Soil Pollution: Human Impact On Earth's Skin

Soil pollution is a serious environmental concern, posing a range of health hazards to humans, animals, and the ecosystem. It occurs when soil is contaminated with higher than normal concentrations of waste materials, such as pesticides, fertilizers, herbicides, heavy metals, and toxic organic chemicals. These pollutants can enter the soil through various human activities, including industrial waste discharge, improper waste disposal, agricultural practices, and urban and industrial sources. Soil pollution has adverse effects on food security, reducing crop yields and quality, and contaminating water sources. It also alters soil biodiversity and compromises its ability to act as a natural filter. Given the finite nature of soil, preventing soil pollution is crucial to ensuring sustainable food production and maintaining ecosystem health.

Industrial waste

Mining activities, for instance, can result in the release of trace elements and waste rock deposits, which can contaminate nearby soils. Additionally, the processing of extracted materials can lead to the emission of pollutants during smelting operations. Manufacturing industries also contribute to soil pollution, with the specific contaminants depending on the manufacturing process and the product being manufactured.

Energy production, construction facilities, and transportation are other industrial sources of soil pollution. Energy production can result in the release of mercury and other heavy metal compounds, which can accumulate in plants and animals, eventually entering the human food chain. Construction activities can result in soil pollution through the use of lead-based paint, while transportation-related activities, such as vehicle exhaust and petrol or diesel spills, can contaminate soils with petroleum hydrocarbons.

The improper disposal of toxic industrial waste is another critical factor in soil pollution. When toxic waste is stored in landfills, it can seep into the soil, contaminating both the soil and groundwater. Industrial waste can also pollute water sources, which are used for irrigation, thereby affecting crop quality and requiring increased use of fertilizers, which further contributes to water pollution.

The chemicals used in industrial processes or generated as byproducts are primary contributors to land pollution. This pollution can result in land degradation, reducing crop yields and rendering crops unsafe for human and animal consumption.

Pesticides and fertilisers

Pesticides are often used as a quick, easy, and inexpensive solution to control weeds and insect pests. However, their use comes at a significant environmental cost. Pesticides contaminate the soil, air, and water across countries, with pesticide residues found in surface and groundwater. They are toxic not only to insects and weeds but also to a host of other organisms, including birds, fish, beneficial insects, and non-target plants. Insecticides are the most acutely toxic class of pesticides, but herbicides can also harm non-target organisms.

Pesticides can reach water bodies through runoff from treated plants and soil, and studies have found pesticides in most water and fish samples from streams and rivers. Pesticides can also persist in the soil for years or decades, continuing to harm soil health and biodiversity. Soil organisms are exposed to a cocktail of toxic chemicals, and mixtures of pesticide residues in the soil are common since farmers often use multiple pesticides simultaneously.

A 2021 peer-reviewed study found that pesticides widely used in American agriculture pose a grave threat to organisms necessary for healthy soil, biodiversity, and the fight against climate change. The study, the largest and most comprehensive review of agricultural pesticides' impacts on soil organisms, showed that pesticides kill or harm soil invertebrates like earthworms, ants, beetles, and ground-nesting bees. It also revealed negative effects across all studied pesticide classes, demonstrating that pesticides are incompatible with healthy soil.

The use of pesticide-coated seeds, such as neonicotinoid-treated seeds, further increases soil organisms' exposure to toxic chemicals. Neonicotinoids are highly harmful to insects, and their use has made American agriculture 48 times more toxic to insect life. While pesticide companies argue that their products are necessary to feed the world, research suggests that the continued use of toxic chemicals undermines the healthy soil ecosystems that sustainable food production depends on.

In addition to the environmental concerns, there are also risks to human health. The long-term effects of low-level exposure to pesticides are influenced by concomitant exposure to other pesticides and pollutants. However, there are inherent difficulties in fully evaluating the risks due to the large number of human variables involved.

Furthermore, the improper disposal of obsolete pesticides can lead to soil pollution. In the early 2000s, developing countries, particularly in Africa, South America, the Caribbean, Central Asia, India, and Eastern Europe, had large stockpiles of outdated pesticides. While international efforts have safely eliminated most above-ground obsolete stocks, buried pesticides and soil polluted by leakage from these stockpiles remain a concern.

Fertilisers, particularly chemical fertilisers, are also a significant contributor to soil pollution. While fertilisers are essential for maintaining soil fertility and increasing agricultural production, their overuse or insufficient application can result in low efficiency of nutrient usage and decreased soil biodiversity and fertility. This, in turn, reduces crop yields and turns productive agricultural land into unproductive areas.

The excessive use of fertilisers and pesticides leads to soil contamination and negatively impacts soil health. It obstructs the breakdown of soil organic matter, alters nutrient cycling, and affects food safety, especially when bioconcentrated pollutants enter organisms within food chains.

Therefore, the pollution caused by pesticides and fertilisers has far-reaching consequences for the environment, human health, and food security.

Poor agricultural practices

Synthetic fertilizers, commonly used in industrial crop production, can also degrade soil health. The excessive application of fertilizers contributes to the buildup of salts and heavy metals in the soil, affecting plant growth and causing soil salinization. Fertilizers produced from fossil fuels can decrease soil microbiological diversity and favour the growth of more pathological strains.

Soil erosion is another consequence of poor agricultural practices. Intensive tillage and monocropping, combined with inadequate soil management, can lead to significant wind and water erosion. The loss of topsoil results in a decline in soil fertility and the loss of nutrients and organic matter essential for plant growth.

The inappropriate selection of crops and fertilizers can further exacerbate the problem. Certain crops may be more susceptible to erosion, and the wrong choice of fertilizer can increase soil acidification and eutrophication.

To address these issues, sustainable agricultural practices are being promoted. The Food and Agriculture Organization (FAO) has developed guidelines for sustainable soil management, encouraging nutrient recycling, agronomic practices, and improved land management. Conservation agriculture, precision fertilization methods, and afforestation are also recommended to restore and maintain soil health.

Mining and construction

Soil contamination by heavy metals is a critical issue stemming from mining operations. Arsenic, cadmium, lead, mercury, and zinc ions have been detected in soil, posing risks to vegetation, wildlife, and human health. These contaminants interfere with root functioning, hindering plants' ability to capture soil resources. Additionally, soil acidification through pH diminution by chemical contamination reduces species diversity and modifies nutrient availability, leading to vegetation loss.

The construction of mines often results in deforestation and habitat destruction, causing soil erosion and degradation in surrounding areas. Mountaintop removal mining, for instance, blasts the entire top of a mountain with explosives, creating massive canyon-sized holes in the land. This exposes hillsides to erosion, impacting nearby drainages, creeks, and rivers.

Furthermore, mining activities generate toxic tailings—the leftover materials after valuable resource extraction. These tailings, often stored in tailings dams, contain harmful substances such as cyanide, mercury, and arsenic. Leakages from these tailings can contaminate soil and water sources, even years after a mine's decommissioning.

Underground mining techniques, such as phytomining and asteroid mining, are emerging as potentially less invasive alternatives. These methods may reduce ecological scarring and waste production, offering more sustainable approaches to mining. However, it is essential to enhance environmental standards, regulations, and transparency in mining practices to minimise soil pollution and its adverse effects.

Radioactive emissions

One of the primary sources of soil pollution from radioactive emissions is the improper disposal of radioactive waste. This waste may contain radioactive matter that mixes with the soil, rendering it highly toxic and infertile. Radioactive substances such as radium, thorium, uranium, and nitrogen can infiltrate the soil, creating toxic effects. The Fukushima nuclear accident in 2011, for example, resulted in the displacement of 110,000 people, and the Japanese government is now under pressure to decontaminate the affected areas.

The consequences of radioactive soil pollution are far-reaching. It can lead to cell modification and genetic mutations in living organisms, including humans. The most common disease associated with exposure to radioactive pollution is cancer. Other diseases linked to radioactive waste exposure include anaemia, leukaemia, haemorrhages, and cardiovascular issues. Additionally, plants grown in contaminated soil may absorb radiation, which can then move up the food chain when herbivores and carnivores consume these plants.

Radioactive contamination of soils is also considered a separate type of degradation, reducing soil fertility. This degradation is caused by technogenic radionuclides, which can come from nuclear weapons tests, the operation of nuclear facilities, and radioactive waste. The release of radionuclides into water sources and the environment can further contaminate soil and plants.

To address the issue of radioactive soil pollution, proper disposal of radioactive waste is crucial. Additionally, the FAO's Revised World Soil Charter recommends that national governments implement regulations to limit the accumulation of contaminants and promote sustainable soil management practices.

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