The contamination of air, water, or soil by substances that are harmful to living organisms. Pollution can occur naturally, for example through volcanic eruptions, or as the result of human activities, such as the spilling of oil or disposal of industrial waste. Light from cities and towns at night that interferes with astronomical observations is known as light pollution. It can also disturb natural rhythms of growth in plants and other organisms. Continuous noise that is loud enough to be annoying or physically harmful is known as noise pollution. Heat from hot water that is discharged from a factory into a river or lake, where it can kill or endanger aquatic life, is known as thermal pollution.
Water Pollution
Water Pollution, contamination of water by foreign matter such as micro-organisms, chemicals, industrial or other wastes, or sewage. Such matter deteriorates the quality of the water and renders it unfit for its intended uses.
Water is a major constituent of every organism and thus the most important resource to man. The pollution of water makes some rivers and lake unsafe to drink or use. Water shortage could cause devastating effects on human existance. Major water pollutants come from industries rather than domestic use. In the U.S.A water pollution has reached a higher level than any other part of the world infact not a single river in the States of America is safe to drink from!
Our life has now been simplified and as a result made it more leisure. Our improved way of living has introduce systems such as the municipal, industrial and agricultural systems. Though these systems are of advantage and therefore important to us for the continuity of healthy living they have side effects on us too.
Sewage, Infectious agents,Exotic organic chemicals such as pesticides, Inorganic minerals and chemical compounds, are all considered to be major water pollutants. Excess mineral salts from farm lands are washed away by rain water or rivers. These salts cause an artificial enrichment of salt levels in the water, this inturns provide a suitable environment for the growth of microoraganism particularly the blue algea resulting to what is know as eutrophication . These algeas flourish and cover the water surface, since they respire anaerobically they require oxygen. Their existance results to oxygen depletion in the water and a subsequent most of the aquatic plants and animals in such water die off. These dead organisms are then decomposed causing a further decrease in oxygen levels. The process of eutrophication can produce aesthetic problems such as bad tastes and odours and other chemical changes such as precipitation of calcium carbonate in hard waters. .
Sewage and other oxygen demanding wastes contribute to oxygen depletion as well.and unsightly green scums of algae, as well as dense growth of rooted plants, oxygen depletion in the deeper waters and bottom sediments of lakes, and other chemical changes such as precipitation of calcium carbonate in hard waters.
Another problem caused by water pollution, which is of growing concern in recent years, is acid rain, which has left many lakes in northern and eastern Europe and north-eastern North America totally devoid of life.
Oilspills though do not oftenly occur cause massive pollution the little while they do. Oil spills largely affect aquatic birds and since oil prevents oxygen from diffusing into the water, it also affects aquatic plants and animals.
All of the above are chemical pollutants, items such as glass and plastics bottles and bags thrown into water bodies are also considered as pollutants.
ACTION TAKEN!
Countries such as U.S.A and other developed worlds laws have been set to regulate the realise of industrial water into sewers and rivers. Proper control of water pollution has not been reached, however options are available in controlling industrial waste water. Control can take place at the point of generation within the plant; wastewater can be pretreated for discharge to municipal treatment systems; or wastewater can be treated completely at the plant and either reused or discharged directly into receiving waters.Under the current pollution law it is an offense to discharge water that has been used for any industrial purpose, into a sewer or directly into a river without the consent of the appropriate water authority. Wastes from commercial feeders are contained and disposed of on land; their main threat to natural waters, therefore, is via run-off and leaching. Control may involve settling basins for liquids, limited biological treatment in aerobic or anaerobic lagoons, and a variety of other methods. In practise this may reduce pollution but does not stop it!
Air Pollution
The presence in the atmospheric environment of natural and artificial substances that affect human health or well-being, or the well-being of any other specific organism. Pragmatically, air pollution also applies to situations where contaminants impact structures and artifacts or esthetic sensibilities (such as visibility or smell). Most artificial impurities are injected into the atmosphere at or near the Earth's surface. The lower atmosphere (troposphere) cleanses itself of some of these pollutants in a few hours or days as the larger particles settle to the surface and soluble gases and particles encounter precipitation or are removed through contact with surface objects. Unfortunately, removal of some pollutants (for example, sulfates and nitrates) by precipitation and dry deposition results in acid deposition, which may cause serious environmental damage. Also, mixing of the pollutants into the upper atmosphere may dilute the concentrations near the Earth's surface, but can cause long-term changes in the chemistry of the upper atmosphere, including the ozone layer.
Effects
The major concern with air pollution relates to its effects on humans. Since most people spend most of their time indoors, there has been increased interest in air-pollution concentrations in homes, workplaces, and shopping areas. Much of the early information on health effects came from occupational health studies completed prior to the implementation of general air-quality standards.
Air pollution principally injures the respiratory system, and health effects can be studied through three approaches, clinical, epidemiological, and toxicological. Clinical studies use human subjects in controlled laboratory conditions, epidemiological studies assess human subjects (health records) in real-world conditions, and toxicological studies are conducted on animals or simple cellular systems. Of course, epidemiological studies are the most closely related to actual conditions, but they are the most difficult to interpret because of the lack of control and the subsequent problems with statistical analysis. Another difficulty arises because of differences in response among different people. For example, elderly asthmatics are likely to be more strongly affected by sulfur dioxide than the teenage members of a hiking club. See also Epidemiology.
Damage to vegetation by air pollution is of many kinds. Sulfur dioxide may damage field crops such as alfalfa and trees such as pines, especially during the growing season (Fig. 1). Both hydrogen fluoride (HF) and nitrogen dioxide (NO2) in high concentrations have been shown to be harmful to citrus trees and ornamental plants, which are of economic, importance in central Florida. Ozone and ethylene are other contaminants that cause damage to certain kinds of vegetation.
Air pollution can affect the dynamics of the atmosphere through changes in longwave and shortwave radiation processes. Particles can absorb or reflect incoming short-wave solar radiation, keeping it from the Earth's surface during the day. Greenhouse gases can absorb long-wave radiation emitted by the Earth's surface and atmosphere.
Carbon dioxide, methane, fluorocarbons, nitrous oxides, ozone, and water vapor are important greenhouse gases. These represent a class of gases that selectively absorb long-wave radiation. This effect warms the temperature of the Earth's atmosphere and surface higher than would be found in the absence of an atmosphere (the greenhouse effect). Because the amount of greenhouse gases in the atmosphere is rising, there is a possibility that the temperature of the atmosphere will gradually rise, possibly resulting in a general warming of the global climate over a time period of several generations. See also Greenhouse effect.
Researchers are also concerned with pollution of the stratosphere (10–50 km or 6–30 mi above the Earth's surface) by aircraft and by broad surface sources. The stratosphere is important, because it contains the ozone layer, which absorbs part of the Sun's short-wave radiation and keeps it from reaching the surface. If the ozone layer is significantly depleted, an increase in skin cancer in humans is expected. Each 1% loss of ozone is estimated to increase the skin cancer rate 3–6%. See also Stratosphere.
Visibility is reduced as concentrations of aerosols or particles increase. The particles do not just affect visibility by themselves but also act as condensation nuclei for cloud or haze formation. In each of the three serious air-pollution episodes discussed above, smog (smoke and fog) were present with greatly reduced visibility.
Soil Pollution
DEFINITION:
Soil pollution is defined as the build-up in soils of persistent toxic compounds, chemicals, salts, radioactive materials, or disease causing agents, which have adverse effects on plant growth and animal health.
The wars that hit the earth are probably the immediate cause of soil pollution. Not talking in the sense of how many people died but in that it is through this period that many countries found the necessity to improve their living standards. After the world war two, many countries suffered from food shortage and this facilitated the intoruction of fertilizers and other agricultural chemicals. Although KNP [ Potassium, Nitrogen, Phosphorus] fertilisers has not led to soil pollution, the application of trace elements has.
Pesticides such as DDT [dichlorodiphenyltrichloroethane]a colourless chemical pesticide, which is a potent nerve poison in insects was first widely used to combat diseases such as yellow fever and malaria. It was later used to control and/ or eradicate disease carrying and crop eating insects. DDT was later on discovered to cause endagerement of species in the same food chain as the
controlled insects, particularly birds. DDT prevents the shelling of bird eggs and in humans causes health threats.
In yet another famous war of Vietnam in 1970's was introduced another Chemical substance which had a more adverse effect than that of DDT, Dioxin a chemical impurity resulting from the production of the auxin 2,4,5T. Dioxin is a toxic chemical and was used as a defoliant by the American army. Dioxin was a major constituent of argent orange which was applied on trees which would then fall off reaviling enemy camps. After the war it was found that the chemical cause congenital deformalities and mental effects to the children born to the American soldiers and in the area over which it was applied. In minute amount dioxin has the ability to cause cancer,chloracne, miscarriage, and fetal abnormalities.
Glass industries have also been responsible of soil pollution. The glass industries uses Arsenic to eliminate a green colour caused by impurities of iron compounds. because arsenic is a violent poison, yet it is widely used and therefore is a frequent contaminant. James Marsh, supplies a simple method for detecting traces of arsenic so minute that they would escape discovery in ordinary analysis. Arsenic is sometimes added to lead to harden it and is also used in the manufacture of such military poison gases as lewisite and adamsite. Until the introduction of penicillin, arsenic was of great importance in the treatment of syphilis. In other medicinal uses, it has been displaced by sulpha drugs or antibiotics. Lead arsenate, calcium arsenate, and Paris green are used extensively as insecticides. Pollution of land by heavy metals is a result of the mining of ores to extract metals such as tin, silver, nickel, lead, iron, chromium and copper. Most of these metals occur naturally as ions in the soils. Though some metals, such as copper, iron, and zinc , are necessary for plant growth. It is the high concentration if these ions that renders the land unsuitable for plant growth. Soil pollution is widely linked to chemical substances but irrigation. is somehow linked to it as well.
CONTROL
Soil pollution has been slightly controlled by putting regulations on the use of DDT and introduction of alternatives to it. However the task of eliminating completely soil pollution is not easy, third some third world countries still utilize pollutants such as DDT as pesticides. Mining cannot be stopped because we are in constant need for mineral ores for different applications
Noise pollution
The undesireable sound heard which irritates the human beings is sound pollution.
