been amazingly useful in many products. Discovered in the 1930s by American chemist Thomas Midgley, CFCs came to be used in refrigerators, home insulation, plastic foam, and throwaway food containers.
Only later did people realize the disaster CFCs caused in the stratosphere. There, the chlorine atom is removed from the CFC and attracts one of the three oxygen atoms in the ozone molecule. The process continues, and a single chlorine atom can destroy over 100,000 molecules of ozone.
In 1974, Sherwood Rowland and Mario Molina followed the path of CFCs. Their research proved that CFCs were entering the atmosphere, and they concluded that 99% of all CFC molecules would end up in the stratosphere.
Only in 1984, when the ozone layer hole was discovered over Antarctica, was the proof truly conclusive. At that point, it was hard to question the destructive capabilities of CFCs.
Even if CFCs were banned, problems would remain. There would still be no way to remove the CFCs that are now present in the environment. Clearly though, something must be done to limit this international problem in the future.
EFFECT
Even minor problems of ozone depletion can have major effects. Every time even a small amount of the ozone layer is lost, more ultraviolet light from the sun can reach the Earth.
Every time 1% of the ozone layer is depleted, 2% more UV-B is able to reach the surface of the planet. UV-B increase is one of the most harmful consequences of ozone depletion because it can cause skin cancer.
The increased cancer levels caused by exposure to this ultraviolet light could be enormous. The EPA estimates that 60 million Americans born by the year 2075 will get skin cancer because of ozone depletion. About one million of these people will die.
In addition to cancer, some research shows that a decreased ozone layer will increase rates of malaria and other infectious diseases. According to the EPA, 17 million more cases of cataracts can also be expected.
The environment will also be negatively affected by ozone depletion. The life cycles of plants will change, disrupting the food chain. Effects on animals will also be severe, and are very difficult to foresee.
Oceans will be hit hard as well. The most basic microscopic organisms such as plankton may not be able to survive. If that happened, it would mean that all of the other animals that are above plankton in the food chain would also die out. Other ecosystems such as forests and deserts will also be harmed.
The planet's climate could also be affected by depletion of the ozone layer. Wind patterns could change, resulting in climatic changes throughout the world.
SOLUTIONS
The discovery of the ozone depletion problem came as a great surprise. Now, action must be taken to ensure that the ozone layer is not destroyed.
Because CFCs are so widespread and used in such a great variety of products, limiting their use is hard. Also, since many products already contain components that use CFCs, it would be difficult if not impossible to eliminate those CFCs already in existence.
The CFC problem may be hard to solve because there are already great quantities of CFCs in the environment. CFCs would remain in the stratosphere for another 100 years even if none were ever produced again.
Despite the difficulties, international action has been taken to limit CFCs. In the Montreal Protocol, 30 nations worldwide agreed to reduce usage of CFCs and encouraged other countries to do so as well.
However, many environmentalists felt the treaty did "too little, too late", as the Natural Resources Defense Council put it. The treaty asked for CFC makers to only eliminate half of their CFC production, making some people feel it was inadequate.
By the year 2000, the US and twelve nations in Europe have agreed to ban all use and production of CFCs. This will be highly significant, because these countries produce three quarters of the CFCs in the world.
Many other countries have signed treaties and written laws restricting the use of CFCs. Companies are finding substitutes for CFCs, and people in general are becoming more aware of the dangers of ozone depletion.
GLOBAL WARMING
On June 23, 1988, James Hansen, the director of the Goddard Institute at NASA, told the Senate Committee on Energy and Natural Resources that global warming was a reality and that is was extremely dangerous.
Global warming, also known as the greenhouse effect, immediately received international attention. Scientists, environmentalists, and governments around the world took an interest in the subject.
Global warming is called the greenhouse effect because the gases that are gathering above the earth make the planet comparable to a greenhouse. By trapping heat near the surface of the earth, the greenhouse effect is warming the planet and threatening the environment.
Current fears stem largely from the fact that global warming is occurring at such a rapid pace. Models are predicting that over the next century, the global temperature will rise by several degrees.
Some scientists still do not think that the effects of global warming are as severe as some people say. They think that droughts, hurricanes, and floods often blamed on global warming might actually have other causes.
CAUSES
Global warming has a variety of causes. One of the largest factors contributing to global warming is the general problem of overpopulation and its many effects.
The greater number of people consume more items which take more energy to make, they drive more cars, and create larger amounts of garbage. These factors all increase the global warming problem. Many different gases can increase the planet's temperature. The number of different products and human activities that contribute to global warming are so numerous that finding solutions to the problem is very difficult.
Using a refrigerator releases dangerous gases, turning on the lights requires energy from a power plant, and driving to work causes gas emissions from the car. Countless other normal activities lead to global warming.
Though having an atmosphere is important, the greenhouse effect may be making it excessively thick. The levels of gases covering the Earth have soared with industrialization, and developed countries now produce about 75% of greenhouse gases.
The most common gas is carbon dioxide, accounting for about 50% of all greenhouse gases. Other gases, including methane, CFCs, nitrogen oxides, and ozone, also contribute to forming the greenhouse layer.
Because these gases are produced by so many important and common processes, limiting their production to prevent global warming will be difficult. As population increases and Third World countries begin to use greater amounts of energy, the problem may expand rather than contract.
EFFECT
To know just what the effects of global warming will be in the future is extremely difficult, if not impossible. Scientists use computer models to study the effects of global warming. These computer models have been fairly consistent in predicting general future trends, but often differ greatly when looking at the specifics.
Some scientists say global warming has already been going on for a while. Others say that we do not have enough information now to know for sure. Despite the disagreements, most scientists are convinced that greenhouse gases are warming the Earth. What they are still trying to figure out is how quickly temperatures are rising, and what will happen as a result.
The climate changes that will result from global warming are extremely difficult to predict. The weather is determined by so many factors that it is often compared to chaos by scientists. Changing the temperature will likely have some effect on the planet's weather, but just what that effect will be is nearly impossible to predict.
If temperatures do indeed rise significantly, the most important result would be that some portion of the polar icecaps would melt, raising global sea levels. The rise in sea levels would be disastrous for some places. Islands would disappear, meaning their millions of inhabitants would have to relocate. Flooding would occur along coastlines all over the world, displacing more people and ruining cropland.
In the case of major global warming and melted ice caps, some countries might simply cease to exist. Global warming, if uncontrolled, could cause a major catastrophe.
SOLUTIOS
The threat of global warming is among the most important of all modern environmental problems. There are a variety of ways of dealing with it, each attempting to combat one of the many causes of global warming.
The problems that cause global warming include overpopulation, deforestation, ozone depletion, garbage dumping, and many others. These all have unique solutions which are now being promoted by environmentalists.
Certain laws and treaties are aimed at reducing the emission of pollutants that result in global warming. In 1988, the International Conference on the Changing Atmosphere drew scientists and decision makers from 48 countries.
Some policies could successfully reduce global warming. Raising fossil fuel prices, taxing emissions, and encouraging people to take environmentally friendly action through such activities as planting trees will all help.
Because many problems leading to global warming are caused or contributed to by overpopulation, people are beginning to work to reduce family sizes. Family planning services actually help in the fight against global warming.
Education is a key method of reducing the greenhouse effect. By teaching people about such things as deforestation, environmental activists hope to prevent the problems that ultimately lead to global warming.
Widespread media attention to the global warming problem is also increasing awareness. This is causing both individuals and governments to act more responsibly towards the environment.
Ecological Footprint
The Ecological Footprint is a resource management tool that measures how much land and water area a human population requires to produce the resources it consumes and to absorb its wastes under prevailing technology. In order to live, we consume what nature offers. Every action impacts the planet's ecosystems.
Today, humanity's Ecological Footprint is over 23% larger than what the planet can regenerate. In other words, it now takes more than one year and two months for the Earth to regenerate what we use in a single year. We maintain this overshoot by liquidating the planet's ecological resources. This is a vastly underestimated threat and one that is not adequately addressed.
By measuring the Ecological Footprint of a population (an individual, a city, a nation, or all of humanity) we can assess our overshoot, which helps us manage our ecological assets more carefully. Ecological Footprints enable people to take personal and collective actions in support of a world where humanity lives within the means of one planet.
Today, most countries, and the world as a whole, are running ecological deficits. The world's ecological deficit is equal to its ecological overshoot. From the graph above, we can see that in 2003, the ecological was overshoot. We know that the bio-capacity of earth is only 1. Bio-capacity means the ability of ecosystems to produce useful biological materials and to absorb wastes generated by humans, using current management and extraction technologies. Useful biological materials are defined as those materials that the human economy actually demanded in a given year. The Ecological Footprint measures demand on this productive capacity. The graph above shows how humanity has moved from using, in net terms, about half the planet's bio-capacity in 1961 to over 1.25 times the bio-capacity of the Earth in 2003.
Therefore, The footprints of nations and their biological capacity can be directly compared because resource flows are translated into a common unit of biologically productive area, global hectares" (or "global acres"). A global hectare is the average per hectare regenerative capacity of all the planet's biologically productive surfaces. Currently, the planet has approximately 11.2 billion hectares (27.7 billion acres) of biologically productive land and sea surfaces.
Dividing the 11.2 billion hectares available by the global population indicates that there are on average 1.8 bio-productive hectares per person on the planet. The 2004 Living Planet Report indicates that the actual usage was 13.5 billion global hectares or 2.2 hectares per person – more than a 20% overshoot. The overshoot result indicates that our annual draw down of natural capital is liquidating natural capital income, as well as reducing natural capital itself . Such an overshoot is ecologically unsustainable. Time series of the global Ecological Footprint indicate that human activities have been in an overshoot position for approximately three decades, and the overshoot is increasing over time. So, we can make prediction that what will happened to our earth in next 10 or 20 years later.
The picture shows the components of the world's average per person Ecological Footprint
Comparing the footprint between middle and lower countries with high income countries
References
Cunningham and Cunningham. 2008. Principle of Environmental Science.
Fourth Edition. New York: Mc Graw Hill Companies, Inc.
Botkin and Keller. 2005. Environmental Science. Fifth Edition. United States: John Wiley and Sons, Inc.
Cunningham and Cunningham. 2004. Principle of Environmental Science. Second
Edition. New York : Mc Graw Hill Companies, Inc.
Daniel D. Chiras. 2006. Environmental Science. Seventh Edition. United States :
Jones and Bartlett Publisher, Inc.
Scott Brennan and Jay Withgott. 2005. Essential Environment. The Science Behind
The Stories. United States : Pearson Education, Inc.
V. Subramaniam. 2002. Environmental Science. New Delhi : Alpha Science
International Ltd.
Beychok, M.R. (2005). Fundamentals Of Stack Gas Dispersion, 4th Edition, author- published. ISBN 0-9644588-0-2. www.air-dispersion.com
Turner, D.B. (1994). Workbook of atmospheric dispersion estimates: an introduction to dispersion modeling, 2nd Edition, CRC Press. ISBN 1-56670-023-X. www.crcpress.com
http://www.lbl.gov/Education/ELSI/pollution-main.html
http://www.yeenet.eu/leave%20no%20footprints.htm
http://www.umich.edu/~gs265/society/waterpollution.htm
Wednesday, December 31, 2008
MOHD FIRDAUS KHAIRI BIN NO BADERY
NAME: MOHD FIRDAUS KHAIRI BIN NO BADERY
I/D: D20061026297
PROGRAM: SCIENCE EDUCATION (PHYSICS)
COURSE: ENVIRONMENTAL SCIENCE (TSE2013)
LECTURE GROUP: H (TUESDAY 5.00PM-7.00PM)
Earth
From the perspective we get on Earth, our planet appears to be big and sturdy with an endless ocean of air. From space, astronauts often get the impression that the Earth is small with a thin, fragile layer of atmosphere. For a space traveler, the distinguishing Earth features are the blue waters, brown and green land masses and white clouds set against a black background. Many dream of traveling in space and viewing the wonders of the universe. In reality all of us are space travelers. Our spaceship is the planet Earth, traveling at the speed of 108,000 kilometers (67,000 miles) an hour.
Earth is the only planet whose English name does not derive from Greek/Roman mythology. The name derives from Old English and Germanic. There are, of course, hundreds of other names for the planet in other languages. In Roman Mythology, the goddess of the Earth was Tellus which mean the fertile soil. Earth is the third planet from the Sun. Earth is the largest of the terrestrial planets in the Solar System in diameter, mass and density. It is also referred to as the Earth, Planet Earth, the World, and Terra.
Home to millions of species, including humans, Earth is the only place in the universe where life is known to exist. Scientific evidence indicates that the planet formed 4.54 billion years ago, and life appeared on its surface within a billion years. Since then, Earth's biosphere has significantly altered the atmosphere and other abiotic conditions on the planet, enabling the proliferation of aerobic organisms as well as the formation of the ozone layer which, together with Earth's magnetic field, blocks harmful radiation, permitting life on land.
Earth's outer surface is divided into several rigid segments, or tectonic plates, that gradually migrate across the surface over periods of many millions of years. About 71% of the surface is covered with salt-water oceans, the remainder consisting of continents and islands; liquid water, necessary for all known life, is not known to exist on any other planet's surface. Earth's interior remains active, with a thick layer of relatively solid mantle, a liquid outer core that generates a magnetic field, and a solid iron inner core.
Earth interacts with other objects in outer space, including the Sun and the Moon. At present, Earth orbits the Sun once for every roughly 366.26 times it rotates about its axis. This length of time is a sidereal year, which is equal to 365.26 solar days. The Earth's axis of rotation is tilted 23.4° away from the perpendicular to its orbital plane, producing seasonal variations on the planet's surface with a period of one tropical year (365.24 solar days). Earth's only known natural satellite, the Moon, which began orbiting it about 4.53 billion years ago, provides ocean tides, stabilizes the axial tilt and gradually slows the planet's rotation. A bombardment during the early history of the planet played a role in the formation of the oceans. Later, asteroid impacts caused significant changes to the surface environment.
Composition and structure
Earth is a terrestrial planet, meaning that it is a rocky body, rather than a gas giant like Jupiter. It is the largest of the four solar terrestrial planets, both in terms of size and mass. Of these four planets, Earth also has the highest density, the highest surface gravity and the strongest magnetic field.
Shape
The Earth's shape is very close to an oblate spheroid, a rounded shape with a bulge around the equator, although the precise shape (the geoids) varies from this by up to 100 meters. The average diameter of the reference spheroid is about 12,742 km. More approximately the distance is 40,000 km/π because the meter was originally defined as 1/10,000,000 of the distance from the equator to the North Pole through Paris, France.
The rotation of the Earth creates the equatorial bulge so that the equatorial diameter is 43 km larger than the pole to pole diameter. The largest local deviations in the rocky surface of the Earth are Mount Everest (8,848 m above local sea level) and the Mariana Trench (10,911 m below local sea level). Hence compared to a perfect ellipsoid, the Earth has a tolerance of about one part in about 584, or 0.17%, which is less than the 0.22% tolerance allowed in billiard balls. Because of the bulge, the feature farthest from the center of the Earth is actually Mount Chimborazo in Ecuador.
Chemical composition
The mass of the Earth is approximately 5.98×1024 kg. It is composed mostly of iron (32.1%), oxygen (30.1%), silicon (15.1%), magnesium (13.9%), sulfur (2.9%), nickel (1.8%), calcium (1.5%), and Aluminum (1.4%); with the remaining 1.2% consisting of trace amounts of other elements. Due to mass segregation, the core region is believed to be primarily composed of iron (88.8%), with smaller amounts of nickel (5.8%), sulfur (4.5%), and less than 1% trace elements.
The geochemist F. W. Clarke calculated that a little more than 47% of the Earth's crust consists of oxygen. The more common rock constituents of the Earth's crust are nearly all oxides; chlorine, sulfur and fluorine are the only important exceptions to this and their total amount in any rock is usually much less than 1%. The principal oxides are silica, alumina, iron oxides, lime, magnesia, potash and soda. The silica functions principally as an acid, forming silicates, and all the commonest minerals of igneous rocks are of this nature. From a computation based on 1,672 analyses of all kinds of rocks, Clarke deduced that 99.22% were composed of 11 oxides (see the table at right.) All the other constituents occur only in very small quantities.
Internal structure
The interior of the Earth, like that of the other terrestrial planets, is chemically divided into layers. The Earth has an outer silicate solid crust, a highly viscous mantle, a liquid outer core that is much less viscous than the mantle, and a solid inner core. The thickness of the crust varies, averaging 6 km under the oceans and 30–50 km on the continents.
The internal heat of the planet is probably produced by the radioactive decay of potassium-40, uranium-238 and thorium-232 isotopes. All three have half-life decay periods of more than a billion years. At the center of the planet, the temperature may be up to 7,000 K and the pressure could reach 360 GPa. A portion of the core's thermal energy is transported toward the crust by Mantle plumes; a form of convection consisting of upwelling of higher-temperature rock. These plumes can produce hotspots and flood basalts. The Earth is divided into several layers which have distinct chemical and seismic properties (depths in km):
• 40 Crust
• 40- 400 Upper mantle
• 400- 650 Transition region
• 650-2700 Lower mantle
• 2700-2890 D’’ layer
• 2890-5150 Outer core
• 5150-6378 Inner cores
The crust varies considerably in thickness; it is thinner under the oceans, thicker under the continents. The inner core and crust are solid; the outer core and mantle layers are plastic or semi-fluid. The various layers are separated by discontinuities which are evident in seismic data; the best known of these is the Mohorovicic discontinuity between the crust and upper mantle. Most of the mass of the Earth is in the mantle, most of the rest in the core; the part we inhabit is a tiny fraction of the whole (values below x1024 kilograms):
• Atmosphere = 0.0000051
• Oceans = 0.0014
• Crust = 0.026
• Mantle = 4.043
• Outer core = 1.835
• Inner core = 0.09675
The core is probably composed mostly of iron (or nickel/iron) though it is possible that some lighter elements may be present, too. Temperatures at the center of the core may be as high as 7500 K, hotter than the surface of the Sun. The lower mantle is probably mostly silicon, magnesium and oxygen with some iron, calcium and aluminum. The upper mantle is mostly olivine and pyroxene (iron/magnesium silicates), calcium and aluminum. We know most of this only from seismic techniques; samples from the upper mantle arrive at the surface as lava from volcanoes but the majority of the Earth is inaccessible. The crust is primarily quartz (silicon dioxide) and other silicates like feldspar. Taken as a whole, the Earth's chemical composition (by mass) is:
Surface
The Earth's terrain varies greatly from place to place. About 71.8% of the surface is covered by water (including oceans, lakes, and streams), with much of the continental shelf below sea level. The submerged surface has mountainous features, including a globe-spanning mid-ocean ridge system, as well as undersea volcanoes, oceanic trenches, submarine canyons, oceanic plateaus and abyssal plains. The remaining 28.2% not covered by water consists of mountains, deserts, plains, plateaus, and other geomorphologies.
The planetary surface undergoes reshaping over geological time periods due to the effects of tectonics and erosion. The surface features built up or deformed through plate tectonics are subject to steady weathering from precipitation, thermal cycles, and chemical effects. Glaciations, coastal erosion, the build-up of coral reefs, and large meteorite impacts also act to reshape the landscape.
As the tectonic plates migrate across the planet, the ocean floor is sub ducted under the leading edges. At the same time, upwelling of mantle material creates a divergent boundary along mid-ocean ridges. The combination of these processes continually recycles the oceanic crustal material. Most of the ocean floor is less than 100 million years in age. The oldest oceanic crust is located in the Western Pacific, and has an estimated age of about 200 million years. By comparison, the oldest fossils found on land have an age of about 3 billion years.
The continental crust consists of lower density material such as the igneous rocks granite and andesite. Less common is basalt, a denser volcanic rock that is the primary constituent of the ocean floors. Sedimentary rock is formed from the accumulation of sediment that becomes compacted together. Nearly 75% of the continental surfaces are covered by sedimentary rocks, although they form only about 5% of the crust. The third form of rock material found on Earth is metamorphic rock, which is created from the transformation of pre-existing rock types through high pressures, high temperatures, or both. The most abundant silicate minerals on the Earth's surface include quartz, the feldspars, amphibole, mica, pyroxene and olivine. Common carbonate minerals include calcite (found in limestone), aragonite and dolomite.
The pedosphere is the outermost layer of the Earth that is composed of soil and subject to soil formation processes. It exists at the interface of the lithosphere, atmosphere, hydrosphere and biosphere. Currently the total arable land is 13.31% of the land surface, with only 4.71% supporting permanent crops. Close to 40% of the Earth's land surface is presently used for cropland and pasture, or an estimated 1.3×107 km² of cropland and 3.4×107 km² of pastureland.
Unlike the other terrestrial planets, Earth's crust is divided into several separate solid plates which float around independently on top of the hot mantle below. The theory that describes this is known as plate tectonics. It is characterized by two major processes: spreading and subduction. Spreading occurs when two plates move away from each other and new crust is created by upwelling magma from below. Subduction occurs when two plates collide and the edge of one dives beneath the other and ends up being destroyed in the mantle. There is also transverse motion at some plate boundaries (i.e. the San Andreas Fault in California) and collisions between continental plates (i.e. India/Eurasia). There are (at present) eight major plates:
• North American Plate - North America, western North Atlantic and Greenland
• South American Plate - South America and western South Atlantic
• Antarctic Plate - Antarctica and the "Southern Ocean"
• Eurasian Plate - eastern North Atlantic, Europe and Asia except for India
• African Plate - Africa, eastern South Atlantic and western Indian Ocean
• Indian-Australian Plate - India, Australia, New Zealand and most of Indian Ocean
• Nazca Plate - eastern Pacific Ocean adjacent to South America
• Pacific Plate - most of the Pacific Ocean (and the southern coast of California!)
There are also twenty or more small plates such as the Arabian, Cocos, and Philippine Plates. Earthquakes are much more common at the plate boundaries. Plotting their locations makes it easy to see the plate boundaries. The elevation of the land surface of the Earth varies from the low point of −418 m at the Dead Sea, to a 2005-estimated maximum altitude of 8,848 m at the top of Mount Everest. The mean height of land above sea level is 840 m.
Hydrosphere
The abundance of water on Earth's surface is a unique feature that distinguishes the "Blue Planet" from others in the solar system. The Earth's hydrosphere consists chiefly of the oceans, but technically includes all water surfaces in the world, including inland seas, lakes, rivers, and underground waters down to a depth of 2,000 m. The deepest underwater location is Challenger Deep of the Mariana Trench in the Pacific Ocean with a depth of −10,911.4 m. The average depth of the oceans is 3,800 m, more than four times the average height of the continents. The mass of the oceans is approximately 1.35×1018 metric tons, or about 1/4400 of the total mass of the Earth, and occupies a volume of 1.386×109 km³. If all of the land on Earth were spread evenly, water would rise to an altitude of more than 2.7 km. About 97.5% of the water is saline, while the remaining 2.5% is fresh water. The majority of the fresh water, about 68.7%, is currently in the form of ice.
About 3.5% of the total mass of the oceans consists of salt. Most of this salt was released from volcanic activity or extracted from cool, igneous rocks. The oceans are also a reservoir of dissolved atmospheric gases, which are essential for the survival of many aquatic life forms. Sea water has an important influence on the world's climate, with the oceans acting as a large heat reservoir. Shifts in the oceanic temperature distribution can cause significant weather shifts, such as the El Niño-Southern Oscillation.
Atmosphere
The atmospheric pressure on the surface of the Earth averages 101.325 kPa, with a scale height of about 8.5 km. It is 78% nitrogen and 21% oxygen, with trace amounts of water vapor, carbon dioxide and other gaseous molecules. The height of the troposphere varies with latitude, ranging between 8 km at the poles to 17 km at the equator, with some variation due to weather and seasonal factors.
Earth's biosphere has significantly altered its atmosphere. Oxygenic photosynthesis evolved 2.7 billion years ago, forming the primarily nitrogen-oxygen atmosphere that exists today. This change enabled the proliferation of aerobic organisms as well as the formation of the ozone layer which, together with Earth's magnetic field, blocks ultraviolet solar radiation, permitting life on land. Other atmospheric functions important to life on Earth's include transporting water vapor, providing useful gases, causing small meteors to burn up before they strike the surface, and moderating temperature.
This last phenomenon is known as the greenhouse effect: trace molecules within the atmosphere serve to capture thermal energy emitted from the ground, thereby raising the average temperature. Carbon dioxide, water vapor, methane and ozone are the primary greenhouse gases in the Earth's atmosphere. Without this heat-retention effect, the average surface temperature would be −18 °C and life would likely not exist.
Magnetic field
Figure of The Earth's magnetic field, which approximates a dipole.
The Earth's magnetic field is shaped roughly as a magnetic dipole, with the poles currently located proximate to the planet's geographic poles. According to dynamo theory, the field is generated within the molten outer core region where heat creates convection motions of conducting materials, generating electric currents. These in turn produce the Earth's magnetic field. The convection movements in the core are chaotic in nature, and periodically change alignment. This results in field reversals at irregular intervals averaging a few times every million years. The most recent reversal occurred approximately 700,000 years ago. The field forms the magnetosphere, which deflects particles in the solar wind. The sunward edge of the bow shock is located at about 13 times the radius of the Earth. The collision between the magnetic field and the solar wind forms the Van Allen radiation belts, a pair of concentric, torus-shaped regions of energetic charged particles. When the plasma enters the Earth's atmosphere at the magnetic poles, it forms the aurora.
Orbit and rotation
Relative to the background stars, it takes the Earth, on average, 23 hours, 56 minutes and 4.091 seconds (one sidereal day) to rotate around the axis that connects the north and the south poles from west to east. From Earth, the main apparent motion of celestial bodies in the sky (except that of meteors within the atmosphere and low-orbiting satellites) is to the west at a rate of 15°/h = 15'/min. This is equivalent to an apparent diameter of the Sun or Moon every two minutes. (The apparent sizes of the Sun and the Moon are approximately the same.)
Earth orbits the Sun at an average distance of about 150 million kilometers every 365.2564 mean solar days (1 sidereal year). From Earth, this gives an apparent movement of the Sun with respect to the stars at a rate of about 1°/day (or a Sun or Moon diameter every 12 hours) eastward. Because of this motion, on average it takes 24 hours—a solar day—for Earth to complete a full rotation about its axis so that the Sun returns to the meridian. The orbital speed of the Earth averages about 30 km/s (108,000 km/h), which is fast enough to cover the planet's diameter (about 12,600 km) in seven minutes, and the distance to the Moon (384,000 km) in four hours.
The Moon revolves with the Earth around a common barycenter every 27.32 days relative to the background stars. When combined with the Earth–Moon system's common revolution around the Sun, the period of the synodic month, from new moon to new moon, is 29.53 days. Viewed from the celestial north pole, the motion of Earth, the Moon and their axial rotations are all counter-clockwise. The orbital and axial planes are not precisely aligned: Earth's axis is tilted some 23.5 degrees from the perpendicular to the Earth–Sun plane (which causes the seasons); and the Earth–Moon plane is tilted about 5 degrees against the Earth-Sun plane (without this tilt, there would be an eclipse every two weeks, alternating between lunar eclipses and solar eclipses).
Because of the axial tilt of the Earth, the position of the Sun in the sky (as seen by an observer on the surface) varies over the course of the year. For an observer at northern latitude, when the northern pole is tilted toward the Sun the day lasts longer and the Sun climbs higher in the sky. This results in warmer average temperatures from the increase in solar radiation reaching the surface. When the northern pole is tilted away from the Sun, the reverse is true and the climate is generally cooler. Above the Arctic Circle, an extreme case is reached where there is no daylight at all for part of the year. (This is called a polar night.)
This variation in the climate (because of the direction of the Earth's axial tilt) results in the seasons. By astronomical convention, the four seasons are determined by the solstices, the point in the orbit of maximum axial tilt toward or away from the Sun, and the equinoxes, when the direction of the tilt and the direction to the Sun are perpendicular. Winter solstice occurs on about December 21, summer solstice is near June 21, spring equinox is around March 20 and autumnal equinox is about September 23. The axial tilt in the southern hemisphere is exactly the opposite of the direction in the northern hemisphere. Thus the seasonal effects in the south are reversed.
The angle of the Earth's tilt is relatively stable over long periods of time. However, the tilt does undergo a slight, irregular motion (known as nutation) with a main period of 18.6 years. The orientation (rather than the angle) of the Earth's axis also changes over time, processing around in a complete circle over each 25,800 year cycle; this precession is the reason for the difference between a sidereal year and a tropical year. Both of these motions are caused by the varying attraction of the Sun and Moon on the Earth's equatorial bulge. From the perspective of the Earth, the poles also migrate a few meters across the surface. This polar motion has multiple, cyclical components, which collectively are termed quasiperiodic motion. In addition to an annual component to this motion, there is a 14-month cycle called the Chandler wobble. The rotational velocity of the Earth also varies in a phenomenon known as length of day variation.
In modern times, Earth's perihelion occurs around January 3, and the aphelion around July 4 (for other eras, see precession and Milankovitch cycles). The changing Earth-Sun distance results in an increase of about 6.9% in solar energy reaching the Earth at perihelion relative to aphelion. Since the southern hemisphere is tilted toward the Sun at about the same time that the Earth reaches the closest approach to the Sun, the southern hemisphere receives slightly more energy from the Sun than does the northern over the course of a year. However, this effect is much less significant than the total energy change due to the axial tilt, and most of the excess energy is absorbed by the higher proportion of water in the southern hemisphere.
The Hill sphere (gravitational sphere of influence) of the Earth is about 1.5 Gm (or 1,500,000 kilometers) in radius. This is maximum distance at which the Earth's gravitational influence is stronger than the more distant Sun and planets. Objects must orbit the Earth within this radius, or they can become unbound by the gravitational perturbation of the Sun. Earth, along with the Solar System, is situated in the Milky Way galaxy, orbiting about 28,000 light years from the center of the galaxy, and about 20 light years above the galaxy's equatorial plane in the Orion spiral arm.
Habitability
A planet that can sustain life is termed habitable, even if life did not originate there. The Earth provides the (currently understood) requisite conditions of liquid water, an environment where complex organic molecules can assemble, and sufficient energy to sustain metabolism. The distance of the Earth from the Sun, as well as its orbital eccentricity, rate of rotation, axial tilt, geological history, sustaining atmosphere and protective magnetic field all contribute to the conditions necessary to originate and sustain life on this planet.
Natural resources and land use
The Earth provides resources that are exploitable by humans for useful purposes. Some of these are non-renewable resources, such as mineral fuels, that are difficult to replenish on a short time scale.
Large deposits of fossil fuels are obtained from the Earth's crust, consisting of coal, petroleum, natural gas and methane clathrate. These deposits are used by humans both for energy production and as feedstock for chemical production. Mineral ore bodies have also been formed in Earth's crust through a process of Ore genesis, resulting from actions of erosion and plate tectonics. These bodies form concentrated sources for many metals and other useful elements.
The Earth's biosphere produces many useful biological products for humans, including (but far from limited to) food, wood, pharmaceuticals, oxygen, and the recycling of many organic wastes. The land-based ecosystem depends upon topsoil and fresh water, and the oceanic ecosystem depends upon dissolved nutrients washed down from the land. Humans also live on the land by using building materials to construct shelters.
Natural and environmental hazards
Large areas are subject to extreme weather such as tropical cyclones, hurricanes, or typhoons that dominate life in those areas. Many places are subject to earthquakes, landslides, tsunamis, volcanic eruptions, tornadoes, sinkholes, blizzards, floods, droughts, and other calamities and disasters.
Many localized areas are subject to human-made pollution of the air and water, acid rain and toxic substances, loss of vegetation (overgrazing, deforestation, desertification), loss of wildlife, species extinction, soil degradation, soil depletion, erosion, and introduction of invasive species.
A scientific consensus exists linking human activities to global warming due to industrial carbon dioxide emissions. This is predicted to produce changes such as the melting of glaciers and ice sheets, more extreme temperature ranges, significant changes in weather conditions and a global rise in average sea levels.
Earth Fact Sheet
Bulk parameters
Mass (1024 kg) 5.9736
Volume (1010 km3) 108.321
Equatorial radius (km) 6378.1
Polar radius (km) 6356.8
Volumetric mean radius (km) 6371.0
Core radius (km) 3485
Ellipticity (Flattening) 0.00335
Mean density (kg/m3) 5515
Surface gravity (m/s2) 9.798
Surface acceleration (m/s2) 9.780
Escape velocity (km/s) 11.186
GM (x 106 km3/s2) 0.3986
Solar irradiance (W/m2) 1367.6
Black-body temperature (K) 254.3
Topographic range (km) 20
Moment of inertia (I/MR2) 0.3308
Number of natural satellites 1
Planetary ring system No
Orbital parameters
Semi major axis (106 km) 149.60
Sidereal orbit period (days) 365.256
Tropical orbit period (days) 365.242
Perihelion (106 km) 147.09
Aphelion (106 km) 152.10
Mean orbital velocity (km/s) 29.78
Max. Orbital velocity (km/s) 30.29
Min. orbital velocity (km/s) 29.29
Sidereal rotation period (hrs) 23.9345
Length of day (hrs) 24.0000
North Pole of Rotation
Right Ascension: 0.00 - 0.641T
Declination : 90.00 - 0.557T
Reference Date: 12:00 UT 1 Jan 2000 (JD 2451545.0)
T = Julian centuries from reference date
Terrestrial Magnetosphere
Dipole field strength: 0.3076 gauss-Re3
Latitude/Longitude of dipole N: 78.6 degrees N/70.1 degrees W
Dipole offset (planet center to dipole center) distance: 0.0725 Re
Latitude/Longitude of offset vector: 18.3 degrees N/147.8 degrees E
Note: Re denotes Earth radii, 6,378 km
Terrestrial Atmosphere
Surface pressure: 1014 mb
Surface density: 1.217 kg/m3
Scale height: 8.5 km
Total mass of atmosphere: 5.1 x 1018 kg
Total mass of hydrosphere: 1.4 x 1021 kg
Average temperature: 288 K (15 C)
Diurnal temperature range: 283 K to 293 K (10 to 20 C)
Wind speeds: 0 to 100 m/s
Mean molecular weight: 28.97 g/mole
Atmospheric composition (by volume, dry air):
Major : 78.084% Nitrogen (N2), 20.946% Oxygen (O2),
Minor (ppm): Argon (Ar) - 9340; Carbon Dioxide (CO2) - 380
Neon (Ne) - 18.18; Helium (He) - 5.24; CH4 - 1.7
Krypton (Kr) - 1.14; Hydrogen (H2) - 0.55
Water is highly variable, typically makes up about 1%
References
Cunningham and Cunningham. 2008. Principle of Environmental Science.
Fourth Edition. New York: Mc Graw Hill Companies, Inc.
Botkin and Keller. 2005. Environmental Science. Fifth Edition. United States: John Wiley and Sons, Inc.
Cunningham and Cunningham. 2004. Principle of Environmental Science. Second
Edition. New York : Mc Graw Hill Companies, Inc.
Daniel D. Chiras. 2006. Environmental Science. Seventh Edition. United States :
Jones and Bartlett Publisher, Inc.
Scott Brennan and Jay Withgott. 2005. Essential Environment. The Science Behind
The Stories. United States : Pearson Education, Inc.
V. Subramaniam. 2002. Environmental Science. New Delhi : Alpha Science
International Ltd.
Beychok, M.R. (2005). Fundamentals Of Stack Gas Dispersion, 4th Edition, author- published. ISBN 0-9644588-0-2. www.air-dispersion.com
Turner, D.B. (1994). Workbook of atmospheric dispersion estimates: an introduction to dispersion modeling, 2nd Edition, CRC Press. ISBN 1-56670-023-X. www.crcpress.com
http://earthday.net/
http://www.enchantedlearning.com/subjects/rainforest/
http://www.eoearth.org/
http://en.wikipedia.org/wiki/Earth
I/D: D20061026297
PROGRAM: SCIENCE EDUCATION (PHYSICS)
COURSE: ENVIRONMENTAL SCIENCE (TSE2013)
LECTURE GROUP: H (TUESDAY 5.00PM-7.00PM)
Earth
From the perspective we get on Earth, our planet appears to be big and sturdy with an endless ocean of air. From space, astronauts often get the impression that the Earth is small with a thin, fragile layer of atmosphere. For a space traveler, the distinguishing Earth features are the blue waters, brown and green land masses and white clouds set against a black background. Many dream of traveling in space and viewing the wonders of the universe. In reality all of us are space travelers. Our spaceship is the planet Earth, traveling at the speed of 108,000 kilometers (67,000 miles) an hour.
Earth is the only planet whose English name does not derive from Greek/Roman mythology. The name derives from Old English and Germanic. There are, of course, hundreds of other names for the planet in other languages. In Roman Mythology, the goddess of the Earth was Tellus which mean the fertile soil. Earth is the third planet from the Sun. Earth is the largest of the terrestrial planets in the Solar System in diameter, mass and density. It is also referred to as the Earth, Planet Earth, the World, and Terra.
Home to millions of species, including humans, Earth is the only place in the universe where life is known to exist. Scientific evidence indicates that the planet formed 4.54 billion years ago, and life appeared on its surface within a billion years. Since then, Earth's biosphere has significantly altered the atmosphere and other abiotic conditions on the planet, enabling the proliferation of aerobic organisms as well as the formation of the ozone layer which, together with Earth's magnetic field, blocks harmful radiation, permitting life on land.
Earth's outer surface is divided into several rigid segments, or tectonic plates, that gradually migrate across the surface over periods of many millions of years. About 71% of the surface is covered with salt-water oceans, the remainder consisting of continents and islands; liquid water, necessary for all known life, is not known to exist on any other planet's surface. Earth's interior remains active, with a thick layer of relatively solid mantle, a liquid outer core that generates a magnetic field, and a solid iron inner core.
Earth interacts with other objects in outer space, including the Sun and the Moon. At present, Earth orbits the Sun once for every roughly 366.26 times it rotates about its axis. This length of time is a sidereal year, which is equal to 365.26 solar days. The Earth's axis of rotation is tilted 23.4° away from the perpendicular to its orbital plane, producing seasonal variations on the planet's surface with a period of one tropical year (365.24 solar days). Earth's only known natural satellite, the Moon, which began orbiting it about 4.53 billion years ago, provides ocean tides, stabilizes the axial tilt and gradually slows the planet's rotation. A bombardment during the early history of the planet played a role in the formation of the oceans. Later, asteroid impacts caused significant changes to the surface environment.
Composition and structure
Earth is a terrestrial planet, meaning that it is a rocky body, rather than a gas giant like Jupiter. It is the largest of the four solar terrestrial planets, both in terms of size and mass. Of these four planets, Earth also has the highest density, the highest surface gravity and the strongest magnetic field.
Shape
The Earth's shape is very close to an oblate spheroid, a rounded shape with a bulge around the equator, although the precise shape (the geoids) varies from this by up to 100 meters. The average diameter of the reference spheroid is about 12,742 km. More approximately the distance is 40,000 km/π because the meter was originally defined as 1/10,000,000 of the distance from the equator to the North Pole through Paris, France.
The rotation of the Earth creates the equatorial bulge so that the equatorial diameter is 43 km larger than the pole to pole diameter. The largest local deviations in the rocky surface of the Earth are Mount Everest (8,848 m above local sea level) and the Mariana Trench (10,911 m below local sea level). Hence compared to a perfect ellipsoid, the Earth has a tolerance of about one part in about 584, or 0.17%, which is less than the 0.22% tolerance allowed in billiard balls. Because of the bulge, the feature farthest from the center of the Earth is actually Mount Chimborazo in Ecuador.
Chemical composition
The mass of the Earth is approximately 5.98×1024 kg. It is composed mostly of iron (32.1%), oxygen (30.1%), silicon (15.1%), magnesium (13.9%), sulfur (2.9%), nickel (1.8%), calcium (1.5%), and Aluminum (1.4%); with the remaining 1.2% consisting of trace amounts of other elements. Due to mass segregation, the core region is believed to be primarily composed of iron (88.8%), with smaller amounts of nickel (5.8%), sulfur (4.5%), and less than 1% trace elements.
The geochemist F. W. Clarke calculated that a little more than 47% of the Earth's crust consists of oxygen. The more common rock constituents of the Earth's crust are nearly all oxides; chlorine, sulfur and fluorine are the only important exceptions to this and their total amount in any rock is usually much less than 1%. The principal oxides are silica, alumina, iron oxides, lime, magnesia, potash and soda. The silica functions principally as an acid, forming silicates, and all the commonest minerals of igneous rocks are of this nature. From a computation based on 1,672 analyses of all kinds of rocks, Clarke deduced that 99.22% were composed of 11 oxides (see the table at right.) All the other constituents occur only in very small quantities.
Internal structure
The interior of the Earth, like that of the other terrestrial planets, is chemically divided into layers. The Earth has an outer silicate solid crust, a highly viscous mantle, a liquid outer core that is much less viscous than the mantle, and a solid inner core. The thickness of the crust varies, averaging 6 km under the oceans and 30–50 km on the continents.
The internal heat of the planet is probably produced by the radioactive decay of potassium-40, uranium-238 and thorium-232 isotopes. All three have half-life decay periods of more than a billion years. At the center of the planet, the temperature may be up to 7,000 K and the pressure could reach 360 GPa. A portion of the core's thermal energy is transported toward the crust by Mantle plumes; a form of convection consisting of upwelling of higher-temperature rock. These plumes can produce hotspots and flood basalts. The Earth is divided into several layers which have distinct chemical and seismic properties (depths in km):
• 40 Crust
• 40- 400 Upper mantle
• 400- 650 Transition region
• 650-2700 Lower mantle
• 2700-2890 D’’ layer
• 2890-5150 Outer core
• 5150-6378 Inner cores
The crust varies considerably in thickness; it is thinner under the oceans, thicker under the continents. The inner core and crust are solid; the outer core and mantle layers are plastic or semi-fluid. The various layers are separated by discontinuities which are evident in seismic data; the best known of these is the Mohorovicic discontinuity between the crust and upper mantle. Most of the mass of the Earth is in the mantle, most of the rest in the core; the part we inhabit is a tiny fraction of the whole (values below x1024 kilograms):
• Atmosphere = 0.0000051
• Oceans = 0.0014
• Crust = 0.026
• Mantle = 4.043
• Outer core = 1.835
• Inner core = 0.09675
The core is probably composed mostly of iron (or nickel/iron) though it is possible that some lighter elements may be present, too. Temperatures at the center of the core may be as high as 7500 K, hotter than the surface of the Sun. The lower mantle is probably mostly silicon, magnesium and oxygen with some iron, calcium and aluminum. The upper mantle is mostly olivine and pyroxene (iron/magnesium silicates), calcium and aluminum. We know most of this only from seismic techniques; samples from the upper mantle arrive at the surface as lava from volcanoes but the majority of the Earth is inaccessible. The crust is primarily quartz (silicon dioxide) and other silicates like feldspar. Taken as a whole, the Earth's chemical composition (by mass) is:
Surface
The Earth's terrain varies greatly from place to place. About 71.8% of the surface is covered by water (including oceans, lakes, and streams), with much of the continental shelf below sea level. The submerged surface has mountainous features, including a globe-spanning mid-ocean ridge system, as well as undersea volcanoes, oceanic trenches, submarine canyons, oceanic plateaus and abyssal plains. The remaining 28.2% not covered by water consists of mountains, deserts, plains, plateaus, and other geomorphologies.
The planetary surface undergoes reshaping over geological time periods due to the effects of tectonics and erosion. The surface features built up or deformed through plate tectonics are subject to steady weathering from precipitation, thermal cycles, and chemical effects. Glaciations, coastal erosion, the build-up of coral reefs, and large meteorite impacts also act to reshape the landscape.
As the tectonic plates migrate across the planet, the ocean floor is sub ducted under the leading edges. At the same time, upwelling of mantle material creates a divergent boundary along mid-ocean ridges. The combination of these processes continually recycles the oceanic crustal material. Most of the ocean floor is less than 100 million years in age. The oldest oceanic crust is located in the Western Pacific, and has an estimated age of about 200 million years. By comparison, the oldest fossils found on land have an age of about 3 billion years.
The continental crust consists of lower density material such as the igneous rocks granite and andesite. Less common is basalt, a denser volcanic rock that is the primary constituent of the ocean floors. Sedimentary rock is formed from the accumulation of sediment that becomes compacted together. Nearly 75% of the continental surfaces are covered by sedimentary rocks, although they form only about 5% of the crust. The third form of rock material found on Earth is metamorphic rock, which is created from the transformation of pre-existing rock types through high pressures, high temperatures, or both. The most abundant silicate minerals on the Earth's surface include quartz, the feldspars, amphibole, mica, pyroxene and olivine. Common carbonate minerals include calcite (found in limestone), aragonite and dolomite.
The pedosphere is the outermost layer of the Earth that is composed of soil and subject to soil formation processes. It exists at the interface of the lithosphere, atmosphere, hydrosphere and biosphere. Currently the total arable land is 13.31% of the land surface, with only 4.71% supporting permanent crops. Close to 40% of the Earth's land surface is presently used for cropland and pasture, or an estimated 1.3×107 km² of cropland and 3.4×107 km² of pastureland.
Unlike the other terrestrial planets, Earth's crust is divided into several separate solid plates which float around independently on top of the hot mantle below. The theory that describes this is known as plate tectonics. It is characterized by two major processes: spreading and subduction. Spreading occurs when two plates move away from each other and new crust is created by upwelling magma from below. Subduction occurs when two plates collide and the edge of one dives beneath the other and ends up being destroyed in the mantle. There is also transverse motion at some plate boundaries (i.e. the San Andreas Fault in California) and collisions between continental plates (i.e. India/Eurasia). There are (at present) eight major plates:
• North American Plate - North America, western North Atlantic and Greenland
• South American Plate - South America and western South Atlantic
• Antarctic Plate - Antarctica and the "Southern Ocean"
• Eurasian Plate - eastern North Atlantic, Europe and Asia except for India
• African Plate - Africa, eastern South Atlantic and western Indian Ocean
• Indian-Australian Plate - India, Australia, New Zealand and most of Indian Ocean
• Nazca Plate - eastern Pacific Ocean adjacent to South America
• Pacific Plate - most of the Pacific Ocean (and the southern coast of California!)
There are also twenty or more small plates such as the Arabian, Cocos, and Philippine Plates. Earthquakes are much more common at the plate boundaries. Plotting their locations makes it easy to see the plate boundaries. The elevation of the land surface of the Earth varies from the low point of −418 m at the Dead Sea, to a 2005-estimated maximum altitude of 8,848 m at the top of Mount Everest. The mean height of land above sea level is 840 m.
Hydrosphere
The abundance of water on Earth's surface is a unique feature that distinguishes the "Blue Planet" from others in the solar system. The Earth's hydrosphere consists chiefly of the oceans, but technically includes all water surfaces in the world, including inland seas, lakes, rivers, and underground waters down to a depth of 2,000 m. The deepest underwater location is Challenger Deep of the Mariana Trench in the Pacific Ocean with a depth of −10,911.4 m. The average depth of the oceans is 3,800 m, more than four times the average height of the continents. The mass of the oceans is approximately 1.35×1018 metric tons, or about 1/4400 of the total mass of the Earth, and occupies a volume of 1.386×109 km³. If all of the land on Earth were spread evenly, water would rise to an altitude of more than 2.7 km. About 97.5% of the water is saline, while the remaining 2.5% is fresh water. The majority of the fresh water, about 68.7%, is currently in the form of ice.
About 3.5% of the total mass of the oceans consists of salt. Most of this salt was released from volcanic activity or extracted from cool, igneous rocks. The oceans are also a reservoir of dissolved atmospheric gases, which are essential for the survival of many aquatic life forms. Sea water has an important influence on the world's climate, with the oceans acting as a large heat reservoir. Shifts in the oceanic temperature distribution can cause significant weather shifts, such as the El Niño-Southern Oscillation.
Atmosphere
The atmospheric pressure on the surface of the Earth averages 101.325 kPa, with a scale height of about 8.5 km. It is 78% nitrogen and 21% oxygen, with trace amounts of water vapor, carbon dioxide and other gaseous molecules. The height of the troposphere varies with latitude, ranging between 8 km at the poles to 17 km at the equator, with some variation due to weather and seasonal factors.
Earth's biosphere has significantly altered its atmosphere. Oxygenic photosynthesis evolved 2.7 billion years ago, forming the primarily nitrogen-oxygen atmosphere that exists today. This change enabled the proliferation of aerobic organisms as well as the formation of the ozone layer which, together with Earth's magnetic field, blocks ultraviolet solar radiation, permitting life on land. Other atmospheric functions important to life on Earth's include transporting water vapor, providing useful gases, causing small meteors to burn up before they strike the surface, and moderating temperature.
This last phenomenon is known as the greenhouse effect: trace molecules within the atmosphere serve to capture thermal energy emitted from the ground, thereby raising the average temperature. Carbon dioxide, water vapor, methane and ozone are the primary greenhouse gases in the Earth's atmosphere. Without this heat-retention effect, the average surface temperature would be −18 °C and life would likely not exist.
Magnetic field
Figure of The Earth's magnetic field, which approximates a dipole.
The Earth's magnetic field is shaped roughly as a magnetic dipole, with the poles currently located proximate to the planet's geographic poles. According to dynamo theory, the field is generated within the molten outer core region where heat creates convection motions of conducting materials, generating electric currents. These in turn produce the Earth's magnetic field. The convection movements in the core are chaotic in nature, and periodically change alignment. This results in field reversals at irregular intervals averaging a few times every million years. The most recent reversal occurred approximately 700,000 years ago. The field forms the magnetosphere, which deflects particles in the solar wind. The sunward edge of the bow shock is located at about 13 times the radius of the Earth. The collision between the magnetic field and the solar wind forms the Van Allen radiation belts, a pair of concentric, torus-shaped regions of energetic charged particles. When the plasma enters the Earth's atmosphere at the magnetic poles, it forms the aurora.
Orbit and rotation
Relative to the background stars, it takes the Earth, on average, 23 hours, 56 minutes and 4.091 seconds (one sidereal day) to rotate around the axis that connects the north and the south poles from west to east. From Earth, the main apparent motion of celestial bodies in the sky (except that of meteors within the atmosphere and low-orbiting satellites) is to the west at a rate of 15°/h = 15'/min. This is equivalent to an apparent diameter of the Sun or Moon every two minutes. (The apparent sizes of the Sun and the Moon are approximately the same.)
Earth orbits the Sun at an average distance of about 150 million kilometers every 365.2564 mean solar days (1 sidereal year). From Earth, this gives an apparent movement of the Sun with respect to the stars at a rate of about 1°/day (or a Sun or Moon diameter every 12 hours) eastward. Because of this motion, on average it takes 24 hours—a solar day—for Earth to complete a full rotation about its axis so that the Sun returns to the meridian. The orbital speed of the Earth averages about 30 km/s (108,000 km/h), which is fast enough to cover the planet's diameter (about 12,600 km) in seven minutes, and the distance to the Moon (384,000 km) in four hours.
The Moon revolves with the Earth around a common barycenter every 27.32 days relative to the background stars. When combined with the Earth–Moon system's common revolution around the Sun, the period of the synodic month, from new moon to new moon, is 29.53 days. Viewed from the celestial north pole, the motion of Earth, the Moon and their axial rotations are all counter-clockwise. The orbital and axial planes are not precisely aligned: Earth's axis is tilted some 23.5 degrees from the perpendicular to the Earth–Sun plane (which causes the seasons); and the Earth–Moon plane is tilted about 5 degrees against the Earth-Sun plane (without this tilt, there would be an eclipse every two weeks, alternating between lunar eclipses and solar eclipses).
Because of the axial tilt of the Earth, the position of the Sun in the sky (as seen by an observer on the surface) varies over the course of the year. For an observer at northern latitude, when the northern pole is tilted toward the Sun the day lasts longer and the Sun climbs higher in the sky. This results in warmer average temperatures from the increase in solar radiation reaching the surface. When the northern pole is tilted away from the Sun, the reverse is true and the climate is generally cooler. Above the Arctic Circle, an extreme case is reached where there is no daylight at all for part of the year. (This is called a polar night.)
This variation in the climate (because of the direction of the Earth's axial tilt) results in the seasons. By astronomical convention, the four seasons are determined by the solstices, the point in the orbit of maximum axial tilt toward or away from the Sun, and the equinoxes, when the direction of the tilt and the direction to the Sun are perpendicular. Winter solstice occurs on about December 21, summer solstice is near June 21, spring equinox is around March 20 and autumnal equinox is about September 23. The axial tilt in the southern hemisphere is exactly the opposite of the direction in the northern hemisphere. Thus the seasonal effects in the south are reversed.
The angle of the Earth's tilt is relatively stable over long periods of time. However, the tilt does undergo a slight, irregular motion (known as nutation) with a main period of 18.6 years. The orientation (rather than the angle) of the Earth's axis also changes over time, processing around in a complete circle over each 25,800 year cycle; this precession is the reason for the difference between a sidereal year and a tropical year. Both of these motions are caused by the varying attraction of the Sun and Moon on the Earth's equatorial bulge. From the perspective of the Earth, the poles also migrate a few meters across the surface. This polar motion has multiple, cyclical components, which collectively are termed quasiperiodic motion. In addition to an annual component to this motion, there is a 14-month cycle called the Chandler wobble. The rotational velocity of the Earth also varies in a phenomenon known as length of day variation.
In modern times, Earth's perihelion occurs around January 3, and the aphelion around July 4 (for other eras, see precession and Milankovitch cycles). The changing Earth-Sun distance results in an increase of about 6.9% in solar energy reaching the Earth at perihelion relative to aphelion. Since the southern hemisphere is tilted toward the Sun at about the same time that the Earth reaches the closest approach to the Sun, the southern hemisphere receives slightly more energy from the Sun than does the northern over the course of a year. However, this effect is much less significant than the total energy change due to the axial tilt, and most of the excess energy is absorbed by the higher proportion of water in the southern hemisphere.
The Hill sphere (gravitational sphere of influence) of the Earth is about 1.5 Gm (or 1,500,000 kilometers) in radius. This is maximum distance at which the Earth's gravitational influence is stronger than the more distant Sun and planets. Objects must orbit the Earth within this radius, or they can become unbound by the gravitational perturbation of the Sun. Earth, along with the Solar System, is situated in the Milky Way galaxy, orbiting about 28,000 light years from the center of the galaxy, and about 20 light years above the galaxy's equatorial plane in the Orion spiral arm.
Habitability
A planet that can sustain life is termed habitable, even if life did not originate there. The Earth provides the (currently understood) requisite conditions of liquid water, an environment where complex organic molecules can assemble, and sufficient energy to sustain metabolism. The distance of the Earth from the Sun, as well as its orbital eccentricity, rate of rotation, axial tilt, geological history, sustaining atmosphere and protective magnetic field all contribute to the conditions necessary to originate and sustain life on this planet.
Natural resources and land use
The Earth provides resources that are exploitable by humans for useful purposes. Some of these are non-renewable resources, such as mineral fuels, that are difficult to replenish on a short time scale.
Large deposits of fossil fuels are obtained from the Earth's crust, consisting of coal, petroleum, natural gas and methane clathrate. These deposits are used by humans both for energy production and as feedstock for chemical production. Mineral ore bodies have also been formed in Earth's crust through a process of Ore genesis, resulting from actions of erosion and plate tectonics. These bodies form concentrated sources for many metals and other useful elements.
The Earth's biosphere produces many useful biological products for humans, including (but far from limited to) food, wood, pharmaceuticals, oxygen, and the recycling of many organic wastes. The land-based ecosystem depends upon topsoil and fresh water, and the oceanic ecosystem depends upon dissolved nutrients washed down from the land. Humans also live on the land by using building materials to construct shelters.
Natural and environmental hazards
Large areas are subject to extreme weather such as tropical cyclones, hurricanes, or typhoons that dominate life in those areas. Many places are subject to earthquakes, landslides, tsunamis, volcanic eruptions, tornadoes, sinkholes, blizzards, floods, droughts, and other calamities and disasters.
Many localized areas are subject to human-made pollution of the air and water, acid rain and toxic substances, loss of vegetation (overgrazing, deforestation, desertification), loss of wildlife, species extinction, soil degradation, soil depletion, erosion, and introduction of invasive species.
A scientific consensus exists linking human activities to global warming due to industrial carbon dioxide emissions. This is predicted to produce changes such as the melting of glaciers and ice sheets, more extreme temperature ranges, significant changes in weather conditions and a global rise in average sea levels.
Earth Fact Sheet
Bulk parameters
Mass (1024 kg) 5.9736
Volume (1010 km3) 108.321
Equatorial radius (km) 6378.1
Polar radius (km) 6356.8
Volumetric mean radius (km) 6371.0
Core radius (km) 3485
Ellipticity (Flattening) 0.00335
Mean density (kg/m3) 5515
Surface gravity (m/s2) 9.798
Surface acceleration (m/s2) 9.780
Escape velocity (km/s) 11.186
GM (x 106 km3/s2) 0.3986
Solar irradiance (W/m2) 1367.6
Black-body temperature (K) 254.3
Topographic range (km) 20
Moment of inertia (I/MR2) 0.3308
Number of natural satellites 1
Planetary ring system No
Orbital parameters
Semi major axis (106 km) 149.60
Sidereal orbit period (days) 365.256
Tropical orbit period (days) 365.242
Perihelion (106 km) 147.09
Aphelion (106 km) 152.10
Mean orbital velocity (km/s) 29.78
Max. Orbital velocity (km/s) 30.29
Min. orbital velocity (km/s) 29.29
Sidereal rotation period (hrs) 23.9345
Length of day (hrs) 24.0000
North Pole of Rotation
Right Ascension: 0.00 - 0.641T
Declination : 90.00 - 0.557T
Reference Date: 12:00 UT 1 Jan 2000 (JD 2451545.0)
T = Julian centuries from reference date
Terrestrial Magnetosphere
Dipole field strength: 0.3076 gauss-Re3
Latitude/Longitude of dipole N: 78.6 degrees N/70.1 degrees W
Dipole offset (planet center to dipole center) distance: 0.0725 Re
Latitude/Longitude of offset vector: 18.3 degrees N/147.8 degrees E
Note: Re denotes Earth radii, 6,378 km
Terrestrial Atmosphere
Surface pressure: 1014 mb
Surface density: 1.217 kg/m3
Scale height: 8.5 km
Total mass of atmosphere: 5.1 x 1018 kg
Total mass of hydrosphere: 1.4 x 1021 kg
Average temperature: 288 K (15 C)
Diurnal temperature range: 283 K to 293 K (10 to 20 C)
Wind speeds: 0 to 100 m/s
Mean molecular weight: 28.97 g/mole
Atmospheric composition (by volume, dry air):
Major : 78.084% Nitrogen (N2), 20.946% Oxygen (O2),
Minor (ppm): Argon (Ar) - 9340; Carbon Dioxide (CO2) - 380
Neon (Ne) - 18.18; Helium (He) - 5.24; CH4 - 1.7
Krypton (Kr) - 1.14; Hydrogen (H2) - 0.55
Water is highly variable, typically makes up about 1%
References
Cunningham and Cunningham. 2008. Principle of Environmental Science.
Fourth Edition. New York: Mc Graw Hill Companies, Inc.
Botkin and Keller. 2005. Environmental Science. Fifth Edition. United States: John Wiley and Sons, Inc.
Cunningham and Cunningham. 2004. Principle of Environmental Science. Second
Edition. New York : Mc Graw Hill Companies, Inc.
Daniel D. Chiras. 2006. Environmental Science. Seventh Edition. United States :
Jones and Bartlett Publisher, Inc.
Scott Brennan and Jay Withgott. 2005. Essential Environment. The Science Behind
The Stories. United States : Pearson Education, Inc.
V. Subramaniam. 2002. Environmental Science. New Delhi : Alpha Science
International Ltd.
Beychok, M.R. (2005). Fundamentals Of Stack Gas Dispersion, 4th Edition, author- published. ISBN 0-9644588-0-2. www.air-dispersion.com
Turner, D.B. (1994). Workbook of atmospheric dispersion estimates: an introduction to dispersion modeling, 2nd Edition, CRC Press. ISBN 1-56670-023-X. www.crcpress.com
http://earthday.net/
http://www.enchantedlearning.com/subjects/rainforest/
http://www.eoearth.org/
http://en.wikipedia.org/wiki/Earth
MOH NUR ZAIM
HUMAN DEVELOPMENT INDEX (HDI)
INTRODUCTION
The Human Development Index (HDI) is a summary index that measures country` s average achievements in three basic aspects of human development: longevity, knowledge, and a decent standard of living. The index was developed in 1990 by Pakistani economist Mahbub ul Haq and Sir Richard Jolly, with help from Gustav Ranis of Yale University and Lord Meghnad Desai of the London School of Economics. It has been used since then by the United Nations Development Programme in its annual Human Development Report.
Based on available statistics UNDP was able to provide an HDI for 175 countries in the latest Human Development Report. The HDI is today widely used in academia, the media and in policy circles to measure and compare progress in human development between countries and over time.
The HDI combines three basic dimensions: first, Life expectancy at birth, as an index of population health and longevity. Second, Knowledge and education, as measured by the adult literacy rate (with two-thirds weighting) and the combined primary, secondary, and tertiary gross enrollment ratio (with one-third weighting).Third, The standard of living, as measured by the natural logarithm of gross domestic product (GDP) per capita at purchasing power parity (PPP) in USD.
Actually the HDI has been organized in order to highlight the presence of human poverty in both the rich and poor countries. High income per person is no guarantee of a poverty-free country. Even among the richest countries, there is human poverty. It also used to focus attention on the most deprived people and deprivations in basic human capabilities in a country, not on average national achievement. The human poverty indices focus directly on the number of people living in deprivation - presenting a very different picture from average national achievement. It also moves the focus of poverty debates away from concern about income poverty alone. Besides that, the HDI is important to guide national planning for poverty alleviation. Many National Human Development Reports now break down the HPI by region or other socioeconomic groups to identify the areas or social groups within the country most deprived in terms of human poverty. The results can be dramatic, creating national debate and helping to reshape policies.
METHODOLOGY
HDI trends between 1975 and 2004
OECD
Central and eastern Europe, and the CIS
Latin America and the Caribbean
East Asia
Arab States
South Asia
Sub-Saharan Africa
In general to transform a raw variable, say x, into a unit-free index between 0 and 1 (which allows different indices to be added together), the following formula is used:
• Life Expectancy Index, L = LE – min (x)
max (x) - min (x)
• Education Index, E = 2 x ALR + 1 x ER
3 3
• GDP Index, G = log (GDP pc) – log (100)
log (40000) – log (100)
• Total human development index, HDI = L + E + G
3
Examples
Calculation examples of the indices.
Index Measure Minimum value Maximum value Formula
Longevity Life expectancy at birth (LE) 25 yrs
85 yrs
Education Literacy rate (LR) 0% 100%
Combined gross enrollment ratio (CGER) 0% 100%
GDP GDP per capita (PPP)
100 USD
40,000 USD
HDI Total human development index not applicable not applicable
Table 1: Cambodia’s human development index 2005
HDI value Life expectancy at birth
(years) Adult literacy rate
(% ages 15 and older) Combined primary, secondary and tertiary gross enrolment ratio
(%) GDP per capita
(PPP US$)
1. Iceland (0.968) 1. Japan (82.3) 1. Georgia (100.0) 1. Australia (113.0) 1. Luxembourg (60,228)
129. Solomon Islands (0.602) 138. Gambia (58.8) 97. Vanuatu (74.0) 129. Kenya (60.6) 122. Viet Nam (3,071)
130. Lao People's Democratic Republic (0.601) 139. Madagascar (58.4) 98. Kenya (73.6) 130. Zambia (60.5) 123. Bolivia (2,819)
131. Cambodia (0.598) 140. Cambodia (58.0) 99. Cambodia (73.6) 131. Cambodia (60.0) 124. Cambodia (2,727)
132. Myanmar (0.583) 141. Togo (57.8) 100. Egypt (71.4) 132. United Arab Emirates (59.9) 125. Papua New Guinea (2,563)
133. Bhutan (0.579) 142. Sudan (57.4) 101. Madagascar (70.7) 133. Swaziland (59.8) 126. Ghana (2,480)
177. Sierra Leone (0.336) 177. Zambia (40.5) 139. Burkina Faso (23.6) 172. Niger (22.7) 174. Malawi (667)
Figure 1:
The human development index gives a more complete picture than income
This year’s HDI, which refers to 2005, highlights the very large gaps in well-being and life chances that continue to divide our increasingly interconnected world. By looking at some of the most fundamental aspects of people’s lives and opportunities it provides a much more complete picture of a country's development than other indicators, such as GDP per capita. Figure 2 illustrates that countries on the same level of HDI as Cambodia can have very different levels of income.
Of the components of the HDI, only income and gross enrolment are somewhat responsive to short term policy changes. For that reason, it is important to examine changes in the human development index over time.
The human development index trends tell an important story in that aspect. Since the mid-1970s almost all regions have been progressively increasing their HDI score (Figure 2). East Asia and South Asia have accelerated progress since 1990. Central and Eastern Europe and the Commonwealth of Independent States (CIS), following a catastrophic decline in the first half of the 1990s, has also recovered to the level before the reversal. The major exception is sub-Saharan Africa. Since 1990 it has stagnated, partly because of economic reversal but principally because of the catastrophic effect of HIV/AIDS on life expectancy.
Figure 2: HDI Trends
World map indicating Human Development Index (2007)
High
██ 0.950 and over
██ 0.900–0.949
██ 0.850–0.899
██ 0.800–0.849
Medium
██ 0.750–0.799
██ 0.700–0.749
██ 0.650–0.699
██ 0.600–0.649
██ 0.550–0.599
██ 0.500–0.549
Low
██ 0.450–0.499
██ 0.400–0.449
██ 0.350–0.399
██ under 0.350
██ not available
A HDI below 0.5 is considered to represent "low development". All 22 countries in that category are located in Africa. The highest-scoring Sub-Saharan countries, Gabon and South Africa, are ranked 119th and 121st, respectively. Nine countries departed from this category this year and joined the "medium development" group.
A HDI of 0.8 or more is considered to represent "high development". This includes all developed countries, such as those in North America, Western Europe, Oceania, and Eastern Asia, as well as some developing countries in Eastern Europe, Central and South America, Southeast Asia, the Caribbean, and the oil-rich Arabian Peninsula. Seven countries were promoted to this category this year, leaving the "medium development" group: Albania, Belarus, Brazil, Libya, Republic of Macedonia, Russia and Saudi Arabia.
High Income Countries
"High income countries" are defined by the World Bank as countries with a Gross National Income per capita of $11,116 or more. According to the United Nations definition some high income countries may also be developing countries. Thus, a high income country may be classified as either developed or developing.
When using GDP/cap as an indicator of "developed" status, one must take into account how some countries have achieved a (usually temporarily) high GDP/cap through natural resource exploitation (e.g., Nauru through phosphate extraction and Equatorial Guinea) without developing the diverse industrial and service-based economy necessary for "developed" status — similarly, the Bahamas, Barbados, Antigua and Barbuda, and Saint Kitts and Nevis depend overwhelmingly on the tourist industry.
Despite their high per capita GDP, the GCC countries in the Middle East are generally not considered developed countries because their economies depend overwhelmingly on oil production and export; in many cases (notably Saudi Arabia), per capita GDP is also skewed by an unequal distribution of wealth.
Developed Country
The term developed country, or advanced country, is used to categorize countries with developed economies in which the tertiary and quaternary sectors of industry dominate. Countries not fitting this definition may be referred to as developing countries.
This level of economic development usually translates into a high income per capita and a high Human Development Index (HDI). Countries with high gross domestic product (GDP) per capita often fit the above description of a developed economy. However, anomalies exist when determining "developed" status by the factor GDP per capita alone.
Developing Country
A developing country is a country which has an undeveloped or developing industrial base, and an inconsistent varying Human Development Index (HDI) score and per capita income, but is in a phase of economic development. Usually all countries which are neither a developed country nor a failed state are classified as developing countries, despite the above facts, this is not true for all countries as some developing countries are far more developed than some developed countries.
Countries with more advanced economies than other developing nations, but which have not yet fully demonstrated the signs of a developed country, are grouped under the term newly industrialized countries. Other developing countries which have maintained sustained economic growth over the years and exhibit good economic potential are termed as emerging markets. The Big Emerging Market (BEM) economies are Argentina, Brazil, China, Egypt, India, Indonesia, Mexico, Poland, Russia, South Africa, South Korea and Turkey. The application of the term developing country to any country which is not developed is inappropriate because a number of poor countries have experienced prolonged periods of economic decline. Such countries are classified as either least developed countries or failed states.
Development entails a modern infrastructure (both physical and institutional), and a move away from low value added sectors such as agriculture and natural resource extraction. Developed countries, in comparison, usually have economic systems based on continuous, self-sustaining economic growth in the tertiary and quaternary sectors and high standards of living.
High income Upper-middle income Lower-middle income Low income
REFERENCES
Cunningham and Cunningham. 2008. Principle of Environmental Science.
Fourth Edition. New York: Mc Graw Hill Companies, Inc.
Botkin and Keller. 2005. Environmental Science. Fifth Edition. United States: John Wiley and Sons, Inc.
Cunningham and Cunningham. 2004. Principle of Environmental Science. Second
Edition. New York : Mc Graw Hill Companies, Inc.
Daniel D. Chiras. 2006. Environmental Science. Seventh Edition. United States :
Jones and Bartlett Publisher, Inc.
Scott Brennan and Jay Withgott. 2005. Essential Environment. The Science Behind
The Stories. United States : Pearson Education, Inc.
V. Subramaniam. 2002. Environmental Science. New Delhi : Alpha Science
International Ltd.
Beychok, M.R. (2005). Fundamentals Of Stack Gas Dispersion, 4th Edition, author- published. ISBN 0-9644588-0-2. www.air-dispersion.com
Turner, D.B. (1994). Workbook of atmospheric dispersion estimates: an introduction to dispersion modeling, 2nd Edition, CRC Press. ISBN 1-56670-023-X. www.crcpress.com
http://en.wikipedia.org/wiki/Developing_country
http://en.wikipedia.org/wiki/Image:CountryIncome.PNG
http://hdrstats.undp.org/countries/country_fact_sheets/cty_fs_KHM.html
http://www.answers.com/topic/human-development-index
INTRODUCTION
The Human Development Index (HDI) is a summary index that measures country` s average achievements in three basic aspects of human development: longevity, knowledge, and a decent standard of living. The index was developed in 1990 by Pakistani economist Mahbub ul Haq and Sir Richard Jolly, with help from Gustav Ranis of Yale University and Lord Meghnad Desai of the London School of Economics. It has been used since then by the United Nations Development Programme in its annual Human Development Report.
Based on available statistics UNDP was able to provide an HDI for 175 countries in the latest Human Development Report. The HDI is today widely used in academia, the media and in policy circles to measure and compare progress in human development between countries and over time.
The HDI combines three basic dimensions: first, Life expectancy at birth, as an index of population health and longevity. Second, Knowledge and education, as measured by the adult literacy rate (with two-thirds weighting) and the combined primary, secondary, and tertiary gross enrollment ratio (with one-third weighting).Third, The standard of living, as measured by the natural logarithm of gross domestic product (GDP) per capita at purchasing power parity (PPP) in USD.
Actually the HDI has been organized in order to highlight the presence of human poverty in both the rich and poor countries. High income per person is no guarantee of a poverty-free country. Even among the richest countries, there is human poverty. It also used to focus attention on the most deprived people and deprivations in basic human capabilities in a country, not on average national achievement. The human poverty indices focus directly on the number of people living in deprivation - presenting a very different picture from average national achievement. It also moves the focus of poverty debates away from concern about income poverty alone. Besides that, the HDI is important to guide national planning for poverty alleviation. Many National Human Development Reports now break down the HPI by region or other socioeconomic groups to identify the areas or social groups within the country most deprived in terms of human poverty. The results can be dramatic, creating national debate and helping to reshape policies.
METHODOLOGY
HDI trends between 1975 and 2004
OECD
Central and eastern Europe, and the CIS
Latin America and the Caribbean
East Asia
Arab States
South Asia
Sub-Saharan Africa
In general to transform a raw variable, say x, into a unit-free index between 0 and 1 (which allows different indices to be added together), the following formula is used:
• Life Expectancy Index, L = LE – min (x)
max (x) - min (x)
• Education Index, E = 2 x ALR + 1 x ER
3 3
• GDP Index, G = log (GDP pc) – log (100)
log (40000) – log (100)
• Total human development index, HDI = L + E + G
3
Examples
Calculation examples of the indices.
Index Measure Minimum value Maximum value Formula
Longevity Life expectancy at birth (LE) 25 yrs
85 yrs
Education Literacy rate (LR) 0% 100%
Combined gross enrollment ratio (CGER) 0% 100%
GDP GDP per capita (PPP)
100 USD
40,000 USD
HDI Total human development index not applicable not applicable
Table 1: Cambodia’s human development index 2005
HDI value Life expectancy at birth
(years) Adult literacy rate
(% ages 15 and older) Combined primary, secondary and tertiary gross enrolment ratio
(%) GDP per capita
(PPP US$)
1. Iceland (0.968) 1. Japan (82.3) 1. Georgia (100.0) 1. Australia (113.0) 1. Luxembourg (60,228)
129. Solomon Islands (0.602) 138. Gambia (58.8) 97. Vanuatu (74.0) 129. Kenya (60.6) 122. Viet Nam (3,071)
130. Lao People's Democratic Republic (0.601) 139. Madagascar (58.4) 98. Kenya (73.6) 130. Zambia (60.5) 123. Bolivia (2,819)
131. Cambodia (0.598) 140. Cambodia (58.0) 99. Cambodia (73.6) 131. Cambodia (60.0) 124. Cambodia (2,727)
132. Myanmar (0.583) 141. Togo (57.8) 100. Egypt (71.4) 132. United Arab Emirates (59.9) 125. Papua New Guinea (2,563)
133. Bhutan (0.579) 142. Sudan (57.4) 101. Madagascar (70.7) 133. Swaziland (59.8) 126. Ghana (2,480)
177. Sierra Leone (0.336) 177. Zambia (40.5) 139. Burkina Faso (23.6) 172. Niger (22.7) 174. Malawi (667)
Figure 1:
The human development index gives a more complete picture than income
This year’s HDI, which refers to 2005, highlights the very large gaps in well-being and life chances that continue to divide our increasingly interconnected world. By looking at some of the most fundamental aspects of people’s lives and opportunities it provides a much more complete picture of a country's development than other indicators, such as GDP per capita. Figure 2 illustrates that countries on the same level of HDI as Cambodia can have very different levels of income.
Of the components of the HDI, only income and gross enrolment are somewhat responsive to short term policy changes. For that reason, it is important to examine changes in the human development index over time.
The human development index trends tell an important story in that aspect. Since the mid-1970s almost all regions have been progressively increasing their HDI score (Figure 2). East Asia and South Asia have accelerated progress since 1990. Central and Eastern Europe and the Commonwealth of Independent States (CIS), following a catastrophic decline in the first half of the 1990s, has also recovered to the level before the reversal. The major exception is sub-Saharan Africa. Since 1990 it has stagnated, partly because of economic reversal but principally because of the catastrophic effect of HIV/AIDS on life expectancy.
Figure 2: HDI Trends
World map indicating Human Development Index (2007)
High
██ 0.950 and over
██ 0.900–0.949
██ 0.850–0.899
██ 0.800–0.849
Medium
██ 0.750–0.799
██ 0.700–0.749
██ 0.650–0.699
██ 0.600–0.649
██ 0.550–0.599
██ 0.500–0.549
Low
██ 0.450–0.499
██ 0.400–0.449
██ 0.350–0.399
██ under 0.350
██ not available
A HDI below 0.5 is considered to represent "low development". All 22 countries in that category are located in Africa. The highest-scoring Sub-Saharan countries, Gabon and South Africa, are ranked 119th and 121st, respectively. Nine countries departed from this category this year and joined the "medium development" group.
A HDI of 0.8 or more is considered to represent "high development". This includes all developed countries, such as those in North America, Western Europe, Oceania, and Eastern Asia, as well as some developing countries in Eastern Europe, Central and South America, Southeast Asia, the Caribbean, and the oil-rich Arabian Peninsula. Seven countries were promoted to this category this year, leaving the "medium development" group: Albania, Belarus, Brazil, Libya, Republic of Macedonia, Russia and Saudi Arabia.
High Income Countries
"High income countries" are defined by the World Bank as countries with a Gross National Income per capita of $11,116 or more. According to the United Nations definition some high income countries may also be developing countries. Thus, a high income country may be classified as either developed or developing.
When using GDP/cap as an indicator of "developed" status, one must take into account how some countries have achieved a (usually temporarily) high GDP/cap through natural resource exploitation (e.g., Nauru through phosphate extraction and Equatorial Guinea) without developing the diverse industrial and service-based economy necessary for "developed" status — similarly, the Bahamas, Barbados, Antigua and Barbuda, and Saint Kitts and Nevis depend overwhelmingly on the tourist industry.
Despite their high per capita GDP, the GCC countries in the Middle East are generally not considered developed countries because their economies depend overwhelmingly on oil production and export; in many cases (notably Saudi Arabia), per capita GDP is also skewed by an unequal distribution of wealth.
Developed Country
The term developed country, or advanced country, is used to categorize countries with developed economies in which the tertiary and quaternary sectors of industry dominate. Countries not fitting this definition may be referred to as developing countries.
This level of economic development usually translates into a high income per capita and a high Human Development Index (HDI). Countries with high gross domestic product (GDP) per capita often fit the above description of a developed economy. However, anomalies exist when determining "developed" status by the factor GDP per capita alone.
Developing Country
A developing country is a country which has an undeveloped or developing industrial base, and an inconsistent varying Human Development Index (HDI) score and per capita income, but is in a phase of economic development. Usually all countries which are neither a developed country nor a failed state are classified as developing countries, despite the above facts, this is not true for all countries as some developing countries are far more developed than some developed countries.
Countries with more advanced economies than other developing nations, but which have not yet fully demonstrated the signs of a developed country, are grouped under the term newly industrialized countries. Other developing countries which have maintained sustained economic growth over the years and exhibit good economic potential are termed as emerging markets. The Big Emerging Market (BEM) economies are Argentina, Brazil, China, Egypt, India, Indonesia, Mexico, Poland, Russia, South Africa, South Korea and Turkey. The application of the term developing country to any country which is not developed is inappropriate because a number of poor countries have experienced prolonged periods of economic decline. Such countries are classified as either least developed countries or failed states.
Development entails a modern infrastructure (both physical and institutional), and a move away from low value added sectors such as agriculture and natural resource extraction. Developed countries, in comparison, usually have economic systems based on continuous, self-sustaining economic growth in the tertiary and quaternary sectors and high standards of living.
High income Upper-middle income Lower-middle income Low income
REFERENCES
Cunningham and Cunningham. 2008. Principle of Environmental Science.
Fourth Edition. New York: Mc Graw Hill Companies, Inc.
Botkin and Keller. 2005. Environmental Science. Fifth Edition. United States: John Wiley and Sons, Inc.
Cunningham and Cunningham. 2004. Principle of Environmental Science. Second
Edition. New York : Mc Graw Hill Companies, Inc.
Daniel D. Chiras. 2006. Environmental Science. Seventh Edition. United States :
Jones and Bartlett Publisher, Inc.
Scott Brennan and Jay Withgott. 2005. Essential Environment. The Science Behind
The Stories. United States : Pearson Education, Inc.
V. Subramaniam. 2002. Environmental Science. New Delhi : Alpha Science
International Ltd.
Beychok, M.R. (2005). Fundamentals Of Stack Gas Dispersion, 4th Edition, author- published. ISBN 0-9644588-0-2. www.air-dispersion.com
Turner, D.B. (1994). Workbook of atmospheric dispersion estimates: an introduction to dispersion modeling, 2nd Edition, CRC Press. ISBN 1-56670-023-X. www.crcpress.com
http://en.wikipedia.org/wiki/Developing_country
http://en.wikipedia.org/wiki/Image:CountryIncome.PNG
http://hdrstats.undp.org/countries/country_fact_sheets/cty_fs_KHM.html
http://www.answers.com/topic/human-development-index
MAIZATUL AKMAL AHMAD KAMARUDIN
AIR POLLUTION
• Natural Sources of Air Pollution
NAME : MAIZATUL AKMAL AHMAD KAMARRUDIN
MATRIC NO : D20061026288
PROGRAM : SCIENCE (AT 16)
NO TEL : 017-6176164
GROUP : H
LECTURER’S : Ass. Prof Dr Nur Tjahjadi
1.0 INTRODUCTION
The definition of air pollution by Dewan Bahasa dan Pustaka dictionary is the air defilement by gas waste smoke physically or chemically. Normally, air pollution is the human introduction into the atmosphere of chemicals, particulate matter, or biological materials. These effects will cause harm or discomfort to humans besides to other living organisms and can damages the environment. It does also can cause deaths and respiratory disease that in fact dangerous for human. Air pollution is often identifying with major stationary sources, but the greatest source of emissions is mobile sources, mainly automobiles.
In additions, air pollution is the action of environmental contamination with man-made waste into the air. The air we breathe is composed of a mixture of gases: 78% nitrogen, 21% oxygen, and a small percentage of other gases like argon, carbon dioxide, and water vapour. The Earth's air also contains pollutants or harmful material we may also breathe. Some of these air pollutants may be odourless and colourless. Other air pollution may be so apparent that it surrounds us like smog, which is a cloud or haze of air pollution.
Gases such as carbon dioxide, which also can contribute to global warming that can cause greenhouse effect, have recently gained recognition as pollutants by climate scientists. Many times factories release greenhouse gases like carbon dioxide, chlorofluorocarbons (CFCs), methane, and nitrous oxide into the atmosphere. These greenhouse gases trap heat within the atmoshpere, thus raising the temperture of the Earth. There are also other harmful gases that released when fossil fuels are burned. These gases have significant negative health and environmental effects. The following gases that are known as the "Big Six" air pollutants are Carbon Dioxide, Carbon Monoxide, Sulfur Oxide, Nitrogen Oxide, Hydrocarbons, and Particulates.
Air pollution is the part of the daily existence of the many thousands of people who work, live and use the streets in many cities. The poor and socially marginalized in particular tend to suffer strangely from the effects of deteriorating air quality. Despite improvement in many Asian cities, air pollution is still relatively high compare to cities developed world. Particulate matter, nitrogen dioxide, and ozone are the key pollutants that still cause a significant challenge to improving urban air quality.
According to the Environmental Protection Agency (EPA), Americans release some 147 million metric tons of air pollution in each year. While, worldwide emissions of these pollutants are around 2 billion metric tons per year. The EPA estimates that, since 1990, when regulation of the most hazardous materials began, air toxics emissions have been reduced more than 1 million tons per year. This is almost ten times the reductions achieved in the previous 20 years. Since the 1970s, the levels of major pollutants monitored by the EPA have decrease in the
As the pictures below, air pollution is a global crisis. It is not an isolated occurance, but affects every person on Earth. We must become more conscientious and aware that we should take care the pollution so that people will live in the good conditions.
2.0 NATURAL SOURCES OF AIR POLLUTION
As the wealth of a city increases so do the key driving forces. These are mainly road transport, power and heat production, industry, and agriculture. In some countries such as
Once released into the atmosphere, air pollutants undergo chemical reactions resulting in a wide variation in pollutant concentrations with time and location and corresponding exposure of the population. Most conventional pollutants are produce primarily from burning fossil fuels, especially in coal-powered electric plants and in cars and trucks, as well as in processing natural gas and oil. Others especially sulphur and metals are by products of mining and manufacturing processes. Of the 188 air toxics listed in the Clean Air Act, about two-thirds are volatile organic compounds (VOCs), and most of the rest are metal compounds.
Pollutants can classify as two types that are primary or secondary. Primary pollution are substances directly emitted from a process, such as dust from a volcanic eruption, the carbon monoxide gas from a motor vehicle exhaust or sulphur dioxide released from factories. While secondary pollutant produces through reactions between primary pollutants and normal atmospheric compounds such as reaction from sunlight with ozone.
We can say that, the main primary pollutants produced by human activity such as :
I.
It’s a colourless, corrosive gas with a penetrating odour that irritates the eyes and air passages. Once in the atmosphere, it can be further oxidize to sulphur trioxide (SO3), which reacts with water vapour or dissolves in water droplets to form sulphuric acid (H2SO4), which is a major component of acid rain.
The most common sources of sulphur dioxide include fossil fuel combustion, smelting, manufacture of sulphuric acid, conversion of wood pulp to paper, burning of refuse and production of elemental sulphur. Coal burning is the single largest man-made source of sulphur dioxide accounting for about 50% of annual global emissions, with oil burning accounting for a further 25-30%. The most common natural source of sulphur dioxide is volcanoes.
In addition, the effects of sulphur dioxide for human can caused breathing problem, coughing or sore throat and, may cause permanent pulmonary damage. When mix with water and contacted by skin, frostbite may occur. When it makes contact with eyes, redness and pain will occur.
The most common natural source of sulphur dioxide is volcanoes.
II. Nitrogen Oxides (NOx)
Nitrogen oxides are highly reactive gases formed when combustion especially combustion at high temperatures initiates reactions between atmospheric nitrogen and oxygen. At ambient temperatures, the oxygen and nitrogen gases in air will not react with each other. In an internal combustion engine, combustion of a mixture of air and fuel will produces combustion temperatures high enough to drive endothermic reactions between atmospheric nitrogen and oxygen in the flame, yielding various oxides of nitrogen. In areas of high motor vehicle traffic, such as in large cities, the amount of nitrogen oxides emitted into the atmosphere can be quite significant.
The initial product, nitric oxide (NO), oxidizes further in the atmosphere. Once it is mixed with air, it’s quickly combines with oxygen, forming nitrogen dioxide (NO2). It is also present in tobacco smoke. It is a reddish brown, nonflammable, gas with a detectable smell. In significant concentrations it is highly toxic, causing serious lung damage with a delayed effect. Other health effects of exposure to nitrogen dioxide include shortness of breath and chest pains. Nitrogen dioxide is a strong oxidizing agent that reacts in the air to form corrosive nitric acid, as well as toxic organic nitrates. It also plays a major role in the atmospheric reactions that produce ground-level ozone or smog.
In addition, nitrogen oxides can combine with water to form nitric acid, which is also a major component of acid precipitation. Excess nitrogen in water is causing eutrophication of inland waters and coastal seas. It may also encourage the growth of weedy species that crowd out native plants. ( Text : ‘Principles of Environmental Science, 2008, by William P. Cunningham, pages 218 ).
This pictures above are present the sources of Nitrogen Oxide gases that can caused shortness of breath, chest pains and others.
III. Carbon Monoxide (CO)
Carbon monoxide is colourless, odourless, non-irritating but very poisonous gas. It is a product by incomplete combustion of fuel such as natural gas, coal, oil, charcoal or wood. Carbon monoxide forms in preference to the more usual carbon dioxide when there is a reduced availability of oxygen present during the combustion process.
Vehicular exhaust is a major source of carbon monoxide. Land-clearing fires and cooking fires also are major sources of carbon monoxide. About 90 percent of the CO in the air is consuming in photochemical reactions that produce ozone. ( Text : ‘Principles of Environmental Science, 2008, by William P. Cunningham, pages 219 ).
Carbon monoxide is poisonous when inhaled because it combines with haemoglobin, the oxygen-carrying substance in red blood cells. The haemoglobin then cannot take up oxygen from the air. Lack of oxygen causes cells and tissues to die.
Vehicular smoke, cooking fires, and land-clearing fires are major sources of carbon monoxide
IV. Particulate Material
Particulate matter is a complex mixture of organic and inorganic substances, present in the atmosphere as both liquids and solids. Particulate matters such as dust, ash, soot, lint, smoke, pollen, spores, algal cells, and many other suspended materials are the example of the coarse particles that can be regarded as those with a diameter greater than 2.5 micrometres (µm). Aerosols, combustion particles, extremely minute particles, or liquid droplets suspended in the air, are the example of fine particles that is less than 2.5 micrometer.
Particulates often are the most apparent from of air pollution. This is because, they reduce visibility and leave dirty deposits on windows, painted surfaces, and textiles. Breathable particles smaller than 2.5µm are among the most dangerous for humans health. This is because they can damage lung tissues. Asbestos fibbers and cigarette smokes and among the most dangerous respirable particles in urban and indoor air because they are carcinogenic.
Some examples of particulate matter which are pollens and algal cell that have diameter greater that 2.5 micrometres.
V. Volatile Organic Compound (VOCs)
. Volatile Organic Compounds or VOCs are organic chemicals that easily vaporize at room temperature. They are called organic because they contain the element carbon in their molecular structures. VOCs have no colour, smell, or taste. Plants, bogs, and terminates are the largest sources of VOCs, especially that can produce natural gas such as isoprene (C5H6), terpenes (C10H15), butane(C4H10), and methane (CH4). All of these gases are the types of hydrocarbon. These volatile hydrocarbons are generally oxides to CO and CO2 in the atmosphere.
Other dangerous synthetic organic chemicals, such as benzene, toluene, formaldehyde, vinly chloride, phenols, chloroform, and trichloroethylene are released by human activities. Principal sources are incompletely burned fuels from vehicles, power plants, chemical plants, and petroleum refineries. These chemicals play an important role in the formation of photochemical oxidants.
Photochemical oxidants are products of secondary atmospheric reactions driven by solar energy. One of the most important of these reactions involves formation of singlet (atomic) oxygen by splitting nitrogen dioxide (NO2). This atomic oxygen then reacts with another molecule to O2 to make ozone O3. Although ozone is important in the stratosphere, in ambient air it highly reactive and damages vegetation, animal tissues, and building materials. Ozone’s acrid, biting odor is a distinctive characteristic of photochemical smog.
Some examples of power plants.
VI. Lead
Lead is widespread neurotoxins that can damage the nervous system. By some estimate, 20% of all inner city children suffer some degree of development retardation from high environmental lead levels. Long-range transport of lead through the air is causing bioaccumulation in remote aquatic ecosystem, such as arctic lakes and seas.
Anthropogenic sources of six of the primary ‘criteria’ air pollutants in
INDOOR AIR POLLUTION
OUTDOOR AIR POLLUTANT
PRIMARY POLLUTANT SECONDARY POLLUTANT
3.0 CONCLUSION
Every day, the average person inhales about 20,000 liters of air. Every time we breathe, we risk inhaling dangerous chemicals that have found their way into the air. As we already know, air pollution includes all contaminants that can be found in the atmosphere. These dangerous substances can be either in the form of gases or particles. In addition, air pollution can be found both outdoor and indoor. Pollutants can be trapped inside buildings, causing indoor pollution that lasts for a long time.
The sources of air pollution are both come from natural and human-based. As one might expect, humans have been producing increasing amounts of pollution as time has progressed, and they now account for the majority of pollutants released into the air. This will cause serious consequences for the health of human beings and severely affects natural ecosystems.
Air pollution is able to travel easily because it is located in the atmosphere. As a result, air pollution is a global problem and has been the subject of global cooperation and conflict. Some areas now suffer more than others do from air pollution. Cities with large numbers of automobiles or those that use great quantities of coal often suffer most severely from problems of air pollution.
Air pollution has many disastrous effects that need to be curbed. In order to accomplish this, governments, scientists and environmentalists are using or testing a variety of methods aimed at reducing pollution. In the
4.0 BIBLIOGRAPHY
Dieter Schwela et al. (2006). Urban Air Pollution In Asian Cities – Status, Challenges And Managment.
William P. Cunningham and Mary Ann Cunningham. (2008). Principles Of Environmental Science.
http://library.thinkquest.org/26026/Environmental_Problems/air_pollution.html
http://www.ace.mmu.ac.uk/eae/air_quality/Older/Natural_Air_Pollution.html
http://www.doe.gov.my/en/content/sources-air-pollution
http://www.pages.drexel.edu/~cy34/#airpollution
http://en.wikipedia.org/wiki/Air_pollution
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