The lecture by Dr. Rajendra Singh Thakur outlines the definition, formation, components, and pollution of soil. It describes various factors influencing soil formation, the characteristics of soil horizons, and the effects of soil pollution from industrial, urban, and agricultural sources, detailing how pollutants negatively impact health and ecosystems. Remediation strategies for soil pollution are also discussed, emphasizing the importance of clean-up efforts in sensitive environments.

1. SOIL POLLUTION
Lecture by-
Dr. Rajendra Singh Thakur

2. Soil
•INTRODUCTION-
•The word “SOIL” is derived from Latin word “SOLUM”
which means earthy material in which growth of plants
takes place.

3. Soil: Definition
• Solid earth material that has been altered by physical,
chemical and organic processes so that it can support
rooted plant life.
• Soil is mixture of rock particles, decomposing plant
and animal materials,
• Soil is the “stuff” plants grown in.
• The soil contains different salts, minerals, organic
substances, gases, water etc.

4. Formation of Soil
 Soil is the loose, weathered material on Earth's surface in which
plants can grow.
 Soil forms as rock is broken down by weathering and mixes with
other materials on the surface.
 Soil is constantly being formed wherever bedrock is exposed.
 Bedrock is the solid layer of rock beneath the soil.
 Bedrock gradually weathers into smaller and smaller particles that
are the basic material of soil

5. Factors of Soil Formation
There are several factors that determine whether
three layers of soil will form.
Time
Climate
Type of rock
Surface features of the region

6. Time
Time is one of the most important factors in
soil formation.
The longer a rock is exposed to the forces of
weathering, the more it is broken down.
Mature soil is formed if all three layers have
had time to develop.

7. Climate
Climate is another important factor in the
formation of soil.
In areas with heavy rainfall and warm
temperatures, weathering takes place more rapidly.
Heavy rainfall may wash much of the topsoil away.
Since Organisms are more plentiful these areas,
the soil is quickly replaced.
They speed up the chemical and mechanical
weathering of rocks.

8. Type of Rock
The type of rock in an area also affects soil
formation.
Some rocks do not weather as rapidly as other
do. Rocks that do not break down easily do not
form soil rapidly.
In some climates it takes along time for
granite to break down. So soil formation from
granite is slow.
But sandstone breaks easily and forms soil
quickly.

9. Surface Features of Region
The surface features of the region also
determine the speed at which soil is formed.
On very steep slopes, rainwater running off
the land erodes the soil and exposes rock to
weathering.

10. Soil Composition
• Soil is a mixture of rock particles, minerals, decayed organic
material, air and water.
• The type of rock particles and minerals in any given soil depends on
two factors:
Bedrock that was weathered
Type of weathering
• Sand, silt, and clay make up the portion of soil that comes from
weathered rock.
• The decayed organic material in soil is humus. Humus is a dark-colored
substance that forms as plant and animal remains decay.
• Humus helps create spaces in soil for the air and water that plants
must have

11. Soil Components
Soils consist of four major components: (1) mineral (or inorganic), (2) organic, (3)
water, and (4) air.
The relative proportions of these four soil components vary with soil type and
climatic conditions.
Review the approximate proportions (by volume) of the four soil components in a
mineral soil under optimum conditions for plant growth.

12. Soil Profile?
 A Soil Profile is a vertical cross-section of layers of soil found in a
given area.
 Soil is composed of distinct layer which are called soil horizons,
which together from soil profile.
 The soil profile are characteristic of mature soil.
 Layers, varies in thickness, colors, texture, structure, acidity,
porosity and composition.

14. Soil Horizon?
 Soil horizons are the layers in a soil profile used to classify soil
types.
 Horizons based on color, texture, roots, structure, rock
fragments, and any unique characteristic worth noting.
 Master Soil Horizons are depicted by a capital letter in the order
(from top down): O, A, E, B, C, and R

15. Types of Horizon
 Horizon O- The uppermost horizon of soil profile is called
horizon-o liter zone.
 Horizon A- Underlying the litter zone is the horizon A or top soil.
 Horizon E- Small layer between A & B horizons
 Horizon-B- It is dark colored and coir retextured it contains a
little humus also.
 Horizon-C- It contains weathered rock of parent.
 Horizon-E- Deepest soil horizon in the soil profile

16. Types of Horizon
Partially decomposed
organic material dominates
Good mix of mineral
and organic particles
(mainly mineral)
Silicate clays, iron
oxides, aluminium
oxides,
and calcium carbonates
accumulate (little
organic matter)
Least weathered
part of the soil
profile
Regolith (above bedrock)
May be transported (ie.,
can be distinct from
parent material)
http://www.physicalgeography.net
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The exposed wall of
a soil pit or road cut is
called the soil profile

18. O-Horizon
The “Organic Matter”
Horizon
 Surface-layer, at depths of 0-2
feet
 Dark in color, soft in texture
 Humus - rich organic material of
plant and animal origin in a stage
of decomposition
 Leaf litter – leaves, needles,
twigs, moss, lichens that are not
decomposing
 Several O-layers can occur in
some soils, consisting only of O-horizons

19. A-Horizon
“Topsoil” or “Biomantle”
Horizon
 Topmost layer of mineral soil, at
depths of 2-10 feet
 Some humus present, darker in
color than layers below
 Biomantle - most biological
productive layer; earthworms,
fungi, and bacteria live this layer
 Smallest and finest soil particles

20. E-Horizon
The “Leaching Layer” Horizon
 Small layer between A & B
horizons
 At depths of 10-15 feet
 Light in color, mainly sand & silt
 Poor mineral and clay content due
to leaching – the loss of water-retaining
plant nutrients to the
water table
 Soil particles larger than in A
horizon but smaller than in B
horizon

21. B-Horizon
The “Subsoil” Horizon
 At depths of 10-30 feet
 Rich in clay and minerals like Fe
& Al
 Some organic material may
reach here through leaching
 Plant roots can extend into this
layer
 Red/brown in color due to
oxides of Fe & clay

22. C-Horizon
The “Regolith” Horizon
 At depths of 30-48 feet
 Made up of large rocks or lumps
of partially broken bedrock
 Least affected by weathering
and have changed the least
since their origin
 Devoid of organic matter due to
it being so far down in the soil
profile

23. R-Horizon
The “Bedrock” Horizon
 At depths of 48+ feet
 Deepest soil horizon in the soil
profile
 No rocks or boulders, only a
continuous mass of bedrock
 Colors are those of the original
rock of the area

24. Soil Pollution
Soil pollution is pollution of the earth's natural land surface
by industrial, commercial, domestic and agricultural
activities.
The introduction of substances, biological organisms, or
energy into the soil, resulting in a change of the soil quality,
which is likely to affect the normal use of the soil or
endangering public health and the living environment.
Soil contaminants are spilled onto the surface through many
different activities.
Most of these are the result of accidents involving the
vehicles that are transporting waste material from site of
origin to a disposal site.

25. Others involve accidents involving
vehicles (automobiles, trucks and
airplanes) not transporting wastes, but
carrying materials, including fuel, that
when spilled contaminate the soil.

26.  Other spills are the direct action
of humans pouring potentially
toxic materials (solvents, paints,
household cleaning agents, oil,
etc.) onto the soil surface rather
than disposing these materials by
more appropriate means.
 Illegal dumping is the disposal of
waste in unauthorized areas.
 It is also known as “open
dumping”, “fly dumping”, and
“mid-night dumping”
 .
 Illegal dumps occur most often
along isolated roadsides in
remote areas of the country.
 Materials often found in illegal
dumps include large household
appliances, tires, excess building
materials, old furniture, oil,
household chemicals, and common
household refuse.
Washington state
Missouri
Virginia
New York
Iowa

27. Soil Pollution
Information needed to clean up materials added to
soil include:
1) Kind of material - organic or inorganic - is the
material biodegradable, is the material dangerous to
animals and humans,
2) how much material was added to the soil, will it
overload the organisms in the soil;
3) C:N ratio of the material, are additional
nutrients needed ( N & P)

28. Soil Pollution
4) Kind of Soil - will the soil be able to handle the
material before groundwater is contaminated,
5) Growing conditions for the soil organisms - is it
too cold, too wet etc.
6) How long has the material been on the site - is
there evidence of environmental problems, is it
undergoing decomposition.
7) Immediate danger to people and the environment
- Urgency of the situation.

29. Pollutants in Soil
Naturally and synthetic materials affect the
physical, chemical and biological properties of
soil called “soil pollutants”-
Chemical and metallic pollutants.
Agro-chemicals.
Radioactive material.
Biological agents.

30. Pollutants in Soil
 Chemical and metallic pollutants-hazardous
effluent from
 Different type industries
 Metallic industries
 Inorganic polluants (Fe, Cu, Co, Zn, Hg, As, Ni, Cd,
Pb, alkalis and acid etc.
 Agro-chemicals.
 Pesticides, insecticides, weedicides and herbicides
 Soil conditioners and fumigant
 lead, arsenic, mercury, cobalt, cadmium, cyanide.

31. Pollutants in Soil
 Radioactive material.
 Nuclear devices
 Biological agents.
 Algae, fungi, bacteria, protozoa, viruses,
nematodes, worm,
 Industries waste,
 Enter in air, water and food chain.

32. Sources of Soil Pollution
 Industrial Wastes-
 fly ash,
 effluent i.e. organic compound, inorganic complexes, non-biodegradable
 affects chemical and biological properties of soil.
 Urban Waste-
 Commercial and domestic waste
 Solid waste- garbage and rubbish material-plastic, glasses, metallic
cans, fibers, paper, rubbles, fuel residues, leaves, containers.
 Radioactive Pollutants-
 Nuclear dust and radioactive waste
 Thorium, Uranium, Carbon (C-14) substance in soil, rock, water and air
 Nuclear fission, heavy water (Sr-90, Cs-137) cause gama radiation.

33.  Agricultural Practices-
 Pesticides, insecticides, weedicides and herbicides
 Toxic metal-lead, arsenic, mercury, cobalt, cadmium, cyanide etc.
 Chemical and Metallic Pollutants-
 Different type chemical, metallic and fertilizer industries.
 Organic and Inorganic polluants (Fe, Cu, Co, Zn, Hg, As, Ni, Cd, Pb,
alkalis and acid etc.)
 Affect soil texture, fertility and stabilization of soil.
 Biological Agents-
 Large quantity of animal, birds and human excreta cause land pollution
 Leached in soil and cause chronic salts hazardous to plants and animal.
 Pathogenic organism by naturally,
 Pathogenic organism by human excreta,
 Pathogenic organism by animal excreta.

34.  Soil Errosion-
 Natural process of detachment and removal of loosened soil material by
exothermic process (water, wind, ice or gravity).
 Due to running of water, wind, ice or geological agent.
 Agriculture development, construction and strip mining activities fertile top
layer and lost & wasted soil.
 Acid Rain-
 Air pollution- motor vehicle, factory emission etc. cause acid rain (Nox-
HNO3, Sox- H2SO4)

 Other Sources-
 Absorbtion of toxic metal
 Soluble salts, Mining
 Wastewater applied soils
 Solid waste applied soils,
 Food processing waste,
 Sugarcan trash in field,
 Muncipal garbage & composed etc.

35. Effect of Soil Pollution
i) Health effects- There is a very large set of health
consequences from exposure of soil contaminants
especially volatile compounds. Health hazards depend on
pollutant type, pathway of attack and vulnerability of
the exposed population.
ii) Ecosystem-The soil contaminants can alter
metabolism of endemic microorganisms and arthropods
resident in the soil environment, even at low
concentrations and hence can affect primary food
chain (in turn major consequences for predator or
consumer species). Contaminants typically alter plant
metabolism and reduce crop yield. This has given rise
to soil erosion.

36. Effect of Soil Pollution
Major soil pollutants and their effect on human health
MMeettaall SSoouurrccee EEffffeeccttss
Arsenic Occurs naturally Chronic poisoning leads to a loss of appetite and
weight, diarrhea, alternating with constipation,
gastro intestinal disturbances, peripheral neuritis,
conjunctivitis and sometimes skin cancer
Cadmium Mining, metallurgy chemical industry
and electroplating
Leads to chronic poisoning and affects the
proximal tubules of the kidney, causing formation
of kidney stones
Lead Lead smelters storage battery Lead poisoning can lead to severe mental
retardation or death
Mercury Industrial wastes Methyl mercury compounds are much more toxic
than other forms of mercury, causes neurological
problems and damages renal glomeruli and tubules
Cyanides Wastes from heat treatment of
metals, dismantling of electroplating
shops, etc.
Rapid death may follow due to exposure to cyanide
as a result of inhibition of cellular respiration

37. Control of Soil Pollution
 The major concern of soil pollution is that there are many sensitive land uses
where people are in direct contact with soil such as residence, parks,
schools and playgrounds. Hence, it is necessary to cleanup or •remediates
polluted soil.
 The principal remedial strategies are:
1. Aeration of soil at contaminated sites.
2. Bioremediation, involving microbial digestion of certain organic chemicals,
heavy metals and land farming, biostimulation and bioaugmentation of soil
biota with flora.
3. Extraction of groundwater or soil vapors with active electromechanically
system (by using single extraction method or fractionation schemes).
4. Excavate soil and remove it to a disposal site away from sensitive
ecosystem contact.