4. Under Portfolio Activity prepare a brief write up on any one concept
from the list given below.
a) Air-constitution, properties, uses and air pollution-its sources, ill
effects and how to reduce it.
b) Water-constitution, properties, uses and water pollution-its
sources, ill effects and how to reduce it.
c) Soil- constitution, properties, uses and soil pollution-its sources, ill
effects and how to reduce it,
d) Ozone, ozone layer, ozone hole and probable damages
e) Bio geo chemical cycles in nature- water, oxygen, carbon and
nitrogen
Answers
c) Soil- constitution, properties, uses and soil pollution-its sources, ill
effects and how to reduce it,
What is Soil Pollution?
Soil pollution refers to the contamination of soil with anomalous concentrations of toxic substances.
It is a serious environmental concern since it harbours many health hazards. For example, exposure to soil containing high concentrations of benzene increases the risk of contracting leukaemia.
How can Soil Pollution be Controlled?
It is important to understand that all soils contain compounds that are harmful/toxic to human beings and other living organisms. However, the concentration of such substances in unpolluted soil is low enough that they do not pose any threat to the surrounding ecosystem. When the concentration of one or more such toxic substances is high enough to cause damage to living organisms, the soil is said to be contaminated
The root cause of soil pollution is often one of the following:
Agriculture (excessive/improper use of pesticides)
Excessive industrial activity
Poor management or inefficient disposal of waste
The challenges faced in soil remediation (decontamination of soil) are closely related to the extent of soil pollution. The greater the contamination, the greater the requirement of resources for remediation.
What are the Pollutants that Contaminate Soil?
Some of the most hazardous soil pollutants are xenobiotics – substances that are not naturally found in nature and are synthesized by human beings. The term ‘xenobiotic’ has Greek roots – ‘Xenos’ (foreigner), and ‘Bios’ (life). Several xenobiotics are known to be carcinogens.
An illustration detailing major soil pollutants is provided below.
- Heavy Metals
The presence of heavy metals (such as lead and mercury, in abnormally high concentrations) in soils can cause it to become highly toxic to human beings. Some metals that can be classified as soil pollutants are tabulated below.
Polycyclic Aromatic Hydrocarbons
Polycyclic aromatic hydrocarbons (often abbreviated to PAHs) are organic compounds that:
Contain only carbon and hydrogen atoms.
Contain more than one aromatic ring in their chemical structures.
Common examples of PAHs include naphthalene, anthracene, and phenalene. Exposure to polycyclic aromatic hydrocarbons has been linked to several forms of cancer. These organic compounds can also cause cardiovascular diseases in humans.Soil pollution due to PAHs can be sourced to coke (coal) processing, vehicle emissions, cigarette smoke, and the extraction of shale oil
- 2.Industrial Waste
The discharge of industrial waste into soils can result in soil pollution. Some common soil pollutants that can be sourced to industrial waste are listed below.
Chlorinated industrial solvents
Dioxins produced from the manufacture of pesticides and the incineration of waste.
Plasticizers/dispersants
Polychlorinated biphenyls (PCBs)
The petroleum industry creates many petroleum hydrocarbon waste products. Some of these wastes, such as benzene and methylbenzene, are known to be carcinogenic in nature.
- 3 Pesticides
Pesticides are substances (or mixtures of substances) that are used to kill or inhibit the growth of pests. Common types of pesticides used in agriculture include:
- Herbicides – used to kill/control weeds and other unwanted plants.
- Insecticides – used to kill insects.
- Fungicides – used to kill parasitic fungi or inhibit their growth.
However, the unintentional diffusion of pesticides into the environment (commonly known as ‘pesticide drift’) poses a variety of environmental concerns such as water pollution and soil pollution. Some important soil contaminants found in pesticides are listed below.
- Herbicides
- Triazines
- Carbamates
- Amides
- Phenoxyalkyl acids
- Aliphatic acids
- Insecticides
- Organophosphates
- Chlorinated hydrocarbons
These chemicals pose several health risks to humans. Examples of health hazards related to pesticides include diseases of the central nervous system, immune system diseases, cancer, and birth defects
Effects on Plants and Animals
Since soil pollution is often accompanied by a decrease in the availability of nutrients, plant life ceases to thrive in such soils. Soils contaminated with inorganic aluminium can prove toxic to plants. Also, this type of pollution often increases the salinity of the soil, making it inhospitable for the growth of plant life.
Effects on the Ecosystem
Since the volatile contaminants in the soil can be carried away into the atmosphere by winds or can seep into underground water reserves, soil pollution can be a direct contributor to air and water pollution.
It can also contribute towards acid rain (by releasing huge quantities of ammonia into the atmosphere).
Acidic soils are inhospitable to several microorganisms that improve soil texture and help in the decomposition of organic matter. Thus, the negative effects of soil pollution also impact soil quality and texture.
How can Soil Pollution be Controlled?
Several technologies have been developed to tackle soil remediation. Some important strategies.
Answer: Water pollution (or aquatic pollution) is the contamination of water bodies, usually as a result of human activities, in such a manner that negatively affects its legitimate uses. Water pollution reduces the ability of the body of water to provide the ecosystem services that it would otherwise provide. Water bodies include for example lakes, rivers, oceans, aquifers, reservoirs and groundwater. Water pollution results when contaminants are introduced into these water bodies. In addition to damage to many species, water pollution can also lead to water-borne diseases for people. Water pollution traditionally is attributed to four sources, which provide the organization of this article
sewage
industry
agriculture
urban runoff including storm water.
Water pollution can also be classified as surface water pollution (for example lakes, streams, estuaries, and parts of the ocean in marine pollution) or groundwater pollution. Sources of water pollution are either point sources or non-point sources. Point sources have one identifiable cause, such as a storm drain or a wastewater treatment plant. Non-point sources are more diffuse, such as agricultural runoff. Pollution is the result of the cumulative effect over time. Supplying clean drinking water is an important ecosystem service provided by some freshwater systems, but approximately 785 million people in the world do not have access to clean drinking water because of pollution.
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