When people hear the word pollution, they often think about dirty water, smoke from vehicles or plastic waste floating in drains. Soil pollution receives less attention, even though the soil beneath our feet can also become contaminated.
Soil is not simply the ground on which we walk and build houses. It supports vegetation, agriculture and ecosystems, and it can also act as a pathway through which contaminants move into groundwater, plants, animals and eventually humans.
In Environmental Health Science, we are taught to look at the environment as an interconnected system. A substance dumped on land does not necessarily remain exactly where it was placed. Rainwater can carry contaminants through the soil, while plants can absorb certain substances. Contaminated soil can also come into contact with people through farming, construction, waste handling and other activities.
For Ilorin, this is not merely a theoretical concern. Studies conducted around dumpsites in the city have found evidence of changes in soil quality and contamination associated with waste disposal.
What Is Soil Pollution?
Soil pollution occurs when harmful substances accumulate in soil at levels that can negatively affect soil quality, plants, animals, ecosystems or human health.
Possible contaminants include heavy metals, petroleum products, pesticides, chemicals, sewage, pathogens and substances released from decomposing waste.
Some contaminants come from industries and agricultural activities, while others come from everyday waste disposal.
The National Policy on the Environment identifies soil pollution as one of the major forms of environmental pollution in Nigeria and links increasing pollution to factors including population growth, urbanisation, modern agricultural practices and the introduction of new technologies and consumer products (Federal Republic of Nigeria, 2021).
This is particularly important in growing cities.
As populations increase, more waste is generated and more land is used for housing, businesses, transportation and other activities.
What We Learn in Environmental Health
One of the things I have learnt as an Environmental Health Science student at Kwara State University is that environmental hazards should be considered according to their source, pathway and receptor.
This way of thinking is useful when examining contaminated soil.
For example, imagine a dumpsite where different types of waste are thrown together.
The source is the waste.
Rain may pass through the waste and produce contaminated liquid known as leachate.
The leachate can move through the soil.
Groundwater may then become exposed.
A person who uses that groundwater could become a receptor.
The chain can therefore look like this:
Waste → leachate → soil/groundwater → human exposure.
This is one reason environmental health is concerned with proper waste disposal rather than simply moving waste from one visible location to another.
What I Have Seen Around Ilorin
During environmental health training and field activities, one thing that becomes difficult to ignore is the relationship between waste and the surrounding environment.
A pile of refuse may contain food waste, plastics, metals, batteries, containers, broken household items and other materials.
When such materials are mixed together and left exposed, rainwater can pass through the waste.
The resulting liquid may contain substances released from the decomposing materials.
This is why a dumpsite should not be viewed simply as a pile of rubbish.
It is an environmental system with potential effects on soil, water, air, vegetation and human health.
Nigeria’s environmental policy has also identified indiscriminate dumping and inadequate waste collection as major environmental problems, noting that poor waste management can contribute to soil and groundwater pollution (Federal Republic of Nigeria, 2021).
Evidence from Ilorin Dumpsites
Research conducted in Ilorin provides useful local evidence.
Iji and colleagues assessed soil around three municipal dumpsites in Ilorin and compared the results with soil from a dumpsite-free control location. The researchers examined physicochemical characteristics and microorganisms in topsoil samples. They reported bacterial populations in soils from the dumpsites that were higher than those found in the control area and identified several bacterial species in the sampled soils (Iji et al., 2020).
This finding is important from an environmental-health perspective because improperly managed waste can introduce pathogenic microorganisms into the environment.
The issue is not that every microorganism found in soil will automatically make someone sick.
Rather, the finding demonstrates that waste disposal can alter the microbiological characteristics of the surrounding environment.
Heavy Metals Are Another Concern
Some waste materials can introduce heavy metals into soil.
Research examining three major dumpsites in Ilorin—including Ita-Amodu, Sawmill Garage and Kuntu—investigated soil characteristics and metals including cadmium, lead, zinc, iron and copper (Shehu-Alimi et al., 2021).
Another study assessed heavy metals in soil and plants around three waste dumpsites in Ilorin and reported the presence of metals including iron, lead, manganese and zinc in the sampled soils and plants (Donald, 2019).
This is where soil pollution becomes more complicated.
A contaminant in soil does not necessarily remain confined to the soil.
Plants growing in contaminated areas may take up certain substances. Animals may feed on those plants. People may then come into contact with contaminants through environmental or food pathways.
The actual risk depends on the contaminant, concentration, exposure pathway and duration.
The Ipata Area: A Local Case Study
A particularly relevant study was conducted around the Ipata area of Ilorin.
Researchers from Kwara State University and the University of Manchester investigated leachate contamination and groundwater vulnerability around an urban dumpsite in Ipata. Their work used geophysical methods, soil classification and physicochemical investigations to examine the relationship between the dumpsite and surrounding subsurface conditions (Olasunkanmi et al., 2024).
This case study is especially interesting to me because some of the researchers were from KWASU itself.
It demonstrates how environmental problems within our immediate surroundings can become subjects of scientific investigation.
The study was not simply about whether people could see waste at Ipata. It investigated what was happening beneath the surface and considered the vulnerability of groundwater to contamination.
That is exactly the kind of deeper environmental thinking that Environmental Health encourages.
Soil Pollution Can Affect Groundwater
Soil and groundwater cannot always be treated as completely separate environmental compartments.
When rainwater infiltrates contaminated waste, it may produce leachate that moves downward.
The characteristics of the soil and underlying geology influence how quickly and how far contaminants can move.
Research around the Oke-Eleke dumpsite in Ilorin used geophysical and geochemical techniques to investigate soil and groundwater contamination zones. The researchers identified subsurface layers associated with contamination and examined groundwater chemistry around the dumpsite (Olawuyi & Abraham, 2023).
This reinforces an important lesson: what happens on the surface can eventually affect what is happening underground.
Why Farmers Should Be Concerned
Soil is directly connected to agriculture.
When land is contaminated, growing food on that land without understanding the contamination can create potential exposure concerns.
Agricultural chemicals can also become pollutants when they are improperly applied, stored or disposed of.
Pesticides and fertilisers are useful when properly managed, but excessive or inappropriate use can affect soil and water.
This is why environmental health is not simply about removing visible waste.
It is also about ensuring that chemicals and other potentially hazardous materials are handled responsibly.
Soil Pollution and Erosion Are Different
This distinction is important because erosion was covered earlier in the disaster series.
Soil pollution and soil erosion are not the same thing.
Erosion involves the removal and movement of soil by agents such as water and wind.
Soil pollution involves the contamination of soil by harmful substances.
However, the two can interact.
If contaminated surface soil is removed by runoff, pollutants attached to that soil may be transported elsewhere.
Likewise, poor land management can expose soil to erosion while waste disposal introduces contaminants.
Understanding the difference prevents us from treating every environmental problem as though it has the same cause.
What Can Be Done?
The best solution to soil pollution is prevention.
Waste should be properly sorted, collected, transported and disposed of.
Hazardous waste should not simply be mixed with ordinary household waste.
Dumpsites should be properly planned and managed.
Leachate should be controlled so that it does not freely infiltrate surrounding soil and groundwater.
Industrial and agricultural chemicals should be stored and disposed of appropriately.
Contaminated land should also be investigated before being converted to other uses.
Nigeria’s environmental regulatory framework includes regulations covering sanitation and waste management, while NESREA provides regulatory oversight for environmental standards and violations (NESREA, 2026).
What Can Residents Do?
Individuals also have a role.
Do not dump batteries, chemicals, used oil or other potentially hazardous materials indiscriminately.
Do not use empty plots as unofficial dumpsites.
Do not assume that burying waste automatically makes it disappear.
Avoid growing food on visibly contaminated land without appropriate assessment.
Communities should also report serious environmental violations to the relevant authorities.
Small changes in waste handling can prevent contaminants from entering the soil in the first place.
The Environmental Health Perspective
My Environmental Health Science training has taught me that environmental protection is ultimately about protecting people.
When I look at a dumpsite now, I do not see only the visible pile of refuse.
I think about what is underneath it.
I think about leachate.
I think about soil microorganisms.
I think about groundwater.
I think about people living nearby.
I think about waste workers and scavengers who may have direct contact with the materials.
And I think about what happens when contaminated land is eventually developed.
This is why environmental health requires us to look beyond what is immediately visible.
Conclusion
Soil pollution is one of the quieter environmental problems affecting Nigerian cities.
Unlike a large fire or a flood, contaminated soil may not attract immediate attention. Its effects can develop gradually through contact with waste, contaminated groundwater, plants and other environmental pathways.
Ilorin already has scientific evidence demonstrating why the issue deserves attention. Studies around dumpsites in the city have investigated microorganisms, heavy metals, leachate and groundwater vulnerability.
The solution is not simply to move waste away from residential areas.
It is to manage waste properly from the point where it is generated to its final treatment or disposal.
As we are taught in Environmental Health, prevention should come before exposure becomes a public-health problem.
The ground beneath us may look silent, but it can carry the consequences of everything we choose to put on it.
References
- Federal Republic of Nigeria. (2021). National Policy on the Environment.
- Iji, J. O., Mokuolu, O. A., Abdulkadir, T. S., & Oluwaseun, O. V. (2020). Assessment of Quality Status of Soils Around Dumpsites in Ilorin Metropolis, Nigeria.
- Shehu-Alimi, E., Esosa, I., Ganiyu, B. A., Olanrewaju, S., & Daniel, O. (2021). Physicochemical and Heavy Metals Characteristics of Soil from Three Major Dumpsites in Ilorin Metropolis, North Central Nigeria.
- Olasunkanmi, N. K., Ogundele, D. T., Olayemi, V. T., Yahya, W. A., Olasunkanmi, A. R., Yusuf, Z. O., & Aderoju, S. A. (2024). Assessing leachate contamination and groundwater vulnerability in urban dumpsites: A case study of the Ipata Area, Ilorin, Nigeria. Journal of the Nigerian Society of Physical Sciences.
- Olawuyi, A. K., & Abraham, K. (2023). Detection and Delineation of Soil and Groundwater Contamination Zones Using Geophysical and Geochemical Methods around Oke-Eleke Dumpsite, Ilorin.
- National Environmental Standards and Regulations Enforcement Agency (NESREA). Laws & Regulations; Environmental Violations.
