What Is Soil Pollution? Environmental Impacts and Mitigation

Soil pollution refers to the dangerously high concentrations of contaminants in soil. While contaminants such as metals, inorganic ions, salts, and organic compounds naturally occur in soils, these can exceed natural levels and qualify as pollution.

Soil pollution can have far-reaching consequences; it is often detrimental to plant growth, disrupting food chains and entire ecosystems. In turn, it has a direct impact on food security. Here, we'll review the causes of soil pollution, its widespread environmental impacts, and how to improve soil conditions.

Causes of Soil Pollution

As with other types of pollution, the causes of soil pollution often come back to humans.

Industrial Pollutants

Industrial pollutants are among the most common causes of soil pollution. Chemicals are released from industrial facilities in both liquid and solid form. Industrial activities emit large amounts of arsenic fluorides and sulfur dioxide, which raise soil acidity and impact vegetation. Accidental spills and leaks during storage, transport, and usage contribute to soil pollution.

Agricultural Activities

There are several sources of soil pollution in industrial agriculture. Many fertilizers, for example, contain substantial amounts of heavy metals, such as calcium, nitrate, and potassium chloride that can disrupt regular growing seasons. Sewage and other liquid waste from domestic water use, agricultural effluents from animal husbandry, and urban runoff also pollute soils.

Another cause is deforestation; the clearing of trees results in increased soil erosion, which lessens the soil’s ability to support vegetation.  

Environmental Impacts

Soil has a finite capacity to cope with pollutants; when this is surpassed, contaminants will impact other parts of the environment, such as the food chain. As a result, soil pollution also affects food security as it reduces crop yields and quality.

Soil pollution contributes to air pollution as it releases volatile compounds into the atmosphere. Furthermore, air pollution created by the burning of fossil fuels can cause acid rain which produces an acidic environment in the soils. This harms micro-organisms, which improve the soil structure by breaking down organic material and helping water flow.

Chemicals within soils can also be leached into groundwater, which can then reach streams, lakes, and oceans. Also, soils with high levels of nitrogen and phosphorus can leach into waterways, causing algal blooms, which decrease the oxygen available for aquatic life. Likewise, soil erosion can lead to pollution and sedimentation in waterways.

Where Soil Pollution Occurs

Soil pollution can be found all over the world, but particularly in areas in Europe and North America.

Europe

According to the Food and Agriculture Organization of the United Nations, there are approximately 2.8 million potentially polluted sites in Europe, and 19% need remediation or risk-reduction measures. Actions from industrial, commercial, production, waste disposal, and treatment activities have been the main source of point-source soil pollution in Europe. Mining has been a significant contributor 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 is still a significant problem.  

North America

There are thousands of polluted sites in both the U.S. and Canada. There are approximately 23,000 abandoned mines in the state of Colorado alone, which contribute to soil pollution. Additionally, coal combustion from provinces in Canada such as Alberta, Saskatchewan, New Brunswick, and Nova Scotia produces coal ash. Also, lakes and rivers in Alberta and Saskatchewan are currently experiencing very high levels of acid pollution which threatens aquatic ecosystems.

Mitigation

To counter soil pollution on the agricultural level, the EPA has recommended that farmers adopt sustainable practices:

• Nutrient management techniques
• Drainage practices that conserve resources
• Year-round ground covering
• Field buffers
• Conservation tillage
• Access to streams for livestock.

Additionally, Congress passed the Pollution Prevention Act, which has led to the creation of programs and strategies that aims to reduce or eliminate pollution at the source.

Strategies that focus on the mining industry include improving the management of mining waste, restoring the landscape, and conserving topsoil. Urban planning and wastewater treatment are also effective in decreasing urban sources of soil pollution, such as sewage.