What Are the Results of Freshwater Pollution?

Sources

• Pollution comes from a variety of sources. It can include organic waste such as yard clippings, fecal matter, food waste and crop debris. Erosion caused by activities such as clearing land and excavation deposits sediments into lakes and streams. Mining activities often discharge metals such as iron, chromium, zinc, copper, tin, nickel and platinum into lakes and rivers. Power plants cause thermal pollution when they dump the water used for cooling turbines and reactors into local bodies of water. Toxic chemicals enter the water when chemical plants burn toxic waste and when homeowners, merchant farmers, gas stations and airports incorrectly dispose of chemicals such as paint, pesticides, herbicides and dry-cleaning fluid

Environmental Effects

• Freshwater pollution causes a variety of environmental effects. Sediment and minerals prevent sunlight from entering the water, slowing the production of photosynthetic organisms. Excessive heavy metals can also poison aquatic life forms. Excessive levels of nitrogen and phosphorous from farm runoff can cause excessive growth of aquatic plants. This smothers certain plants and creates cloudy water. It can eventually speed up the processes that cause bodies of water to become dry land. Thermal pollution reduces water's ability to retain oxygen, which can affect the reproduction of fish species and speed up the growth of algae.

Health Effects

• Freshwater pollution has a wide range of effects on human health. For example, fecal matter contains the bacteria and pathogens that cause diseases such as E. coli-induced food poisoning, cholera, cryptosporidiosis and typhoid. These diseases cause problems such as diarrhea and increase infant mortality rates in developing nations. Humans who eat too much fish contaminated with mercury can develop brain damage and nervous system damage. Excessive salt caused by overpumping coastal water sources and excessive irrigation can kill crops, reduce yields and leave water undrinkable. Silt from erosion can reduce the quality of drinking water.

Cleaning and Prevention

• Cleaning polluted water is extremely expensive and difficult. Water can sometimes be cleaned by passing it through activated charcoal, which absorbs the pollutants. Cleaning water with an air-stripping technique involves pumping the polluted water out of the ground and then heating it until the contaminant evaporates. In thermal treatment, an electrical current heats the water and soil until the water evaporates; the steam carries the pollution away and deposits it in recovery containers. One way to prevent freshwater pollution is by protecting the watershed, or area that drains into surface or ground water, from contamination by agricultural runoff and development.