Harmful Pollutants in Water

There are pollutants in almost every water supply.

When most people think of water pollutants, they think of toxic chemicals and sludge. Yet even pollutants that are not toxic can have negative effects and be harmful. There are two main categories of pollutants found in water---organic and inorganic. Examples of organic pollutants include sewage, fertilizers, runoff and organic materials like grass clippings. Inorganic pollution can include petroleum, chemicals, radioactive materials, silt, heat and metals. Pollutants can be found to some degree in nearly every body of water that is affected by humans.

Nitrates and Phosphates

The nitrates and phosphates found in sewage, fertilizers, detergents and runoff lead to the growth of algae and aquatic plants. These organisms clog waterways, use up oxygen and block light. Fish and other aquatic life suffocate and die, which negatively affects the food chain. Silt can have a similar negative effect. Heat, which is a byproduct of many factories and power plants, also kills aquatic life by raising water temperatures to inhospitable levels.

Pathogens

Farm runoff, untreated or poorly treated sewage, water from storm drains and septic tank runoff can harbor pathogens. These are harmful bacteria and viruses that can lead to diseases such as typhoid, dysentery, hepatitis A, cholera, skin ailments and gastro-intestinal illnesses. There are also water-borne diseases that infect animals and have a negative affect on the food chain, even if they do not directly harm humans.

Oil

Oil discharges are a not-uncommon form of pollution. Oil is routinely spilled during off-shore drilling, refining and transport. Oil coats and kills birds and marine life, and suffocates aquatic life. It is also a fire hazard.

Radioactive Material and Metals

Radioactive material and metals from nuclear power plants, mining concerns, refineries and other industries have toxic and cancer-causing effects on both humans and animals. Many of these metals, like mercury, are stored in the fatty tissues of fish and marine life, which are then eaten in concentrated levels by humans. Many of the long-term effects of these metals and radioactive elements are not fully understood.

Pesticides and Herbicides

Pesticides and herbicides are used to kill insects and weeds and are a standard ingredient in farm runoff. Pesticides like DDT have been banned for their ability to cause fatal birth defects in the animals that eat the fish that swim in poisoned water, like eagles and other birds of prey. DDT causes thinning of the shells of the eggs of birds of prey, preventing incubation and hatching. Other pesticides have been shown to damage DNA and cause genetic mutations in animals and potentially in humans, in large enough doses. Some pesticides in water occur in high enough concentrations to kill beneficial bacteria and insects in the soil, reducing soil productivity.

References

• University of Michigan: Water Pollution and Society
• Lenntech: Water Pollutant FAQ