Water pollution is the release of chemicals mixed with water into lakes, streams, rivers, estuaries, and oceans to the point where the substances interfere with the beneficial use of water. Apart from the release of substances, trash, or microorganisms, water pollution may also include the release of energy, in the form of heat, or radioactivity, into water bodies.
Sources of Water Pollutants
Water bodies can be polluted by a wide range of pollutants, including organic waste, fertilizers and plant nutrients, toxic chemicals, sediments, heat, petroleum ( oil and grease), and radioactive substances. There are also several types of water pollutants considered below the toxic limits.
Water pollutants come either from point sources or dispersed sources (nonpoint). The point sourceis a pipe or channel, such as those used for discharge from industry or a city sewerage system.
A dispersed (nonpoint)source is a very broad unconfined area from which a variety of pollutants enter the water body, such as runoff from an agricultural area. Point sources of water pollution are easier to control than dispersed sources because the polluted water has been collected and transferred to one single point where it can be treated. Pollution from dispersed sources is difficult to control and continues to cause a large fraction of water pollution.
Domestic sewage is the primary source of water pollution and disease-causing pathogens, and putrescible organic substances. Because pathogens are excreted in feces, all sewage from cities is likely to contain pathogens of some type, potentially presenting a direct threat to human health. Putrescible organic matter presents a different sort of threat to water quality. As organics are decomposed naturally in the sewage by bacteria and other microbes, the dissolved oxygen (DO) content of the water is depleted. This endangers the quality of lakes and streams, where a high level of oxygen is required for fish and other aquatic life to survive. Sewage treatment processes reduce the levels of pathogens and organics in wastewater, but they don’t eliminate them completely.
The improper disposal of solid waste is a major source of water pollution. Solid waste includes garbage, rubbish, electronic waste, trash, and construction and demolition waste. All these are generated by individual, residential, commercial, institutional, and industrial activities. The problem is especially acute in the developing countries that may lack the infrastructure to properly dispose of solid waste or that may have inadequate sources or regulations to limit the improper disposal. In some places, solid waste is directly dumped into water bodies. Land pollution can also become water pollution of the trash or the other debris carried by animals, wind, or rainfall to water bodies.
Significant amounts of solid waste pollution in inland water bodies can also eventually make their way to the ocean. Solid waste pollution is unsightly and damaging to the health of aquatic ecosystems and can harm wildlife directly. Many solid wastes, such as plastic and electronic waste, break down and leach harmful chemicals into the water, making them a source of toxic or hazardous waste.
Toxic Waste (Radioactivity)
Waste is considered toxic if it is poisonous, radioactive, explosive, carcinogenic (causing cancer), mutagenic (damage to chromosomes), teratogenic (causing birth effects), or bioaccumulative ( higher concentration of chemicals in the food chain). Sources of toxic chemicals include improperly disposed wastewater from industrial plants and chemical processes of facilities (lead, mercury, chromium) as well as surface runoff containing pesticides used on agricultural areas and suburban lawns. All these toxic lead to water pollution and disturb water bodies.
Sediments resulting from soil erosion or construction activity can be carried into water bodies by surface runoff causing water pollution. Suspended sediment interferes with the penetration of sunlight and upsets the ecological balance of a water body. It can disrupt the reproductive cycles of fish and other forms of life, and when it settles out of suspension it can smother bottom-dwelling organisms.
Heat is considered to be a water pollutant because it decreases the capability of water to hold dissolved oxygen in solution, and it increases the rate of metabolism of fish. Valuable species of fish can’t survive in water with very low levels of dissolved oxygen. A major source of heat is the practice of discharging cooling water from power plants into water bodies, the discharged water may be as much as 15oC warmer than the naturally occurring water. The rise in water temperatures because of global warming can also be considered a form of thermal pollution.
Petroleum pollutants (oil, grease) from roads, auto workshops, and parking lots are carried in surface runoff into water bodies causing water pollution too. Accidental oil spills are also a source of oil pollutants. Oil slicks eventually move toward shore, harming aquatic life and damaging recreation areas.
Water Pollution Effects
Groundwater contained in underground geological formations (aquifers) is a source of drinking water for every living creature on earth. For example, about half of the people in the United States depend on groundwater for their domestic water supply.
Although groundwater may appear crystal clear, it may still be polluted by dissolved chemicals and by bacteria, and viruses. Sources of chemical pollutants include poorly designed or poorly maintained subsurface sewage disposal systems. Industrial wastes disposed of in improperly lined or unlined landfills or lagoons, leachates from unlined municipal effuse landfills, mining, and petroleum products can cause saltwater intrusion, as water table drops, seawater is drawn into wells which contribute to water pollution.
Is there any solution?
There are several types of water quality standards provided by the EPA (Environment Protection Agency). These standards provide a legal framework for the prevention of water pollution of all types.
Stream standards classify streams, rivers, and lakes on the basis of their maximum beneficial use. They set allowable limits of specific substances or qualities, allowed in these water bodies, based on their given classification.
What can we do to prevent water pollution?
We’re all responsible to some degree for today’s water pollution issue. But still, there are some ways we can protect against water contamination or at least limit our contribution to it.
- Reduce plastic consumption and reuse or recycle plastic when we can.
- Properly dispose of chemical containers, oils, and nonbiodegradable items to keep them going to water bodies.
- Don’t flush old medications, dispose of them in the trash to prevent them from entering the water body.
One of the most effective ways to stand up for water pollution is to speak out in support of the Clean Water Act. Our water bodies serve every one of us. We shall all have a say in how they’re protected.