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Foundation of environmental science
1.What do you mean by environmental science ?
The Environmental science is a multi-disciplinary science because it comprises various
branches of studies like chemistry, physics, medical science, life science, agriculture, public
health, sanitary engineering etc. It is the science of physical phenomena in the environment. It
studies of the biological species in the air, water and soil and the effect of from human activity
upon these.
Douglas and Holland: ‘The term environment is used to describe, in the Aggregate, all the external
forces, influences and conditions, which affect the Life, nature, behavior and the growth, development
and maturity of living organisms
02.Briefly discuss the scope and importance of environmental science.
Scope of Environment: The environment consists of four segments as under:
1. Atmosphere: The atmosphere implies the protective blanket of gases, Surrounding the earth:
(a) it sustains life on the earth.
(b) It saves it from the hostile environment of outer space.
(c) It absorbs most of the cosmic rays from outer space and a major portion of the
Electromagnetic radiation from the sun.
(d) It transmits only here ultraviolet, visible, near infrared radiation (300 to 2500 Nm) and radio
waves. (0.14 to 40 m) while filtering out tissue-damaging ultra violate
Waves below about 300 nm.
The atmosphere is composed of nitrogen and oxygen. Besides, argon, carbon dioxide,
And trace gases.
2. Hydrosphere: The Hydrosphere comprises all types of water resources oceans, Seas, lakes,
rivers, streams, reservoir, polar icecaps, glaciers, and ground Water.
(i) Nature 97% of the earth’s water supply is in the oceans,
(ii) About 2% of the water resources is locked in the polar icecaps and glaciers.
(iii)Only about 1% is available as fresh surface water-rivers, lakes streams, and ground water fit
to be used for human consumption and other uses.
3. Lithosphere: Lithosphere is the outer mantle of the solid earth. It consists

of minerals occurring in the earth’s crusts and the soil e.g. minerals, organic
matter, air and water.
4. Biosphere: Biosphere indicates the realm of living organisms and their
interactions with environment, viz atmosphere, hydrosphere and lithosphere
Importance of environmental science.
1. Environmental science is important for economy and welfare of human society.
2. It helps us in careful handling of the issues like pollution, overexploitation of natural
resources, food security and sustainable development.
3. Excessive use of agrochemicals has degraded the environment and has disturbed the
ecological balance.
4. Environmental science helps us to find ways and means to maintain the ecological balance.
5. It demonstrate how man can derive benefits from environment without destroying it.
6. It trains us to conserve ours fast depleting natural resources.
7. It helps to understand different food chain and ecological balance in nature.
8. It directs attention towards the problems of population explosion, depletion of natural
resources and pollution and the methods of solving such problems.
10.What is biodiversity? Why is biodiversity important?
Biodiversity is the shortened form of two words "biological" and "diversity." It refers to all the
variety of life that can be found on Earth (plants, animals, fungi and micro-organisms) as well as
to the communities that they form and the habitats in which they live.
The Convention on Biological Diversity gives a formal definition of biodiversity in its article 2:
"biological diversity means the variability among living organisms from all sources including,
inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which
they are part; this includes diversity within species, between species and of ecosystems
Biodiversity important?
Everything that lives in an ecosystem is part of the web of life, including humans.
Each species of vegetation and each creature has a place on the earth and plays a vital role in the
circle of life.
Plant, animal, and insect species interact and depend upon one another for what each offers, such
as food, shelter, oxygen, and soil enrichment.

Maintaining a wide diversity of species in each ecosystem is necessary to preserve the web of
life that sustains all living things. In his 1992 best-seller, "The Diversity of Life," famed Harvard
University biologist Edward O. Wilson -- known as the "father of biodiversity," -- said, "It is
reckless to suppose that biodiversity can be diminished indefinitely without threatening humanity
itself."
What is Commensalism?
~Commensalism is a type of symbiosis in which the symbiont benefits from the situation and the
host is neither harmed nor benefited. The term commensalism comes from the latin phrase "com
mesa," which means "sharing a table." Those crafty scientists come up with the most fun words
for parasites, I'll tell ya.
Amensalism,
Ammensalism, is a type of symbiosis, and it refers to a relationship between two species in
which one of the partners in inhibited, while the other is not affected in any significant way.
Usually, the inhibited species is damaged by a chemical released by the other one into their
shared environment.
Parasitism
Parasitism is a type of symbiotic relationship between two different organisms. One common
type of symbionic reaction is that between a parasitic creature and its host. These reactions are
classified by the host recieving damage from the parasite. Parasites are much smaller than their
hosts, and reproduce more quickly and in greater numbers than the hosts they accompany.
Mutualism
Mutualism is a biological interaction that benefits both the host and the parasite. Which means
each individual derives a fitness benefit, like survival. Most mutualisms are facultative, meaning
the partners can successfully live apart.

What are the threats to biodiversity?
An analysis of the issues posing a threat to our habitats and species has revealed the key
pressures and risks to be:
Habitat loss and degradation
 Habitat destruction and fragmentation by development.
 Agricultural intensification and changes in agricultural management practices.
 Changes in woodland and forestry management practices.
 Water abstraction, drainage or inappropriate river management.
 Inappropriate coastal management and coastal squeeze.
 Sea fisheries practices.
Environmental pollution
 Atmospheric pollution (acid precipitation, nitrogen deposition).
 Water pollution from both point and wider (diffuse) agricultural sources.
 Climate change and sea level rise as a result of global warming.
Other factors
 Recreation pressure and human disturbance.
 Invasive and non-native species and diseases
 Over-fishing and fisheries by-catch.
 Harvesting and collection of species (including hunting).
 Intrinsic factors (such as poor recruitment, limited dispersal, low population size, slow
growth rates and natural fluctuations).
 Changes in native species dynamics (including competition, disease, predation, and
declines in prey and food sources).
 Natural disasters (such as droughts, floods and storms)
What is pollution. What differentiate between pollution and
pollutant?
Pollution is the introduction of contaminants into the natural environment that cause adverse
change.[1] Pollution can take the form of chemical substances or energy, such as noise, heat or
light. Pollutants, the components of pollution, can be either foreign substances/energies or

naturally occurring contaminants. Pollution is often classed as point source or nonpoint source
pollution
Difference between pollution and pollutant
A pollutant is a polluting agent ,the substance that actually pollutes an area ,but pollution is the
process of polluting an area like water or air.
pollution is the disturbance created in nature is pollution and the substances that make pollution
are called pollutant.
Define Greenhouse effect. What are the responsible gasses of global
warming?
The greenhouse effect is the natural process by which the atmosphere traps some of the Sun's
energy, warming the Earth enough to support life. Most mainstream scientists believe a human-driven
increase in "greenhouse gases" is increasing the effect artificiall y. These gases include
carbon dioxide, emitted by fossil fuel burning and deforestation, and methane, released from rice
paddies and landfill sites.
The responsible gasses of global warming?
Greenhouse gases are those that can absorb and emit infrared radiation but not radiation in or
near the visible spectrum. In order, the most abundant greenhouse gases in Earth's atmosphere
are:
 Water vapor (H2O)
 Carbon dioxide (CO2)
 Methane (CH4)
 Nitrous oxide (N2O)
 Ozone (O3)

 CFCs
Carbon dioxide
Carbon dioxide is the primary greenhouse gas that is contributing to recent climate change. CO2 is
absorbed and emitted naturally as part of the carbon cycle, through animal and plant respiration, volcanic
eruptions, and ocean-atmosphere exchange.
Methane
Methane is produced through both natural and human activities. For example, natural wetlands,
agricultural activities, and fossil fuel extraction and transport all emit CH4.
Nitrous oxide
Nitrous oxide is produced through natural and human activities, mainly through agricultural activities and
natural biological processes. Fuel burning and some other processes also create N2O.
What is Acid Rain?
Acid rain is a result of air pollution. When any type of fuel is burnt, lots of different chemicals are
produced. The smoke that comes from a fire or the fumes that come out of a car exhaust don't just contain
the sooty grey particles that you can see - they also contains lots of invisible gases that can be even more
harmful to our environment.
The effects of acid rain
Acid rain is rain that contains nitric and sulfuric acid. Snow and fog can also contain nitric and
sulfuric acid, and the dangerous effects are the same whether the acid is falling to the earth by
rain or snow, or dancing in the air via fog. Any precipitation or dust particle that contains
abnormal levels of sulfur dioxide and nitrogen oxides is considered acid rain. Acid rain primarily
affects the United States, Europe, and China.
Ground water
Acid rain directly affects the chemical and pH balances in ground water. Imbalance of the water's
natural minerals might survive. Algae growth is increased by acid rain. Rock scaling microbial
and invertebrate herbivores lose habitation.
Soil
Acid rain leaches calcium out of the soil when it is absorbed by the earth. This directly affects
the mineral levels of the soil and the creatures, such as snails, that rely on that calcium for shell
growth.. Weakened plant life cannot tolerate extreme temperatures or fight off insects and
disease.
Paint

Those seeking an expensive paint job on their car might want to think twice in areas directly
affected by acid rain. The excess sulfur dioxide and nitrogen oxides in acid rain damages
automobile paint and corrodes surfaces. It is believed that the acid rain causes the damage as it
dries on, and evaporates from, the surface. Auto and paint coating manufacturers are trying to
develop protective coatings that prevent acid rain corrosion.
Forest
Acid rain directly impacts forest ecosystems and their inhabitants. The damage to the forest trees
and plants is widespread. Acid rain damages leaves as it falls. Acid rain runoff from the trees and
forest floors infiltrates the forest's water supplie.
Human health
Plants and animals aren't the only victims of acid rain. Acid rain is dangerous to humans. The
same sulphate and nitrate particles that directly affect the soil and water pH balances can cause
serious damage to the respiratory system if inhaled deeply. Studies show an increase of chronic
conditions, such as asthma and bronchitis, in people who are regularly exposed to acid rain.
What is the ozone layer?
The ozone layer is a deep layer in the stratosphere, encircling the Earth, that has large amounts of
ozone in it. The layer shields the entire Earth from much of the harmful ultraviolet radiation that
comes from the sun.
Interestingly, it is also this ultraviolet radiation that forms the ozone in the first place. Ozone is a
special form of oxygen, made up of three oxygen atoms rather than the usual two oxygen atoms.
It usually forms when some type of radiation or electrical discharge separates the two atoms in
an oxygen molecule (O2), which can then individually recombine with other oxygen molecules
to form ozone (O3).

Ozen layer deplation
The stratosphere is in a constant cycle with oxygen molecules and their interaction with
ultraviolet rays. This process is considered a cycle because of its constant conversion between
different molecules of oxygen. The ozone layer is created when ultraviolet rays react with
oxygen molecules (O2) to create ozone (O3) and atomic oxygen (O). This process is called the
Chapman cycle.
1. An oxygen molecules is photolyzed by solar radiation, creating two oxygen radicals:
hν+O2→2O.
2. Oxygen radicals then react with molecular oxygen to produce ozone:
O2+O.→O3
3. Ozone then reacts with an additional oxygen radical to form molecular oxygen:
O3+O.→2O2
4. Ozone can also be recycled into molecular oxygen by reacting with a photon:
O3+hν→O2+O.
It is important to keep in mind that ozone is constantly being created and destroyed by the
Chapman cycle and that these reactions are natural processes, which have been taking place for
millions of years. Because of this, the thickness the ozone layer at any particular time can vary
greatly. It is also important to know that O2 is constantly being introduced into the atmosphere
through photosynthesis, so the ozone layer has the capability of regenerating itself.
Chemistry of Ozone Depletion
CFC molecules are made up of chlorine, fluorine and carbon atoms and are extremely stable.
This extreme stability allows CFC's to slowly make their way into the stratosphere (most
molecules decompose before they can cross into the stratosphere from the troposphere). This
prolonged life in the atmosphere allows them to reach great altitudes where photons are more
energetic. When the CFC's come into contact with these high energy photons, their individual
components are freed from the whole. The following reaction displays how Cl atoms have an
ozone destroying cycle:
Cl+O3→ClO+O2(step 1)
ClO+O.→Cl+O2(step 2)
O3+O.→2O2(Overall reaction)

Chlorine is able to destroy so much of the ozone because it acts as a catalyst. Chlorine initiates
the breakdown of ozone and combines with a freed oxygen to create two oxygen molecules.
After each reaction, chlorine begins the destructive cycle again with another ozone molecule.
One chlorine atom can thereby destroy thousands of ozone molecules. Because ozone molecules
are being broken down they are unable to absorb any ultraviolet light so we experience more
intense UV radiation at the earths surface.
Figure 2. Much like sunscreen for the Earth, the ozone layer shields the Earth from the sun’s
damaging UV-B radiation, which can adversely affect human health and ecosystems. Figure

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