The term "pollutant" refers to any substance that, when introduced to an area, has a negative impact on the environment and its organisms. Pollutants can impact human health, air, water, land and entire ecosystems. Most sources of pollution result from human activity.
Many pollutants have a negative impact on human health. For example, pollutants in the air, such as ozone or particulates in the air, may lead to respiratory health problems such as asthma, chronic bronchitis and decreased lung function. Drinking contaminated water may lead to stomach and other digestive problems. Pollutants such as mercury can accumulate in fish and seafood and can lead to serious health problems, especially for vulnerable populations such as children or pregnant women. Pollutants in the soil, such as contamination by heavy metals, toxins or lead, can lead to serious health problems, including cancer and developmental problems in children.
One of the most common sources of air pollution results from the burning of fossil fuels, such as vehicle and factory emissions. These emissions are a major contributor to smog, a mass of particulate matter than hangs like a cloud over many major cities and industrial areas. A second effect of air pollution is acid rain, which forms when sulfur dioxide and nitrogen oxide in the air combine with oxygen, water and other chemicals in the air. This combination decreases the pH of rainwater, which is typically pH neutral. Acid rain can lead to the death of trees, fish kills in lakes and damage to statues, monuments and building faces.
Water pollution may result from run-off from places such as agricultural fields, construction sites or factories; oil spills; sewage spills; and the accumulation of trash. Water pollution has a deleterious effect on the native plant and animal species that call bodies of water home. Run-off from agricultural fields can lead to algal blooms which choke out other plants and decrease the amount of available oxygen for species of fish and other organisms. Chemicals in the water can affect animal development, leading to deformities, such as extra legs in frogs. Oil spills kill native species of animals including waterfowl and mammal species. Sewage overflow can contaminate sources of human drinking water, leading to serious health problems, as mentioned above. The accumulation of trash in bodies of water may also lead to animal deaths resulting from becoming tangled in plastic items such as plastic bags, fishing wire and other debris.
Pollutants in the soil most often result from industrial sources. Particularly insidious soil pollutants include lead, PCBs and asbestos. These pollutants may negatively affect human health and native plant and animal health. Pesticide use can also impact the land. One undesired impact of using pesticides is the death of native plant and animal species that also reside in the area.
Because each type of pollution (air, water, land) does not occur separately from one another, entire ecosystems are often impacted. For example, the use of pesticides or fertilizers on land may negatively impact terrestrial species of plants and animals. When these materials are introduced to nearby bodies of water, they impact aquatic species of plants and animals. Thus, curbing pollution in one area of an ecosystem can also help protect another part of the ecosystem.
- Environmental Protection Agency
- McDougal Littell Biology; Stephen Nowicki; 2008