Land pollution is a key driver of the degradation of our environment. Scientists suggest that as much as 75% of the land area of the Earth has been affected. The continued pollution of land is already harming plants, wildlife, and up to 3.2 billion people.
Comprehending what land pollution is, and its causes and effects is the first step in tackling this pervasive issue. In this article, we explore the causes and effects of land pollution and consider what can be done to prevent it.
What is land pollution?
Land pollution is the contamination of land by substances that can cause immediate and ongoing damage to human health and the environment. When contaminating substances are present at concentrations above acceptable background levels, this may affect the surface and groundwater of the affected land.
Pollutants are often man-made or at least by-products of human activity. They include hazardous waste, chemicals, or harmful naturally-occurring substances that have been mishandled, displaced from their usual containment, or improperly disposed of.
Land pollution has significant social, financial, health, and environmental costs. Contamination of land can be persistent leading to pervasive effects on plants and wildlife. Human exposure to hazardous substances is a notable cause of disease including cancer, subfertility, and birth defects.
In most societies, wilful and negligent land pollution carries heavy financial penalties, including the costs of cleaning up the contamination.
What are the causes of land pollution?
The causes of land pollution are diverse. Though natural disasters can cause land pollution, the main cause of land contamination is human activity. Here are seven key causes of land pollution:
Intensive farming is one of the biggest causes of land pollution which over time degrades land and reduces its fertility. Excessive use of fertilizers can lead to them being washed out of the ground into waterways, where the excess nitrogen causes an overgrowth of algae that kills aquatic life (eutrophication).
Pesticides that are used to treat crops can be extremely persistent with residues that taint the food that is produced. If used indiscriminately, useful pollinating insects like bees can suffer harm, and insects and microorganisms in the soil that decompose are lost, leading to a deterioration in soil quality.
The improper disposal of agricultural waste is also a key cause of land pollution. Because factory-farmed animals produce more than one million tons of waste daily, manure and slurry may be sprayed onto the fields where it can end up contaminating surface water and introducing harmful antibiotic-resistant bacteria.
Industrial activity is responsible for the release of polluting substances used or generated as part of the manufacturing process or leftover as hazardous waste. The inappropriate use of landfills by industry can cause long-term pollution that is hard to remedy, plus – chemicals that are improperly landfilled can leach into the soil and groundwater, with eventual human consumption.
Industrial accidents like oil spills are well-known causes of devastating land pollution. Land-based spills can take place and oil slicks from off-shore spills can wash up on beaches contaminating large areas. Clean-up is costly and time-consuming, taking decades for affected land to recover as this documentary on the recovery of the Exxon Valdez oil spill shows:
Construction is a polluting activity that often irreparably alters environments and introduces contaminants into the soil and water. In brownfield developments, where the land may already be contaminated, construction work may increase the movement of pollutants or drive them deeper into the soil.
The building process also generates large amounts of waste, especially if demolition is involved. In India, up to 12 million tons of waste is generated daily by the construction sector alone! This mixed waste has to be carefully disposed of or it can become a source of pollution in other areas.
The increased demand for a variety of raw materials, including rare earth metals, precious metals, and coal means that global mining is increasing. But mining is one of the most polluting activities associated with land damage that spans deforestation, erosion, contamination of soils, and long-term alteration of soil composition.
War is a devastating cause of ongoing land pollution and environmental degradation around the world. Military activity is an industrial polluter with munitions, chemicals, and radiation polluting affected territories.
In conflicts, key infrastructure, such as energy or manufacturing facilities are deliberately attacked which also creates extensive land pollution. An example of this was the 1991 Gulf War oil spill, one of the largest ever. The 240 million gallons of oil that were spilled caused massive coastline damage and the loss of tens of thousands of seabirds and other wildlife.
6. Waste management
The global population generates over 2 billion tonnes of municipal solid waste (MSW) each year, with the majority being burnt or sent to landfill. Waste incineration and landfill use can cause land pollution, but a solution for dealing with the vast volumes of waste that need to be handled is limited.
Landfills are particularly polluting as waste decomposes and leeches a range of toxic substances (known as leachate) into the surrounding earth and groundwater. Ashes from waste burning are also landfilled and may release heavy metals and dioxins into the surrounding earth.
7. Nuclear waste
Radioactive pollutants that contaminate soil are a serious hazard and may take decades to clear. Other than the natural discharge of radon gas, this type of land pollution is always man-made.
There is potential for land contamination by radiation at every stage of the production of nuclear energy. Notable sources of land contamination by radioactive pollutants include:
- the excavation of uranium ore
- the processing of uranium
- the disposal of short and long-lived radioactive waste
- the corrosion products
- the nuclear weapons testing
- nuclear accidents (e.g Chornobyl or Fukushima)
Key land pollution sites
There are several categories of contaminated land. The type of site is key to determining the environmental and health hazards present, the impact of the contamination, and the best strategy for cleanup.
Here are the sites that are associated with the most concerning forms of land pollution:
Sites with underground storage tanks
Industrial facilities and gas stations often store hazardous substances underground in tanks. Failure of this subterranean storage leads to leakage of the contained substance into the surrounding soil and groundwater.
The underground storage tanks used by gas stations are at the most risk of leakage when
- tanks are being filled with fluid
- fuel is being dispensed
- during maintenance and repairs
- during the drainage of wastes
Authorities provide detailed advice on the management of underground storage and how these sites can be safely decommissioned. There are heavy fines for businesses that do not comply with guidelines and have inadequate safety standards.
Operational incidents can lead to spillages of a wide range of chemicals and oils. Examples of spillages that cause land pollution include:
- domestic heating oil
- motor oils and fuel spillages at a mechanics workshop
- pesticides and other agricultural chemicals
- land-based oil rigs
Oil is particularly hard to clean up as it seeps into the ground. In industrial facilities, staff should be trained to minimize the risk of spills when they handle substances and use emergency protocols to ensure a safe and thorough cleanup.
Natural disaster locations
Natural disasters like floods, earthquakes, tsunamis, and volcanic activity can also cause acute and long-lasting land pollution. These events can lead to the release of naturally occurring contaminants or disrupt facilities, infrastructure, and storage that handle hazardous materials.
Floods and storms can wash pollutants like agricultural waste, fertilizers, or industrial chemicals out of storage facilities and onto the land.
Sites may become contaminated with radioactive material due to uranium mining and enrichment, weapons production, or the nuclear energy sector.
Substances like Strontium-90, Plutonium-238, and Uranium-235 are introduced to environments due to man’s activity. Other radioactive substances, like radon pollution, are naturally occurring.
The severity and persistence of radioactive pollution depend on the elements involved and the rate at which they degrade and lose their radioactivity (half-life). Improper disposal of radioactive waste may also lead to ongoing land pollution.
Brownfield sites are ex-industrial locations that have fallen into disuse. Their redevelopment is often affected by land contamination related to their former industrial use, so, before construction can take place, the pollution needs to be cleaned up. This adds to the cost of developing these sites.
Locations that have been involved in military activity may be contaminated with ordnance and munitions substances. Across the world, military bases and war zones may be contaminated with hazardous chemical weapons, landmines, and radiation.
If countries lack the resources to clean up these areas, they can cause long-term damage to the environment and human health in their vicinity.
Sites of PCB contamination
Polychlorinated biphenyls (PCBs) are organic chlorine compounds that were widely used in industries that included electronics, building materials, and inks until their harmful effects became known. They have known carcinogens and endocrine disruptors; even small amounts can cause acute poisoning.
The Toxic Substances Control Act of 1979 banned them, but because their use involved so many commercial industries, there are areas of significant PCB contamination.
Disused mining sites
Mining activity leads to the dumping of huge amounts of contaminated waste known as black mountains. This abandoned material often contains metals like lead or copper that can be leached into the soil and groundwater.
Hazardous chemicals like sulfide minerals or cyanide that are used to process gold may also seep into the surrounding environment. Open-pit mining often produces tailings or slurry, which is a source of land pollution that requires careful clean-up once mines go out of use.
How does land pollution affect the environment?
Land pollution is hazardous to human health and the environment. Contaminated sites vary in the type and degree of contamination and the risk they pose to living things.
It’s important to remember that pollutants may not stay at their source but disperse through the environment, potentially affecting areas distant from the originally contaminated site.
However, the unique ecology of a site will determine how much pollution can be tolerated and the type of immediate and long-term effects that will be encountered.
Land pollution has a devastating impact on soil. Soil relies on diverse living organisms to maintain its composition and health. Toxins and other pollutants can poison and kill this living element of soil, leading to long-lasting ecological damage that may be difficult to recover.
Soil contamination may also include slicks and other substances that cover and penetrate the soil, preventing the vital oxygenation needed by soil organisms. The vital work of decomposition, essential to maintain soil hummus, and the cycling of nitrogen and carbon may also be wiped out.
Land pollution can cause marked alteration of soil chemistry, even when the levels of polluting substances are low. Though organisms attempt to adapt, this eventually impacts the metabolism of the resident soil microorganisms and arthropods, which may form part of the food chain of larger species
In the long term, contaminated soils that lack microorganisms and organic matter are vulnerable to soil erosion. Impaired soil cannot support plant life, so lacks the vegetation that holds the soil in place while it is living and then dies and decomposes to replenish the soil. It can then be easily blown or washed away.
Contamination of surface and groundwater
A secondary effect of land contamination is the pollution of ground or surface waters, either by direct contact with polluting substances or the leaching of substances from contaminated soil.
Surface water contamination affects lakes, rivers, ponds, and reservoirs, with pollutants directly entering the water. Groundwater pollutants tend to be absorbed from the ground.
This means that land contamination can affect the potable water supplies that are used for individual or mass consumption. This is particularly hazardous where water is drawn up from private wells that are affected by polluted surface runoff from agriculture with raised levels of harmful bacteria.
Damage to vegetation
Land pollution may have lasting effects on plant life in a contaminated area. Contaminated soil that is humus poor and poorly oxygenated cannot support plants or trees. Chemicals that have leached into the soil may also be taken up by plants by the roots, poisoning them. The loss of plant life on polluted land increases the risk of soil erosion and barrenness.
Even where plants survive land contamination, the radiation or chemical substances they are exposed to accumulate in their tissues, meaning they could potentially harm the humans and animals that eat them.
Harm to animals
The effects of land pollution on animals are wide-ranging and persistent because of bioaccumulation. This is the gradual build-up of pollutants in the tissues of an exposed organism as it attempts to tolerate the new substance in its environment. If small organisms with pollutants in their tissues are consumed by larger animals, the toxins can travel up the food chain, harming a greater number of species.
Many polluting substances are also potent endocrine disruptors, impacting animal reproduction. The added challenge of habitat loss means the population numbers and biodiversity of species are reduced and may not recover even if the pollution is removed.
Impact on human health
Land pollution puts human health at risk as they can be not only directly exposed to hazardous materials in contaminated sites but also ingest toxic substances by eating contaminated crops and meat from animals that have been exposed.
The health effects of land pollution are acute and chronic. Immediate dermal exposure to substances like dioxins may cause skin eruptions and other changes. Sustained exposure to radiation and other forms of land pollution can raise the risk of developing cancer or chronic disease.
The environmental damage from land pollution also has indirect negative effects on communities. Polluted land cannot be cultivated, denying communities in poor countries land for grazing or subsistence farming and leading to population displacement.
What can we do to help prevent land pollution?
Land pollution has diverse causes and its prevention requires a coordinated and cooperative approach that involves:
- Government, regional and local authorities
- Stakeholders in industry, agriculture, and the corporate sector
- Academic and social institutions
- Local communities
As the causes and effects of land pollution have begun to be more widely recognized and understood, efforts have been made to limit or ban the use of polluting substances. Authorities recognize the seriousness of negligent and wilful pollution by industry and enforce punitive fines where land pollution has been identified.
Guidance on the handling of hazardous materials has been produced to educate businesses and workers on how their waste can be safely disposed of. Regulation and compliance monitoring ensure the levels of key pollutants do not become excessive.
Intensive farming is a key source of land pollution. Many producers and growers are implementing sustainable or organic farming methods that avoid antibiotics, pesticides, or fertilizers. Consumers can support these efforts by buying foods that have been produced using methods that do not harm the land.
The communities that are affected or displaced by land pollution also require support and assistance in recovering their land and maintaining healthy soils with compensation if the pollution has been deliberate.
Land pollution has varied causes, but they all have the same detrimental effects; poisoning and degrading the land and decreasing its productivity and biodiversity. Thankfully, the ongoing contamination of land is organized as a significant threat to the environment and human health which needs to be tackled with a concerted effort.