Soil Pollution
Soil Pollution
Soil Pollution
Subject Chemistry
TABLE OF CONTENTS
1. Learning Outcomes
2. Introduction
3. Plastics
3.1. What is plastic pollution?
3.2. Sources of plastic pollution
3.3. Plastics and its environmental hazards
3.4. Effect of plastics on soil
3.5. Prevention and Control
3.6. Waste treatment
4. Summary
1. Learning Outcomes
After studying this module, you shall be able to:
2. Introduction
As you already know, pollution has a deadly impact on not just the environment, but also the
health of living beings. With several sources of soil pollution, briefly discussed in the previous
module, this module mainly focuses on the land or soil pollution and its adverse effects caused by
the excessive use of plastics, polythene wastes etc. and their improper disposal. Essentially, the
soil fertility deteriorates as the plastic bags get mixed up with manure and remain in the soil for
years.
3. Plastics
Plastic pollution is nothing but collection of several types of man-made plastic materials on land,
as well as in water bodies where they create problems for wildlife and their habitats as well as for
human populations.
Plastic is a synthetic polymer that contains chains of polymers together forming even larger chain
of many organic and inorganic compounds, and is mostly derived from petrochemicals like
olefins. Plastic materials are mainly classified as Recyclable Plastics (Thermoplastics): PET,
HDPE, LDPE, PP, PVC, PS, etc. and Non-Recyclable Plastics such as thermoset and includes
Multilayer & Laminated Plastics, Polycarbonate, Melamine, Nylon etc. they are also called as
biodegradable and elastomer plastics. Although plastics is considered to be very useful in several
ways, also it is a very useful part of polymer industry, the disposal and production of plastic pose
a great threat to all the life forms on Earth.
It is estimated that approximately 500-1000 years were taken by a plastic to degrade and this is
just estimation, as it is not possible to know the real time for degradation. The manufacturing of
plastic results in emission of many hazardous chemical which are harmful for animal and human
health. For example ethylene oxide, xylene and benzene are harmful chemicals present in plastic.
The other toxic materials present in plastics are phthalates, adipates, and alkylphenols. For
manufacturing of OVC pipes, vinyl chloride is used and known to be carcinogen.
The traditional materials such as paper and cloths have been replaced by plastics. Now-a-days
plastics are used for various purposes such as packaging and carry bags as they are cost
convenience but this is a wrong choice of material for use. Although plastic bags can be used in
multiple purposes but its disposal is a great pollution problem. During the disposal of plastics, it
will take a long time to decompose and results in soil pollution. Fig1. Depicts the wide usage of
plastic and its relative distribution.
Plastic waste arising out of the discarded electronic components, electronic toys, batteries etc.
(Figure 3), pollute the land and also clog the water bodies like canals, rivers, and lakes, especially
in the urban areas. It is estimated that each year approximately 100 million tons of plastics are
produced and 25 million tons of which comes under the category of non-degradable plastic.
Most of the plastic remains in existence for a long time as it is designed to be a long-lived
substance that does not biodegrade naturally. There are several forms of plastics having different
densities and chemical properties, but they all are similar in one way that if thrown in open,
pollutes our land and water. It is possible that the thin plastic bags break slowly and tear into
pieces, over time, but these small pieces of plastic remains in the soil and eaten by animals
releasing toxins into the animal's system and into our food chain. On the other hand, plastic
household items such as plastic containers and bottles cannot be decomposed into small pieces
and hence are even more toxic.
Ø It is estimated that globally around 70000 tonnes of plastic is dumped in the oceans and
seas. The plastic materials discarded in seas and oceans, can be eaten by terrestrial as
well as aquatic animals and as a result, plastic accumulates inside their bodies. This can
cause choking in them, ultimately leading to their death and reduction in aquatic life and
aquatic flora and fauna.
Ø One plastic drinks bottle can take up to approximately 450 years to decompose in a
landfill site. The rural areas are more prone to this type of pollution.
Ø Plastic accumulation results in the death of many stray animals due to improper disposal
system of plastics.
Ø These plastic materials if dumped in landfills can interact with water and results in the
formation of hazardous chemicals. If these hazardous chemicals enters the ground level,
results in degradation of quality of water and results in groundwater pollution.
Ø Many plastic materials cause blockage, which becomes a negative sign as it helps in
breeding of mosquitoes which then cause several diseases.
Ø Bio-accumulation of plastic inside animals is one of the most recently noticed effects of
plastic pollution. From last many years, accumulation of plastics results in the formation
of harmful chemicals and cause discomfort to the animals. Even after the death of these
animals their body decomposes but the plastic pieces present in their body do not
decompose and remain threat to other animals.
Ø Toxic chemicals such as Styrene trimer, and bisphenol A affect drinking water quality.
Styrene trimer is s by-product of polystyrene. Bisphenol A is known to be a harmful
chemical that damages the reproductive system of animals.
Ø Usually high velocity winds carried out plastic materials especially plastic polythenes
from one place to another. These plastic bags then stuck on fences, trees, towers,
buildings, etc.
Ø Burning of plastics results in air pollution as it releases toxic chemicals and poisonous
gases. Inhalation of these toxic chemicals can cause skin and respiratory problems.
Ø The plastics release chemicals in the soil that are toxic and can decrease the fertility of
the soil, thereby decreasing the soil yield.
Ø When fruits and vegetables are grown on contaminated soil, they also get contaminated
and lack in nutrients.
Ø Eating this contaminated food can cause poisoning and cause health issues.
As we all know there are many materials we use in our daily life made up of plastics. But we
should also know about the harm of its excess of use. One cannot out rule the advantages of
plastic but it is better that we take some effective preventive measures to reduce this type of
pollution.
• Garbage bins should be used at public places for throwing waste material such as
plastic water bottles, containers and other plastic materials. Plastic water bottles,
food containers and other plastic material should be dispose in dust bins.
• One should avoid throwing of plastic and other waste materials in open space.
• People should be made aware of problems caused by plastics and participate in
plastic waste management. People should also help other communities involved
in these programs.
The main focus of plastic waste management programs is to reducethe use of plastic, reuse it,
and then recycle it. Thus, the use of plastics can be controlled and a scientific waste management
system instituted for its disposal.
The newer technology entails the use of degradable plastics. It involves incorporation of some
chemicals in to the plastic to make it photodegradable/biodegradable or chemically treatable. For
example, biodegradable plastics are generally formed by adding starch to normal plastic. When
they are subjected to decompose, they are attacked by several bacteria, which results in breaking
of these plastic materials into tiny ones. These tiny plastic particles disappear into the soil.
When comes to chemically degradable plastics, they can be broken up by spraying a solution
on them to dissolve it. Here spray reacts with plastic components and cause them to dissolve.
The dissolved plastic is less toxic in nature and can be easily flushed down.
On the other hand if plastics disintegrate on exposure to light they are known as
photodegradable plastics.
In India, plastic disposal is a very serious issue of concern. Several new techniques are employed
in order to minimize the effects of plastic pollution on environment.
• Using incinerators: Incinerators can be used for burning plastic waste. A large amount
of plastic wastes can be eliminated by using this method but there are some concerns
related with air pollution due to such burning. Although, efforts has been made in order
to improve such pollution problems.
• Utilization of plastic waste in road construction (Polymer Blended Bitumen Roads).
Plastic wastes can be used in concentration of flexible roads at various places in India. .
• Co-processing of Plastic waste in Cement Kiln (Link).Co-processing of plastic waste
includes use of waste materials including plastics in processes of manufacturing of
cement, lime steel production and power stations.
• Plasma Pyrolysis Technology (PPT). In this technique of prevention and control
method, thermo-chemical property of plastic is integrated. The method is so versatile that
it disposes all type of plastic wastes.
5. Summary
In this module, you have learnt that
• Plastic pollution is accumulation of the plastic material on land and in water bodies where
they create problems for aquatic flora and fauna.
• The sources of plastic pollution are use of plastic material for packaging and synthesis of
electronic devices.
• The hazards of plastic pollution to air, soil and ground water and also to humans and
animals.
• The plastic waste treatment in India using incinerators, in road construction, in cement
kiln and Plasma Pyrolysis Technology.