Pollutants in the land not only contaminate the land but also have far-reaching consequences. Sources can be agricultural, industrial (including mining and metallurgy), and municipal wastes. Acid rain, the spreading of water pollution to surrounding beaches and riverbanks, litter, and even new construction sites can also be sources of land pollution.
Chemical Effects on Life
One of the biggest threats to the ecosystem caused by land pollution is chemical contamination. Plastics, toxins in wastes like anti-freeze and other chemicals seep into the ground where they remain. These chemicals can contaminate groundwater and the land. These include persistent organic pollutants (POPs) that comprise a special group of chemicals.
Persistent Organic Pollutants Contaminate the Ground
An International Institute Sustainable Development Bulletin (IISD) from 2019 explains that POPs are chemicals used by industry and/or in agriculture. These pesticides remain in the environment for a long time.
- Examples of POPs include DDT, dioxins, and polychlorinated bipenols (PCBs).
- Twelve POPs have been banned by the Stockholm Convention, a United Nations environment program which the US signed in agreement.
- A World Health Organization (WHO) report from 2008 explained that POPs are unintended by-products of pesticides. They can be produced by burning "coal, peat, wood, hospital waste, hazardous waste or municipal waste." POPs can also be produced by car emissions.
- In 2019, WHO published an updated The Interneational Code of Conduct on Pesticide Management, as a guide for the agriculture industry and government regulators for pesticide control to protect public health and the environment.
Impact on Biodiversity
All chemicals, including POPs, poison the ground. This can lead to the loss of some types of plant and animal life.
- Plants growing in the ground poisoned by chemicals may become contaminated and survive, passing on the contamination to grazing animals or the plants simply die off.
- Animals dependent on the plants for food may eat the contaminated plants and become ill and die off.
- If the plants die off, the animals dependent on them as a food source must migrate in search of healthy plants. This causes an influx of animals into areas where there isn't enough plant food to sustain them. This overcrowding of the animal population can set up disease and/or starvation.
- Human are affected by various chemicals that make their way into the food-chain and are present in the foods humans eat. This is especially prevalent in animal food sources where chemicals have accumulated in the fat cells, known as bioaccumulation.
POPs in Water, Waterways and Oceans
POPs also accumulate in waterways and oceans through agriculture and urban runoff. These pollutants are carried over long distances around the planet and can affect areas where the chemicals aren't used.
A scientific study in 2016 found that POPs are still a threat to marine life due to bioaccumulation. The WHO report lists the affects POPs can have on wildlife by persisting for centuries unchanged. These affect the immune, enzyme and reproductive systems, and cause tumors in mammals, reptiles, fish, and birds. Some changes seen include, the thinning of bird egg shells and a population decline in seals, snails and alligators.
Damaging Effects to the Land
When land pollution is severe, it damages the soil. This leads to a loss in minerals and beneficial microorganisms, impacting soil fertility. This means native plants may fail to grow in these areas, robbing the ecosystem of a food source for animals.
Spread of Invasive Plant Species
Ecosystems may also be upset by pollution when the soil fails to sustain native plants, but can still support other vegetation. Invasive weeds that choke off the remaining sources of native vegetation can spring up in areas weakened by pollution. According to a report from the University of Florida, invasive weeds are often introduced into areas as part of yard or construction waste dumping.
Loss of Fertility
The Food and Agriculture Organization (FOA) of the United Nations points out the excessive use of chemical fertilizers and pesticides kills beneficial soil microorganisms, reducing their biodiversity with devastating consequences for soil health. Microorganisms are necessary for a couple of things that contribute to the fertility of soil that include:
- Microorganisms are responsible for nutrient cycling that converts nutrients into forms that can be used by crops.
- Microorganisms break down toxic compounds that are the by-products agrochemicals that decreases pollution of the soil. If microorganisms aren't present in the soil, the pollution accumulates and continues to grow toxic.
- The FAO warns that soil is a dynamic ecosystem within its own right. When this balance is upset, it affects the health of plants, animals and subsequently humans.
Sometimes, pollution can damage the soil to the point that vegetation can no longer grow in the contaminated area. This may lead to soil erosion. According to the Union of Concerned Scientists, soil erosion is common in agricultural fields.
Chemical Fertilizers and Pesticides
Chemical fertilizers and pesticides kill microorganisms that are necessary to break down organic matter that improves soil structure. The FAO document on erosion explains that "nearly all soils containing little or no organic matter are very susceptible to erosion."
- Organic matter helps the soil to absorb and store water.
- Organic matter binds the soil with larger aggregates, such as mineral crystals, mineraloid particles or rock particles.
- Fungus helps bind soil particles together. According to the FAO, altered soil salinity (amount of salt) due to chemicals can also reduce fungus species and the number of fungi, making the soil suspectible to erosion since.
- Erosion leads to the loss of topsoil in the earth. The World Wildlife Fund reports that half of earth's topsoil has been lost in just the last 150 years. This can reduce land productivity and cause pollution by clogging waterways.
Land pollution can be caused by contaminated areas, through polluted waterways, or acid rain created from air pollution. This pollution can spread and have a negative impact on surrounding environments.
- Chemicals dumped in cleanup sites leach underground and contaminate groundwater sources.
- The US Environmental Protection Agency (EPA) emphasizes the importance in limiting and containing this damage since groundwater is used for drinking and agriculture purposes.
- According to the EPA, nutrient pollution caused partly by runoff of chemical fertilizers from farms is a major form of pollution. Increased levels of nitrates in water can be harmful to infants even in low quantities.
- The resultant air pollution can affect human "ability to breathe, limit visibility and alter plant growth." Moreover, it can lead to depletion of oxygen in waterways, affecting fish life.
Health Risk to People
Heavy metals and POPs pollutants in land contamination. These pose serious human health concerns.
Heavy metal in soil is polluting food and water, increasing the risk of cancer. For example:
- In China, "cancer villages" are linked to areas where farming occurs in land polluted by over-application of chemical pesticides and other heavy metals according to a scientific publication of 2015.
- In Europe, it is estimated that cancers are caused by arsenic, asbestos, and dioxins; neurological damage and lower IQ results from lead, and arsenic. Kidney, skeletal and bone diseases arise from pollutants like lead, mercury, fluoride, and cadmium. Though cost to people and society is already reckoned in millions of dollars, it is suspected that these estimates of damage may not be comprehensive enough according to a 2013 European Commission report.
The EPA acknowledges that humans and wildlife alike can be affected by exposure to the pollutants through breathing them in, eating them (via water or through food sources), or by touching them. However, they have no estimates of damage at a national level.
The health impacts due to POPs arise from both acute and chronic exposure. These exposures can be found in food contamination as well as environmental.
- The IISD states that POPs even in small doses "lead to cancer, damage to the central and peripheral nervous systems, diseases of the immune system, reproductive disorders and interference with normal infant and child development."
- Mass poisoning due to food contamination has also occurred.
- According to WHO in 1968, rice oil contaminated by PCBs and PCDFs affected more than a thousand people in Japan and Taiwan. Even seven years after women were exposed to these POPs, they gave birth to children with minor deformities and behavioural problems.
The EPA presents a study of five communities and their efforts of redevelopment of brownfields. The negative social impacts that occur from brownfields or polluted land in urban areas are devastating. They include:
- Limit in job growth, economic development and tax revenue
- Reduction in neighboring property values
- Increase in crime rates of suffering communities
Dealing With Land Pollution
Many of the long-lasting effects of land pollution, such as the leaching of chemicals into the soil, cannot be easily reversed. The best way to deal with land pollution is to keep it from happening in the first place. Stepping up recycling efforts and preventing overuse of soil that makes it acidic and contaminates nearby areas will keep the problem from spreading. Wherever possible, contribute to cleanup efforts to help prevent land pollution from becoming worse.