What is soil contamination?
Soil contamination, or soil pollution, is a condition where the presence of contaminants has gone beyond a certain threshold leading to the deterioration of the natural chemical, physical or biological properties of the soil. The condition will cause a multitude of effects, ranging from susceptibility to erosion, inadequate rich soil depth, low nutrient content, and even the presence of toxic chemicals.
All these effects will ultimately prevent the soil from being used for economic activities such as agriculture, building and logistics, and may even create health safety concerns for communities in the present and future. Long-term effects of soil contamination could eventually lead to blighted communities and endemic environmental problems.
In the United Kingdom, there are currently 511 contaminated land sites. However, since the UK has a long industrial history, amplified by 20th century flawed industrial waste disposal practices and aggressive farming methods, the number of contaminated sites are believed to be significantly larger.
Why does soil contamination matter?
Soil pollution occurs when toxic chemicals, polluted substances and waste materials are introduced to the environment. Owing to the type of contaminants and severity, one or a combination of the following will occur:
• The soil’s ability to nurture natural or cultivated plants will deteriorate. This could have serious economic impact to farmland. The reduction or total loss of flora will also affect the food supply of local animals, which could lead to a long chain reaction culminating in a reduction of biodiversity.
• The presence of toxic material could enter the human body. The first and most obvious way is if the toxins enter underground aquifers. A second way is from indirect ingestion of soil when eating vegetables, roots or fruits. The third way is when eating animals reared on contaminated soil. Many chemicals do not cause an immediate reaction in the body. Instead, they only become toxic after the body’s detoxification and immune system becomes overloaded as a result of long-term accumulation.
• The absence of a strong top soil, or plants protecting the soil, could expose the area to wind or water erosion. Over time, this could trigger flash flood, sinkholes and even landslides.
Soil contamination caused by underground storage tanks containing tar. Image courtesy of Wikimedia Commons.
What are the major causes of soil contamination?
An important thing to remember is, soil contaminations almost always occur due to ignorance – very rarely do they happen intentionally. They typically ensue as a result of aggressive industrial and economic activities, which result in the introduction of one of the following chemicals into the soil:
• Heavy metals (lead, cadmium, arsenic, etc.)
• Coal tars, oils and fuel
• Chemical substances and compounds
• Toxic materials (asbestos, silica, soapstone, etc.)
• Radioactive by-products
The most frequent locations of contaminated land include:
• Ancient mines (such as the lead mines in Cornwall, Lake District and Shipham in Somerset)
• Heavy industrial sites (factory, mills, refineries, etc.)
• Large farms with high and prolonged use of chemical fertilisers
• Power plants
• Military testing site
Soil Pollution, a hidden reality
Strategies to Remedy Soil Contamination in UK
The passing of the Environmental Protection Act 1990 has given the Environment Agency broad regulatory powers to manage soil-contamination related issues in the UK. However, they are still very dependent on reports submitted by local councils, which serve as their eyes and ears.
Remedial efforts are quite straightforward – contaminated land can be excavated or capped, or isolated for a period of time for more serious cases.
The key is to ensure no current or potential future contamination occurs. This can be prevented by strict adherence to existing safety standards, particularly waste disposal and management policies, which once again, lie under the jurisdiction of local councils.