Soil contamination by heavy metals: what is the impact?

Soil contamination is becoming an increasingly important issue for people and governments around the world due to its adverse effects on the environment and resulting health problems.

Heavy metals are some of the most common sources of soil contamination. In this article, our environmental services specialists explain the potential consequences of their presence in soil. 

What are heavy metals?

Heavy metals are naturally occurring elements that have a high atomic weight and a density at least 5 times that of water. Lead, copper and zinc are considered heavy metals.

Heavy metals have multiple industrial, domestic, agricultural, medical and technological applications, leading to their widespread use and eventual dispersion into the environment. As a result, here is increasing concern about the potential consequences for human health and the stability of affected ecosystems.

Heavy metals are among the types of contaminants that can be found in residential areas. 

Where heavy metals come from

Heavy metals in the soil, water and atmosphere come from a variety of sources such as landfills, domestic and industrial waste, mining and oil extraction sites, and air pollution.

How heavy metals affect health

Heavy metals are toxic substances that can damage the nervous system and multiple organs, as well as potentially causing cancer in both humans and animals, even at low levels of exposure. Their toxicity depends on several factors, including the variety, amount and type of exposure, as well as the age, sex, genetic makeup and nutritional condition of the people exposed.

Heavy metal contamination in the soil

Many heavy metals occur naturally in soil, so it’s normal for soil tests to detect traces of them. They are only considered a hazard when they are present in larger quantities, at which point they become classified as inorganic contaminants.

Large amounts of heavy metals in soil are doubly dangerous because they can cause both above-ground contamination (plants) and below-ground contamination (groundwater).

Heavy metal crop contamination via phytoextraction

Certain heavy metals are essential to the physiological functions of plants. For example, zinc is involved in photosynthesis and iron plays a major role in chlorophyll and protein synthesis.

However, when large quantities of heavy metals are present in the soil and bioavailable to plants, they can be detrimental to soil fertility and may even be absorbed into the root system, leading to accumulation in the plants’ harvestable parts. This phenomenon is called phytoextraction.

Before setting up a vegetable garden or planting crops in an area that hasn’t undergone a soil analysis and may have been contaminated, it’s best to exercise caution. Otherwise, there is a real risk that contaminants could spread throughout the food chains and affect the health of multiple organisms.

Interestingly, phytoextraction can actually be used as a soil decontamination strategy. In such projects, heavy metals like lead, copper, cadmium, nickel and zinc are extracted from the soil using accumulator or hyperaccumulator plants, whose leaves and stems are regularly cut, incinerated and disposed of in landfills.

Contamination of groundwater near contaminated soil

When an area is contaminated by heavy metals, the impact can extend far beyond the boundaries of one property. Heavy metals can seep down through the soil and contaminate the groundwater and nearby waterways.

When water from precipitation or snowmelt penetrates contaminated soil, it can pick up trace elements of dissolved heavy metals. The contaminated water then seeps down through the soil to the groundwater that flows into the area’s drainage basin. The severity of this phenomenon varies depending on the characteristics of the soil (permeability, acidity, etc.) and the types of heavy metals present.

When heavy metal pollution becomes too severe or too concentrated, the natural breakdown processes within ecosystems fail, disrupting their balance. When the ecosystem and water quality are both compromised, an area is considered to be polluted.

In some areas, this can lead to sources of drinking water being contaminated, putting the health of the local population in danger.

How to decontaminate soil that contains heavy metals

There are several methods for reducing the risks associated with the presence of heavy metals in soil, but ex-situ disposal is possibly the cheapest, fastest and most efficient. 

What is ex-situ disposal?

Ex-situ disposal is a contaminated soil remediation strategy that involves excavating the contaminated soil and transporting it to a secure landfill designated by the authorities. 

Dealing with Heavy Metal Soil Contamination? Contact Enviro Urgence.

At EBI Enviro Urgence, we offer a specialized remediation service for soil contaminated by heavy metals and other hazardous materials. Our methods are carefully designed to protect the most vulnerable ecosystems. They involve several keysteps:

• Assessing the scope of the contamination
• Using the Generic Criteria Grid in accordance with the Soil Protection and Contaminated Sites Rehabilitation policy
• Implementing various options for treating or disposing of the soil
• Excavating and transporting the contaminated soil
• Providing options for treatment or landfill sites

 

Need a property decontaminated? Don’t hesitate to contact us! The situation will be handled by a team of professionals who truly care about the safety of both people and the environment.