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مُساهمةموضوع: pooooooooooooooooooooolution   الجمعة يناير 21, 2011 8:06 am

left]Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms.[1] Pollution can take the form of chemical substances or energy, such as noise, heat, or light. Pollutants, the elements of pollution, can be foreign substances or energies, or naturally occurring; when naturally occurring, they are considered contaminants when they exceed natural levels. Pollution is often classed as point source or nonpoint source pollution. The Blacksmith Institute issues annually a list of the world's worst polluted places. In the 2007 issues the ten top nominees are located in Azerbaijan, China, India, Peru, Russia, Ukraine, and Zambia.[2]

Sources and causes
Air pollution comes from both natural and man made sources. Though globally man made pollutants from combustion, construction, mining, agriculture and warfare are increasingly significant in the air pollution equation.[11]
Motor vehicle emissions are one of the leading causes of air pollution.[12][13][14] China, United States, Russia, Mexico, and Japan are the world leaders in air pollution emissions. Principal stationary pollution sources include chemical plants, coal-fired power plants, oil refineries,[15] petrochemical plants, nuclear waste disposal activity, incinerators, large livestock farms (dairy cows, pigs, poultry, etc.), PVC factories, metals production factories, plastics factories, and other heavy industry. Agricultural air pollution comes from contemporary practices which include clear felling and burning of natural vegetation as well as spraying of pesticides and herbicides[16]
About 400 million metric tons of hazardous wastes are generated each year.[17] The United States alone produces about 250 million metric tons.[18] Americans constitute less than 5% of the world's population, but produce roughly 25% of the world’s CO2,[19] and generate approximately 30% of world’s waste.[20][21] In 2007, China has overtaken the United States as the world's biggest producer of CO2.[22]
In February 2007, a report by the Intergovernmental Panel on Climate Change (IPCC), representing the work of 2,500 scientists from more than 130 countries, said that humans have been the primary cause of global warming since 1950. Humans have ways to cut greenhouse gas emissions and avoid the consequences of global warming, a major climate report concluded. But in order to change the climate, the transition from fossil fuels like coal and oil needs to occur within decades, according to the final report this year from the UN's Intergovernmental Panel on Climate Change (IPCC).[23]
Some of the more common soil contaminants are chlorinated hydrocarbons (CFH), heavy metals (such as chromium, cadmium--found in rechargeable batteries, and lead--found in lead paint, aviation fuel and still in some countries, gasoline), MTBE, zinc, arsenic and benzene. In 2001 a series of press reports culminating in a book called Fateful Harvest unveiled a widespread practice of recycling industrial byproducts into fertilizer, resulting in the contamination of the soil with various metals. Ordinary municipal landfills are the source of many chemical substances entering the soil environment (and often groundwater), emanating from the wide variety of refuse accepted, especially substances illegally discarded there, or from pre-1970 landfills that may have been subject to little control in the U.S. or EU. There have also been some unusual releases of polychlorinated dibenzodioxins, commonly called dioxins for simplicity, such as TCDD.[24]
Pollution can also be the consequence of a natural disaster. For example, hurricanes often involve water contamination from sewage, and petrochemical spills from ruptured boats or automobiles. Larger scale and environmental damage is not uncommon when coastal oil rigs or refineries are involved. Some sources of pollution, such as nuclear power plants or oil tankers, can produce widespread and potentially hazardous releases when accidents occur.
In the case of noise pollution the dominant source class is the motor vehicle, producing about ninety percent of all unwanted noise worldwide.
Tipes of pollution
Air pollution is indication of disturbances to the composition of compounds in the atmosphere, as it may be summarized as shown:
• excess emission of gases/vapors into atmosphere
• saturation of chemical compounds/particulates
• rate of dissipation < (smaller than) rate of absorption through various cycles (i.e. carbon and nitrogen cycle)
• emergence of new chemical reactions of reactive and non-biodegradable compounds.
Global warming, acid rain, smog, ozone depletion are some effects of air pollution.
In relation to this, we may observe the cycle which involves in our daily lives: carbon and nitrogen cycle.These 2 cycles are the most important of all, regulating the composition of carbon and nitrogen of Earth. Imagine the reverse is to happen....

See the left bar to discover exciting facts about the atmosphere and air pollution.
Sources and Methods
________________________________________
We can classify major sources that lead to air pollution to the following categories:
• motor vehicle exhaust
• heat and power generation facilities
• industrial processes
• auto manufacturing
• fertilizers plants
• building demolition
• solid waste disposal
• solvent evaporation
• volcanic eruption
• fuel production
• roadway construction
• electrical components manufacturing
• extraction of metals
• forest fires
• agriculture
________________________________________
Water pollution is contamination of water by foreign matter that deteriorates the quality of the water. Water pollution covers pollutions in liquid forms like ocean pollution and river pollution. As the term applies, liquid pollution occurs in the oceans, lakes, streams, rivers, underground water and bays, in short liquid-containing areas. It involves the release of toxic substances, pathogenic germs, substances that require much oxygen to decompose, easy-soluble substances, radioactivity, etc. that become deposited upon the bottom and their accumulations will interfere with the condition of aquatic ecosystems. For example, the eutrophication: lack of oxygen in a water body caused by excessive algae growths because of enrichment ofpollutants.
Water Cycle and Pollution
________________________________________
Water cycle is, simply saying, the circulation of water in earth. In fact, the water in the earth's biosphere is used and reused again and again. This is called water cycle or continuous movement of water between the earth and the atmosphere. It involves the following mechanisms:
• Evaporation: changing of water from liquid to gas
• Transpiration: Release of water vapor from plant leaves
• Condensation: changing of vapor to liquid (cooled down)
• Precipitation: Water that returns to the earth (water droplets in clouds become large enough and there comes the rain).
What's the relation of water cycle and pollution?
According to the water cycle, naturally, water around us will be absorbed to the land (soil) and rivers will stream from the upstream to the downstream and released to the sea. In normal situation organic pollutants are biodegraded by microbes and converted to a form that brings benefits to the aquatic life. And for the inorganic pollutants, in the same situation, don't bring to much hazards because they are widely dispersed and have almost no effect to the environment which they are released to.
In a small scale, both inorganic and organic pollutants safely decompose throughout the stream, their concentration decrease in the sea, and they don't harm the sea ecosystem and its distribution. But in an excessive scale, communities in beach and estuary will be affected by the pollutants, and can heavily harm them.
Sources and Methods

We can classify major sources that lead to water pollution to the following categories:
• petroleum products
• synthetic agricultural chemicals
• heavy metals
• hazardous wastes
• excess organic matter
• sediment
• infectious organisms
• air pollution
• thermal pollution
• soil pollution


Revered to as soil pollution, land pollution involves the following mechanism:
• Deposition of solid waste
• Accumulation of non-biodegradable materials
• Toxification of chemicals into poisons
• Alteration of soil chemical composition (imbalance of chemical equilibrium to soil medium)
By as much, land pollution of this has amass globally, everyday threatening the very foundation and mechanical support of every matter on earth. Statistically, it has been shown that:
• loss of 6 million hectares of land per year
• loss of 24 billion tons of topsoil per year
• loss of minimum 15 million acres prime agricultural land to overuse and mismanagement
• desertification of land results in the lost of 16 million per square miles of world's land surface
The causes for such devastation are generally due to 2 (two) forms of malpractices:
• Unhealthy soil management methods;
o improper tillage of soil in which excessive tillage result in the deterioration of soil structure
o non-maintenance of a proper supply of organic matter in the soil from the imbalance composition of the reserves of organic matter especially nitrogen, phosphorus and sulfur unplenished supply after cultivation of vegetation, living the soil prone to soil infertility, unable to stabilize the soil physicality which ultimately let to desertification
o irregular maintenance of a proper nutrient supply of trace elements gives rise to theuse of excessive synthetic fertilizers, which are non biodegradable and accumulate in the soil system which eventually destroys useful organisms such as bacteria, fungi and other organisms
o improper maintenance of the correct soil acidity which ultimately disrupt theadaptation of various crops and native vegetation of different soils as the solubility of minerals present will be affected. In a more acidic soil, minerals tend to be more soluble and washed away during rainfall while alkaline soil, minerals are more insoluble which form complex minerals unable to be absorbed into the flora system physiological usage.
• Improper irrigation practices;
o poorly drained soil result in salt deposits leading to high soil salinity that inhibit plant growth and may lead to crop failure
o unirrigated land giving rise to stagnation of agriculture waste products whichaccumulates and increases land toxicity and also decreasing
o irregular irrigation leads to decreasing moisturization of land for soil medium andreplenishments of solvents for minerals
Sources and Methods
________________________________________
We can classify major sources that lead to land pollution to the following categories:
• agriculture
• mining and quarrying
• sewage sludge
• dredged spoils
• household
• demolitions and constructions
• industrial
The most important solutions for a clean environment:
As stormwater flows over driveways,
lawns, and sidewalks, it picks
up debris, chemicals, dirt,
and other pollutants. Stormwater
can flow into a storm sewer
system or directly to a lake,
stream, river, wetland, or coastal
water. Anything that enters a
storm sewer system is discharged
untreated into the waterbodies
we use for swimming, fishing, and
providing drinking water. Polluted
runoff is the nation’s greatest threat to
clean water.
By practicing healthy household habits, homeowners can keep common
pollutants like pesticides, pet waste, grass clippings, and automotive fluids off
the ground and out of stormwater. Adopt these healthy household habits and
help protect lakes, streams, rivers, wetlands, and coastal waters. Remember
to share the habits with your neighbors!
Healthy Household Habits for Clean Water
Vehicle and Garage
• Use a commercial car wash or wash your car on a lawn or other unpaved surface to minimize
the amount of dirty, soapy water flowing into the storm drain and eventually into your local
waterbody.
• Check your car, boat, motorcycle, and other machinery
and equipment for leaks and spills. Make repairs as soon as
possible. Clean up spilled fluids with an absorbent material
like kitty litter or sand, and don’t rinse the spills into a
nearby storm drain. Remember to properly dispose of the
absorbent material.
• Recycle used oil and other automotive fluids at
participating service stations. Don’t dump these
chemicals down the storm drain or dispose of them in
your trash.
Lawn and Garden
• Use pesticides and fertilizers sparingly. When use is
necessary, use these chemicals in the recommended
amounts. Avoid application if the forecast calls for rain;
otherwise, chemicals will be washed into your local
stream.
• Select native plants and grasses that are drought- and pestresistant. Native plants require less water, fertilizer, and pesticides.
• Sweep up yard debris, rather than hosing down areas. Compost or recycle yard
waste when possible.
• Don’t overwater your lawn. Water during the cool times of the day, and don’t let water run off
into the storm drain.
• Cover piles of dirt and mulch being used in landscaping projects to prevent these pollutants
from blowing or washing off your yard and into local waterbodies. Vegetate bare spots in your
yard to prevent soil erosion.
Home Repair and Improvement
• Before beginning an outdoor project, locate the nearest storm drains
and protect them from debris and other materials.
• Sweep up and properly dispose of construction debris such
as concrete and mortar.
• Use hazardous substances like paints, solvents, and
cleaners in the smallest amounts possible, and
follow the directions on the label. Clean up spills
immediately, and dispose of the waste safely. Store
substances properly to avoid leaks and spills.
• Purchase and use nontoxic, biodegradable, recycled,
and recyclable products whenever possible.
• Clean paint brushes in a sink, not outdoors. Filter
and reuse paint thinner when using oil-based paints.
Properly dispose of excess paints through a household
hazardous waste collection program, or donate unused
paint to local organizations.
• Reduce the amount of paved area and increase the amount of
vegetated area in your yard. Use native plants in your landscaping
to reduce the need for watering during dry periods. Consider directing
downspouts away from paved surfaces onto lawns and other measures to increase
infiltration and reduce polluted runoff
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