- Pollution is any undesirable change in physical, chemical or biological characteristics of air, land, water or soil. This creates Environmental issues.
- The Agents that bring about such an undesirable change are called pollutants.
- In order to control environmental pollution, the Government of India has passed the Environment (Protection) Act, 1986 to protect and improve the quality of our environment (air, water and soil).
AIR POLLUTION AND ITS CONTROL
- We are dependent on air for our respiratory needs. Air pollutants cause injury to all living organisms.
- They reduce the growth and yield of crops and cause the premature death of plants.
- Air pollutants also deleteriously affect the respiratory system of humans and animals. There are several ways of removing particulate matter, the most widely used of which is the electrostatic precipitator.
- which can remove over 99 per cent particulate matter present in the exhaust from a thermal power plant.
- It has electrode wires that are maintained at several thousand volts, which produce a corona that releases electrons.
- These electrons attach to dust particles giving them a net negative charge.
- The collecting plates are grounded and attract the charged dust particles
- The velocity of air between the plates must be low enough to allow the dust to fall.
- A scrubber can remove gases like Sulphur Dioxide. In a scrubber, the exhaust is passed through a spray of water or lime.
- Recently we have realised the dangers of particulate matter that are very small and are not removed by these precipitators.
- According to the Central Pollution Control Board (CPCB). particulate size 2.5 micrometres or less in diameter (PM 2.5) are responsible for causing the greatest harm to human health.
- The fine particulates can be inhaled deep into the lungs and can cause breathing and respiratory symptoms, irritation, inflammation and damage to the lungs and premature deaths.
WATER POLLUTION AND ITS CONTROL
- Human beings have been abusing the water-bodies around the world by disposing into them all kinds of waste.
- We tend to believe that water can wash away everything not taking cognizance of the fact that the water bodies are our lifeline as well as that of all other living organisms.
- It Can be you list what all we tend to try and wash away through our rivers and drains? Due to such activities of humankind, the ponds, lakes, stream, rivers, estuaries and oceans are becoming polluted in several parts of the world.
- Realising the importance of maintaining the cleanliness of the water bodies, the Government of India has passed the Water (Prevention and Control of Pollution) Act, 1974 to safeguard our water resources.
DOMESTIC SEWAGE AND INDUSTRIAL EFFLUENTS.
- we wash everything into drains. Have you ever wondered where the sewage that comes out of our houses go? What happens in villages?.
- Is the sewage treated before being transported to the nearest river and mixed with it? A mere 0.1 per cent impurities make domestic sewage treatment plant for human.
- Solids are relatively easy to remove, what is most difficult to remove are dissolved salts such as nitrates, phosphates, and other nutrients, and toxic metal ions and organic compounds.
- Domestic sewage primarily contains biodegradable organic matter, which readily decomposes thanks to bacteria and other micro-organisms, which can multiply using Eutrophication is the natural ageing of a lake by nutrient enrichment of its water.
- In a young lake, the water is cold and clear, supporting little life. With time, streams draining into the lake.
- introduce nutrients such as nitrogen and phosphorus, which encourage the growth of aquatic organisms.
- As the lake’s fertility increases, plant and animal life burgeons, and organic remains begin to be deposited on the lake bottom.
- Over the centuries, as silt and organic debris pile up, the lake grows shallower and warmer, with warm-water organisms supplanting those that thrive in a cold environment.
- Marsh plants take root in the shallows and begin to fill in the original lake basin.
- Eventually, the lake gives way to large masses of floating plants (bog), finally converting into the land.
- these organic substances as substrates and hence utilise some of the components of sewage.
- It is possible to estimate the amount of biodegradable organic matter in sewage water by measuring Biochemical Oxygen Demand (BOD).
- micro-organisms and the amount of biodegradable matter. shows some of the changes that one may notice following the discharge of sewage into a river.
- Micro-organisms involved in biodegradation of organic matter in the receiving water body consume a lot of oxygen.
- As a result, there is a sharp decline in dissolved oxygen downstream from the point of sewage discharge.
- This causes mortality of fish and other aquatic creatures. natural ageing of a lake may span thousands of years.
- However, pollutants from man’s activities like effluents from the industries and homes can radically accelerate the ageing process.
- This phenomenon has been called Cultural or Accelerated Eutrophication.
- During the past century, lakes in many parts of the earth have been severely eutrophic by sewage and agricultural and industrial wastes.
- The prime contaminants are nitrates and phosphates, which act as plant nutrients.
- They overstimulate the growth of algae, causing unsightly scum and unpleasant odours, and robbing the water of dissolved oxygen vital to other aquatic life.
- At the same time, other pollutants flowing into a lake may poison whole populations of fish, whose decomposing remains further deplete the water’s dissolved oxygen content.
- In such fashion, a lake can literally choke to death.
- Solid wastes refer to everything that goes out in the trash. Municipal solid wastes are wastes from homes, offices, stores, schools, hospitals, etc.
- that are collected and disposed of by the municipality. The municipal solid wastes generally comprise paper, food wastes. plastics, glass, metals, rubber, leather, textile, etc.
- Burning reduces the volume of the wastes, although it is generally not burnt to completion and open dumps often serve as the breeding ground for rats and flies.
- Sanitary landfills were adopted as the substitute for open-burning dumps. In a sanitary landfill.
- wastes are dumped in a depression or trench after compaction and covered with dirt every day.
- If you live in a town or city, do you know where the nearest landfill site is? Landfills are also not really much of a solution since the amount of garbage generation especially in the metros has increased so much that these sites are getting filled too.
- There is a danger of seepage of chemicals, etc., from these landfills polluting the underground water resources.
AGRO-CHEMICALS AND THEIR EFFECTS
- In the wake of the green revolution, the use of inorganic fertilisers and pesticides has increased manifold for enhancing crop production.
- The Pesticides, herbicides, fungicides, etc., are being increasingly used.
- These incidentally also toxic to non-target organisms that are important components of the soil ecosystem.
- Do you think these can be biomagnified in the terrestrial ecosystems? We know what the addition of increasing amounts of chemical fertilisers can do to aquatic ecosystems eutrophication.
- The current problems in agriculture are, therefore, extremely grave.
- Initially, nuclear energy was hailed as a non-polluting way of generating electricity.
- Later on, it was realised that the use of nuclear energy has two very serious inherent problems.
- The first is accidental leakage, as occurred in the Three Mile Island and Chernobyl incidents and the second is safe disposal of radioactive wastes.
- Radiation, that is given off by nuclear waste is extremely damaging to organisms because it causes mutations at a very high rate. At high doses,
- nuclear radiation is lethal but at lower doses, it creates various disorders, the most frequent of all being cancer.
- Therefore, nuclear waste is an extremely potent pollutant and has to be dealt with utmost caution.
GREENHOUSE EFFECT AND GLOBAL WARMING
- The term “Greenhouse effect’ has been derived from a phenomenon that occurs in a greenhouse.
- Have you ever seen a greenhouse? It looks like a small glasshouse and is used for growing plants especially during winter.
- In a greenhouse, the glass panel lets the light in but does not allow heat to escape.
- Therefore, the greenhouse warms up, very much like inside a car that has been parked in the sun for a few hours.
- The greenhouse effect is a naturally occurring phenomenon that is responsible for heating of Earth’s surface and atmosphere. Responsible for greenhouse effects.
- You would be surprised to know that without greenhouse effect the average temperature at the surface of Earth would have been a chilly -18°C rather than the present average of 15°C.
- In order to understand the greenhouse effect, it is necessary to know the fate of the energy of sunlight that reaches the outermost atmosphere Clouds CFCs.
- The gases reflect about one-fourth of the incoming solar radiation.
- It absorbs some of it but almost half of the incoming solar radiation falls on Earth’s surface heating it, while a small proportion is reflected back.
- Earth’s surface 20% re-emits heat in the form of infrared radiation Methane 60% but part of this does not escape into space as Carbon dioxide atmospheric gases (e.g., carbon dioxide, methane, etc.) absorb a major fraction of it.
- The Relative contribution of various molecules of these gases radiates heat energy, greenhouse gases to total global and a major part of which again comes to warming Earth’s surface, thus heating it up once again.
- 281 This cycle is repeated many times. The above-mentioned gases – carbon dioxide and methane – are commonly known as greenhouse gases because they are responsible for the greenhouse effect
- ozone is found in the upper part of the atmosphere called the stratosphere, and it is as a shield absorbing ultraviolet radiation from the sun.
- UV rays are highly injurious to living organisms since DNA and proteins of living organisms preferentially absorb UV rays.
- It’s high energy breaks the chemical bonds within these molecules.
- 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).
- Ozone gas is continuously formed by the action of UV rays on molecular oxygen and also degraded into molecular oxygen in the stratosphere.
- There should be a balance between production and degradation of ozone in the stratosphere. Of late, the balance has beam disrupted due to the enhancement of ozone degradation by chlorofluorocarbons (CFCs) refrigerants.