ENVIRONMENTAL
ISSUES
ENVIRONMENTAL
ISSUES
·
Pollution: is any undesirable changed in
physical chemical or biological characteristics of air, land, water or soil.
·
Pollutant: Any solid, liquid or gas released
into the environment in such a huge quantities that make our environment
unhealthy is called pollutant.
·
Environment
(protection) Act, 1986 to
protect and improve the quality of our environment (air, water and soil)
AIR
POLLUTION AND ITS CONTROL:
Effect of
air pollution:
·
Cause
injury to all living organisms.
·
Reduce
growth and yield of crops.
·
Cause
premature death of plants.
·
Affects
the respiratory system of human being.
·
Particulate
size 2.5 micrometers or less are responsible for breathing and respiratory
symptoms like irritation, inflammations and damage to the lungs and premature
death.
Pollution
caused by thermal power plant:
·
Sources
of particulate matter: thermal power plant, smelters
·
These
plants release particulate matter and gaseous air pollutant.
·
A
harmless gas released by these plants is Nitrogen and Oxygen.
Prevention
of air pollution: ways to remove particulate matter:
·
Electrostatic
precipitator
o
Widely
used to remove particulate matter in the exhaust from a thermal power plant.
o
Electrode
wires that are maintained at several thousand volts, which produce a corona
that release electrons.
o
Electron
binds with particulate matter giving them a net negative charge.
o
Positively
charged collecting plates attract the charged dust particle.
·
Scrubber:
o
Removes
gases like sulphur dioxide.
o
The
exhaust is passed through a spray of water or lime.
·
Methods
to reduce vehicular pollution:
o
Use
of lead free petrol or diesel can reduce vehicular pollution.
o
Catalytic
converter:
§ Having expensive metals namely
platinum, palladium and rhodium as the catalyst.
§ These metals reduce emission of
poisonous gases.
§ The unburnt hydrocarbons are
converted into CO2 and H2O.
§ Carbon monoxide and nitric oxide are changed
to carbon dioxide and nitrogen gas respectively.
§ Motor vehicle equipped with
catalytic converter should use unleaded petrol because lead in the
petrol inactivates the catalyst.
Controlling
Vehicular pollution: A case study of Delhi:
·
Use
of CNG (compressed natural gas):
Advantages
of CNG
·
CNG
burns most efficiently.
·
Very
little remain unburnt.
·
Cannot
be siphoned
·
Cannot
be adulterated like petrol or diesel.
·
CNG
is cheaper than petrol and diesel.
Problem of
use of CNG:
·
Difficulty
in laying down pipelines to deliver CNG
·
Non-assurance
of uninterrupted supply.
Other parallel steps taken in Delhi:
·
Phasing
out old vehicles.
·
Use
of unleaded petrol.
·
Use
of low-sulphur petrol and diesel.
·
Use
of catalytic converter in vehicle.
·
Application
of strict pollution level norms for vehicle.
New auto fuel policy to cut down
vehicular pollution.
·
Steadily
reducing the sulphur and aromatic content in petrol and diesel fuels.
·
Euro-II
norms
o
Sulphur
reduced to 350 ppm in diesel.
o
Sulphur
reduced to 150 ppm in petrol
o
Aromatic
hydrocarbon to be reduced to 42 %.
o
Up
gradation of vehicle engines.
·
Due
to above steps taken by Delhi Govt. there is substantial fall in CO2
and SO2 level between 1997 and 2005.
NOISE
POLLUTION:
- Undesirable high level of sound
is called noise pollution.
Harm full
effect of noise pollution:
- Psychological and physiological
disorder in humans.
- High sound level, 150dB or more
may damage ear drums.
- Noise causes sleeplessness
- Increased heart rate.
- Altered breathing pattern.
Prevention
of Noise Pollution:
- Use of sound
absorbent materials or by muffling noise in industries
- Demarcation
of horn free zones around hospitals and schools.
- Permissible
sound levels of crackers,
- Timings after
which Loudspeakers cannot be played
WATER
POLLUTION AND ITS CONTROL:
Domestic
sewage and industrial effluents:
- A mere 0.1 percent impurities
make domestic sewage unfit for human use
- Sewage contains dissolve salts
like nitrates, phosphates, and other nutrients, and toxic metal ions and
organic compounds.
- The amount of organic matter in
water is estimated by BOD.
- Biochemical oxygen demand: the amount of Oxygen required
oxidizing all organic matter present in one liter of water.
- Changes take place on discharge
of sewage into the river.
- Micro-organism involved in
biodegradation of organic matter in the receiving water body consume a
lot of oxygen, hence there is sharp decline in dissolved oxygen
downstream from the point of discharge.
- Due to low DO there is
mortality of fish and other aquatic animals.
- Presence of large amount of
nutrients in water also causes excessive growth of Planktonic (free
floating) algae, called algal bloom.
- Algal bloom imparts distinct
color to water bodies.
- Deterioration of water quality
and fish mortality.
- Some bloom-forming algae are
extremely toxic to human and animals.
- The world’s most problematic
aquatic weed is water hyacinth (Eichhornia crassipes) called ‘Terror of
Bengal’.
- Introduced to India for their
lovely flowers.
- Excessive growth causes blocks
in waterways.
- They grow abundantly in
eutrophic water bodies.
- Causes imbalance in ecosystem
and dynamics of water body.
- Sewage associated with
diseases:
- Sewage from home and hospital
contain pathogenic microbes.
- Discharge of such sewage
without proper treatment causes diseases like dysentery, typhoid,
jaundice, cholera etc.
- Toxic heavy metals (defined as
elements with density > 5g/cm3), released from:-
- Petroleum industry.
- Paper manufacturing.
- Metal extraction and
processing.
- Chemical manufacturing
industries.
- Biomagnifications: increase in concentration of
the toxicant at successive trophic level is called biological
magnification or biomagnifications.
- Toxic substance accumulated by
an organism cannot be metabolized or excreted.
- The accumulated toxic passed
to the next trophic level.
- This phenomenon is well known
for mercury and DDT.
- Bio magnification of DDT in
Aquatic food chain.
- Eutrophication: The process of nutrient
enrichment of water and consequent loss of species diversity is referred
to as Eutrophication.
- Natural Eutrophication:
- Streams draining into the lake
increase nutrients like nitrogen and phosphorus.
- Increase in nutrient
encourages growth of aquatic organisms.
- Over centuries, as silt and
organic debris pileup the lake grows shallower and warmer.
- Warm-water organisms dominate
over 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 land.
Cultural or Accelerated
Eutrophication:
o
Pollutants
from man’s activities like effluents from the industries and homes can
radically accelerate the aging process. This phenomenon is called Cultural
or Accelerated Eutrophication.
Causes:
·
Sewage
and agricultural and industrial wastes.
·
Prime
contaminants are nitrates and phosphates.
Effects:
·
Unsightly
scum and unpleasant odors.
·
Robbing
the dissolved oxygen form water.
·
Pollutant
inflow kills the fish.
·
Decomposition
of dead fish causes further depletion of DO.
·
Finally
a lake can literally choke to death.
Thermal pollution:
Cause:
·
Heated
(thermal) waste waters flowing out of electricity-generating units. E.g.
thermal power plants.
Effects:
·
Thermal
wastewater eliminates or reduces the number of organism sensitive to high
temperature.
·
Enhance
the growth of plants and fish in extremely cold areas but only after causing
damage to the indigenous flora and fauna.
A case
study of integrated waste water treatment:
·
Wastewater
including sewage can be treated in an integrated manner, by utilizing a mix of
artificial and natural process.
·
It
has been done in town of Arcata, in the northern coast of California.
·
The
treatment is done in two stages:-
o
The
conventional sedimentation, filtering and chorine treatment are given.
o
The
biologist developed a series of six connected marshes over 60 hectares of
marshland.
o
Appropriate
plants, algae, fungi and bacteria were seeded into this area, which neutralize,
absorb and assimilate the pollutant
o
The
water flows through the marshes, it get purified naturally.
·
The
marshes also constitute a sanctuary, with high level of biodiversity in the
form of fishes, animals and birds that now reside there.
·
A
citizens group called Friends of the Arcata Marsh (FOAM) is responsible
for the upkeep and safeguarding of this project.
Ecological
sanitation:
·
Ecological
sanitation is a sustainable system for handling human excreta, using dry
composting toilets.
·
This
is a practical, hygienic, efficient and cost-effective solution to human waste
disposal.
·
With
this composting method human excreta can be recycled into are source (as
natural fertilizer).
·
‘EcoSan’
toilets are being used in Kerala and Srilanka.
SOLID
WASTES:
·
Solid
wastes refer to everything that goes out
in trash.
·
Municipal
solid wastes are
wastes from homes, offices, stores, schools, hospitals etc. It comprises paper,
food wastes, plastics, glass, metals rubber, leathers, textiles etc.
·
Open
damp of these wastes serve as the breeding ground for rats and flies.
·
Sanitary
landfills were adopted as substitute for
open-burning dumps.
Sanitary
landfills:
·
Wastes
are dumped in a depression or trench after compaction and covered with dirt
everyday.
Disadvantages:
·
Shortage
of space for huge garbage’s.
·
Danger
of seepage of chemicals, polluting the ground water resources.
Solution
to solid wastes:
·
All
solid wastes are categorized into three types:
o
Bio-degradable.
o
Recyclable.
o
Non-biodegradable.
·
All
the garbage generated is sorted first.
·
Recyclable
material to be separated and send for recycles.
·
Biodegradable
wastes can be put into deep pits in the ground and be left for natural
breakdown.
·
Only
Non-biodegradable wastes are left and required to be disposed.
Prevention:
·
The
need to reduce our garbage generation should be a prime goal.
·
Reduction
in use of plastics and use of eco-friendly packaging.
·
Carrying
cloth or other natural fiber carry bags when we go shopping.
·
Refusing
polythene bags.
Case study
of Remedy for Plastic wastes: (Ahmed Khan)
·
Polyblend, a fine powder of recycled modified
plastic, was developed by his company.
·
Polyblend
is mixed with bitumen that is used to lay roads.
·
It
increases the water repelling property of bitumen, and helped to increase road
life by a factor of three.
·
The
raw material used for polyblend is plastic film waste.
Hospital
wastes:
- Hospitals generate hazardous
wastes that contain disinfectants and other harmful chemicals, and also
pathogenic organisms.
- The use of incinerators is
crucial to disposal of hospital wastes.
Electronic
wastes (e-wastes):
- Irreparable computers and other
electronic goods are known as electronic wastes (e-wastes).
- E- Wastes are buried in
landfills or incinerated.
- Metals like copper, iron,
silicon, nickel and gold are recovered during recycling process of
e-wastes.
- Manual recycling process
exposes workers to toxic substances present in e-wastes.
- Recycling is the only solution
for the treatment of e-wastes.
AGRO-CHEMICAL
AND THEIR EFFECTS:
- Use of inorganic fertilizers
and pesticides has increased manifold for enhancing crop production.
- Pesticides, herbicides,
fungicides etc., are being increasingly used.
- These are toxic to non-target
organisms that are important components of the soil ecosystem?
- Increasing amounts of
artificial fertilizers causes eutrophication.
Case study
of organic farming: (Ramesh Chandra Dagar of Sonipat)
- Integrated organic farming is a
cyclical, zero waste procedure, where waste products from one process are
cycled in as nutrients for other processes.
- Maximum utilization of resource
and increase the efficiency of production.
- He includes bee-keeping, diary
management, water harvesting, composting and agriculture in a chain of
processes, which support each other and allow an extremely economical and
sustainable venture.
Advantages:
- There is no need of use of
chemical fertilizers for crops
- Cattle excreta are used as manure.
- Crop waste used to create
compost, which can be used as a natural fertilizer or can be used to
generate natural gas for energy need.
RADIOACTIVE
WASTES:
- Nuclear energy was hailed as a
non-polluting way for generating electricity.
- Later on it was realized that
it has two very serious inherent problem:-
- Accidental leakage, as
occurred in Three Mile Island and Chernobyl.
- Safe disposal of radioactive
wastes.
- Radiation from radioactive
waste causes mutation at very high rate.
- High dose of nuclear radiation
is lethal, but lower doses create genetic disorders and also cause cancer.
Disposal
of nuclear wastes:
- Storage of nuclear waste, after
sufficient pre-treatment, should be done in suitably shielded containers
buried within the rocks about 500 m deep below the earth’s surface.
GREEN
HOUSE EFFECT AND GLOBAL WARMING:
- The term “Greenhouse effect”
has been derived from a phenomenon that occurs in greenhouse.
- 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.
- Without greenhouse effect the
average temperature at surface of earth would have been a chilly -18o
C rather than the present average of 15o C.
- Clouds and gases reflect about
one-fourth of the incoming solar radiation and absorb some of it but half
of incoming solar radiation falls on Earth’s surface heating it, while a
small portion is reflected back.
- Earth’s surface re-emits heat
in the form of infrared radiation but some part of this does not escape
into space because of atmospheric gases (e.g. carbon dioxide, methane etc.).
- The molecule of these gases
radiate heat energy and a major part of which again comes to Earth’s
surface, thus heating it up once again.
- Carbon dioxide and methane –
are commonly called as greenhouse gases because they are responsible for
greenhouse effect.
- Increase in the level of
greenhouse gases has led to considerable heating of Earth leading to global
warming or enhanced green house effect.
- During the past century, the
temperature of Earth has increased by 0.6o C.
Effect of
global warming:
- Deleterious changes in the environment
and resulting in odd climatic changes (e.g. El Nino effect).
- 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.
Control of
global warming:
- Reduce use of fossil fuel.
- Improving efficiency of energy
usage.
- Reducing deforestation.
- Promoting afforestation
programme.
- Slowing down growth of human
population.
- International initiative to be
taken to reduce emission of greenhouse gases.
OZONE
DEPLETION IN THE STRATOSPHERE:
- ‘Bad’ ozone formed in the lower atmosphere
(troposphere) that harms plants and animals.
- There is ‘good’ ozone
also; this ozone is found in the upper part of the atmosphere called stratosphere,
and it acts as a shield absorbing ultraviolet radiation from the sun.
- The thickness of ozone layer is
measured in terms of Dobson units (DU)
- Ozone (O3) 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 proper balance
of formation and degradation of ozone.
Ozone
depletion:
- Balance of ozone in
stratosphere is disrupted due to enhancement of ozone degradation by chlorofluorocarbons
(CFCs).
- CFCs find wide use as
refrigerants.
- CFCs discharged in the lower part
of atmosphere move upward and reach stratosphere.
- In stratosphere, UV rays acts
on CFCs and release active Cl atoms.
- Cl degrades ozone releasing
molecular oxygen.
- Cl acts as catalysts and not
consumed during reaction.
- Whatever CFCs are added to the
stratosphere, they have permanent and continuing affects one Ozone levels.
- The depletion is marked
particularly over the Antarctic region. This has resulted in
formation of a large area of thinned ozone layer, commonly called as the ozone
hole.
Effects of
UV rays:
- UV radiations shorter than UV-B
are almost completely absorbed by Earth’s atmosphere, if the ozone layer
is intact.
- DNA and proteins of living
organisms are damaged by UV rays as they potentially absorb it.
- The high energy of UV rays
breaks the chemical bond in these molecules.
- UV – B damages DNA and mutation
may occur.
- It causes ageing of skin.
- Damage skin cells and causes
skin cancers.
- In human eye cornea absorb UV –
B radiation and high dose of UV – B causes inflammation of cornea called snow-blindness,
cataract etc.
- Such exposes may damage cornea.
Prevention:
- Montreal Protocol was signed at Montreal (Canada)
in 1987 to control emission of ozone depleting substances.
- Many efforts are being made to
reduce emission of ozone depleting substances.
DEGRADATION
BY IMPROPER RESOURCE UTILIZATION AND MAINTENANCE:
Soil
erosion
- The removal of top fertile
layer due to human activities
Reasons:
-
- Over
cultivation
- Unrestricted
grazing
- Deforestation
- Poor
irrigation practices
Water logging
and soil salinity:
- Irrigation with proper
drainage, leads to water lodging in the soil.
- Draws salt to the surface of
the soil.
- The salt starts collecting at
the roots of the plants.
- The salt damages the roots and
crop productions.
Deforestation:
- Conversion of forested areas to
non-forested one.
How
deforestation does occurs:
- Slash and burn agriculture/jhum
cultivation
- Farmers cut down the trees of
the forest and burn the plant remains.
- Ash is used as fertilizer and
land is used for farming or cattle grazing
- Later, Land is left
uncultivated for several years for replenishment of minerals
Effects of
deforestation
- Leads to global warming due to
excess carbon-dioxide
- Loss of biodiversity
- Damage to hydrological
cycle
- Leads to soil erosion
- Desertification of land
Reforestation
- Restoring forest that was
existing earlier E.g. Observing Van-Mahotsavas
- It also occurs
naturally
- Afforestation Developing a
forest in a new area where no such forest existed in that area.
A case
study of people‘s participation in forest conservation
- A king of Jodhpur wanted to
arrange wood for his new palace in 1731.
- Few Bishnois hugged the
trees and asked to cut them first rather than cutting trees.
- 365 persons lost their lives in
this act
- A small temple is now present
there in remembrance of this act
- Amrita Devi Bishnois Wild Life
Protection Award is instituted for individuals of rural areas who take
keen interest in protecting wild life.
- Chipko movement
- It was started by local women
of Garhwali; they hugged the trees to protect them from the axes of
contractors.
- Joint forest management (jfm)
- Strategy Government of India in
1980
- Local communities worked with
the government to save the forest.
- Communities get forest products
for encouragement.
CPCB:
Central Pollution Control Board
BOD: Biological Oxygen Demand
CNG: Compressed Natural Gas
FOAM: Friends of Arcata Marsh
JFM: Joint Forest Management.
