What is positive soil pollution?
In the positive
soil pollution there occur an overuse of chemical fertilizers,
air pollutants and pesticides along with herbicides and fumigants. The air pollutants
have the ability to move down with the rain. The pesticides and
weedicides are defined as the chemicals which have the ability to kill
the insects,
fungi, rodents, algae, weeds so that the agriculture output is
increased. The insecticides are most commonly used. They are sprayed on
the plants as powders or fine mist. They are mainly
broad spectrum
and affect the animals and plants. They are also referred as biocides.
They may also involve the man. It includes the chlorinated hydrocarbons
which involve DDT, DDE, aldrin, endrin and BHC. They are toxic and the
dieldrin is the most common toxic form. It is many times toxic and
poisonous than DDT. These are always persistent and mobile in the
ecosystem. These hydrocarbons are mainly soluble in the fat and
aggregate in the living organisms. The zooplankton which acts on many
aquatic
phytoplankton cells has
pesticide in their tissues. Their levels are not static. They keep on
changing with as high as 1 part pesticide per million parts of the fat.
There are certain fishes which feed on the zooplankton and have further
higher levels of pesticide which range around 5 parts per million. The
birds which feed on fishes have further higher levels of pesticide which
range around 3000 parts per million. This increase in the level of
pesticides at the higher trophic levels in the food pyramids is referred
as the biological magnification. They affect the brain, liver, heart
and may cause cancer in the human beings. They may also affect the birds
and lead to the defective egg shell production. The shell of the eggs
is very thin and can be broken by the bird’s weight. The developing
embryos
are also adversely affected. . So, the numbers of birds are decreased.
The herbivorous animals feed on the pesticide rich vegetation. The
humans feed on their meat and milk and take pesticides in their tissues.
There are other groups of chemicals which are included and are known as
Organo pesticides. These include the organo phosphorous compounds like
malathion, parathion, triothion, ethion and carbamates. They are
poisonous and can be degraded. They are difficult to handle and may lead
to nausea, vomiting, salivation and diarrhea along with the tremors in
muscle. There are another group of pesticides which are known as the
inorganic pesticides and contain arsenic and sulphur. They can be
poisonous to both the plants and animals. They cannot be degraded. The
weedicides are also known as herbicides. They are used to clear the
forest so that new buildings can be built. They also help to control the
weed in agriculture, horticulture and in the management of forest. They
are mainly the inhibitors of metabolism which interfere in the process
of photosynthesis. It may lead to the death of plant. They also effect
the multiplication of phloem cells which inhibits the transport of
organic food.
The weeds in Aswan dam were killed by the weedicides. They not only
affect the agricultural fields but also have an impact on the fish
production in sea. There is a process which is known as ecological
boomerang
in which there are adverse ecological effects of substances in the
later period. It is also known as the ecological backlash. The
industrial wastes can be solid or liquid. They are dumped on the soil.
It consists of many metals, cyanides, acids, alkalies, solvents and
chromates. In the mining areas mine dust is the main source of
pollution. It can spread with the help of winds and with the help of
purification plants. The waste of these plants also pollutes the
environment. It destroys the vegetation along with the poisonous gases
and toxic materials. They also affect the animals and plants by causing
deformities and diseases. The fertilizers have the ability to enter the
crops and may also go to the water table. They become a part of
underground water. The nitrogen fertilizers make high concentration of
nitrate and nitrite. It occurs in the leaves and fruits. There are
canned foods which contain nitrate and may lead to the corrosion of tin
present in the can.
The tin can
also produce the nitrous oxide. The drinking water with the excess of
nitrates increases the toxicity. The bacteria change the nitrates and
nitrites in the alimentary canal. They enter the blood and combine with
the hemoglobin to form met haemoglobin. It forms a condition known as
the met haemoglobinaemia which occurs due to the reduced transport of
oxygen. They lead to cyanosis in the infants and the breathlessness in
adults. The nitrate poisoning can be fatal in the infants. It is treated
by the use of methylene blue. The soil deterioration occurs by the use
of excessive fertilizers. The populations of natural bacteria like
nitrifying; nitrogen fixing is decreased and also destroys the crumb
structures. The fertilizers also increase the salt content of soil.
There are other pollutants which affect the soil. The air and
water pollutants ultimately go to the soil. The
weathering
of rocks also adds the toxic materials to soil. The lead released by
the automobiles also adds to the soil present near the roadside. The
surface soil of Bombay has a lead concentration of 41 micro grams per
gram as reported by the Khandekar in the year 1984. It can enter the
food chain. The water and food chain has the fluoride and in plants it
has the ability to combine with the magnesium ions of
chlorophyll.
It affects the process of photosynthesis and may lead to the death of
plant. The fluoride pollution can be indicated by the maize plant. The
excess of fluorides lead to a condition known as fluorosis. It leads to
the mottling of teeth. It can be followed by the fluorosis of bone. The
bones become weak and there is a knocking of knees along with the boat
shaped posture. The animals which graze over the fields rich in fluoride
show ill health and teeth, weak and swelled bones.
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