Soil Pollution - Definition, Causes, Effects, Control, FAQs

Soil pollution has been referred to as an invisible environmental crisis. Yet, its impacts are deep and far-reaching. Soil basically sustains our ecosystems in various ways: as a medium for plant growth, for filtering water, and for keeping biodiversity. Soil contamination is basically caused by dangerous elements like heavy metals, pesticides, and industrial wastes that collect in the soil at a level likely to cause risk to health and/or the environment.

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This Story also Contains

1. Understanding Soil Pollution
2. Control of soil pollution:
3. Industrial wastes:
4. Waste Management
5. Green Chemistry
6. Types and Causes of Soil Pollution
7. Real Life Connection/Application
8. Some Solved Examples
9. Conclusion

Understanding Soil Pollution

Therefore, soil Pollution can be defined as the presence of these toxic chemicals or pollutants in the soil at concentrations enough to cause a potential risk to human health and the Ecosystem. This material is either natural or man-made, and its concentration goes way above the normal levels in the soil. The chief contributors to soil pollution are:

• Industrial discharges
• Agricultural practices
• Improper waste disposal

The sol or earth has been recognized as the mother of all plants, animals, and human beings. It is very essential either directly or indirectly for the survival and maintenance of various biological species including man, as it produces food for all. The chief components of the soil are inorganic matter(90-95%) and organic matter(5-10%). Besides, the soil contains water and air. The composition of soil varies considerably from place to place.
The soil has become the dumping ground of most of the waste products, i.e, domestic, human, animal, industrial, and agricultural. Every year the solid wastes dumped into the soil are increasing at an alarming rate all over the world. Different kinds of poisonous materials are being used these days and the whole earth is increasingly being poisoned and polluted as a consequence. The problem of soil pollution has been aggravated by the use of agrochemicals such as pesticides, fungicides, insecticides, fertilizers, and manures. Besides, the soil is polluted by deadly pathogenic organisms.

During World War II, DDT was found to be of great use in the control of malaria and other insect-borne diseases. Therefore, after the war, DDT was put to use in agriculture to control the damage caused by insects, rodents, weeds, and various crop diseases.

These days, the pesticide industry has shifted its attention to herbicides such as sodium chlorate (NaClO₃), sodium arsenite (Na₃AsO₃)and many others. During the first half of the last century, the shift from mechanical to chemical weed control provided the industry with a flourishing economic market. But one must remember that these are also not environment friendly.

Most herbicides are toxic to mammals but are not as persistent as organo-chlorides. These chemicals decompose in a few months. Like organo-chlorides, these too become concentrated in the food web. Some herbicides cause birth defects. Studies show that corn fields sprayed with herbicides are more prone to insect attack and plant disease than fields that are weeded manually.

Pesticides and herbicides represent only a very small portion of widespread chemical pollution. A large number of other compounds that are used regularly in chemical and industrial processes for manufacturing activities are finally released into the atmosphere in one or another form.

Control of soil pollution:

(i) The use of chemical fertilizers can be reduced by applying biofertilizers and manures. Biological methods of pest control can also reduce the use of pesticides and thereby minimize soil pollution.
(ii) Recycling and recovery of materials appears to be a reasonable solution for reducing soil pollution. Materials such as paper, glass and some kinds of plastics can be recycled. This would decrease the volume of refuse and help in the conservation of natural resources. For example, recovery of one tonne of paper can save 17 trees.
(iii) Control of land loss can be attempted by restoring forest and grass cover to check soil erosion and floods. Crop rotation or mixed cropping can improve the fertility of the land

Industrial wastes:

Industrial solid wastes are also sorted out as biodegradable and non-degradable wastes. Biodegradable wastes are generated by cotton mills, food processing units, paper mills, and textile factories. Non-biodegradable wastes are generated by thermal power plants which produce fly ash; integrated iron and steel plants which produce blast furnace slag and steel melting slag. Industries manufacturing aluminium, zinc and copper produce mud and tailings. Fertilizer industries produce gypsum. Hazardous wastes such as inflammable, composite explosives, or highly reactive substances are produced by industries dealing in metals, chemicals, drugs, pharmaceuticals, dyes, pesticides, rubber goods, etc.

The disposal of non-degradable industrial solid wastes, if not done by a proper and suitable method, may cause a serious threat to the environment. New innovations have led to different uses of waste material. Nowadays, fly ash and slag from the steel industry are utilised by the cement industry. Large quantities of toxic wastes are usually destroyed by controlled incineration, whereas small quantities are burnt along with factory garbage in open bins. Moreover, solid wastes if not managed effectively, affect the components of the environment.

Waste Management

Solid waste is not the only waste, which you see in your household garbage box. Besides household discards, there are medical, agricultural, industrial, and mining wastes. The improper disposal of waste is one of the major causes of environmental degradation. Therefore, the management of waste is of utmost importance.

Green Chemistry

Green chemistry is a way of thinking and is about utilizing the existing knowledge and principles of chemistry and other sciences to reduce the adverse impact on the environment. Green chemistry is a production process that would bring about minimum pollution or deterioration to the environment. The byproducts generated during a process, if not used gainfully, add to the environmental pollution. Such processes are not only environmentally unfriendly but also cost-ineffective. The waste generation and its disposal both are economically unsound. Utilization of existing knowledge base for reducing chemical hazards along with developmental activities is the foundation of green chemistry.

Types and Causes of Soil Pollution

There are broad categories of land pollution which can be based on their sources:

Some effects of soil pollution are dangerous and can lead to the following: -

• Soil infertility -
• Consumption of contaminated foodstuffs -
• Negative Impacts on human and wildlife health

1. Agricultural Pollution:

This comes as a result of the excessive use of chemical fertilizers and pesticides. For example, if the application of nitrogen-based fertilizers is a bit excessive, then it might cause nutrient runoff that harms the water bodies, thus affecting aquatic life.

2. Industrial Pollution:

Most industries directly discharge their by-product wastes onto the land. Heavy metals like lead and mercury may be present in the waste. The mining industries also form one of the major causes of degradation of land due to the release of their toxic byproducts.

3. Urban Pollution:

The process of urbanization results in soil pollution, which is caused by the improper disposal of refuse and by chemicals released from domestic products that reach landfills, eventually reaching the land and negatively impacting the soil.

4. Solid Waste Pollution:

Soil pollution may be caused by the improper disposal of solid wastes such as plastics and e-waste. For instance, when plastics break down, dangerous chemicals are released into the environment.

Each of the various kinds of soil pollution is a challenge unto itself and specific solutions will be required to mitigate their impacts.

Real Life Connection/Application

Soil pollution is relevant to both public health and food security. Lowered agricultural productivity can decrease food supplies due to contaminated soil, thereby increasing the risk of malnutrition. For example, research has proved that crops raised on polluted soils usually include unsafe levels of heavy metals that might finally build up in the food chain and end up in human bodies.

Again, respiratory problems, skin diseases, and cancer, especially in children and elderly people, are some of the health effects attributed to soil pollution. According to the reports by the European Environment Agency, more than 500,000 deaths prematurely caused annually across the world are linked to factors relating to soil pollution.

A number of initiatives and policies have flowed out as a result of the developing crisis related to soil pollution. The zero pollution action plan of the European Union had set the goal to reduce hazardous chemicals considerably by the year 2030 and advance less polluting and more sustainable agricultural practices. The United Nations shows that, for health and reducing pollution, it is necessary to manage the soils in a better way.

Working interventions are copiously illustrated with case studies across the world. On their part, community-driven initiatives in organic farming in India have made some milestones in helping farmers reduce dependence on chemical-based fertilizers and maintain good soil health. Obviously, such efforts are intended not only to enhance agriculture productivity but for the general well-being of communities.

Recommended topic video on (Soil Pollution)

Some Solved Examples

Example 1
Question:
Which of the following statements is an incorrect reason for eutrophication?

(A) Excess usage of fertilizers
(B) Excess usage of detergents
(C) Dense plant population in water bodies
(D) Lack of nutrients in water bodies that prevent plant growth

Choose the most appropriate answer from the options given below:

1) (D) only
2) (B) and (D) only
3) (A) only
4) (C) only

Solution:
The incorrect statement related to eutrophication is the lack of nutrients in water bodies that prevent plant growth. Eutrophication occurs due to an excess of nutrients, not a lack. Hence, the answer is (1) (D) only.

Example 2
Question:
Given below are two statements:

Statement I: Non-biodegradable wastes are generated by thermal power plants.
Statement II: Biodegradable detergents lead to eutrophication.

In light of the above statements, choose the most appropriate answer from the options given below:

1) Both Statement I and Statement II are false
2) Both Statement I and Statement II are true
3) Statement I is false and Statement II is true
4) Statement I is true and Statement II is false

Solution:
Non-biodegradable wastes are indeed generated by thermal power plants (e.g., fly ash), and biodegradable detergents can lead to eutrophication by causing excessive nutrient enrichment in water bodies. Therefore, both statements are true. Hence, the answer is (2).

Example 3
Question:
Which of the following elements causes damage to the kidney and liver when they are present more than their tolerance limit?

1) Cd
2) Hg
3) Ni
4) All of these

Solution:
Elements such as cadmium (Cd), mercury (Hg), and nickel (Ni) can all cause damage to the kidney and liver when present in amounts exceeding their tolerance limits. Hence, the answer is (4) All of these.

Example 4
Question:
Eutrophication leads to:

1) Depletion of dissolved oxygen in water
2) Death of animals
3) Depletion of ozone
4) Only 1 & 2

Solution:
Eutrophication leads to the depletion of dissolved oxygen in water and the death of animals due to the resulting hypoxic conditions. It does not affect ozone levels. Hence, the answer is (4) Only 1 & 2.

Example 5
Question:
Spraying of DDT on crops causes pollution of:

1) Air, water, and soil pollution
2) Air and soil pollution
3) Air and water pollution
4) Soil and water pollution

Solution:
Spraying DDT on crops leads to pollution of air, water, and soil due to its persistence and bioaccumulation properties. Hence, the answer is (1) Air, water, and soil pollution.

Conclusion

Among many ecological issues, the most prominent and grievous risks to human health, food security, and ecological balance come from soil pollution. Soil pollution can be defined as Dangerous substances into the soil arising from agricultural activities, industrial discharges, and the management of urban waste. High levels of soil pollution have serious implications: they lead to a decrease in fertility, deterioration of food security, and negative impacts on human and wildlife health.