water pollution

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  • 1. By: Mohd AhmedAli HaiderAdam BarbourAdibSaif Rashid

2. Water pollution is the contamination of waterbodies (e.g. lakes, rivers, oceans andgroundwater). Water pollution occurs whenpollutants are discharged directly or indirectlyinto water bodies without adequate treatment toremove harmful compounds.Water pollution affects plants and organismsliving in these bodies of water; and, in almost allcases the effect is damaging not only toindividual species and populations, but also tothe natural biological communities. 3. Toxic Substance -- A toxic substance is achemical pollutant that is not a naturally occurringsubstance in aquatic ecosystems. The greatestcontributors to toxic pollution are herbicides,pesticides and industrial compoundsThermal Pollution -- Thermal pollution canoccur when water is used as a coolant near apower or industrial plant and then is returned tothe aquatic environment at a higher temperaturethan it was originally. Thermal pollution can leadto a decrease in the dissolved oxygen level inthe water while also increasing the biologicaldemand of aquatic organisms for oxygen. 4. Organic Substance -- Organic pollution occurs when anexcess of organic matter, such as manure or sewage,enters the water. When organic matter increases in apond, the number of decomposers will increase. Thesedecomposers grow rapidly and use a great deal of oxygenduring their growth. This leads to a depletion of oxygen asthe decomposition process occurs. A lack of oxygen cankill aquatic organisms. As the aquatic organisms die, theyare broken down by decomposers which leads to furtherdepletion of the oxygen levels. A type of organic pollutioncan occur when inorganic pollutants such as nitrogen andphosphates accumulate in aquatic ecosystems. High levelsof these nutrients cause an overgrowth of plants andalgae. As the plants and algae die, they become organicmaterial in the water. The enormous decay of this plantmatter, in turn, lowers the oxygen level. The process ofrapid plant growth followed by increased activity bydecomposers and a depletion of the oxygen level is calledeutrophication. 5. Ecological Pollution -- Ecological pollution takesplace when chemical pollution, organic pollution orthermal pollution are caused by nature rather than byhuman activity. An example of ecological pollutionwould be an increased rate of siltation of a waterwayafter a landslide which would increase the amount ofsediments in runoff water. Another example would bewhen a large animal, such as a deer, drowns in a floodand a large amount of organic material is added to thewater as a result. Major geological events such as avolcano eruption might also be sources of ecologicalpollution. 6. Point sources-- of pollution occur whenharmful substances are emitted directlyinto a body of water. The Exxon Valdez oilspill best illustrates a point source waterpollution. 7. Nonpoint sources-- deliver pollutantsindirectly through environmental changes. Anexample of this type of water pollution is whenfertilizer from a field is carried into a stream byrain, in the form of run-off 8. Farming:Farms often use large amounts of herbicides andpesticides, both of which are toxic pollutants.These substances are particularly dangerous tolife in rivers, streams and lakes, where toxicsubstances can build up over a period of time.Farms also frequently use large amounts ofchemical fertilizers that are washed into thewaterways and damage the water supply and thelife within it. Fertilizers can increase the amountsof nitrates and phosphates in the water, whichcan lead to the process of eutrophication. 9. Allowing livestock to graze near water sources oftenresults in organic waste products being washed intothe waterways. This sudden introduction of organicmaterial increases the amount of nitrogen in thewater, and can also lead to eutrophication.Four hundred million tons of soil are carried by theMississippi River to the Gulf of Mexico each year. Agreat deal of this siltation is due to runoff from theexposed soil of agricultural fields. Excessiveamounts of sediment in waterways can blocksunlight, preventing aquatic plants fromphotosynthesizing, and can suffocate fish byclogging their gills. 10. Business:Clearing of land can lead to erosion of soil into theriver.Waste and sewage generated by industry can getinto the water supply, introducing large organicpollutants into the ecosystem.Many industrial and power plants use rivers,streams and lakes to dispose of waste heat. Theresulting hot water can cause thermal pollution.Thermal pollution can have a disastrous effect onlife in an aquatic ecosystem as temperatureincreases decrease the amount of oxygen in thewater, thereby reducing the number of animals thatcan survive there. 11. Water can become contaminated with toxic orradioactive materials from industry, mine sitesand abandoned hazardous waste sites.Acid precipitation is caused when the burning offossil fuels emits sulfur dioxide into theatmosphere. The sulfur dioxide reacts with thewater in the atmosphere, creating rainfall whichcontains sulfuric acid. As acid precipitation fallsinto lakes, streams and ponds it can lower theoverall pH of the waterway, killing vital plant life,thereby affecting the whole food chain. It canalso leach heavy metals from the soil into thewater, killing fish and other aquatic organisms.Because of this, air pollution is potentially one ofthe most threatening forms of pollution to aquaticecosystems. 12. How do we know when water ispolluted?Some forms of water pollution are very obvious: everyone has seen TVnews footage of oil slicks filmed from helicopters flying overhead. Waterpollution is usually less obvious and much harder to detect than this. Buthow can we measure water pollution when we cannot see it? How do weeven know its there?There are two main ways of measuring the quality of water. One is totake samples of the water and measure the concentrations of differentchemicals that it contains. If the chemicals are dangerous or theconcentrations are too great, we can regard the water as polluted.Measurements like this are known as chemical indicators of waterquality. Another way to measure water quality involves examining thefish, insects, and other invertebrates that the water will support. If manydifferent types of creatures can live in a river, the quality is likely to bevery good; if the river supports no fish life at all, the quality is obviouslymuch poorer. Measurements like this are called biological indicators of 13. People throw their garbage into lakes and rivers.When this garbage decays, oxygen which is neededby fishes and aquatic plants will be used up. As aresult ,these fishes and aquatic plants will die soon. 14. Factories throw their chemical wastes into thebodies of water. These harmful chemicals such aslead, mercury, and arsenic acids pollute the waterof the rivers. Fish, mussels (tahong) , and otheraquatic animals growing in it could eat thesechemicals. The people who eat these aquaticanimals could get poisoned. 15. Washing clothes and dishes in the rivers andlakes is also not a good practice. Thedetergents used by the people for washingcould poison the fish and the other aquaticanimals and plants living in them. 16. Fertilizers sprayed by people on their plants couldalso pollute the bodies of water. When it rains , thesechemicals will find their way into the rivers and seas.With the abundance of nutrients and organic matterin the water, many algae and other plants will thenreduce the oxygen content of the river and the otherbodies of water. The result is the death of fish andother aquatic animals. 17. The crude oil that spills from boats and shipspollutes the seas and oceans, too. When they coverthe surface of water , the oxygen from the air cannotdissolve in it . Aquatic animals that rely on oxygen tolive will not be able to breathe. They will soon die. 18. When people continuously do these practices, manymicroscopic organisms called dinoflagellates willgrow in bodies of water. These organism producepoisonous substances which give a reddish color tothe water. This is known as the Red Tide. WhenRed tide is present , many of our fishes , mussels ,and other shells foods are affected . It can evencause their death. 19. How can we stop waterpollution? easy way to solve water pollution; if thereThere is nowere, it wouldnt be so much of a problem. Broadlyspeaking, there are three different things that can helpto tackle the problemeducation, laws, andeconomicsand they work together as a team.EducationMaking people aware of the problem is the first step tosolving it. In the early 1990s, when surfers in Britain grewtired of catching illnesses from water polluted with sewage,they formed a group called Surfers Against Sewage to forcegovernments and water companies to clean up their act.People whove grown tired of walking the worlds pollutedbeaches often band together to organize community beach-cleaning sessions. Anglers who no longer catch so many fishhave campaigned for tougher penalties against factories thatpour pollution into our rivers. Greater public awareness can 20. LawsOne of the biggest problems with water pollution is its transboundarynature. Many rivers cross countries, while seas span whole continents.Pollution discharged by factories in one country with poor environmentalstandards can cause problems in neighboring nations, even when theyhave tougher laws and higher standards. Environmental laws can makeit tougher for people to pollute, but to be really effective they have tooperate across national and international borders. This is why we haveinternational laws governing the oceans, such as the 1982 UNConvention on the Law of the Sea (signed by over 120 nations), the1972 London Dumping Convention, the 1978 MARPOL InternationalConvention for the Prevention of Pollution from Ships, and the 1998OSPAR Convention for the Protection of the Marine Environment of theNorth E