Competitive Exams Causes & conservation: Water Pollution are important topics for

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Water Pollution

Water pollution refers to the degradation of water quality as measured by biological. chemical, or physical criteria. Degradation of water is generally judged m terms of the intended use, departure from the norm, effects on public health or ecological impacts. There are many different materials that may pollute surface water or groundwater. The following list describes some of the major forms of water pollution:

  • The addition of organic matter to water usually initiates the process of decomposition. Most decomposers require oxygen to complete this process. As a result. oxygen levels in the water decline with activity. Humans commonly use water bodies, like rivers, lakes and ocean, as a means of disposing of organic wastes. However, adding too much organic matter to a water body can cause it to become polluted because of a reduction in oxygen content. Low levels of oxygen can kill off fish , plants, and other organisms. Biochemical Oxygen Demand (BOD) is a measure of the amount of oxygen consumed in water by bacteria activity. BOD is measured as milligrams per Liter of oxygen consumed over 5 days at 20 degrees Celsius. All water bodies have some capability to degrade organic waste. Problems result when the water body is overloaded with BOD-demanding Waste.

  • Fecal coliform bacteria and other disease carrying microorganisms are important biological pollutants. Many of these organisms increase in numbers when water is polluted with organic matter and waste. Among the major waterborne human diseases are cholera and typhoid, which are common in many poor developing countries.

  • Nutrients (like nitrogen and phosphorus) released by human activity can cause lake eutrophication and nitrite contamination of drinking water. Excess nitrogen and phosphorous from farm animal waste and agricultural fertilizers is causing a major pollution problem in streams, lakes, and the coastal marine environment in many nations.

  • Oil discharge into surface water, usually ocean, has caused major pollution problems.

  • Heavy metals such as mercury, zinc, and cadmium are dangerous pollutants and are often deposited with natural sediment in the bottoms of streams.

  • The hot-water emission from industrial and power plants cause thermal pollution. Many industries cool machinery and products with water drawn from rivers, lakes, or the ocean. After the heat is dissipated into the water, the water is returned to its source. Heated water changes the nature of the aquatic system by reducing its ability to hold dissolved oxygen and by favoring species of fauna and flora that are adapted to warmer conditions.

  • Radioactive materials in water may be dangerous pollutants. Of particular concern are possible effects to people, other animals and plants to long-term exposure to low doses of radioactivity.

  • By volume, sediment is the greatest water pollutant. In many areas, sediment is choking streams and filling lakes, reservoirs, ponds, canals, drainage ditches, and harbors. Human activity has increased the amount of sediment entering the hydrologic system mainly through the disturbance of natural habitats, agriculture, and forestry. All of these activities enhance the process of erosion either through the removal of vegetation or via processes that disturb the soil surface layer (soil cultivation).

Water Conservation Techniques

A number of techniques and technologies can be used to make agricultural, industrial and domestic water use more efficient. Reductions can easily occur in the following areas: Reducing Agricultural Waste, lrrigation accounts for about 70 % of the worlds water use. Most irrigation systems deliver water to crops by flooding the land surface, diverting water to fields via open channels, or by sprinkler systems that apply water to the field surface. In general, these methods are very inefficient as only 50 % of the water applied is absorbed by the plants. The rest is lost to the atmosphere by evaporation. Micro-irrigation techniques can reduce the amount of water applied to crops by 40 to 60%. Other strategies that can be used to reduce agricultural water waste include:

  • The cultivation of food crops that require less water for growth.

  • The use of lined or covered irrigation canals to reduce infiltration and evaporation losses.

  • Irrigating crops at night or early morning when evaporation potentials are low.

  • Reduce water subsidies and encourage the proper pricing of this resource.

  • Reducing Industrial Waste -Industry is the second largest user of water supplies. Reducing the amount of water used in industry not only makes more water available for other purposes but it can also reduce the volume of pollution. Industry used water reductions can be achieved by:

  • Designing industrial processes to recycle water. For example, water used for industrial cooling purposes can be cooled down in a cooling tower and then reused.

  • Increasing the cost of water to industries to encourage water recycling.

  • Recycling materials themselves can also greatly reduce water demand. For example, manufacturing a ton of aluminum from scrap rather than from virgin ore can reduce the volume of water used by 97%. Reducing Domestic Waste some strategies for reducing domestic consumption include:

  • Replace lawns in semiarid and arid urban areas with grass surfaces.

  • Encourage the use of efficient irrigation systems for home garden and lawn use.

  • Manufacture and legislate the use of more efficient dishwashers, washing machines, and bathroom showers and toilets.

  • Encourage leak detection and repair for distribution systems. Distribution systems in many of the worlds urban areas are losing between 25 and 50% of their water supplies due to leaks in pipes.

  • Properly price water for domestic u se. This price must reflect the environmental cost of over consumption and resource degradation. Many studies have shown that higher prices for water provide motivation for people to conserve. The introduction of water meters in Boulder, Colorado reduced water use by about 30%. In Canada, water is metered in approximately two-thirds of the municipalities. Apart from these education can encourage people to reduce the amount of personal consumption.