Pollutant is a name given to a substance already present in nature, but human activities increase its concentration to an undesirable limit. This spoils or harms the environment and reduces the quality of life. On the other hand a substance not present in nature, that gets introduced in significant amount only by human activity or accident is called contaminant. It also spoils the environment and quality of life, e.g. waste plastic bags.
Environmental pollution may be caused by- Chemical agents (gases, pesticides, particulates).
- Physical agents (heat, noise, radiation).
- Biological agents (micro-organism).
For example,
- It can lead to illness or even death in case of humans and animals.
- The growth of some plants can be retarded and this may cause them severe injury.
- It results in corrosion of metals, building materials and marble.
- Some pollutants distribute themselves over long distances in short periods. For example, radioactive fallout from atmospheric nuclear tests can spread to a large geographical area within days. Similarly, chlorofluorocarbons, DDT and its metabolites spread over long distances and produce adverse effects.
Problem
1. Are there any similarities between pollutants and contaminants? How do these differ?
Solution
Both pollutant and contaminant are similar aspects of environment pollution. They both cause harm to the environment by being introduced in undesirable amounts.
Pollutants refer to an excess of substances already present in nature. Oxides of nitrogen from vehicle exhaust in cities is an example of pollutant. However, contaminant are substances that do not occur naturally but are introduced in significant amounts into the atmosphere by human action or accident. The infamous Union Carbide Bhopal tragedy of the 1980s, caused accidental spillage of deadly industrial chemicals used in making pesticides. This led to the death of thousands of people and is an example of contaminant.