Environmental pollution enters air, soil and water and is spread across the land and oceans by natural forces including wind and water flow. Some pollutants degrade in the environment and others may persist for thousands of years. As pollution spreads and accumulates in the environment, the cost and difficulty of cleanup increases. Over time, the effects of pollution on the environment can be slowed and potentially reversed through a combination of removing the sources of pollution and cleanup.
Sources of Pollution
Cities contribute pollution from many sources, including factory smokestacks and wastewater; car exhaust; liquid leaking out of landfills; sewage treatment plant leakages and released gases; and residences. Pollution from rural and forest lands includes crop fertilizers in stormwater runoff; smoke from field burning and forest fires; blowing dust; soil erosion from logging; and acid and chemicals in stormwater runoff from mining areas. Pollution that enters air, soil and water can continue to spread even long after the sources are stopped.
Persistence of Environmental Pollution
Soluble or volatile pollutants may degrade when exposed to air or microbes in soil or groundwater. Other pollutants move with groundwater in the subsurface as particles or in a solution. "Hydrophobic" pollutants repel water and are held in the ground because they are attracted to soil or sediment particles, making them difficult and costly to clean up. They can "persist" in the environment and move through the food chain from soil to food to people, or from sediment to fish to people.
Cleaning Up Pollution
Removing the biggest sources of pollution could include, for example, more complete treatment of industrial wastewater or stormwater that carries fertilizers and road pollutants to reduce the amount of pollution entering streams and the ocean. Many technologies can be used to remove pollutants from soil and water. For example, charcoal filters can remove contaminants; certain chemicals can neutralize or bond with pollutants; microorganisms can be used to break down chemicals; and certain plants can be used to extract or break down pollutants. These technologies can be combined to make cleanup more effective.
Curbing Sources of Pollution
Part of reversing the effects of pollution requires the government and individuals to embrace efforts to reduce waste and ensure resource sustainability. Recycling and changes in product packaging can reduce how much waste is generated and placed in landfills. Alternative chemicals can be used by industries as well as homeowners to reduce the toxicity of chemicals that wind up in wastewater. Using alternative energy sources can reduce the amount of fossil fuels that are burned and the toxicity of air emissions.