Saturday, November 30, 2013

Causes Of Water Pollution


Water pollution is contamination of water bodies such as rivers, oceans, lakes, and groundwater caused by human activities.

1. Urbanisation
As more and more people move into cities and towns, a number of factors cause pollution:
• the physical disturbance of land due to construction of houses, industries, roads, etc.;
• chemical pollution from industries, mines, etc.;
• inadequate sewage collection and treatment;
• Increase in fertilizers to grow more food. These results in an increase in nutrients (nitrates and phosphates) in
the water which causes enhanced plant growth (algal blooms). When this plant material dies and decays the bacteria
uses the oxygen in the water. This lowering of oxygen levels results in the death of other water life that needs
oxygen to survive, eg. fish, etc. This process is called eutrophication; litter, which causes disease and has a
negative visual impact.

2. Deforestation
Clearing land for agriculture and urban growth often leads to water pollution. When soil is stripped of its protective
vegetation it becomes prone to soil erosion. This leads to an increase in the murkiness of the water which can cause
the following:
• it can block the gills of fish;
• bottom dwelling plants cannot photosynthesize as the rays cannot reach them; and
• there is an increase in disease as bacteria and viruses use the soil particles as a method of transportation.

3. Damming of rivers
Damming of rivers can have an impact on water in the following ways:
• Water flowing out of dams:
• has reduced suspended material as a large amount settles to the bottom of dams; is depleted of nutrients; and is
often more saline with detrimental effects on downstream agriculture and fisheries.
• Enhanced eutrophication may result due to the water spending a longer time in the dam.
• There is also increased evaporation in dams, especially those with a large surface area.

4. Destruction of Wetlands

Wetlands are natures way of cleaning water as well as damming water (they hold back water in summer and release it in
winter). Destruction of wetlands:
• Destroys the habitat of many birds and fish;
• Removes the natural filters capable of storing and degrading many pollutants, such as phosphorus and heavy metals;
• Destroys natural dams and causes flooding further downstream.

5. Industries

Industries produce waste that can affect the:
• pH of water (whether it is acid, neutral or alkaline);
• colour of water;
• amount of nutrients (increase in nutrients can cause eutrophication);
• temperature (increase or decrease in temperature can have an impact on temperature sensitive organisms living in the
water);
• amount minerals and salts (too much can cause health problems);
• murkiness of water (can block fish gills; bottom dwelling plants cannot photosynthesize as the suns rays cannot reach
them; increase in disease as bacteria and viruses use the soil particles as a method of transportation).

6. Mining
Mines produce waste that:
• can increase the amount of minerals and salts in the water (too much can cause health problems);
• can affect the pH of the water (whether it is acid, neutral or alkaline);
• can increase the murkiness of the water.

7. Agriculture:

• Increases soil erosion due to the physical disturbance of soil and vegetation due to ploughing, overgrazing, logging
and road building. This affects the murkiness and the amount of salts and minerals in water;
• Increases nutrients due to fertilisers and excreta, which contribute worrying amounts of nitrates and phosphates to
water supplies (this can cause eutrophication);
• Increased pesticide use.

8. Accidental Water Pollution

Accidental water pollution can arise from many sources (such as burst pipes and tanks, major leaks, fires and oil
spills) and can cause varying degrees of damage, depending on the quantity, toxicity and persistence of the pollutant,
and the size and adaptability of the water body.
9. Sanitary wastes
• human and animal excreta
10. Solid wastes
• City droppings - For e.g., carbaneaceous paper / cloth / wooden materials
• Animal droppings and slaughter house wastes - For e.g., decomposable drug / slaughter house wastes
• Domestic wastes - For e.g., vegetable / food wastages
• Industrial solid wastes - For e.g., paper wastes, iron filings, metal chips
• Market Wastes - For e.g., vegetable / fruit rottings

11. Natural Resources
• Death of animals, birds
Reasons - Ammonia released by carcasses of animals, birds.
• Water collection from forest areas - For e.g., Nitrates and ammonia compounds from rich forest soils
• Natural mineral deposits - For e.g., Deposits of bauxites

The reasons for pollution was more than I bargained for and there are many more too. But whether we are aware or not, the act is going on. The only thing I would like to say is, try not to increase or add from our part.

See you tomorrow.

Until then, take care, bye.

Meena

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