BIOLOGY –GENERAL SCIENCE NOTES FOR IAS
ENVIRONMENTAL ISSUES-CLASS12 NCERT/CBSE CHAPTER 16
Pollution is defined as any undesirable change in the physical, chemical and biological characteristics of air, water and soil that adversely affects the living organisms.
Pollutants are those substances/agents which bring about undesirable changes in the properties of air, water, soil, that affect the living organisms.
Noise is undesirable high level of sounds.
Biological/Biochemical Oxygen Demand (BOD)
Biological oxygen demand is the measure of oxygen required by aerobic decomposers for the biochemical degradation of biodegradable organic wastes.
These Pollutants/substances which cannot be broken into simpler and harmless substances by the action of decomposers/microbes are called non-biodegradable pollutants.
Those pollutants /substances which can be broken into simpler and harmless substances by the action of decomposers/microbes, are called biodegradable Pollutant.
Eutrophication refers to the nutrient enrichment in the water bodies leading to lack of oxygen and deadening of life-supporting environment.
The excess /profuse proliferation of planktonic algae imparting distinct colours to the water is called algal bloom.
Biological magnification is the phenomenon in which harmful chemicals/pollutants get accumulated in the tissues of organisms in increasing concentrations, as they travel along the food chain.
Electronic Wastes (e-wastes)
Irreparable computers and other electronic goods, are known as electronic wastes.
Green House Effect
Green House Effect is a naturally occurring phenomenon, in which the shortwave radiations are absorbed and the long wave radiations are reflected by the earth and is responsible for heating of earth’s surface and atmosphere.
The increase in the global mean temperature, is known as global warming.
Polar vortex refers to the natural circulation of wind that completely isolates the Antarctic air from the rest of the world.
The inflammation of cornea caused by a high dose of UV-B is known as snow-blindness
The decline in the thickness of spring time ozone layer , is called ozone hole.
Deforestation is the conversion of forested areas into non-forested ones.
Reforestation is the process of restoring a forest, that once existed, but was removed at some point of time in the past.
Posted by Akash Pandey | Sunday, 28 September 2014 | 9:42:00 am