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5 Water Pollution: Classification and Effects
Look at the cartoons and say what problems are illustrated in them.
Give your comments on each of them.
If the human body has about two-thirds water, our planet has about 70 % of it, which establishes the fact that water constitutes a major portion in both body masses. And that is what is alarming. If 70 % of the earth is surface is made up of water, then humankind should have been very wary of anything that would pollute this major portion of the planet. Water pollution is now a global problem.
Water pollution may be defined as the addition of any substance (pollutant) to water resource which may change the physical and chemical characteristics in any way which may interfere with its use for legitimate purposes.
The water pollution may be caused by the wastewater discharges either from point source or non-point sources. Point sources include effluent outfalls from industries, waste treatment plants etc., that discharge effluents of varying quality directly into the water resources. Non-point sources include contaminants that enter the water resources such as human waste washed off from open defecated area via pesticide runoff from farm fields as well as runoff of automotive fluids and other chemicals from roads, parking lots, and other surfaces.
There are many types of water pollutants but these can be segregated into four classifications: natural, agricultural, municipal and industrial pollutants. Natural water pollutants could include all the natural phenomena that happen from time to time such as volcanic eruptions, earthquakes that cause major upheavals in the ocean floor and storms that cause flashfloods. Even global warming could be qualified as a cause of water pollution.
Agricultural pollution consists mainly of poultry and other agricultural animal wastes that are carelessly thrown off to bodies of water near farms. It could also be the fertilizers or pesticides that are used to make better crops, which erode into lakes, rivers or streams. Municipal wastes are those that come from residential areas. This is the liquid waste that households throw into bodies of water. Industrial pollution consists of all the wastes that major industrial firms chuck into the waters. This last classification is the most severe and most rampant among the three - and it is also the one that has caused the most damage. Industrial waste could include contaminants that are hard to take off from the waters once they spread - petroleum from oil spills or nuclear wastes.
The pollutants can be broadly classified into organic, inorganic and radioactive substance. Organic pollutants are oxygen depleting wastes which include the following domestic and industrial bio-degradable organic wastes;
Inorganic pollutants comprise of mineral acids, inorganic salts, finely divided into metals or metal compounds, trace elements, heavy metals, sulfates, nitrates, organo metallic compounds and complexes of metals with organics include toxic chromium, lead, mercury and chloride.
The radioactive water pollutants may originate from mining and processing of ores, e.g., uranium tailings, increasing use of radio-active isotopes in research, agricultural and medical applications, nuclear power plants and nuclear reactors, testing and use of nuclear weaponry. Radioactive pollutants are known as carcinogenic.
The toxic substances render the water unfit for the downstream use. Contamination of drinking water resulting in the transmission of water-borne diseases such as cholera, typhoid, diarrhea, dysentery, polio and infectious hepatitis in humans. Nitrates restrict the amount of oxygen reaching the brain causing blue-baby syndrome (mathemaglobanemia) in infants. Nitrogen also cause digestive tract cancer and affect lungs. Most of synthetic organic chemicals are potentially toxic to plants, animals and humans and known as carcinogen. Oil spills can cause skin irritations and rashes.
Water pollution effects the depletion of dissolved oxygen (DO) in surface water bodies, thus affecting the fish and other aquatic life. Invasive species can compete native species and reduce biodiversity. Invasive plants can contribute debris and bio molecules (allelopathy) that can alter soil and chemical compositions of an environment, often reducing native species competitiveness. Pollution disrupts the natural food chain. Toxic pollutants such as lead, chromium, mercury, cadmium etc., are consumed by tiny animals. Later, these animals are consumed by fish and the food chain continues to be disrupted at all higher levels. Eventually, humans are affected by this process as well. Organic nutrients such as nitrates and phosphates may stimulate the growth of algae and other aquatic weeds in the receiving water body. This unwildly plant-growth results in the degradation of the water quality, intended for drinking and other uses by causing odor, taste etc. The increased water temperature due to discharge of effluent from thermal power stations causes the heat stress or death of sensitive species; and enhanced microorganism respiration.
The bodies of water in the world are in catastrophic danger, what with all the industries in the world today, plus our individual wastes all put together. No wonder mankind now drinks from bottles instead of just scooping water from running streams. The effects of water pollution to humanity are staggering. But we should also consider all the other life forms that suffer - the fishes and other animals such as birds, and plants.
Exercise 1. Match the synonyms from A to В
Exercise 2. Match the antonyms from A to В
Exercise 3. Complete the sentences translating the Russian words
Exercise 4. Match the terms with their definitions
Exercise 5. Put the sentences into logical order
Exercise 6. Say whether the sentences are true or false