16.1 Pollution:
Pollution is any undesirable change in physical, Chemical or biological characteristics of air, land, water or soil.
The factors or agents or substances that cause pollution are called pollutants.
Types: Air, Water, Soil, Noise, Radiation etc.
Major Cause: Human population.
In order to control environmental pollution, the Government of India has passed the Environmental Protection Act, 1986 to protect and improve the quality of our environment.
World Environmental Day is celebrated on 5th June.
16.2 Air Pollution and its Control:
Air Pollution is an undesirable change in physical, chemical or biological characteristics of air.
Smog:It is a mixture of air pollutants (like NO, Arsenic, CO, and lead etc.), dust and fog.
Air pollutants: It is divide into two types as follows;
Particulate pollutants: metallic particles, dust particles, soot, aerosol and smoke.
Gaseous Pollutants: sulfur dioxides, carbon monoxide, nitrogen dioxide and hydrogen sulfide.
Effects:
Air pollutants cause injury to all living organisms.
They reduce growth and yield of crops.
They cause premature death of plants (chlorosis and defoliation).
They affect the respiratory system of humans and animals.
Cause Acid Rain and Greenhouse effect.
Ozone depletion
Causes:
Automobiles, Industries, Thermal power plants, volcanic eruptions, forest fire and mining activities.
16.2.1 Control of air pollution from industries:
Smokestacks of thermal plants, smelters and other industries release suspended particulate matter and harmful gaseous air pollutants along with harmless oxygen, nitrogen etc.
Removing or separating suspended particulate matter which is harmful before releasing into the environment.
There are several ways of removing particulate matter; the most widely used as follows;
Electrostatic precipitators and
Scrubbers.
16.2.1.1 Electrostatic Precipitators:
It is a device that removes suspended dust particles from a gas or exhaust by applying a high-voltage electrostatic charge and collecting the particles on charged plates.
The electrostatic precipitator can remove over 99% 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 (positively charged) 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.
According to the Central Pollution Control Board (CPCB), a particular size of 2.5 micrometers or less can cause breathing and respiratory symptoms, irritation, inflammations, damage to the lungs and premature deaths.
16.2.1.2 Scrubber:SAVINAY KUMAR J C
Scrubbers are air pollution control devices that use liquid to remove particulate matter or gasses from an industrial exhaust or flue gas stream.
A scrubber can remove gasses like sulfur dioxide.
In a scrubber, the exhaust is passed through a spray of water or lime.
Water dissolved gasses and lime react with sulfur dioxide to form a precipitate of calcium sulfate or sulfite.
16.2.2 Control of air pollution from automobiles:
Proper maintenance of automobiles along with the use of lead free petrol or diesel.
Use of catalytic converters in automobiles.
16.2.2.1 Catalytic converter:
Catalytic converters contain platinum-palladium and rhodium as the catalyst, and are fitted into automobiles for reducing emission of poisonous gases.
As the exhaust passes through the catalytic converter, unburnt hydrocarbons are converted into carbon dioxide and water.
Carbon monoxide and nitric oxide are changed to carbon dioxide and nitrogen gas.
The vehicles fitted with catalytic converter should use unleaded petrol because lead in the petrol inactivates the catalyst.
16.2.3 Noise pollution:
In India, the Air (Prevention and Control of Pollution) Act came into force in 1981, but was amended in 1987 to include noise as an air pollutant.
Noise pollution is an undesired or harmful level of sound or noise.
The measuring unit of sound is dB (decibel). Comfortable sound up to 50dB, Non-hazardous is 60dB, and hazardous above 61dB.
Effects:
High sound level greater than 150 dB or more generated by takeoff or a jet plane or rocket may damage eardrums thus permanently impairing hearing ability.
Noise also causes sleeplessness, increased heart beating, altered breathing pattern, thus considerably stressing humans.
Causes:
Burning of crackers.
Transportation system.
Aircraft and rail traffic.
Control of noise pollution:
Use of sound absorbent materials or by muffling noise.
Making horn free zones around hospitals and schools.SAVINAY KUMAR J C
Using permissible sound levels of crackers and of loudspeakers.
Laying down timings after which loudspeakers cannot be played.
16.2.4 Controlling vehicular air pollution: a case Study of Delhi:
Delhi is the city with the most cars in India.
Delhi ranked 4th among the 41 most polluted cities of the world.
The Delhi government asked to use Compressed Natural Gas (CNG) in public transport.Due to the Supreme Court of India with respect to PIL (Public Interest Litigation) filed against air pollution.
16.2.4.1 Advantages of CNG:
CNG burns more efficiently than diesel and petrol.
Very little of it is left unburnt.
CNG is cheaper than petrol or diesel.
It cannot be siphoned (drawn off) by thieves.
It cannot be adulterated like petrol or diesel.
16.2.4.2 Disadvantage of CNG:
The problem of using CNG is the difficulty of laying down pipelines to deliver CNG through distribution points or pumps and ensuring uninterrupted supply.
16.2.4.3 Measuring steps taken in Delhi for reducing vehicular pollution:
Using CNG in public transport.
Phasing out of old vehicles
Use of unleaded petrol
Use of low-sulfur petrol and diesel.
Use of catalytic converters in vehicles.
Application of stringent pollution level norms for vehicles.
Petrol Vehicles Older than 15 years and diesel vehicles older than 10 years are banned in Delhi.
16.2.4 Auto fuel policy norms laid by government of India:
Steadily reducing the sulfur and aromatics content in petrol and diesel fuels.
Euro II norms, for example, stipulates that sulfur be controlled at 350 parts per million (ppm) in diesel and 150 ppm in petrol (Crude oil contains (500ppm).
Euro III emission norms: Introduced separate limits for hydrocarbons and nitrogen oxide emissions for petrol engines, and a separate nitrogen oxide limit for diesel engines. This rule was first introduced in India in 11 cities as follows; Delhi, Mumbai, Kolkata, Chennai, Bangalore, Hyderabad, Ahmadabad, Pune, Surat, Kanpur and Agra.
Euro IV emission norm:The aim is concentrated on cleaning up emissions from diesel cars, especially reducing particulate matter and oxides of nitrogen.
Euro VI emission norms: Reduce levels of harmful car and van exhaust emissions, both in petrol and diesel cars. This includes nitrogen oxide (NOx), carbon monoxide (CO), hydrocarbons and particulate matter, which is basically soot from diesel cars.
Aromatic hydrocarbons are to be contained at 42% of the concerned fuel; it is reducing to 15%(in 2019).
Corresponding to the fuel, vehicle engines will also need to be upgraded.
Note:
In a recent ruling, The Supreme Court has ruled that BS4 vehicles will not be sold after March of 2020 when the BS6 norms are put in place. The BS (Bharat Stage) norms are based on EURO (European) emissions standards.
16.3 Water Pollution and its Control:
Water pollution is an undesirable change in physical, chemical or biological characteristics of water.
Causes: sewage waste, industrial waste, Thermal waste water, chemical fertilizers and pesticides.
The Government of India has passed the Water (Prevention and Control of Pollution) Act, 1974 to protect the water resources.
Major Impurities of water:
A mere (ಕೇವಲ) 0.1 % impurities make domestic sewage unfit for human consumption.
Suspended solids like sand, slit and clay
Colloidal materials like fecal matter, bacteria, paper fibers and cloth.
Dissolved nutrients like nitrates, ammonia, phosphates, sodium and calcium. These nutrients are most difficult to remove at the time of sewage treatment.
Effects:
The sewage waste directly released to water sources stimulates the increase of pathogenic microbes. It causes water borne disease.
The nutrition enrichment in water results in eutrophication and algal bloom. It increases the BOD (Biological Oxygen Demand).
The pesticides entering the water resources lead to biomagnification.
The mercury that enters human beings through the food chain causes Minamata disease(Neurological syndrome).
Thermal wastewater can eliminate the number of organisms sensitive to high temperature and also can enhance the growth of plants and fish in extremely cold areas but only after causing damage to the indigenous flora and fauna.
Note:
Biological Oxygen Demand: It is a measurement of the amount of dissolved oxygen (DO) that is used by aerobic microorganisms when decomposing organic matter in water.
Eutrophication: (Greek eutrophus, "well-nourished"), or hypertrophication. It is the natural aging of a lake by biological enrichment of its water. Due to the addition of nutrients such as nitrogen and phosphorus.
The pollutants from man’s activities such as effluents from the industries and homes radically accelerate the aging of the lake. This phenomenon is called Cultural or Accelerated Eutrophication.
Algal blooms: Presence of large amounts of organic nutrients in water causes excessive growth of planktonic or free floating algae called algal bloom. Due to this the color of water bodies changes. This may cause deterioration of the water quality and fish mortality.
Water hyacinth (Eichhornia crassipes): It is the world’s most problematic aquatic weed. They are introduced into India for their beautiful flowers that have caused havoc by their excessive growth by causing blocks in our water bodies. This weed is commonly known as ‘Terror of Bengal’.
Biomagnification:Toxic wastes present in industrial wastes and water from farmhouses containing pesticides and weedicides enters the food chain of aquatic organisms.
The increase in concentration of toxicant at each successive trophic level is called biological magnification.
The most common toxicant that gets accumulated at successive trophic levels includes DDT and Mercury.
High concentrations of DDT disturb calcium metabolism in birds, which causes thinning of eggshells and their premature breaking, eventually causing decline in bird populations.
16.3.1 A Case Study Integrated Waste Water Treatment:SAVINAY KUMAR J C
Wastewater including sewage can be treated in an integrated way, by combining artificial and natural processes.
An example of such an initiative is the town of Arcata, situated along the northern coast of California .The native people in collaboration with Humboldt State University created an integrated waste water treatment process within a natural system. The cleaning occurs in two stages –
The conventional sedimentation, filtering and chlorine treatments are given.
The biologists developed a series of six connected marshes over 60 hectares of marshland.
Plants, algae, fungi and bacteria were seeded into this area, which neutralize, absorb and assimilate the pollutants (dissolved nutrients).
The water flows through the marshes, it gets purified naturally.
The marshes also constitute a sanctuary, with a high level of biodiversity in the form of fish, animals and birds that now reside there.
A marsh is a wetland that is dominated by herbaceous rather than woody plant species.
A citizens group called Friends of the Arcata Marsh (FOAM) is responsible for the upkeep and safeguarding of this wonderful project.
16.3.2 Ecological sanitation or Eco San:
It is a sustainable system for handling human excreta, using dry composting toilets.
With the help of ecological sanitation human excreta can be recycled into a resource (as natural fertilizer).
There are working ‘EcoSan’ toilets in many areas of Kerala and Sri Lanka.
16.3.3 Control of Water Pollution:
It is necessary to control water pollution, therefore it leads to waterborne diseases like Jaundice, Cholera, Typhoid, etc., and also it is a site for vector growth like mosquitoes.
The waste water should be treated before dumping in rivers and lakes.
Domestic waste water can be mildly treated and used for irrigation.
Planting of trees to reduce acid rain and pollution of groundwater.
Rainwater harvesting, and reduce wastage of fresh water to conserve water.
Use of dry composting toilets that do not require water, also the human waste collected can be used as a good natural fertilizer.
16.4 Solid Wastes:
Solid wastes refer to everything that goes out in trash.
Municipal solid wastes are wastes from home, offices, stores, schools, hospitals etc. that are collected and disposed of by the municipality.
It consists of paper, food wastes, plastics, glass, metals, rubber, leather, textile etc.
Major Types of Municipal Solid Wastes:
Biodegradable
Recyclable and
Non-biodegradable.
Methods of solid waste disposal:
Burning of solid waste: It reduces the volume of the wastes but the waste generally is not burnt to completion and open dumps often serve as the breeding ground for rodents and flies.
Sanitary Land Filling:
It was used as a substitute for open burning dumps where wastes are dumped in a depression or trench after compaction and covered with dirt every day.
Drawback:There is a danger of seepage of chemicals from the landfills that pollute the underground water resources.
The biodegradable materials:It can be put into deep pits in the ground and be left for natural breakdown.
Recycling: Kabadiwallahs and rag-pickers do a great job of separating materials for recycling of different kinds of wastes.
Incinerators (burning) are used for disposal of hospital wastes.
16.4.1 A remedy for plastic waste:
Ahmed Khan invented polyblend in 2002.
Polyblend is a fine powder of recycled modified plastic which is mixed with the bitumen.
Bitumen is used for road surfacing and roofing.
Polyblend and bitumen, when used to lay roads, enhanced the bitumen’s water repellent properties, and helped to increase road life.
16.4.2 Electronic wastes:
Unrepairable computers and other electronic goods are known as electronic wastes (e-wastes).
Disposal of E-waste Management:
E-wastes are buried in landfills or incinerated.
Over half of the e-wastes generated in the developed world are exported to developing countries, mainly to China, India and Pakistan, where metals like copper, iron, silicon, nickel and gold are recovered during the recycling process.
E-wastes recycling is carried out in an environmentally-friendly manner.
16.5 Soil Pollution (Agro-Chemicals and Their Effects):
The inorganic fertilizers and pesticides used for enhancing crop production are called agrochemicals.
Advantage: Use of inorganic fertilizers and pesticides has increased many fold due to the green revolution for enhancing crop production.
Disadvantage:
The pesticides and insecticides are toxic to non-target organisms and micro flora that are important components of the soil ecosystem.
They are biomagnified in the terrestrial ecosystem and also cause eutrophication in aquatic ecosystems.
16.5.1 Case Study of Organic Farming:
Integrated organic farming is a cyclic, zero-waste procedure in which waste products from one process are cycled in as nutrients for other processes to allow the maximum utilization of resources and increase the efficiency of production.
Ramesh Chandra Dagar, A farmer in Sonipat, Haryana started integrated organic farming. His farming includes bee-keeping, dairy management, water harvesting, composting (natural gas) and agriculture in a chain of processes which support each other and allow an extremely economical and sustainable venture.
No chemical fertilizer is used in this process.
Dargar has created the Haryana Kisan Welfare Club, with a current membership of 5000 farmers.
16.6 Radioactive Wastes:
Radioactive waste is a byproduct of nuclear reactors and any discarded nuclear material emits radiation.
Types: high level and low level.
Effects: High level radioactive waste causes mutations and low level radioactive waste causes cancer.
16.6.1 Inherent problems associated with nuclear energy:
It is difficult to avoid an accidental leakage of nuclear radiation.
Ex: Three Mile Island and Chernobyl incidents.
It is very difficult to dispose of radioactive waste safely.
16.6.2 Radioactive waste management:
Radioactive waste management involves the pre-treatment, storage, and disposal
There are four methods recommended as follows for pre-treatment;
Limiting the generation of waste is the first and most important consideration in managing radioactive wastes.
Delay and decay is frequently an important strategy because much of the radioactivity in nuclear reactors and accelerators is very short lived.
Concentrating and containing is the objective of treatment activities for longer-lived radioactivity.
For wastes having low radioactivity,dilution and dispersion are adopted.
The method recommended for the storage of nuclear waste after pretreatment is stored in suitable shielded containers buried within the rocks about 500m deep below the earth’s surface.
16.7 Greenhouse Effect and Global Warming:
The warm condition maintained on the earth’s surface due to the presence of greenhouse gasses is called the greenhouse effect.
Greenhouse gasses have the capability to absorb heat from sun radiations. This leads to a warm up earth surface.
Greenhouse gasses like CO2, CH4, N2O, CFC-12 etc.
In the absence of the greenhouse effect, the earth would have been a chilly -18°C rather than the present average of 15°C.
Due to increase in the level of greenhouse gasses in the atmosphere leads to Global Warming.
16.7.1 Phenomenon of Greenhouse Effect:
Clouds and gasses reflect about one-fourth of the incoming solar radiation, and absorb some of it.
Almost half of incoming solar radiation falls on Earth’s surface heating it, while a small proportion is reflected back.
Earth’s surface re-emits heat in the form of infrared radiation but part of this does not escape into space as greenhouse gasses in the atmosphere absorb a major fraction of it.
The molecules of these gasses radiate heat energy, and a major part of which again comes to earth’s surface, thus heating it up once again. This cycle is repeated many times.
16.7.2 Global Warming:
Gradual increase in the average air temperature or atmospheric temperature of earth surface due to greenhouse gasses in the atmosphere is called Global Warming.
The global mean temperature has increased by 0.6°C in the 20th century.
16.7.2.1 Effects of Global Warming:
El Nino Effect: It is an abnormal weathering pattern caused by global warming.
Increased melting of polar ice caps as well as of other places like the Himalayan snow caps.
Rise in sea level that can submerge many coastal areas.
16.7.2.2Control of Global Warming:
Controlling or slowing down the growth of the human population.
Reducing the emission of greenhouse gases into the atmosphere.
Cutting down use of fossil fuel.
Improving efficiency of energy usage.
Reducing deforestation.
Planting trees or promoting the afforestation and reforestation programs.
Using non-conventional sources of energy like solar, wind, tidal and biogas.
Earth Summit and Kyoto protocol: To reduce the emission of Greenhouse Gases
16.8 Ozone depletion in the Stratosphere:
Ozone trioxygen (O3) is an inorganic molecule and it is a pale blue gas with a distinctively pungent smell.
Based on Ozone's location in the atmosphere, it recognizes good or bad.
If Ozone is located above the atmosphere (Stratosphere), this ozone layer is good for nature and for living organisms.
If Ozone is located below the atmosphere (troposphere), this ozone layer is bad or harmful for plants and animals.
Stratospheric Ozone protects life on Earth from the Sun's ultraviolet (UV) radiation.
The unit used to measure the thickness of the ozone is the Dobson Unit (DU).
Chloro-Fluoro-Carbons are called Freons.
16.8.1 Mechanism of Ozone depletion:
Thinning of the upper ozone layer due to degradation by chlorofluorocarbon (CFCs) is known as Ozone Depletion.
UV-rays split CFCs and release atomic chlorine (Cl).
UV-rays also split ozone into oxygen.
Chlorine atoms trap oxygen atoms and ozone is not formed again from oxygen. This leads to depletion of ozone in the stratosphere.
16.8.2 Effects of Ozone depletion or UV-B radiations:
The upper part of the atmosphere with lesser concentration of ozone is called ozone hole.
Damage DNA and proteins of living organisms.
It causes DNA mutation.
It causes skin aging and skin cancer.
A high dose of UV-B causes inflammation of the cornea called snow-blindness.
16.8.3 Control of ozone depletion:
Limit fossil fuel powered transportation.
Prevent any use of CFCs.
Use renewable energies.
Montreal Protocol:
Montreal (Canada) Protocol adopted theKigali amendment to phase down production and consumption of hydrofluorocarbons (HFCs) worldwide.
HFCs are widely used alternatives to ozone depleting substances such as hydrochlorofluorocarbons (HCFCs) and chlorofluorocarbons (CFCs), already controlled under the Protocol.
Note:SAVINAY KUMAR J C
There are around 10 types of UV rays. Out of these the most common ones are UV-A, UV-B, and UV-C.
UV-A or Black light (long wave): It is used in tanning beds and to find counterfeit money.
UV-B (Medium Wave): Absorbed by ozone layer under normal conditions.
UV-C (short wave): Used as a germicidal, in laboratories and in the treatment of water.
16.9 Degradation by improper resource utilization and maintenance:
The degradation of natural resources can occur, not just by the action of pollutants but also by improper resource utilization practices.
16.9.1 Soil Erosion:
The loss of topmost fertile soil due to natural and human activities called soil erosion.
Natural Causes: Floods, LandSlide, Wind.
Anthropogenic Causes: over-cultivation, unrestricted grazing, deforestation, urbanization and poor irrigation practices.
Effect: Desertification
The process of transformation of fertile land into desert is known as desertification.
Prevention:vegetation, crop rotation, mulch or adding organic fertilizers, and retaining walls (preventing water flow).
16.9.2 Water-logging:
Water (whether as rain or irrigation) in excess of the capacity of the soil to absorb. This type of soil or land is called water-logging.
Effect: It draws salts to the surface of soil and affects the growth of crops, germination of seeds.
16.10 Deforestation:
It is the conversion of forested area to non-forested area.
16.10.1 Causes of Deforestation:
Increasing human population,
Trees are axed for timber, firewood, cattle ranching and for several other purposes.
Expansion of agriculture,
Slash and burn agriculture (Jhum Cultivation),
Hydroelectric projects,
Urbanization and Industrialization.
16.10.2 Jhum Cultivation:
The farmers cut down the trees of the forest and burn the plant remains.
The ash is used as a fertilizer 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.
16.10.3 Effects of Deforestation:
Increased CO2 concentration in the atmosphere leads to global warming.
Loss of biomass and biodiversity due to habitat destruction.
Causes Soil Erosion.
Disturbs hydrological cycle and
May lead to desertification in extreme cases.
16.10.4 Control of deforestation:
Governments have to initiate strong protection acts for forests.
India around 1988 brought National Forest Policy, according to this policy India has recommended 33% forest cover for the plains and 67 % for the hills.
Conservation of forest,
Afforestation: It is the process of planting trees or sowing seeds in a barren land devoid of any trees to create a forest.
Reforestation:It is the process of restoring a forest in a deforested area.
Controlling of human population and urbanization.
16.11 Case study of people’s participation in conservation of forests:
16.11.1 Bishnois Community in the Conservation of forest:
In 1731, the king of Jodhpur in Rajasthan asked one of his ministers to arrange wood for constructing a new palace.
The minister and workers went to a forest near a village, inhabited by Bishnois, to cut down trees.
The effort to cut down trees by the kings was thwarted by the Bishnois.
A Bishnoi woman Amrita Devi showed exemplary courage by hugging a tree and daring the king's men to cut her first before cutting the tree.
Sadly, the king’s men did not heed to her pleas, and cut down the tree along with Amrita Devi.
Her three daughters and hundreds of other Bishnois followed her and thus lost their lives saving trees.
Due to this reason the Bishnoi community is known for peaceful co-existence with nature.
The Government of India has recently instituted the Amrita Devi Bishnoi Wildlife Protection Award for individuals or communities dedication in protecting wildlife.
16.11.2 Chipko Movement:
In 1974, Vimla Bahuguna was a local woman of Garhwal Himalayas who showed enormous bravery in protecting trees from the axe of contractors by hugging them, hence called chipko movement.
Vimal Bahuguna her husband was Sundarlal Bahuguna. Under his leadership the chipko movement was taken, due to this father of chipko movement was called by Sundarlal Bahuguna
In Karnataka, Panduranga Hegde is a pioneer in popularizing the chipko movement as the appiko movement.
16.11.3 Joint Forest Management (JFM):
It is the concept introduced by the government of India in the 1980s.
JFM is the relationship between local communities and forest departments working together in protecting, developing and managing forest.
Benefits: In this method, local communities get benefit of various forest products like fruits, gum, rubber, medicine etc., and thus the forest can be conserved in a sustainable manner.
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