Chapter-16
ENVIRONMENTAL ISSUES
IMPORTANT TERMS:
Pollution: Any undesirable change in physical, chemical and biological characteristics of air ,water and soil and
adversely affects the living organisms.
Pollutant: Agent or substances that cause pollution.
Noise: Undesirable high level of sound.
BOD( Biological/Biochemical Oxygen Demand): Measure of oxygen required by aerobic decomposer for
biochemical degradation of biodegradable organic waste.
Biodegradable Pollutants: Pollutants that can be broken into simple and harmless substances by decomposers or
microbes.
Non-Biodegradable Pollutants: Pollutants that can not be broken into simple and harmless substances by
decomposers or microbes.
Algal Bloom: Excessive growth of planktonic algae on water body surface.
Biomagnification: Increase in concentration of harmful chemical/ pollutants along the food chain.
Electronic Wastes: Irreparable computer and other electronic goods are known as e-waste.
Eutrophication: nutrient enrichment in water bodies leading to lack of oxygen.
Accelerated Eutrophication: Man- induced nutrient enrichment and lack of oxygen in water body
Organic Farming: A zero-waste producer where waste products from one process are cycled in as nutrients for
other processes.
Green House effect: short wave length radiations are absorbed and long wavelength radiations are reflected back
by earth surface, responsible for heating of earth’s surface and atmosphere.
Stratosphere: upper part of the atmosphere containing ozone layer.
Sanitary land fills: Wastes are dumped in a depression after compaction and cover with soil.
Snow blindness: The inflammation of cornea caused by a high dose of UV-B.
Ozone Hole: decline in the thickness of spring time ozone layer.
Soil Erosion: Loss of fertile top-soil.
Soil Salinity: Increase in salt contents of the soil.
Water-logging: Accumulation of water on the soil surface.
Deforestation: Conservation of forest area to non-forested area.
Reforestation: Restoring a forest, that once existed, but was removed at some point of time in the past.
Jhum cultivation: Slash and burn agriculture.
Desertification: Formation of desert by the extension and meeting of large barren patches.
Electrostatic Precipitator: Device used to remove particular matter present in exhaust from thermal power plant.
Catalytic Convertor: Expensive metal which convert unburned hydrocarbons in to CO2 and water, CO and nitric
oxides into CO2 and N2 gas.
Plankton: Passively free-floating organisms.
Pyrolysis: Burning without oxygen.
Synergism: Increased toxicity of secondary pollutantsformed by interaction among the primary pollutants.
IMPORTANT DIAGRAMS
POINTS TO REMEMBER:
Pollution is of three types, air, water and soil.
Though pollution at times occurs naturally due to volcanic eruption, deforest fire etc.
It is mainly man made, anthropogenic, due to enormous growth in human population size.
Pollutants are of two types, biodegradable and non-biodegradable.
Air Pollution:
Is caused by smoke stakes from thermal plants, smelters and other industries.
Burning of fossil fuel , smoke from forest fire, volcanic eruptions etc. and decomposition of garbage resulting in
release of unwanted gases in atmosphere
Air pollutants are metallic particles, dust particles, CO2, NO2, SO2 and CO
It affects human respiratory system and cause injury, premature death and reduction in growth in plants.
Electrostatic Precipitator: it removes 99% particulate matter present in the exhaust from thermal plant.
It has electrode wires and a stage of collecting plates.
The electrodes releases electrons due to production of corona, these electrons get attached to the dust and give
them a net negative charge.
The collecting plates attract the charged particles.
Scrubber: It removes gases like SO2 industrial exhaust.
Catalytic Convertor: Used in automobiles for reducing emission of harmful gases.
Vehicles fitted with catalytic converter should use unleaded petrol as leaded petrol inactivates the catalyst.
Control of Vehicular Air Pollution in Delh:
The switching over of public transport from diesel to compressed natural gas from the end of 2002.
Application of euro –II norms for vehicles.
Auto Fuel Policy: The Government of India laid out a road map to cut down the vehicular air policy in many cities
of India.
Noise: it causes the following harmful effects on human beings:
sleeplessness,
Increased rate of heart beat,
altered breathing pattern ;
and stress.
Can damage the eardrum and permanent loss of hearing.
Can be control by use of sound absorbent material, acoustic material in the wall of home, silencers can be fitted to
automobiles.
Water Pollution:
It can be classified into Domestic Sewage, Agricultural runoff and Industrial wastes.
Domestic sewage contains pathogens and cause diseases like typhoid, jaundice, dysentery etc.
Industrial Chemical Wastes causes biological magnification; high concentrations of DDT disturb the calcium
metabolism in birds and causes thinning of egg shell.
Thermal Waste Water eliminates or reduces many organisms that are sensitive ti high temperature.
Solid Wastes: is of following types: Municipal solid waste,
Fly ash, Defunct ships, Hospital Waste, Industrial waste, e-waste,.
Solid wastes:
Everything that goes into trash.
They are of following types:
Municipal Solid Wastes: From homes, offices, schools etc.
Fly Ash: Generated by thermal power plant, composed of silica, iron, aluminium and low concentration of toxic
heavy metals.
Defunct Ship: they are broken down in developing countries for scrap metal; contain toxic substances such as
asbestos, lead, mercury etc.
Hospital wastes: It contains pathogenic microbes and other harm full chemicals.
Industrial Waste: Industries produce large amount of corrosive and highly inflammable chemicals.
Disposal:
Municipal wastes are burnt to reduce volume
Fly ash is used in construction industry or buried as landfills.
Municipal wastes are incinerated and the heat emitted is used to generate electricity.
Soil Pollution:
The main sources are
Fertilizers and pesticides from crop lands;
Solid wastes from industries and houses;
Heavy metals washed off with rain, acid rain.
Harm full effects: may cause biomagnification, reduce soil fertility and may affect many living organisms of the soil.
Organic Farming: this allows maximum utilization of the resources and increases the efficiency of production.
Radioactive Waste:
Is of three types depending on the amount of radioactivity:
Low level, Intermediate level and high level radioactive waste
Of these, the high level radioactive wastes consist of spent fuel and generate a lot of heat and require cooling.
Nuclear energy has two most serious problems:
The accidental leakage of radioactivity and
The safe disposal of radioactive waste.
Green House Effect:
Phenomenon that is responsible for heating earth’s surface and atmosphere.
Earth’s surface emits heat in the form of infrared radiation to the space, but most of it is absorbed by gases like
carbon dioxide, nitrous oxide, chlorofluoro carbon and methane.
The molecule of these gases radiate heat energy that comes back to the earth’s surface and heat it up.
Global Warming:
Increase in the level of green house gases responsible for this.
The measures to control global warminginclude:
•
Reducing the use of fossils fuel.
•
Improving energy efficiency,
•
Reducing deforestation and use of nitrogen fertilizers.
Ozone Depletion:
ozone formed in troposphere is called ‘bad ozone’ as it harm plants and animal, while ozone formed in
stratosphere is called ‘good ozone’ that act as a shield and absorbs the ultraviolet radiations from sun.
The thickness of ozone in a column of air is measured in terms of Dobson Unit.
The depletion of ozone is marked over Antarctic region in spring and thinning of the ozone layer is called ozone
hole.
As a result the UV-radiation reaches the earth and following are the consequences:
•
Damage DNA and mutation arise
•
Cause aging of skin, damage skin cells and cause skin cancer
•
Lethal to microorganism.
Restoring Ozone Level: Montreal Protocol was signed act Montreal in 1987, became effective in 1989.
Modified in Beijing in 1999, objective is to control emission of ozone depleting substances.
Degradation by improper Utilization and Maintenance of Resources:
Resources are not degraded only by pollutants but also by improper practices of their utilization.
Soil erosion is caused by human activities like:
•
Over cultivation & mono culture
•
Over grazing
•
Deforestation
Irrigation without proper drainage leads to water logging of soil that affect the crop productivity and cause
deposits of salt on the land surface; saline soil become uncultivable
Deforestation: 40% forests have been lost in tropics and 1% in temperate region.
In India, at the beginning of twentieth century, forest covered about 30% land whereas by the end it reduce to
19.4%
The National Forest Policy (1988) has recommended 33% forest cover in plains and 67% for hills.
Causes:
•
Forests are converted into agricultural land.
•
Cleared for making home and establishing industries
•
Jhum cultivation in north-eastern states.
Consequences:
•
CO2 concentration will increase.
•
Loss of biodiversity due to habitat destruction.
•
Disturbs hydrological cycle.
•
Soil erosion that may leads to desertification.
People’s Participations to Protect Forest:
The Govt. of India has instituted Amrita Devi Bishnoi Wildlife Protection Award, given to individuals that show
extraordinary coverage and dedication to protect tree.
Chipko Movement started in Garhwal, Himalayas in 1974, aims at saving tree and forests
Joint Forest Management, to work closely with local communities for protecting and managing forests, the
communities get benefit of various forest products.
ONE MARKS QUESTIONS
1. What is pollution?
Ans: Any undesirable change in physical, chemical and biological characteristics of air ,water and soil and adversely
affects the living organisms.
2. What is the role of catalytic convertor?
Hint: Conversion of poisonous gases
3. . Identify the catalytic convertor from the following:
a. Platinum b. Palladium c. Lead d. Radium
4.. Accidental leakage and safe disposal are the problems of which energy?
Hint: Nuclear energy
5. In Bangalore recycled plastic is modified as _________________
6. In Delhi, the current auto fuel policy is ____________
7. A cyclical zero waste procedure of cropping is __________
Hint: Organic farming
8. what photochemical oxidants pollute air?
Ans: Peroxyacyl nitrate, ozone and aldehyde.
9, What is PAN?
Ans: Peroxyacyl nitrate.
10. What are secondary pollutants? Mention two examples.
Ans: Those formed by interaction among primary pollutants such as PAN, Ozone.
12. How much pollution of air is due to human activities?
Ans. Just 0.05% of the total annual emission in to air.
13. Expand the tern CNG.
Ans: Compressed Natural Gas.
14 Name the world’s most problematic weed. What is the nature of water body in which the weed grows
abundantly.
Ans: Water Hyacinth, These plants grow in eutrophic water bodies and leads to imbalance in the ecosystem
dynamics of the water body.
15. Give scientific name of poisonous weed called Assam Lata.
Ans. Eupatorium.
16. Give the noise value of moderate conversation.
Ans. 30-60dB
17. Which sound causes noise pollution?
Ans: Sound with a decibel value above 80dB
18. What are sonic booms?
Ans. Rattling of windows, doors etc. caused by the jet planes moving above the velocity of sound.
19.Give two examples of radioactive nuclides.
Ans Radium-224 & Uranium-238
20. Who gave the term Smog?
Ans. Des voeux.
TWO MARKS QUESTIONS
1.
2.
What is eutrophication? Discuss the effect of green house gases on the growth of plants.
To what type of wastes do irreparable computers and other electronic
goods belong to ?
Ans: Defunct ships and e-waste.
3. Name four metals which are recovered during the recycling of e-waste?
Ans: Copper, Iron Silicon Nickel and Gold.
4. Complete the following:
A
B
1. ____________
Carbon monoxide & Nitrogen oxide
2. Electrostatic precipitator
______________________
3. _____________
High noise level
4. Land fills
_____________________
Ans: 1. Catalytic converter
2. Particulate matter
3. Earmuffs
4. Solid waste
5. Water Zooplanktons Small fish Fish eating birds
DDT (0.003ppm) (0.04ppm) (0.5ppm) (5ppm)
Why is the concentration of DDT increasing from the producers to consumers in the
above food chain?
6. Why are grains and vegetables produced in organic farms supposed to be better for human
consumption than those produced in farms where chemical fertilizers, pesticides etc. has been used?
Ans: Chemical fertilizers / pesticides --non -biodegradable , enter into food chain through vegetables /
grains , causes biomagnification in humans . In organic farms manure is used , whose produce causes no
harm to human health .
7. Study the graph and answer the questions given below
a. What measures would you take to decrease BOD and increase DO?
b. What kind of sewage discharge will increase BOD?
THREE MARKS QUESTIONS:
1. Why is CNG preferred than petrol or diesel?
Hint: Fuel efficiency, no adulteration, no theft
2.Why do certain organisms that disappear at the point of sewage disposal reappear at a certain distance in a
river?
Hint: BOD increases, O2 utilized in decomposition, DO becomes zero. After complete decomposition, BOD lowers
and DO increases as oxygen dissolves in water .
3. In a survey it is observed that the population of fish-eating birds living on the bank of lake is continuously
declining, where DDT is regularly sprayed to check mosquitoes.
i) What could be the reason behind this?
ii) Name the phenomenon involved.
Hint: (i) Increase in the level of DDT with each trophic level.
(ii) Biomagnifications
4. Nuclear energy is the most suitable source of energy in future. But still this idea can not be materialized
effectively. Mention the problems associated with it ?
Hint: (i) Accidental leakage (ii) disposal of radioactive waste.
5. Describe how the population of fish-eating birds living on the bank of a lake, where DDT is regularly sprayed to
check mosquito growth for many years, would differ from that living on the bank of another lake, which is free
from insecticides. Name the phenomenon involved.
FIVE MARKS QUESTIONS:
1. What measures would you take to reduce environmental pollution?
Hint: no biomass burning, judicious vehicle use, no tobacco, use of electric chimney, control on noise, tree
plantation, disposable and recyclable material, minimize fossil fuels.
2. What is meant by Ozone shield? Name two ozone depleting substances. How do the ozone-depleting substances
affect the ozone shield? Write one damaging effect of ozone-depletion on human and plant respectively.
3. Discuss the causes and effect of global warming. What measures need to be taken to control global warming?
Ans: Increase in the level of green house gases .
The measures to control:
•
Reducing the use of fossils fuel.
•
Improving energy efficiency,
•
Reducing deforestation and use of nitrogen fertilizers.
4. Suppose your father is planning to set up a factory. .
(i) What measures would you suggest to him to provide protection against noise pollution.
(ii) Mention two harmful effects of noise pollution.
Hint: (i) a) Planting trees around the factory .
b) Walls should be equipped with sound absorbent material.
c) Workers should be equipped with ear-muffs.
(ii) a) impairing hearing ability
b) Sleeplessness, increased heart beat
HOTS QUESTIONS
1.
Give the difference between
BOD & COD
Biological magnification & Eutrophication
th
2.
A decade back, the enormous vehicular traffic in Delhi had made Delhi rank 4 among polluted cities of
the world. Two measures taken by Delhi Government brought marked improvement in air quality by
2005. What were there two measures and how did they reduce air pollution?
3.
What would be the impact on the environment around a thermal power plant if its electrostatic
precipitator stops functioning? Give reason.
4.
The figure given show relative contributions of various green house gases to the total global warming
(i) Name the gas a & b
(ii) Explain how increase in green house gases in earth’s atmosphere leads to rise in sea water level?
5.
What are flocs? State their role in effluent treatment and their ultimate fate in sewage treatment tank.
6.
(a).Why the people living in West Bengal prove to black food disease?
(b) What is blue-baby syndrome? Explain.
7. Why are cloudy, dusty and humid nights warmer than clear, dust-free and dry night?
8. Why is ozone hole formed over Antarctica?
9. Observe the following diagram and answer the questions at the end
a. Name the gases.
b. Comment on the consequences of increase in the level of each gas (any
three)