Environmental Issues notes for neet

 

Environmental Issues

 Pollution is the undesirable change brought about by chemical, particulate matter, or biological materials to air, water, or soil.

 Air Pollution

● Air is a complex, dynamic natural reality, which is essential for supporting life on earth.

 ● Air pollutant is a substance that causes harm to the humans and other living organisms.

● Some of the common pollutants of air

○ Nitrogen dioxide

○ Sulphur dioxide

 ○ Carbon monoxide and carbon dioxide

○ Volatile organic composites

○ Particulate matter




Control of Air Pollution

 ● Air pollution causes severe respiratory diseases in humans and other creatures and also affects plants. It can be controlled by the following ways:

o   Fitting smokestacks and smelters, with filters to separate pollutants from the inoffensive gases

o   Particulate matter can be removed by using an electrostatic precipitator. It contains electrode cables maintained at several thousand volts, which produce electrons. These electrons cleave on to dust patches and give them a net negative charge and are attracted by collecting plates, which are predicated. The haste of air passing through the plates should be low enough to allow the dust to fall.

o   A scrubber can be used to remove gases similar as SO2 wherein the exhaust passes through a spray of water or lime.

o   Vehicular pollution can be reduced by using less contaminating energies similar as CNG, which is more effective and less expensive as compared to petrol or diesel. In 2002, all the buses were switched to CNG in Delhi and this has indeed led to a fall in pollution situations in the megacity.




o   Vehicles can be fitted with catalytic transformers that have metals similar as platinum, precaution, and rhodium as catalysts. These catalysts carry out the following transformations:

Unburnt hydrocarbons → CO2 and H2O

Carbon monoxide → Carbon dioxide

Nitric oxide → Nitrogen gas

Unleaded petrol must be used with catalytic transformers as presence of lead in the petrol inactivates the catalyst.

 Greenhouse Effect

It's a natural miracle that keeps the earth’s atmosphere warm.

o   Without this miracle, the temperature of the earth would come too cold for living beings to survive.

o   The greenhouse gases (CO2, methane,etc.) absorb the heat of sun and the earth and emit it back to the earth’s face.

o   Therefore, these gases help a part of heat rays from escaping into atmosphere.

o   This cycle is repeated numerous times to maintain the earth’s temperature to an optimum 15ºC.

The attention of these gases has increased due to increased industrialisation, leading to the heating up of the earth’s surface ( global warming).

This has increased the overall temperature of the earth, performing in changes in the earth’s climate. During the last century, the temperature of earth has increased by 0.6 ºC.



This increase in temperature is eventually believed to cause the melting of polar ice caps, rise in the ocean position, and submerging of the coastal areas.

Greenhouse effect can be controlled by reducing the use of fossil energies, which produce greenhouse gases on burning, afforestation, effective energy operation, etc.

Water Pollution

● Water is veritably essential for the conservation of life on earth.

● Due to human activities, water bodies have come defiled each over the world.

● Some of the common pollutants and their sources are

Domestic sewage- It substantially contains organic matter, which is biodegradable. Microorganisms involved in their declination consume a lot of oxygen and the BOD of the water body increases leading to the death of fishes and other submarine life.




Sewage also contains numerous pathogenic microbes, which may cause the outbreak of numerous conditions similar as typhoid, jaundice,etc.

Industrial Effluents − Industrial effluents contain inorganic poisonous substances, which may suffer biomagnification ( increase in attention of a poison at consecutive trophic situations). The poison gets accumulated in the body of an organism and is passed on to the coming position. For example, DDT and other heavy metals similar as mercury, cadmium,etc.

Thermal wastewater discharge − Heated water flowing out of the thermal power plants increase the temperature of the water body. It eliminates the cold water species and promotes the warm water species. In the long run, it causes damage to the indigenous biodiversity of the water body.



● Eutrophication

o   It's the ageing of a water body due to nutrient enrichment of its water. It can be natural or artificial.

o   The natural process takes thousands of times, but due to human activities, this process has got accelerated ( accelerated/ artistic eutrophication).

o   Release of nutrient rich sewage and industrial effluents lead to preface of nutrients similar as nitrogen and phosphorus and increase in temperature and BOD of the water body, causing increased natural exertion, thereby leading to algal blooms. This results in the loss of indigenous flora and fauna.

o    In some cases, large millions of floating plants (bog) develop, eventually converting the water body into land.

 Control of Water Pollution

·       Raw sewage can be treated using natural and other means to remove the solid, suspended, and inorganic accoutrements before it's released back into the terrain.

·       Nitrogenous fertilizers can be denitrified using microbes, which can convert nitrate and nitrite into gasseous nitrogen by a process called de-nitrification.

 

Integrated waste water management as rehearsed in Arcata, California ¬ In this approach, the water is first treated by conventional means similar as filtration, sedimentation, and chlorine treatment, followed by bioremediation. (Marshes having applicable plants, bacteria, fungi, and algae were planted, which assimilate dangerous pollutants similar as heavy metals)

 Solid Waste

·       Consists of all the unwanted uninvited accoutrements thrown into the dustbin

·       It may be composed of biodegradable or non-biodegradable wastes.

·       Open dumps used for disposing solid waste serves as breeding ground for rats and canvases. Therefore, sanitary landfills are used as a substitute for these.

·       Biodegradable wastes can be either aerobically on anaerobically broken down using microbes. The non-biodegradable waste can be reclaimed, reused, or dumped in landfills.

·       Hospitalv wastes also contain dangerous accoutrements, which have to be disposed duly. Hospital wastes are generally incinerated.

·       Irrecoverable computers and other electronic goods make up e-wastes, which are moreover ditched in land fills or are incinerated. E-waste can be recycled also to recover metals similar as copper, iron, silicon, gold,etc.

·       To use the plastic waste in an effective way, polyblend, a fine powder of recycled modified plastic, has been developed. When polyblend is mixed with bitumen, it can be used to lay roads with lesser water repellent capacity and lesser life.

Agrochemicals and Radioactive Wastes

Agrochemicals

● The increased use of pestiicides, fertilizers for increasing the produce has led to eutrophication and biomagnifications in water sources.

 ● In order to check this, the concept of organic farming is increasingly getting popular. In this fashion, rather of using chemical fertilizers and pesticides, natural materials and ways similar as organic manure (cow soil ordure), compost, natural pest control, and crop gyration are used. This leads to a balanced soil, which doesn't cause soil infertiliity, but causes the revivification of the soil.

Radioactive Wastes

·       Nuclear energy is a non-polluting energy except the threats posed by accidental leakage and delicate disposal of radioactive waste.

·       Radioactive substances cause severe damages similar as mutations and cancer in lower doses and advanced doses can be murderous.

·       Radioactive wastes should be suitably pre-treated in shielded holders buried under rock shells about 500 m under the earth’s surface.

 Improper Utilisation of Resources

● Natural resources can get degraded by their improper use.

o   Soil erosion and desertification – Over-cultivation,overgrazing, deforestation, and poor irrigation ways lead to soil corrosion and desertification.

o   Water logging and soil saltness ¬ Lack of proper drainage leads to water logging, which affects the crops and also leads to increase in the saltness of the soil.

 

Ozone Depletion and Deforestation

Ozone Depletion

 


·    The ozone layer is found in the upper part of the stratosphere.

·  It protects the earth from the dangerous UV rays of the Sun. High energy UV rays break the bonds within the molecules similar as DNA and proteins.

·  Ozone is formed by the action of UV rays on oxygen patch and its consistence is measured in Dobson units (DU).

·    The ozone   is getting depleted by the action of chlorofluorocarbons (CFCs) plant in refrigerants and scents.


·   The CFCs are acted upon by UV rays in the stratosphere, liberating the Cl atoms, which act as catalysts to degrade ozone into molecular oxygen.

·       The ozone depletion is particularly lesser in Antarctica, performing in the conformation of a large thinned ozone layer generally known as ozone hole.

·       The UV rays of shorter wavelength cause skin cancers, mutations in the cellular DNA, snow-blindness, cataract, etc.

·       To check this ozone depletion, Montreal Protocol was passed in 1987 to control the use of substances thatcauseozone depletion.

Deforestation

● It's the unlimited cutting of trees and conversion of forests into cultivable land.

● In the beginning of 20 th century, India had 30 of its area under forestss, which was reduced to just 19.4 by the end of 20 th century.

● Deforestation is a result of a number of human activity similar as increased population and the demand for land.

● Trees are cut for forests, energy, and also for Slash and burn agriculture, also called Jhum civilization. In this, trees are cut and factory remains in the forests are burned since the ash acts as a fertilizer.

● Some of the major goods of deforestation are the increase in carbon-dioxide levels, loss of habitat for wild creatures, soil corrosion, and consequent desertification.

● Deforestation can be controlled by reforestation and afforestation.

● In 1980s, the conception of Joint Forest Management was introduced by the government of India. In this, support of original communities was taken for conservation of forestss and in return, the local people were free to use the products obtained from the forests.

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