2. Soil pollution can occur either because of human activities or
because of natural processes.
However, mostly it is due to human activities. The soil
contamination can occur due to the presence of pesticides and
herbicides in an excess amount, fertilizers for long term usage,
non-degradable plastic wastes and High levels of chemicals like lead,
zinc, etc.
Soil pollution refers to anything that causes contamination of soil and
degrades the soil quality. It occurs when the pollutants reduce the
quality of the soil and convert the soil inhabitable for micro
organisms and macro organisms living in the soil.
3. Soil pollution due to pesticides
Modern agricultural practices are depending upon chemical
pesticides for pest control and its continuous usage pollutes
the soil to a large extent. Today, large quantities of pesticides,
fertilizers, herbicides, etc., are used to increase the crop yield.
Pesticides are synthetic toxic chemicals that definitely kill
different types of pests and insects causing damage to
agriculture but it has many ecological repercussions. DDT was
found to be extremely used for the killing of
rodents, weeds, insects, etc. Later pests became resistance to
DDT due to the chemicals regular use. Hence this led to the
introduction of other harmful chemicals such as Aldrin and
Dieldrin.
4. They are generally insoluble in water and non-biodegradable.
Therefore, these chemicals will not gradually decompose and
keep on accumulating in the soil. They may get absorbed by soil
particles which may contaminate root crops grown in soils and
thus transferred from lower to higher trophic level via the food
chain. Hence, it will cause many metabolic and physiological
disorders in humans.. Pesticides also kill predatory insects
which destroy pest species. Thus, pesticides inhibit biological
control.
5. Pesticides may affect many useful non target organisms. For
example, DDT causes significant decrease in the rate of
photosynthesis of several algal populations. Pesticides may
cause several harmful effects in human body. DDT enters
human body through contaminated food and causes
cancer in tissues. DDT interferes with calcium metabolism
resulting in calcium deficiency. It will also cause hormonal
disturbance resulting in delayed ovulation.
In 1957, in Kerala pesticide poisoning caused the death of
102 people. In 1984, 2500 people died at Bhopal due to
methyl isocyanate poison which was leaked out from an
insecticide plant of Union Carbide.
6. Now -a-days, in the field of agriculture artificial fertilizers are used in
large amounts. These fertilizers contain one or more oi the plant
nutrients, i.e., nitrogen, phosphorus and potassium. Excessive use of
these fertilizers especially nitrogen fertilizers leads to acidification of
soil and contaminate the agricultural soil. Excess use of fertilizers can
also alter fertility of the soil. Hence it is also known as agrochemical
pollution.
Generally fertilizers are retained by the soil and crop
efficiently but there are some possibilities for the nitrates to be washed
out due to negligence appliances in applying fertilizers to arable lands
[lands for growing crops]. These nitrates may cause undesirable
effects on the water quality of low land lakes.
Soil pollution due to long term use of fertilizers
7. Soil Pollution due to Plastics
Despite the multiple benefits offers, plastics are associated
with high levels of waste and harmful impact to the environment.
This is the result of single-use plastics applications, inadequate
end of-life treatment, low recyclability and reusability rates and
high potential of disintegration into microplastics.
Plastic materials are thrown on land makes the soil less fertile.
When plastic is burned they release toxic chemicals that are
deposited in soil and surface water and on plants. Chlorinated
plastic can release harmful chemicals into the surrounding soil,
which can then into groundwater or other surrounding water
sources and also the ecosystem. This can cause serious harm to
the species that drink the water. Landfill areas contain many
different type of plastics.
8. Plastic pollution causes harm to humans, animals and plants through toxic
pollutants. It can take hundreds or even thousands of years for plastic to break down
so the environmental damage is long-lasting. It affects all organisms in the food chain
from tiny species like plankton through to whales.
Toxic chemicals leach out of plastic and are found in the blood and tissue of nearly
all of us. Exposure to them is linked to cancers, birth defects, impaired immunity,
endocrine disruption and other ailments.
The problem is more acute in big cities of developed countries. Waste plastic
articles are extremely stable and do not biodegrade. Recently, new methods have been
developed to separate and recycle the plastic wastes. Thus, polythene, polyethene
tetraphthalate (PET), PVC, etc., may be recycled to yield low quality plastics which are
used in making plastic toys, hard low grade slippers, buckets, cans, etc.
