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Environmental biology is one of the critical Biology Topics that involves understanding how humans impact the environment and how to address environmental issues.
Various Environmental Pollutants and Their Terrible Effect on Our Environment
Environmental issues are harmful aspects of human activities in the biophysical environment. Major current environmental issues may include climate change, pollution, environmental degradation, resource depletion, etc. The conservation movement lobbies for the protection of endangered species and the protection of any ecologically valuable natural areas. There are many environmental issues like air pollution, water pollution, garbage, and pollution of the natural environment which pose challenges for the earth. Environmental issues are one of the primary cause of diseases, health issues, and long-term livelihood impact globally. The environment is more polluted by the effects of modern lifestyle.
The most appropriate definition of environmental pollution would be the introduction of different harmful pollutants into certain environments that make this environment unhealthy to live in. The most common pollutants are chemicals, garbage, and wastewater. Environmental pollution is happening in many parts of the world, especially in the form of air and water pollution. Globally, the environmental pollution problem is much bigger than we think it is. Even in many of our cities, there are problems with dirty air or sound pollution from traffic and different other disturbing noises. The most severe environmental pollution is happening in developing countries of the third world because not only do they lack any form of sustainable management but they also lack basic sanitation. It is easily understood how bad the environmental condition is in these countries. The scenario of environmental issues is properly described in this chapter.
Pollution of the environment is causing great damage to the ecosystem that depends upon the health of this environment. Pollution levels need to be controlled all the time if we want to keep our environment safe and healthy. A healthy environment is a prerequisite for a healthy life for us and our children, and fighting pollution is definitely the best way to keep our environment healthy.
Environmental Pollution
As the human population is increasing rapidly, demand for food, water, electricity, homes, automobiles, and roads are also increasing, creating a huge pressure on nature. This in turn is creating an imbalance, causing pollution. Pollution is the introduction of contaminants into the natural environment that cause adverse changes. Pollution can take the form of chemical substances. Pollutants, the components of pollution is often classified as point source or non-point source.
Pollution is the unfavorable alteration of our environment, largely as a result of human activities. (Southwick, 1976).
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Pollution is an undesirable change in the physical, chemical, and biological characteristics of our air, land, and water that may or will harmfully affect human life or that of desirable species, our industrial processes, living conditions, and cultural assets (Odum, 1971).
The term pollution is used to refer to harmful materials introduced by man into the environment. According to Michael (1984), pollution is the release in excess of permeable limits of foreign substances within the environment. Various types of pollution are classified in different ways. On the basis of the type of environment being polluted, we may recognize air pollution, water pollution, land or soil pollution, marine pollution, sound pollution, etc.
Different Forms of Pollution
In the environment, there are several major forms of pollution which are listed below with the respective contaminant relevant to each of them.
1. Air Pollution:
In this form of pollution, chemicals, and particulates are released into the atmosphere. Common gaseous pollutants include carbon monoxide [CO], Sulphur dioxide [SO2], Chlorofluorocarbons [CFCs], and various oxides of nitrogen that are produced by industries and motor vehicles.
2. Water Pollution:
This is a form of pollution in which wastewater from commercial and industrial waste is discharged into the surface waters. In other way, discharges of untreated domestic sewage and chemical contaminants such as chlorine [Cl] from the treated sewage, the release of waste and contaminants into surface runoff flowing to surface water, waste disposal and leaching into the groundwater as well as forming eutrophication and littering also act as sources of water pollution.
3. Soil Pollution:
In this form of pollution, soil becomes contaminated when the chemicals are released by the underground leakage. Among these, the most important soil contaminants are hydrocarbons, heavy metals, herbicides, pesticides, and chlorinated hydrocarbons.
4. Noise Pollution:
This form of pollution encompasses roadway noise, aircraft noise, and industrial noise. Prolonged and continued high-intensity noise not only causes some hearing loss but may cause a permanent loss of hearing. Human efficiency also decreases as an effect of noise pollution. Noise can cause a lack of concentration, and headaches by dilating blood vessels of the brain, impair the development of the nervous system of unborn babies, and lead to abnormal behavior in their later life.
5. Radioactive Pollution:
This form of pollution results from 20th-century activities in atomic physics such as nuclear power generation and nuclear weapons research and manufacture.
6. Thermal Pollution:
In this form of pollution, a temperature change in natural water bodies caused by human influence takes place, such as the use of water as coolant in a power plant.
Pollutants
Pollutants are nothing but the creators of pollution. Every human society, be it rural, urban, or industrial, and the most technologically advanced society, disposes of certain kinds of byproducts and waste products. They are injected into the biosphere in quantities so great that they affect the normal functioning of ecosystems and have an adverse effect on plants, animals, and man. They are collectively called pollutants (Smith, 1977).
Types of Pollutants
According to environmental viewpoint, pollutants may be classified into two basic types: Biodegradable pollutants and Non-biodegradable pollutants.
1. Biodegradable Pollutants:
These pollutants which are decomposed rapidly by natural processes and molecule atoms are returned to their natural cycle are called biodegradable pollutants, e.g., domestic sewage, animal excreta, animal or plant body parts, etc.
2. Non-biodegradable Pollutants:
Such materials which do not degrade or may degrade but very slowly in the natural environment are called non-biodegradable pollutants. Such substances are often biologically magnified when they are introduced within the food chain, e.g., plastic, glass, aluminium cans, mercurial salts, steel, DDT, etc.
According to existence in nature, pollutants can be quantitative or qualitative-
- Quantitative: May be naturally present or added by man but if their concentration reaches beyond the threshold value, they cause harm to the environment, e.g., CO2, CO, NO2.
- Qualitative: Added to the environment through man-made activities only, e.g., fungicides, and pesticides.
According to the form of persistence of pollutants in the environment, pollutants may be primary or secondary pollutants.
- Primary Pollutant: They remain in nature in the same form in which they are released, e.g., DDT.
- Secondary Pollutants: They are produced when primary pollutants react with UV rays of the sunlight and so become more toxic than the primary forms, e.g., H2SO4, PAN.
Such an enhancement of toxicity by a combination of primary pollutants is called synergism. Environmental pollutants are classified into
- Gaseous Pollutants: CO2, CO, SO2, NO, Cl, NH2 etc.
- Chemical Substances: Hydrogen Fluoride, Aldehyde, Arsenide, Detergent etc.
- Particulate Matter: Smoke, fly ash, coal tar, etc.
- Metal: Zn, Al, Fe, Cr, Cd, Mn, Ni, Arsenic etc.
- Toxic Chemical Substances: Herbicide, Insecticide, larvicide etc.
- Wastes: Domestic and Municipal wastes.
- Radioactive Substances: Radioactive substances due to nuclear explosion.
- Sound: Loudspeakers, crackers, electric horns of cars, buses, trucks, etc.
- Non-degradable Substances: Polythene, Plastic, Ash, Tar, etc.
Differences between Primary and Secondary Pollutants:
| Primary Pollutants | Secondary Pollutants |
| 1. They remain in nature as they are released directly from the source. | 1. These pollutants form due to the reaction of primary pollutants with the atmosphere. |
| 2. No photochemical reactions occur. | 2. Secondary pollutants are formed due to photochemical reactions. |
| 3. Primary pollutants do not enhance their effect with time. | 3. They show enhancement effect or synergism with time. |
| 4. Chemicals may be reductants or oxidants. | 4. They are usually oxidants. |
General Causes of Pollution
Some main reasons causing pollution are population explosion, rapid industrialization, unplanned urbanization, deforestation, and scientific and technological advancement. On one hand, these are indicative of the progress of society while on the other hand causing a severe imbalance in nature, curbing the natural resources and polluting the environment.
Effects on Nature Due to Pollution
Some of the harmful effects include deterioration of the quality of the environment, adverse effects on human health, depletion of the ozone layer causing entry of UV radiations from the sun, global warming, imbalance in seasons, acid rains, damage to cultural assets, and loss of biodiversity.
Differences between Biodegradable and Non-biodegradable Pollutants:
| Biodegradable Pollutants | Non-biodegradable Pollutants |
| 1. Such pollutants can be degraded by microbes. | 1. They cannot be degraded by microbes. |
| 2. These are rapidly decomposed. | 2. May be decomposed, but at a very slow rate. |
| 3. They can also be reused as compost, manure, and biogas to produce energy. | 3. They can sometimes be recycled but not always. |
| 4. Examples: Sewage, animal waste, papers. | 4. Examples: BHC, DDT, plastics, glass. |