Industrial and agricultural activities often release contaminants into the environment that can disrupt the various species living in an ecosystem. From toxicity to radioactivity, contaminants can have a wide range of effects on organisms. These effects depend on the nature of the contaminants and how long they persist in the environment. While pollution severely affects plant life in an ecosystem, the EPA is utilizing plants to actually draw contaminants out of the environment.
Sources and Types of Contamination
From landfill seepage to chemical spills to illegal dumping, land pollution can come from a variety of sources. Unfortunately, small-scale pollution enters the ground on a regular basis -- often without our knowledge. Evidence of steady, localized pollution is often detected years after it has been occurring.
Oil spills are some of the more noteworthy land pollution events because they are frequently detected as they are happening. In September 2013, a farmer discovered oil seeping up from below his wheat field near Tioga, North Dakota. The oil spill, which leaked about 20,000 barrels in total, was eventually traced to a pipeline owned by the Tesoro Corporation. Oil or petroleum spills are hazardous because they are toxic, flammable and potentially explosive. Other types of pollution-related hazards considered by the EPA include chemical reactivity and radioactivity.
Metal Contaminants and Effects
According to the EPA, soil pollution is defined as hazardous substances that are mixed with naturally occurring soil. These artificial contaminants are either attached to soil particles or are trapped within the soil. The EPA categorizes these contaminants as either metals or organics.
Arsenic is a metallic pollutant that is used in several manufacturing and industrial processes, including those conducted on mining and agricultural lands. When plants take in arsenic, it can disrupt metabolic processes and lead to cell death.
Lead is another metallic pollutant that can affect all types of organisms in an environment. Released to the environment from coal-fired power and other combustion processes, lead may also be deposited on land as slag, dust, or sludge. Lead can disrupt the nervous system of animals and interfere with their ability to synthesize red blood cells. These effects can become more dramatic and deadly as lead concentrations in an environment increase.
Organic Contaminants and Effects
The EPA is also concerned with organic contaminants, such as DDT or Dieldrin, that were commonly used in industrial production after World War II. Referred to by the EPA as persistent organic pollutants (POPs), many of these chemicals remain in the environment long after their initial intended use. According to the EPA, POPs have been linked to population declines, "diseases, or abnormalities in a number of wildlife species." These chemicals have also been linked to "behavioral abnormalities and birth defects in fish, birds, and mammals in and around the Great Lakes," the EPA said in a report on its website.
While plants can be severely affected by land pollution, the EPA is actually using them to clean up contaminated sites -- through a process called phytoremediation. First tested in the early 1990s, phytoremediation uses plants to draw contaminants out of the soil or groundwater and is now used at more than 200 sites across the United States.Trees explicitly planted for phytoremediation at a site in Oregon have been shown to take up toxic organic compounds -- based on tissue sample analyses. "The success of the trees at the Oregon Poplar site supports the notion that phytoremediation may be an innovative technology worthy of nationwide consideration," the EPA reported. The federal agency has said it tends to use native species for phytoremediation because it helps revive the heritage of flora lost through human activities.
- Journal of Hazardous, Toxic, and Radioactive Waste: Seepage Control Strategies at Bioreactor Landfills
- EPA Superfund Risk Assessment: Human Health: Acute Hazards
- Frontiers in Physiology: Arsenic Toxicity: The Effects on Plant Metabolism
- EPA SUperfund: Ecological Soil Screening Levels for Lead
- Lead Action News: Effects of lead on the environment
- EPA: Persistent Organic Pollutants: A Global Issue, A Global Response
- EPA: Using Phytoremediation to Clean Up Sites
About the Author
Brett Smith is a science journalist based in Buffalo, N.Y. A graduate of the State University of New York - Buffalo, he has more than seven years of experience working in a professional laboratory setting.
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