Land pollution can occur due to poor handling of hazardous materials, unintended accidents, and even acts of nature such as floods and hurricanes. Contaminated sites in urban and rural areas contribute to the contamination of various landscapes, as does poor management of soil. Depending on the site, the pollution may be low and not much of a threat, but where pesticides, fertilizer, and toxic materials and metals are found in high concentrations, they may flow with runoff from rain water and enter the water supply, food chain, and waterways, leading to adverse health effects on wildlife and people.
The leading causes of land pollution, which can have detrimental impacts on animal and human health, water/air quality, and economic sectors such as tourism, include:
Contamination of Soil
Compounds used in the environment cause pollution in various ways. Fertilizers, pesticides, insecticides, and herbicides are used with good intentions but have negative side effects. The salinity they contribute can make life uninhabitable for crops and microorganisms. A loss of minerals and fertility can make the land less valuable. Once crops are harvested, the remaining soil is easily eroded by water and wind, and a loss of nutrients leaves behind land that’s of little use.
Contaminated surface water, leakage of industrial and landfill waste and sewage, rupture of underground hazardous materials storage, and acid rain can harm the soil as well. Another problem is soil erosion brought on by deforestation. It reduces the amount of available land for farming and other agricultural operations. In 2016, the Food and Agriculture Organization of the United Nations revealed that 75 billion tons of soil around the world are lost every year, resulting in the loss of hundreds of billions of dollars in agricultural production. Also, 95 percent of food is produced in soil across the globe, emphasizing contamination as a major land pollution concern.
Extraction of large amounts of materials can leave open areas devoid of plants and wildlife. Underground operations increase the risk of subsidence and the collapse of top layers of ground, affecting ecosystems and potentially damaging buildings and infrastructure. Open pits and piles of waste rock and other materials are unsightly in areas that would otherwise be pristine.
High-level nuclear waste includes radioactive materials such as plutonium. These are often disposed of in underground steel silos, but the need to keep them contained for thousands of years means the storage media must hold up. Waste from nuclear weapons production and contaminated industrial waste present disposal challenges, while uranium mill tailings or radioactive materials left after uranium is extracted can trigger radon emissions and contaminate ground water.
Nuclear waste is presently stored underground in several states, upon consideration of a centralized national repository. The controversial Yucca Mountain Repository in Nevada has been under study since 1987. Following a 2015 Safety Evaluation Report and a subsequent environmental impact statement, the Nuclear Regulatory Commission determined the site would be able to isolate stored waste for a specified period of one million years.
Wood, bricks, metal, and plastics are often left behind on construction sites. These materials can affect the aesthetics of an urban, suburban, or rural location, and create hazards for anyone who strays too close. Construction debris contributes to the burden on landfills, while the extraction of raw materials often requires deforestation for access to the land. Harmful oils, paints, and chemicals can get into the ground, polluting the surface and where ground water flows.
Large urban landfills can be hundreds of feet high and cover large tracts of land. As of 2009, the U.S. Environmental Protection Agency counted over 1,900 municipal solid waste landfills in the country, collecting household and non-hazardous commercial waste. Landfills exceeding their capacity expose the environment to waste. Residual materials from sewage treatment are also sent to landfills, potentially adding more pollutants to the environment.
Also known as fracking, this process involves drilling wells thousands of feet down and pumping water, chemicals, sand, and fracking fluid into the shale rock. Used to remove oil and gas, fracking can release methane and toxic chemicals into the surrounding rock and soil. Methane is known as a greenhouse gas, with its potential to induce climate change, while various chemicals can contaminate groundwater.
In addition to underground leaks, fracking comes with the risk of poorly treated waste fluids of seeping into water tables from above-ground facilities. Oil and other toxic spills can taint soils with chemicals. The Associated Press reported a high number of wastewater spills from dumping, storage tank overflow, and pipeline ruptures in North Dakota over several years. Salt and chemicals in the wastewater can kill large areas of crops and vegetation.
The fracking process also increases the risk of stream sedimentation due to construction, and the runoff of pollution when it rains.
Contaminated Sites: Identification by the U.S. Environmental Protection Agency (EPA)
The EPA has identified several types of contaminated sites that can be targeted for remediation. Land pollution has a major impact on agriculture, wildlife and human health, and even property development. To address the issue, the agency has created several labels to determine cleanup priorities, which include:
Superfund sites: Abandoned hazardous waste sites that are abandoned or uncontrolled, and targeted by the federal government for involvement in cleanup efforts.
Brownfields: Real properties with sources of pollutants and hazardous substances; response and cleanup is typically managed by state and tribal programs.
Underground storage tanks: Sites where petroleum products or substances labeled under the Superfund program have leaked from storage.
Treatment, storage and disposal facilities: Those covered under the Resource Conservation and Recovery Act, and suspected of releasing contaminants and slowing reuse or redevelopment.
Federally owned properties with radioactive waste, unexploded ordnance, and other hazards are identified by the EPA as well. So are sites addressed by state Superfund, Brownfield, and other cleanup programs. It can be difficult to clean up and restore polluted land and mitigate its impacts. However, the EPA has established a Land Revitalization Program to protect the environment and public health, and restore the productivity of previously unusable land. The program has addressed some of the main causes of land pollution in the nation, focusing on cleanup, removal, and redevelopment.