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Water pollution occurs mostly when people overload the water environment with wastes. Its defined as contamination of streams, lakes, underground water, bays or oceans by substances harmful to living things. Water is necessary to life on earth. All organisms contain it, some drink it, some live in it.
Plants and animals require water that is moderately pure, and they cannot survive if their water is loaded with toxic chemicals or harmful microorganisms. If severe, water pollution can kill large numbers of fish, birds, and other animals, in some cases killing all members of a species in an affected area. Pollution makes streams, lakes, and coastal waters unpleasant to look at, to smell, and to swim in. Fish and shellfish harvested from polluted waters may be unsafe to eat. People who ingest polluted water can become ill and if theyre exposed for a long time, may develop cancers, or have children with birth defects.
There are two types of water pollution; point source and nonpoint source. Point sources of pollution occur when harmful substances are put directly into a body of water (such as an oil spill). A nonpoint source is when pollutants enter the water indirectly through environmental changes (like when fertilizer is carried into a stream by rain) The major water pollutants are chemical, biological, and physical materials that lessen the water quality. Pollutants can be separated into eight different classes:
- Petroleum Products - oil and chemicals from oil are used for fuel, lubrication, plastics manufacturing, and many other purposes.
The petroleum products get into water by accidental spills from ships, tanker trucks, and leaky underground storage tanks. Many petroleum products are poisonous if ingested by animals and spilled oil damages the feathers of birds and the fur of animals, often causing death. Pesticides and Herbicides - chemicals used to kill unwanted animals and plants may be carried into streams by rainwater. The chemicals in these that are not biodegradable can remain dangerous for a long time.
When an animal eats a plant thats been treated with certain non-degradable chemicals, the chemicals are absorbed into the tissues or the organs of the animals. When other animals feed on a contaminated animal, the chemicals are passed up to them. As it goes up through the food chain, the chemical becomes more harmful, so animals at the top of the food chains may suffer cancers, reproductive problems, and death. More than 14 million Americans drink water contaminated by pesticides, and the EPA estimates that ten percent of wells contain pesticides. Nitrates can cause a lethal form of anemia called blue baby syndrome in infants. Heavy Metals - heavy metals, such as copper, lead, mercury, and selenium, get into the water from industries, automobile exhaust, mines, and natural soil.
Heavy metals also become more harmful as they follow the food chain. When they reach high levels in the body, they can be immediately poisonous, or can result in long-term health problems. They can sometimes cause diarrhea and, over time, liver and kidney damage. Children exposed to lead in water can suffer mental retardation. Hazardous Wastes - chemical wastes that are either toxic, reactive, corrosive, or ignitable. If not treated or stored properly, they can pollute water supplies.
They can reach toxic levels when animals eat one another. Excess Organic Matter - fertilizers and other nutrients used to promote plant growth on farms and in gardens may fine their way into water. At first the nutrients will help the plants and algae in the water grow, but when they die and settle underwater, microorganisms decompose them, while decomposing them the microorganisms take in oxygen that is dissolved in the water. The oxygen levels in the water may drop so low that fish and other oxygen-dependent animals in the water suffocate, and die. Sediment - soil particles carried to a stream bed, lake, or ocean, if in large amounts, can also be a pollutant. Soil erosion can damage a stream or lake by adding too much nutrient matter.
Sedimentation can also cover stream bed gravel where many fish lay their eggs. Infectious Organisms - many disease causing organisms that are present in small numbers in most natural waters are considered pollutants when found in drinking water. These parasites can cause illness, especially in people who are very young or very old, and in people who are already suffering from other diseases.
Thermal pollution can speed up the biological processes in plants and animals or lower the oxygen level in the water. Fish and other wildlife near the discharge source, may die. Another cause of pollution, pathogens (bacteria, viruses, and protozoan) can cause many illnesses from typhoid and dysentery to minor respiratory and skin diseases. They enter waterways through untreated sewage, storm drains, septic tanks, runoff from farms, and boats that dump sewage. To help, we need to learn about ways for disposing harmful household wastes so they dont end up in sewage treatment plants or landfills. In our yards, we should determine whether or not we need to add nutrients before fertilizers are applied, and look for alternatives where fertilizers may run off into surface waters.
We need to preserve existing trees and plant new trees and shrubs to help prevent soil erosion. Around the house we should we need to keep litter, pet waste, leaves, and grass clippings out of gutters and storm drains, and buy as many heavily packaged foods, certain boxes, cartons, bottles, etc that are made with polluting dyes.
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Free research essays on topics related to: heavy metals, water pollution, food chain, petroleum products, soil erosion
Research essay sample on Soil Erosion Heavy Metals
