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NEET Biology Notes Environmental Issues Solid Waste Management

NEET Biology Notes Environmental Issues Solid Waste Management

Solid Waste Management

Solid waste means everything that goes out in trash.
It can be of following types :

  •  Municipal solid waste includes wastes from homes, offices, schools, etc., that are collected and disposed by the municipality consists of paper, waste food materials, leather, textile, rubber, etc.
  • Fly ash is generated by thermal power plants, which is composed of oxides of silica, iron and aluminium.
  • Hospital wastes include hazardous wastes.
  • Industrial wastes include paper, rubber, pesticides, dye, etc.

Disposal of solid wastes is done in following ways :

  1. Municipal waste is burnt to reduce volume.
  2.  Sanitary landfills are used as open dumps.
  3. Fly ash is used in construction of industry or buried in landfills.
  4. E-wastes are buried in landfills.

Radioactive Waste Management

Radioactive wastes are divided into three categories based on the amount of radioactivity

  1. Low level of radioactive wastes.
  2.  Intermediate level of radioactive wastes.
  3.  High level of radioactive wastes.

Of these, the high level radioactive Wastes consist of spent fuel and generate a lot of heat and require cooling. These wastes are concentrated to reduce volume and then kept for 50-100 years in small pond, where the radioactivity decays with time. Subsequently, they are stored in shielded containers and buried within the rocks about 500 m deep inside thi earth.

Nuclear energy has two most serious problems

  1. The accidental leakage of radioactivity.
  2. The safe disposal of radioactive wastes.
  • Greenhouse Effect and Global Warming

It is a naturally occurring phenomenon that is responsible for heating of earth’s surface and atmosphere. Without greenhouse effect the average temperature of earth surface would have been a chilly -18°C rather than the present average of 15°C.
Main gases responsible for greenhouse effect are carbon dioxide (60%), methane (20%), CFCs or chlorofluorocarbons (14%) andN20 (6%) contribution.
It is selective energy absorption by carbon dioxide in atmosphere, which allows short wavelength energy to pass through but absorbs longer wavelengths and reflects heat back to earth.
Increase in the level of greenhouse gases has led to considerable heating of earth causing global warming. During the past century, the temperature of earth has increased by 0.6°C, most of it during the last three decades
Scientists believe that global warming is leading to deleterious changes in the environment and resulting in odd climatic changes, (e.g. El Nino effect), thus leads to increased melting of polar ice caps as well as of other places like Himalayan snow caps.
Reducing use of fossil fuels, improving efficiency of energy usage, reducing deforestation, planting trees and slowing down the growth of human population can control the global warming. Kyoto hosted an international conference from December 1-10, 1997 of G 77 (a group of 140 developing countries) to discuss global warming. Scientists agreed that the greenhouse gases have been accumulating in the atmosphere leading to the greenhouse effect.
To assess the role of human activities in climate change, the World Meteorological Organisation (WMO) and United Nations Environmental Programme (UNEP) set up an Intergovernmental Panel on Climate Change (IPCC) in 1988. The IPCC and United Nations Framework on Climate Change (UNFCC) that had reviewed the situation in October 1997, submitted their report in Kyoto as Kyoto Protocol.

  • Ozone Depletion

Ozone layer present in stratosphere protects us from harmful ultraviolet radiations. Such ozone layer is being destroyed by some pollutants like chlorofluorocarbons.
Increase in the amount of ozone in the lower atmosphere (troposphere), where it is formed from oxygen, is responsible for ozone pollution.
The thickness of the ozone in a column of air from the ground to the top of the atmosphere is measured in terms of Dobson units (Du). Increase in the amount of ozone in the upper atmosphere (stratosphere) is useful because it acts as a shield absorbing Ultra Violet (UV) radiations from the sun.
Chlorofluorocarbons (CFCs), methane and N02 are responsible for degradation of ozone layer in stratosphere or formation of ozone hole. Ozone hole is present maximum over the Antarctic region, where ozone depletion resulted in the formation of a large area of thinned ozone layer and creates a hole in it. CFCs widely used as refrigerants, discharged in the lower part of atmosphere move upward and reach in stratosphere.
They react with ozone layer and start depleting it.
Ultraviolet rays are highly injurious to living organisms, since DNA and proteins of living organisms preferentially absorb UV rays and its high energy breaks the chemical bonds within these molecules. Ultra violet-B radiations damage DNA and can cause mutation. Ultra violet rays can cause ageing of skin, damage to skin cells and various types of cancers.
In human eye, cornea absorbs UV-B radiation and a high dose of UV-B causes inflammation of cornea, called snow-blindness cataract. Such exposure may also permanently damage the cornea.
Montreal protocol was signed at Montreal (Canada) in 1987 (effective in 1989) to control the emission of ozone depleting substances.

  • Deforestation

It is the conversion of forested areas to non-forested ones. In India at the beginning of 20 th century, forests covered about 30% of total land but at the end of the century, it had shrunk to 19.4%.
National Forest Policy (1988) of India has recommended 33% forest cover for plains and 67% for hills. Cutting of trees for timber, fire wood, cattle ranching and Jhum cultivation are responsible for deforestation.
Slash and burn agriculture, commonly called as Jhum cultivation is common in North-Eastern states of India. In Jhum cultivation, the farmers cut down the trees of the forest and burn the plant remains. The ash is used as a fertiliser and the land is then used for farming or cattle grazing. After cultivation, the area is left for several years so as to allow its recovery. The farmers then move on to other areas and repeat this process. Reforestation is the process of restoring a forest that once existed but was removed in the past.

Case Studies Addressing
These are as follows :

Environmental Issues

There are many examples of people’s involvement time to time for the causes leading to environmental issues.

  • Bishnoi Community
    A Bishnoi woman Amrita Devi showed exemplary courage by protecting trees from the men cutting them. She sacrified her life along with her three daughters, while hugging the trees to protect them from axemen. The Government of India has recently instituted the Amrita Devi Bishnoi Wildlife Protection Award for the individuals or communities from rural areas that, have shown extraordinary courage and dedication in protecting wildlife.
  • Chipko Movement
    Chipko movement started in Garhwal Himalayas in 1974. In 1974, local women showed enormous bravery and courage in protecting trees from the axe of contractor by hugging them.
    In 1973, the Chipko Movement was launched by Chandi Prasad Bhatt and Sunder Lai Bahuguna in Chamoli district of Garhwal Himalayas. By this movement, local women showed enormous bravery in protecting trees from the axemen of contractor by hugging the trees.
    The Government of India has introduced Joint Forest Management (JFM) so as to work closely with the local communities for protecting and managing forests. In return, the communities get benefit of various forest products.

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