Soil pollution defines dangerously high concentrations of contaminants in the soil. While contaminants such as metals, inorganic ions, salts and organic compounds occur naturally in soils, these contaminants can exceed natural levels and become pollution.
The impacts of soil pollution can be detrimental to soil, plant growth and entire habitats. Soil pollution also has a direct impact on food security; the quality and safety of the food we eat depends on the health of our soil.
Causes of soil pollution
As with other types of pollution, the causes of soil pollution are often man-made.
Industrial pollutants are among the most common causes of soil pollution. Chemicals are released from industrial facilities into the ground in liquid and solid form. Industrial activities emit large amounts of arsenic fluorides and sulfur dioxide, and accidental spills and leaks during storage, transport and use contribute to soil pollution.
Agricultural activities such as excessive use of fertilizers and pesticides are other anthropogenic sources of soil pollution. Many fertilizers contain heavy metals such as calcium, nitrate and potassium chloride which accumulate in soils, contaminating them.
Other unsustainable agricultural practices such as intensive agricultural production deplete the soil, compromising its ability to degrade organic pollutants. This results in an accumulation of contaminants in the soil. Sewage and other liquid wastes from domestic water use, agricultural effluents from livestock and urban runoff also pollute soils.
A related cause is deforestation; the clearing of trees leads to increased soil erosion, which reduces the soil’s ability to support vegetation.
Soil pollution affects the soil’s ability to filter contaminants. Soil has a limited capacity to cope with pollutants, and when this capacity is exceeded, contaminants will impact other parts of the environment such as the food chain. Therefore, soil pollution also affects food security as it reduces crop yields and quality.
Soil pollution contributes to air pollution because it releases volatile compounds into the atmosphere. Additionally, air pollution created by the burning of fossil fuels can cause acid rain which produces an acidic environment in soils. This harms microorganisms, which improve soil structure by breaking down organic matter and promoting water runoff.
Chemicals in soils can also leach into groundwater, which can then reach streams, lakes and oceans. Additionally, soils rich in nitrogen and phosphorus can leach into waterways, causing algal blooms, which decrease the oxygen available to aquatic life. Similarly, soil erosion can lead to pollution and sedimentation of waterways.
Where does soil pollution occur
Soil pollution can be found all over the world, but particularly in parts of Europe and North America.
There are approximately 2.8 million potentially polluted sites in Europe, and 19% require remediation or risk reduction measures. The actions of industrial, commercial, production, waste disposal and treatment activities have been the main source of point source pollution of soils in Europe. Mining has contributed significantly to soil pollution in Cyprus, Slovakia and North Macedonia.
Although there have been improvements in waste management and legislation has become stricter, recent assessments in countries such as Bosnia and Herzegovina, Kosovo and Turkey indicate that soil pollution remains a significant problem. .
There are thousands of polluted sites in the United States and Canada. There are approximately 23,000 abandoned mines in the state of Colorado alone, which contribute to soil pollution. In addition, burning coal in Canadian provinces such as Alberta, Saskatchewan, New Brunswick and Nova Scotia produces coal ash. In addition, lakes and rivers in Alberta and Saskatchewan are currently experiencing very high levels of acid pollution that threaten aquatic ecosystems.
To counter soil pollution at the agricultural level, the EPA has recommended that farmers adopt sustainable practices:
- Nutrient management techniques
- Drainage practices that conserve resources
- Ground cover all year round
- Field pads
- Conservation tillage
- Access to streams for livestock.
Additionally, Congress passed the Pollution Prevention Act, which led to the creation of programs and strategies to reduce or eliminate pollution at the source.
Strategies focused on the mining industry include improving mine waste management, landscape restoration and topsoil conservation. Urban planning and wastewater treatment are also effective in reducing urban sources of soil pollution, such as sewage.