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TOPIC 1 – NON METALS AND THEIR COMPOUNDS
TOPIC 5 – QUALITATIVE ANALYSIS
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Pollution can be defined as the introduction by human (or animal) activities, directly or indirectly, of substances or energy into the environment resulting in harmful effects which may endanger human health and harm living resources and ecosystems.
Concept of Pollution
The Concept of Pollution
Pollution can also be defined as the introduction of contaminants or pollutants into the natural environment. The environment comprises of living (biotic) and non-living (abiotic) things such as plants, animals, air, land and water.
Contaminants or pollutants are harmful substances introduced into the environment that disturb the balance of nature. Pollution can be in the form of chemical substances or energy such as noise, heat or light.
Human activities play a major role in the pollution of the environment. Humans engage in a myriad of activities such as agriculture, manufacturing, transport, waste disposal, mining etc. All of these activities contribute to environmental pollution in one way or another.
There are three main types of pollution:
Terrestrial (land) pollution
Aquatic (water) pollution
Aerial (air) pollution
Terrestrial Pollution
The Concept of Terrestrial Pollution
Terrestrial pollution is the degradation or destruction of the earth’s surface and soil, directly or indirectly, as a result of human activities. The human activities refer to any activities performed by man that lessens the quality and or productivity of the land as an ideal resource for agriculture, forestation, construction, etc.
Human Activities which Cause Terrestrial Pollution
The human activities responsible for this kind of pollution include poor agricultural practices, mining, waste dumping and urban waste disposal. Below are some causes of terrestrial pollution.
Agricultural activities
Because of the ever-increasing human population, demand for food has increased rapidly. Farmers often use fertilizers to increase crop production and pesticides to get rid of pests, fungi and bacteria that destroy the crops or harm animals. The overuse of such agrochemicals results in the contamination and poisoning of the soil. Other causes of soil pollution from agricultural activities include:
poor methods of irrigation which causes the leaching of cations down the soil surface;
manure heaped on land, which may leach down the soil; and oil spillages that seep into the soil.
Mining activities
During mineral extraction, several land spaces are created beneath the soil surface. The underground holes dug during mining causes the land to sag or subside (caving in). This is nothing but the nature‟s way of filling the spaces left out after mining or extraction activities. This destroys the land and makes it unfit for use.
Mining involves the use of toxic chemicals used for mineral separation. When these chemicals drain into the soil, it gets polluted.
Rain water often leaches harmful substances from the exposed mining waste into the ground. These harmful substances are like heavy metals (e.g. arsenic) and sulphuric acid or chemicals used in processing the ores (e.g. cyanide. These chemicals are another cause of soil contamination.
Deforestation and soil erosion
Deforestation refers to indiscriminate cutting of trees in search of land for agriculture, settlement, mining, industrialization etc. Trees have got a number of advantages which include attracting rainfall, checking soil erosion and breaking strong winds. The act of cutting down trees carelessly leaves the land bare and hence exposes it to agents of erosion.
Soil erosion causes land pollution. The eroded soil loses its nutrients and organic matter, as well as its ability to hold water. As such, soil erosion can render a fertile land as no longer suited for agriculture, or even turn originally fertile lands into barren deserts.
Other than causing soil erosion, deforestation has also been linked to floods which can, in turn, be seen as another cause of land and water pollution.
Sewage disposal
Sewage refers to a waste, in solution or suspension, carried off in sewers or drains with intention of removing it from the community.
In areas where there are no water bodies into which to dump urban sewage directly, it is dumped into sewage pools that are usually dug far away from residential areas to avoid bad smell emitted by the deposited sewage.
The toxins and poisonous chemicals in the sewage gradually seep down into the ground, thus polluting the land and killing beneficial soil microorganisms.
Garbage disposal
Tonnes of garbage are produced each year, especially in urban and industrial areas. Garbage is collected and moved to the dumping sites allocated for that purpose.
The garbage in dumping sites comprises of biodegradable and non-biodegradable wastes. The biodegradable wastes are those that can be broken down easily by the action of microorganisms,e.g.
bacteria and fungi. The degradable waste matter may include materials such as rotten foods, kitchen wastes etc.
The non-biodegradable wastes are those that cannot be decomposed by microorganisms and thus remain on the ground for a long time. The non-biodegradable wastes are such as plastic, polythene bags, metal, some clothing and glass.
One of the common causes of land pollution in dumping sites is the contamination of the soil with toxic and even hazardous substances. Needless to say, the ability of this soil to support life is significantly affected.
Transfer of toxic wastes
Industries in developed countries produce much toxic wastes, including the deadly, reactive nuclear wastes. However, these countries have very strict laws which prohibit the dumping of such toxic wastes in their countries. The easiest and cheapest alternative is to dump them in the developing third-world countries. This is because of the greedy and selfish leaders in poor countries are easily that agree to sign contracts to allow the disposal of such dangerous wastes on their lands for their own economic gains.
Hazards Caused by Terrestrial Pollution
The extent of terrestrial pollution is often overlooked because its effects are not well evident to most people. However, land pollution has got a number of negative effects to soil, soil organisms, man, plants and animals. The following are some effects of terrestrial pollution:
- Wastes dumped carelessly can endanger the health of man as well as other organisms. Broken glass, metal and other sharp objects may pierce one’s skin and introduce disease germs into the body. Empty cans, glass and plastic containers are potential breeding grounds for mosquitoes which spread malaria and other diseases. Rotten organic matter may harbour many disease germs and they also produce noxious smell when they rot. The rotten wastes also attract flies which transmit a number of enteric diseases like dysentery, cholera, diarrhoea, etc.
- Land pollution causes chemical contamination to the ecosystem. This occurs when the chemicals in the waste matter poison the soil. Then plants growing on the poisoned soil, animals that eat these plants and even humans are all affected by these chemicals. This process is called biomagnifications and is a serious threat to the ecology. It can lead to the loss of some types of plants and animal life as well as create long-term health problems such as cancer and other deformities in humans. Radiation from nuclear wastes causes healthy problems such as cancers and other deformities.
- Piles of waste in urban areas keep growing due to increase in waste. When this waste is burned it produces a lot of smoke that leads to air pollution.
- Soil erosion (as a form of land pollution) leads to loss of land for agriculture, settlement, forest cover, fodder patches for grazing, etc.
- Land pollution leads to loss of ecosystem and hence directly or indirectly cause change in climatic patterns.
- Deforestation causes imbalance in the rain cycle. A disturbed rain cycle affects a lot of factors such as reduction in the green cover. Plants help absorb excess carbon dioxide from the air and release oxygen to the atmosphere. This process helps to balance the atmosphere. Without vegetation cover, excessive accumulation of carbon dioxide in the atmosphere causes concerns like global warming, the greenhouse effect, irregular rainfall, and floods are among other imbalances.
- Land pollution damages terrestrial life, especially plants. This greatly affects wildlife and other animal species which are forced to move further away and adapt to new regions or die trying to adjust.
- Heaps of different wastes from mining activities make the environment unsightly and ugly.
- Terrestrial pollution is a big problem in urban areas where waste production outweighs waste disposal. In such areas you find poor and blocked sewage system, effluent from domestic toilets flowing on the streets and roads, and dirty water carelessly poured on the ground. This makes life in urban areas uncomfortable and a mere nuisance.