Download Environmental geology lecture 1 Dr. jwad k. manii What is

Environmental geology
lecture 1
Dr. jwad k. manii
What is Environment and why do we now notice so much interest in
Environmental Studies? And what do we exactly mean by Environmental
Studies?
Environment is the sum total of all conditions and influences that affect the
development and life of all organisms on earth. The living organisms vary from the
lowest micro-organisms such as bacteria, virus, fungus, etc. to the highest,
including man. Each organism has its own environment.
The word “environment” can mean many things to many people. Some consider it
to be preservation of a scenic natural landscape or dwindling wildlife species.
According to some, it is industrial pollution or threat to citizens’ amenities caused
by the building of a road or a big factory. Others may treat it as
the mother of natural resources—energy, land, water, atmosphere and minerals.
The functions of the environment in relation to man have been analysed: (1)
recreation; (2) source of natural resources—agricultural, mineral and forestry
which man consumes directly or indirectly; (3) “sink” for receiving wastes
produced by man and his activities. The capacity of the environment to carry
out these functions is damaged by human activities which
imposes four stresses on the environment: (i) “eutrophic”, i.e. the task of
decomposing wastes produced by consumption and production activities; (ii)
“exploitative”, i.e. cropping of plants, extraction of minerals and hunting of
animals; (iii) disruptive—brought about by activities like deforestation,
construction of highways and towns; and (iv) “chemical” and “industrial” stress
which results from industrial development.
Environmental Studies
The earth provided the right environment—pure air, pure water, pure land, carbon
dioxide which in presence of strong sunlight helped in the development of the
living world consisting of plants, animals and man.
Nature through its own cycles has readily helped in the evolution of life forms.
These Natural cycles—water cycle, oxygen cycle, nitrogen cycle, carbon
cycle,etc.—are conducted in harmony with Environment. In the early stage man
lived in harmony with Nature but over the years this equilibrium was disrupted by
man as he tried to improve his life style with the help of science and technology
and as population grew beyond control which increased the need for more and
more food, water and shelter.
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Environmental geology
lecture 1
Dr. jwad k. manii
Man’s greed’s and needs led to exploitation of natural resources which caused
environmental degradation and world-wide crisis threatening human survival. It is
now urgently felt that the public in general and the student community in particular
should be made aware of all aspects of human environment—physical, biological,
socio-economic and cultural—in order to handle current environmental issues
properly. The studies of all these aspects comprise Environmental Studies which is
becoming important more tha never before in the new century and particularly so,
for the student community.
The need for environmental awareness and education was strongly felt in the
western countries in the 1960s and they introduced environmental courses in the
universities. In India it happened in the 1980s and seriously from the 1990s. In
view of the growing concern about environmental degradation and
threat to mankind, the Supreme Court of India stepped forward and in their
landmark judgment in 1991 urged all the universities to introduce common course
on environment for undergraduate students (B.Sc.).
NATURAL(NON-ANTHROPOGENIC)ANDMAN-MADE
(ANTHROPOGENIC) CHANGES IN ENVIRONMENT AND DISASTERS:
Natural Changes in Environment:
The environment is always subject to changes and these changes will continue in
future. When life first appeared, there was no oxygen in the atmosphere which was
full of carbon dioxide and other gases including water vapor. This primitive
climate changed very slowly—it took over 2 billion years to accumulate enough
oxygen in the atmosphere which helped in the evolutions of life forms (aerobic
organisms). Most of the oxygen in the atmosphere to-day has come from water
through the photosynthetic activities of green plants. Such change is natural(nonanthropogenic) but it altered the chemical composition of air which led to other
changes in the environment. From oxygen of the atmosphere ozone was formed
which slowly passed into the stratosphere where it served as a protective
umbrella of ozone layer. The latter protects life on earth by absorbing the harmful
ultraviolet radiation from the sun.
Continental drifting is an important part of natural changes. The continents were
not stationary but they were slowly drifting apart. The entire outer shell of the earth
is made up of huge tectonic plates1 which float on the molten fluid core of the
earth. Initially the continents were all joined together forming a single
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Environmental geology
lecture 1
Dr. jwad k. manii
landmass—later on they drifted very slowly. This movement isthe phenomenon of
continental drift.
The continents have drifted for about 2500 million years and the annual rate of
drifting is 20 to 75 mm. Such movement can cause splitting of part of a continent
forming oceans such as the Atlantic Ocean, seas such as the Red Sea and lakes
such as Lake Baikal. Collision of one tectonic plate with another
can cause earthquakes, volcanic explosions and formation of mountains. Collision
of Indian plate with Asian plate gave rise to the world’s highest mountain, our
Himalayas some50 million years ago.
The earth’s environment also passed through drastic changes in average
temperature of the earth’s surface creating the Ice Ages. During the earth’s history
the temperature fluctuated between relatively stable states about 30 times due to
earth’s rotation on its axis and changes in the sun’s activity. The last Ice Age was
about 18,000 years ago when a vast sheet of ice advanced from the North Pole
covering Canada,
Greenland and up to U.K. including the North Sea. As the ice moved back, vast
quantities of cold water flooded the Atlantic disturbing the ocean currents. The Ice
Age was over by 3000 BC and normal temperature slowly restored.
Natural Disasters
The environment has undergone sweeping changes by natural disasters. cyclone,
typhoon, hurricane, tornado, earthquake,volcanic eruptions etc. The latter have
caused enormous damages on lives and properties. Cyclone, typhoon and hurricane
are the same weather
phenomenon occurring in different regions of the world. Cyclones are storms that
originate in the Indian Ocean and bring about extensive flood and damage in the
Indian sub-continent including Sri Lanka and Mynamar.
Typhoons are storms in the Pacific Ocean which cause havoc in South-East Asia
while those in the North Atlantic Ocean that destroy South East USA are
hurricanes.
Hurricanes arise from tropical seas when the latter are warmed by the solar heat.
They are powered by the heat released when the rising water vapour condenses.
Most of the hurricane’s energy is used to lift the air mass at the centre of the storm.
Hurricanes, typhoons are in the form of spiraling air column which can have a
speed of over 250 km/hr., up rooting big trees, tearing off house roofs, lifting
people, cattle, cars and sucking almost anything on their path. They can whip up
high waves on the surface of seas, oceans as sea level is
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Environmental geology
lecture 1
Dr. jwad k. manii
raised as high as 8 m or 25 ft. This can cause flash floods along the coastal region.
They are also accompanied by torrential rains in the region.
The earthquakes have a rather high frequency, about 100earthquakes/hr all over the
world. But most of them are of low magnitudes. The earthquake-prone zones in the
world encircle the Pacific ocean (Zone 1) and on the other side, stretch from Spain,
Turkey, Northern Mediterranean to Japan,Himalayas and Indonesia (Zone 2).
These two zones meet near New Guinea (North of Australia). The earth’s outer
crust is divided into seven large tectonic plates and in between them there are more
than 20 smaller plates. The plates move slowly over a partially molten mass of
metals and minerals—they often converge, collide and sometimes one plate slips
below another
plate releasing tremendous energy in the form of seismic waves that shake the
ground violently. This causes earthquake. The intensity of an earthquake is
measured on Richter scale(1 Richter is the minimum intensity detectable on the
instrument, Seismograph). The earthquake
measured 6.0 on the Richter scale its destructive force was equivalent to more than
100 Hiroshima—type atomic bombs.
Volcanoes sometimes erupt with devastating power, throwing molten lava, silicate
dust and sulphuric acid into the atmosphere. When Mt. Pinatubo in the Philippines
erupted in1991, it increased the dust content of the atmosphere to morethan 50
times its normal level. As a result, Indonesia, Malayasia missed summer in 1991.
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Environmental geology
lecture 1
Dr. jwad k. manii
Conditions
Influences ‫تاثير‬
Dwindling ‫تضائل‬
Threat ‫تهديد‬
Recreation ‫تسلية‬
Consumes ‫تستهلك‬
Eutrophic‫االثرا‬
Exploitative ‫استغالل‬
Disruptive ‫تعطيل‬
deforestation, ‫ازالة‬
survival ‫البقاء‬
Aware ‫متطلع‬
Mankind ‫بشرية‬
Stationary‫مستقر‬
Entire ‫تام‬
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