What is the Main Cause of Soil Contamination

This is a question we’re asked frequently, and our answer is rarely a short one! This is because there is more than one source where contamination of soil is concerned, and a more specific answer can depend on several factors. Before we begin to explore the causes, we first need to explain exactly what soil contamination is.

Soil contamination (or soil pollution) refers to the presence of toxic chemicals or pollutants in soil at levels where there is a risk to human health, or that of the environment. This issue has drawn attention over the last few decades due to the effects on ecosystems, agriculture, and public health. In order to help prevent contamination going forward, we need to understand the primary causes through recent history.

One of the leading contributors to soil contamination are industrial operations such as manufacturing, mining, and chemical processing, which can release pollutants directly into the soil. Previous industrial activities (such as former gas works and factories), waste disposal (such as old landfills) or accidental release of chemicals (for example, leaking oil tanks) have been the cause of much contamination, but in some cases, there are naturally occurring high levels of chemicals, which are also detrimental to land soils.

Many of these industries have now vanished from our landscape but they may have contaminated the ground they once operated on over long periods of time. Years ago, there was no stringent environmental legislation in place, so contamination often went undetected.

Modern agriculture heavily relies on chemical interventions to enhance crop yields and protect plants from disease and pests. Excessive use of fertilisers, pesticides, and herbicides can lead to soil contamination. Not all of the properties in fertilisers are absorbed into crops; the remainder accumulates in the soil or is lost as runoff, which can lead to groundwater pollution. Their overuse can also cause chemical changes in soil composition and disrupt the micro-organism communities in the soil’s structure.

Landfills, if they are poorly managed, can contribute to soil contamination by leaking hazardous substances into the surrounding soil. Leachate (a liquid that forms when water percolates through waste) can carry dissolved materials into the soil which leads to contamination. Electronic waste contains toxins like lead, mercury, and cadmium, and if these are not disposed of properly, they can leach into the soil affecting plant and animal life.

Accidental release of hazardous chemicals or substances during storage, transport, or use can contaminate soil. Similarly, industrial accidents such as oil spills can also have a devastating effect on soil quality, sometimes making it unfit for agricultural or recreational purposes. Leaks from underground storage tanks containing petroleum products or chemicals can release hydrocarbons and other pollutants into soil.

With the need for housing increasing, construction is still a big business! The rapid expansion of urban areas and their associated construction activities can disturb soils and introduce contamination. Construction sites often use various chemicals, so improper handling or accidental spills can lead to soil pollution. Demolition sites where older buildings are knocked down to make way for new, may release hazardous materials like asbestos into the soil, which creates a massive health risk to nearby communities.

Some pollutants are airborne; industrial emissions, vehicle emissions, and other sources can settle on soil surfaces, leading to contamination. This is known as atmospheric deposition and can introduce heavy metals and other toxic substances into soil. Over time these contaminants can build up, especially in areas of heavy traffic or other industrial activity.

The use of untreated or inadequately treated sewage and wastewater intended for irrigation and fertilisers can put pathogens, heavy metals, and other organic pollutants into soils. This practice is a double-edged sword, as it not only contaminates the soil, but also risks the health of consumers of the produce grown within these soils.

The use of chemical agents during conflict and war can lead to severe soil contamination. The chemicals can stay in the environment for extended lengths of time leaving the soil toxic and unsuitable for agriculture and habitation. As an example, mustard gas stored during World War II has contaminated soil in some regions ever since.

The primary contributors of soil contamination come from human activity, but natural process can also play a role. Natural accumulation of compounds in soil due to imbalances between atmospheric deposition and leaching can lead to contamination. Phenomena such as erosion, increased salt content, loss of organic carbon, compacting, acidification and chemical pollution are also major causes of soil degradation.

Soil contamination continues to pose a significant threat to human health, agriculture, and the environment. Addressing this requires a combination of regulatory measures, sustainable practices, and community awareness to mitigate its impact and restore soil health. If you need help and advice regarding soil contamination treatment, you can contact us here.