- TROPOSPHERIC POLLUTION
- GLOBAL WARMING
- ACID RAIN
- THE OZONE HOLE
-INTERNATIONAL STANDARDS FOR DRINKING WATER
- WASTE DUMPING
STRATEGIES TO CONTROL ENVIRONMENTAL DAMAGE
-GREEN CHEMISTRY IN DAY-2-DAY LIFE
•The term “Environment” literally means “surrounding”.
It comprises of the following four major components:
(1) Atmosphere, (2) Hydrosphere, (3) Lithosphere
and (4) Biosphere.
• “ENVIRONMENT CHEMISTRY” is a branch of science
which deals with the chemical phenomena occurring in
the environment, i.e., study of origin, transport,
reactions, effects and fates of chemical species in the
•“Environment pollution” is the effect of undesirable
changes in our surroundings that have harmful effects
on the plants, animals and human beings. A substance,
which causes pollution , is known as “pollutant”.
Pollutants can be solid, liquid or gaseous substances
present in the greater concentration than in natural
abundance and are produced due to human activities or
due to natural happenings.
Air pollution is defined as the addition of undesirable materials
into the atmosphere either due to natural phenomena or due to
human activity on the earth which adversely affect the quality of
the air and hence affects the life on the earth. It is also known as
Atmospheric pollution is generally studied as Tropospheric
and Statospheric pollution.
•Tropospheric pollution occurs due to the presence of
undesirable solid or gaseous particles in the air. The
following are the major gaseous and particulate
pollutants present in the troposphere:
1.Gaseous air pollutants: These are oxides of sulphide,
hydrocarbons, ozone and other oxidants.
2.Particulate pollutants: These are dust, mist, fumes,
smoke, smog etc.
1.Gaseous Air Pollutants
(a) Oxides of Sulphur
Oxides of sulphur are produced when sulphur
containing fossil fuel is burnt. The most common
species, sulphur dioxide, is a gas that is poisonous
to both animals and plants. It has been reported that
even a low concentration of sulphur dioxide causes
respiratory diseases. However, the presence of
particulate matter in polluted air catalysts the
oxidation of sulphur dioxide to sulphur trioxide.
2SO2 (g) + O2 (g) → SO3 (g)
SO2 (g) + O3 (g) → SO3 (g) + O2 (g)
SO2 (g) + H2O2 (l) → H2SO4 (as)
(b) Oxides of Nitrogen
Dinitrogen and dioxygen are the main constituents of
air. These gases don’t react with each other at a
normal temperature. At high altitudes when lightning
strikes, they combine to form oxides of nitrogen. NO2
is oxidized to nitrate ion. When fossil fuel is burnt,
dinitrogen and dioxygen combine to yield significant
quantities of nitric oxide (NO) and nitrogen dioxide
N2 (g) + O2 (g) → 2NO (g) [at 1483K]
2NO (g) + O2 (g) → 2NO2 (g)
NO (g) + O3 (g) → NO2 (g) + O2 (g)
Hydrocarbons are composed of hydrogen and carbon
only and are formed by incomplete combustion of fuel
used in automobiles. Hydrocarbons are carcinogenic,
i.e., they cause cancer. They harm plants by causing
ageing, breakdown of tissues and shedding of leaves,
flowers and twigs.
(d) Oxides of Carbon
(i) Carbon monoxide: Carbon monoxide is one of the
most serious air pollutants. It is a colorless and
odorless gas, highly poisonous to living beings because
of its ability to block the delivery of oxygen to the organs
and tissues. It is mainly released by automobiles. It
binds to haemoglobin to form carbonhaemoglobin,
which is about 300 times more stable than the
oxygen-haemoglobin complex. This results in headache,
weak eyesight, nervousness and cardiovascular
(ii) Carbon dioxide: Carbon dioxide is released into the
atmosphere by respiration, burning of fossil fuels for
energy, and by decomposition of limestone during the
manufacture of cement. Normally it is about 0.03% by
volume of the atmosphere. Green plants need carbon
dioxide for photosynthesis and they, in turn, emit
oxygen, thus maintaining the delicate balance. The
increase in mount of carbon dioxide in the air is mainly
responsible for global warming.
About 75% of the solar energy reaching the earth is
absorbed by the earth’s surface, which increases its
temperature. The rest of the heat radiates back to
the atmosphere. Some of the heat is trapped by
gases like carbon dioxide, methane, ozone,
chlorofluorocarbon compounds (CFCs) and water
vapour in the atmosphere. Thus, they add to the
heating of the atmosphere. This causes “Global
Just as the glass in a greenhouse holds the sun’s
heat near the earth’s surface and keeps it warm.
This is called natural greenhouse effect.
Causes of Global Warming
•Increase in concentration of carbon dioxide which is
emitted by automobiles, industries, etc,.
•Increase in concentration of methane which is emitted
when vegetation is burnt, paddy fields, coal mines etc,.
•Increase in concentrations of CFCs which is commonly
produced or emitted by refrigerators, A.C.s, etc,.
We are aware that normally rain water has a pH of 5.6
due to presence of Hydrogen ions formed by reaction
of rain water with carbon dioxide present in the
H2O (l) + CO2 (g) ↔ H2CO3 (aq)
H2CO3 (aq) ↔ H+ (aq) + HCO3− (aq)
When the pH of the rain water drops below 5.6, it is
called acid rain. Oxides of sulphur and nitrogen in the
atmosphere produces acid rain. Burning of fossil fuels
such as coal and oil in power stations or petrol and
diesel in motor engines produce SO2 and NO2 after
oxidation and reaction with water are major
contributors to acid rain.
2SO2 (g) + O2 (g) + H2O (l) → 2H2SO4 (aq)
4NO2 (g) + O2 (g) + H2O (l) → 4HNO3 (aq)
• Results of Acid Rain
Acid rain is harmful for agriculture, trees and plants
as it dissolves and washes away nutrients needed for
their growth. It causes respiratory ailments in
human beings and animals.
When acid rain falls and flows as ground water to
reach rivers, lakes etc. it affects plants and animal
life in aquatic ecosystem. It corrodes water pipes
resulting in the leaching of heavy metals such as
iron, lead and copper into drinking water.
Particulates pollutants are the minute solid particles
or liquid droplets in air. These are present in vehicle
emissions, smoke particles from fires, dust particles
and ash from industries. Particulates in the
atmosphere may be viable or non-viable. The viable
particulates e.g., bacteria, fungi, moulds, algae etc.,
are minute living organisms that are dispersed in the
atmosphere. They cause plant diseases.
• Non-viable particulates can be classified according to
their size and nature as follows:
(a) Smoke particulate consist of solid and liquid
particles formed during combustion of organic
matter. Ex. Cigarette and oil smoke.
(b) Dust is composed of fine solid particles, produced
during crushing, grinding and attribution of solid
materials. Sand from sand blasting, saw dust from
wood works, cement and fly ash from factories etc.
(c) Mists are produced by particles of spray liquids and
by condensation of vapours in air.
(d) Fumes are generally obtained by the condensation of
vapours during sublimation, distillation, boiling and
several other chemical reactions.
• The effect of particulate pollutants are largely
dependent on the particle size. Air borne particles
are dangerous for human health.
•The word smog is derived from smoke and fog. This is
the most common example of air pollution that occurs
in many cities throughout the world. There are two types
(a) Classical smog occurs in cool humid climate. It is the
mixture of smoke, fog and sulphur dioxide.
Chemically it is a reducing mixture and so it is also
called as reducing smog.
(b) Photochemical smog occurs in warm, dry and sunny
climate. The main components result from the action
of sunlight on unsaturated hydrocarbons and
nitrogen oxides produced by automobiles and
Photochemical smog has high concentration of oxidizing
agents and is, therefore, called as oxidizing smog.
•FORMATION OF PHOTOCHEMICAL
•When fossil fuels are burnt, a variety of pollutants are
emitted into the earth’s troposphere. A chain reaction
takes place between hydrocarbons and nitrogen oxide in
interaction with sunlight and forms nitrogen dioxide.
This nitrogen dioxide absorbs energy and breaks up into
nitric oxide and free oxygen atom.
Oxygen atoms are very reactive and
Combines with dioxygen to form ozone
•The ozone formed in the above equation (ii) reacts
rapidly with NO (g) formed in equation (i) to regenerate
•Ozone is a toxic gas and both nitrogen dioxide and
ozone are strong oxidizing agents and can react with
unburnt hydrocarbons in the polluted air to produce
chemical such as formaldehyde, acrolein and
peroxidyacetyl nitrate (PAN).
•EFFECTS OF PHOTOCHEMICAL
•They damage metals, stones,
•Produce irritation in the eyes and respiratory system.
•THE OZONE HOLE
In 1980s atmospheric scientists in Antarctica
reported about the depletion of ozone layer. In
summer season, NO2 and methane react with
chlorine monoxide and chlorine atoms forming
chlorine sinks, preventing much ozone depletion. In
winter season a stratospheric cloud formed
providing surface on which chlorine nitrate and gets
hydrolyzed to form hypochlorous acid which reacts
with hydrogen chloride to form molecular chlorine.
EFFECTS OF DEPLETION OF OZONE LAYER
With the depletion of ozone layer, more UV radiation
filters into the troposphere. UV radiations lead to
ageing of skin, cataract, sunburn, skin cancer,
killing of many phytoplanktons, damage to fish
The plant protein gets easily affected which leads to
the harmful mutation of cells. Increase in UV
radiations damage paints and fibres, causing them
to fade faster.
•Water is essential for our life. Without water there
would be no life. Pollution of water originates from
human activities. Through different paths, pollution
reaches surface or ground water. Easily identified
source of pollution is called as point source. e.g..,
municipal and industrial discharge pipes where
pollutants enter the water-source.
•Causes of Water Pollution
(1)Pathogens: The most serious water pollutants are the
disease causing agents called pathogens include
bacteria and other organisms that enter water from
domestic sewage and animal excreta.
(2)Organic wastes: The other major water pollutant is
organic matter such as leaves, grass, trash etc.
Excessive phytoplankton's growth within water is also
a cause of water pollution.
• A large population of bacteria decomposes organic
matter present in water. They consume oxygen
dissolved in water. The amount of oxygen that water
can hold in the solution is limited. The concentration
of dissolved oxygen is very important for aquatic life.
•If too much organic matter is added to water, all the
available oxygen is used up. This causes oxygen
dependent aquatic life to die. Thus amount of oxygen
required by the bacteria to break down organic matter
present in a certain volume of a sample of water is
called BIOCHEMICAL OXYGEN DEMAND (BOD).
(3) Chemical pollutants: As we know that water is an
excellent solvent, water soluble heavy metals such as
cadmium, mercury, nickel etc. constitute an
important class of pollutants. All these metals are
dangerous to humans because our body can’t
• The organic chemicals are another group of
substances that are found in polluted water.
Petroleum products pollute many sources of water.
•International Standards for Drinking
•Fluoride: For drinking purpose, water should be tested
for fluoride ion concentration. Its deficiency in drinking
water is harmful to man and causes diseases such as
tooth decay etc.
•Lead: Drinking water gets contaminated with lead when
lead pipes are used for transportation of water. Lead
can damage kidney, liver, reproductive system etc.
•Sulphate: Excessive sulphate in drinking water causes
laxative effect, otherwise at moderate levels it is
•Nitrate: The max. limit of nitrate in water is 50ppm.
Excess nitrate can cause methmoglobinemia (‘blue baby’
Soil pollution or soil contamination is
caused by the presence of xenobiotic (human
made) chemicals or other alterations in the
natural soil and environment..
Pesticides and Insecticides
WASTE DUMPING :
Industrial solid wastes and sludge
are the major sources of soil
Industrial emissions such as fly ash
from thermal power plants can
contaminate the surrounding soil.
Nuclear testing laboratories and the
increased number of radioactive
nuclear reactions can contaminate
the soil. Radioactive materials are
thriving in the soil for long periods
of time, since they often have a long
half-life. Strontium-90, for example,
a half life of 28 years, and half-life
of cesium-137 is 30 years.
Modern mining projects leave behind disrupted communities,
damaged landscapes, and polluted water.
Mining also affects ground and surface waters, the aquatic
life, vegetation, soils, animals, and the human health.
Acid mine drainage can cause damage to streams which in
return can kill aquatic life.
The vast variety of toxic chemicals released by mining
activities can harm animals and aquatic life as well as their
Mining gas and petroleum also pollutes the land. Petroleum
extraction and manufacturing contaminates the soil with
bitumen, gasoline, kerosene and mining brine solutions.
Opencast mining, which is a process where the surface of the
earth is dug open to bring out the underground mineral
deposits, destroys the topsoil and contaminates the area with
toxic metals and chemicals.
Many of the chemicals used in pesticides are
persistent soil contaminants, which adversely
affect soil conservation.
The use of pesticides decreases the
general biodiversity in the soil.
The insecticides DDT, methyl parathion and
especially pentachlorophenol have been
shown to interfere with legumerhizobium chemical signaling. Reduction of
this symbiotic chemical signaling results in
reduced nitrogen fixation and thus reduced
Animals may be poisoned by pesticide
residues that remain on food after spraying,
for example when wild animals enter sprayed
fields or nearby areas shortly after spraying
Widespread application of pesticides can
eliminate food sources that certain types of
animals need, causing the animals to
relocate, change their diet, or starve.
Poisoning from pesticides can travel up
the food chain and bioacculmulate.
STRATEGIES TO CONTROL
ENVIRONMENTAL DAMAGE :
The public is becoming increasingly aware
that the natural environment is fragile.
The recent reports by media have focused
Deaths and population declines of birds
and fish because of the large oil spills
Deaths of porpoises and whales along
the coasts as a result of pollutants and
Fish contaminated with polychlorinated
Contamination of rivers and lakes by
dioxin and other pollutants that may
cause cancer and reproductive
These events may be omens that other forms of
life, including people, could become threatened
if environmental conditions continue to worsen.
But how much worse must conditions be before
wildlife and human life are in danger? Or are
they in danger already? Clearly, better methods
are needed to predict the probability of future
environmental and health problems based on
present evidence. Such information could guide
environmental regulators and decision makers in
taking actions in time to minimize damage to the
environment and human health.
And an important strategy to control such
environmental damage is :
WASTE MANAGEMENT :
Waste management is the collection, transport, processing or
disposal, managing and monitoring of waste materials. The
term usually relates to materials produced by human activity,
and is generally undertaken to reduce their effect on health,
the environment or aesthetics. Waste management is a distinct
practice from resource recovery which focuses on delaying the
rate of consumption of natural resources. The management of
wastes treats all materials as a single class whether solid,
liquid, gaseous or radioactive substances, and tried to reduce
the harmful environmental impacts of each through different
The two major concepts which are widely used for waste
management are :
Polluter Pays Principle
Methods Of Waste Management :
Disposing of waste in a landfill involves burying the waste, and this remains a common
practice in most countries. Landfills are often established in abandoned or
unused quarries, mining voids or borrow pits. A properly designed and well-managed
landfill can be a hygienic and relatively inexpensive method of disposing of waste
materials. Older, poorly designed or poorly managed landfills can create a number of
adverse environmental impacts such as wind-blown litter, attraction of vermin, and
generation of liquid leachate.
Design characteristics of a modern landfill include methods to contain leachate such as
clay or plastic lining material. Deposited waste is normally compacted to increase its
density and stability, and covered to prevent attracting vermin. Many landfills also have
landfill gas extraction systems installed to extract the landfill gas. Gas is pumped out of
the landfill using perforated pipes and flared off or burnt in a gas engine to generate
AVOIDANCE & REDUCTION METHODS :
An important method of waste management is the prevention of waste
material being created, also known as waste reduction.
Methods of avoidance include :
-Reuse of second-hand products
-Repairing broken items instead of buying new
-Designing products to be refillable or reusable (such as cotton instead of
plastic shopping bags)
-Encouraging consumers to avoid using disposable products (such as
-Removing any food/liquid remains from cans
-Designing products that use less material to achieve the same purpose
(for example, light weighting of beverage cans)
noun [grēn ′kem·ə·strē]
It means producing the chemicals of our daily
needs using such reactions and chemical
processes which neither use toxic chemicals
nor emit such chemicals into the atmosphere.
•Green chemistry, also called sustainable chemistry, is a philosophy of
chemical research and engineering that encourages the design of products
and processes that minimize the use and generation of hazardous
substances. While environmental chemistry is the chemistry of the natural
environment, and of pollutant chemicals in nature, green chemistry seeks to
reduce and prevent pollution at its source.
•As a chemical philosophy, green chemistry applies to organic
chemistry, inorganic chemistry, biochemistry, analytical chemistry, and
even physical chemistry. Click chemistry is often cited as a style of chemical
synthesis that is consistent with the goals of green chemistry. The focus is on
minimizing the hazard and maximizing the efficiency of any chemical choice.
•The year 2005 witnessed three key developments in the field of green
- use of supercritical carbon dioxide as green solvent
- aqueous hydrogen peroxide for clean oxidations
- use of hydrogen in asymmetric synthesis
•Examples of applied green chemistry are : Supercritical water oxidation
On water reactions
Dry media reactions
•The term "Green Chemistry" was coined by Paul Anastas in 1991, who is
renowned worldwide as “The Father of Chemistry”.
GREEN CHEMISTRY IN DAY-TO-DAY LIFE :
Dry Cleaning Of Clothes:
Tetra chloroethene (Cl2C=CCl2) was earlier used as solvent for dry
cleaning. The compound contaminates the ground water and is
also a suspected carcinogen. The process using this compound is
now being replaced by a process, where liquefied carbon dioxide,
with a suitable detergent is used. Replacement of halogenated
solvent by liquid CO2 will result in less harm to ground water.
These days hydrogen peroxide(H2O2) is used for the purpose of
bleaching clothes in the process of laundry, which gives better
results and makes use of lesser amount of water.
Bleaching of Paper:
Chlorine gas was used earlier for bleaching paper.
These days, hydrogen peroxide (H2O2) with suitable
catalyst, which promotes the bleaching action of
hydrogen peroxide, is used.
Synthesis Of Chemicals:
Ethanal(CH3CHO) is now commercially prepared by one step
oxidation of ethene in the presence of ionic catalyst in aqueous
medium with a yield of 90%.
“The world has achieved brilliance without wisdom, power
without conscience. Ours is a world of nuclear giants
and ethical infants.”
By:- ZEEL PATEL
Roll No.:- 1139