Soil pollution is an important chapter in the environmental chemistry syllabus that focuses on educating the students about causes of soil pollution, the harmful effects of soil pollution, harmful pollutants and so on. It is important to know thoroughly about the common aspects of this chapter since it has a good weightage in the NEET exam paper. So, in order to score high marks, students should be able to understand the basic causes and effects of soil pollution.
What is Soil Pollution?
The contamination or degradation of soil due to the presence of impurities like chemicals, xenobiotics, toxic wastes, plastic, etc that alters the natural composition of the soil is termed as soil pollution. There are many causes that lead to soil pollution. Some of them are-
Acidification of soil by acid rain
long term leaching of base
excessive land use practices
use of inorganic nitrogen fertilizers
All these processes and causes lead to production of either H+ ions or CO2 which further get dissolved into soil water and form carbonic acid. Such soil is not good for cultivation.
The basic cause of soil pollution is toxic chemicals mixing in the upper nutritious soil. These toxins and pesticides or herbicides continue to induce long term ill effects on human health, nature and on the soil environment.
Soil Pollutions is either- Naturally caused or by Anthropogenic means
Natural Soil Pollution occurs mostly by accumulation of compounds containing the perchlorate anions. Or, sometimes, some contaminants are naturally produced in the soil under the effect of certain environmental conditions.
On the other hand, Anthropogenic pollution of soil is common and occurs in most of the cases. Many human activities pollute the soil. These include:
The demolition of old buildings releases a lot of wastes and this can involve the contamination of nearby soil with asbestos.
Usage of lead-based paint during construction activities pollute the soil with hazardous lead wastes.
Spillage of petrol and diesel during transportation contaminates soil with the hydrocarbons found in petroleum.
Activities associated with metal casting factories mostly cause the dispersion of metallic contaminants into the nearby soils. This in turn poses a major soil pollution threat.
Underground mining activities may contaminate the layers of soil with heavy metals.
Improper disposal of highly toxic industrial waste can severely pollute the soil. For example, the storage of toxic wastes in landfills can result in the seepage of the waste into the upper layers of soil. This waste may even pollute the groundwater reserves by easily coming in contact with it.
Chemical pesticides contain several hazardous pollutants. So, use of chemical pesticides can result in severe soil pollution.
Sewage produced in urbanized areas can also contaminate soil due to improper disposal. These wastes may also contain several carcinogenic substances which may pollute the soil badly.
Let’s have a look at some solved Multiple Choice Questions on Soil Pollution.
1. What is negative Soil Pollution?
It indicates reduction in soil productivity due to erosion and over use
Reduction in soil productivity due to addition of pesticides
Converting fertile land into harden land by dumping ash, sludge and garbage
None of the above
2. The quantity of DDT at each trophic level in the Food Chain
Remains the same
3. DDT is a major contributor to Pollution because
It kills useful microorganisms
It destroys valuable species of worms
It is non biodegradable
It interferes with pesticides
4. The chemicals released due to unsustainable agricultural practises and cause Soil Pollution are
5. Slash and burn agriculture, which is not a healthy technique of farming and depletes soil of the important nutrients, is a part of which of the following?
None of the above
6. In a coal fired power plant Electrostatic precipitators are installed to control the emission of
7. How are PAHs related to Soil Pollution?
They are carcinogenic organic compounds
They are fertilizer wastes
They are inorganic wastes from industries
They are harmful metals that pollute the soil
8. Soil pollution due to PAHs can be sourced to
extraction of shale oil
All of the above
9. Benzene and Methylbenzene the major Soil Pollutants mostly from the Petroleum Industries are
Heavy organic pollutants
None of the above
10. Which of these pollutants is a Herbicide?
11. Which of the following serves as an indicator of Atmospheric Pollution
12. Why is area treatment important for Soil?
(a) To reduces the impact of raindrops on the soil
(b) To maximize surface run-off
(c) Not treating the upper catchment and proceeds towards an outlet
(d) Not storing surplus rainwater