Unit 4 polluted soil and its remediation sol220

1. Polluted Soil
and
remediation
•By- Dr. Kamini Roy
•Associate Professor,
Agricultural Chemistry and
soil science,
•Lovely Professional
University, Phagwara
•(First ICAR Accredited
University)
By Dr. Kamini Roy

2. Soil pollution
• It is the the buildup of contaminants, toxic compounds,
radioactive materials, salts, chemicals disease and cancer-
causing agents above the permissible limit.
• The most common soil pollutants are hydrocarbons, heavy
metals (cadmium, lead, chromium, copper, zinc, mercury and
arsenic), herbicides, pesticides, oils
• Productive soils are necessary for agriculture to supply the
world with sufficient food.
By Dr. Kamini Roy

3. POLLUTED SOILS:
“Soil pollution” refers to the presence of a chemical or substance out
of place and/ or present at a higher than normal concentration that
has adverse effects on any non-targeted organism (FAO, 2015).
Although the majority of pollutants have anthropogenic origins, some
contaminants can occur naturally in soils as components of minerals
and can be toxic at high concentrations.
Soil pollution often cannot be directly assessed or visually perceived,
making it a hidden danger.
By Dr. Kamini Roy

4. • Soil pollution” refers to the presence of a
chemical or substance out of place and/ or
present at a higher than normal
concentration that has adverse effects on any
non-targeted organism .
• A. True
• B. False
By Dr. Kamini Roy

5. Sources of soil pollution
A. Agrochemicals
1. Pesticide
2. Insecticides
3. Herbicides
4. Fungicides
5. Fertilizers
B. Industrial wastes
1. Effluent
2. Dust and other solid wastes
3. Radioactive waste
4. Heavy metals
5. Acid precipitation
By Dr. Kamini Roy

6. • C. Urban wastes
• 1. Municipal solid wastes
• 2. Municipal sewage
• 3. Vehicular exhaust
• D. Rural wastes
• 1. Home wastes
• 2. Litter
• 3. Livestock wastes
• 4. Plant residues
• 5. Sediment
By Dr. Kamini Roy

7. Pesticide pollution
• Pesticides include insecticides, fungicides, nematicides,
rodenticide and herbicide
• Their potential as a pollutant depends on their bio-
degradability and toxicity to animals and human beings.
• Pesticide that can persist in soils for a long time affect the
food chain by the process called biological magnification,
meaning accumulation and subsequent concentration in
the food chain. They may cause severe damage to non
target animals
By Dr. Kamini Roy

8. • Pesticides include insecticides, fungicides,
nematicides, rodenticide and herbicide
• A. True
• B. False
By Dr. Kamini Roy

9. Soil pollution due to excessive use of
fertilizers
• Indiscriminate use of fertilizers
• Soil nutrients are important for plant growth and
development. Plants obtain carbon, hydrogen and oxygen
from air and water. But other necessary nutrients like
nitrogen, phosphorus, potassium, calcium, magnesium, sulfur
and more must be obtained from the soil. Farmers generally
use fertilizers to correct soil deficiencies.
By Dr. Kamini Roy

10. • Effects of chemical fertilizers
• i. Chemical fertilizers are generally used far in excess of the
requirements of the crop. The unutilized fertilizers cause soil
pollution.
• ii. Toxic concentrations of nitrogen fertilizers cause
characteristic symptoms of nitrite or nitrate toxicity in plants,
particularly in the leaves. Nitrogenous fertilizers generally
cause deficiency of potassium, increased carbohydrate
storage and reduced proteins, alteration in amino acid
balance and consequently change in the quality of proteins.
• iii. Ammonium fertilizers produce ammonia around the roots
that may escape the soil and cause ammonia injury to plants.
By Dr. Kamini Roy

11. • Ammonium fertlizers if used over extended periods
produce acids in the soil and increase soil acidity.
• Excessive potash in the soil decreases ascorbic acid and
carotene in the plants.
• Phosphatic fertilizer in excessive use cause deficiency
Zn in plants by interfering with their uptake.
Phosphorus induced Zn deficiency
• Excessive lime prevents the release of Co, Ni, Mn and
Zn from the soil and their uptake by plants is reduced
causing their deficiency symptoms.
By Dr. Kamini Roy

12. • Ammonium fertlizers if used over extended
periods produce acids in the soil and increase
soil acidity.
• A. True
• B. False
By Dr. Kamini Roy

13. Effects of industrial effluents
i. Various inorganic and organic substances are present in the
industrial effluents. These substances mostly remain tied up
in the soil and are not readily available to plants. However,
they affect various soil characteristics.
ii. Effluents affect soil pH, exchangeable base status etc. of the
soil and thus indirectly affect the plants
iii. The pH of the soil is disturbed making soil either acidic or
alkaline.
iv. Various inorganic and organic chemicals are accumulated in
the soil up to levels toxic to plants.
v. In highly polluted soils, plants absorb and accumulate toxic
substances (bioaccumulation). These substances may or may
not produce direct injury symptoms in plants By Dr. Kamini Roy

14. • Industries effluents are the source of heavy metal
pollution in soils, Depending on the industry, specific
heavy metals are added with discharge in water
• Many small to medium scale industries operating in
peri-urban residential areas of cities are disposing their
contaminated effluents directly in sewage system.
• Studies have documented that direct disposal of
effluents to land and water bodies has potential to
contaminate surface, ground waters as well as soils
and crops grown on these soils with heavy metals
which will have bearing on human health.
By Dr. Kamini Roy

15. • Nitrate pollution in ground water is mainly contributed by
nitrogenous fertilizers, industrial effluents.
• Being an anion, NO3 is not adsorbed by the negatively charged soil
surfaces and is easily transported through soil profiles into ground
water.
• Heavy rain or irrigation after nitrogen application can carry
nitrogen deep in to soil to drainage waters, sandy soils are
particularly susceptible to leaching
• Rise in concentration of nitrate in ground water has been observed
in a number of countries globally and is cause of concern to health
authorities.
• Higher concentration of nitrate in a groundwater well used for
drinking water causes a health problem in infant called
methemoglobinemia (bluebaby syndrome)
By Dr. Kamini Roy

16. • Nitrate pollution in ground water is mainly
contributed by nitrogenous fertilizers,
industrial effluents
• A. True
• B. False
By Dr. Kamini Roy

17. Effects of Soil Pollution on crop production
• Reduced soil fertility
• Reduced nitrogen fixation
• Increased erodibility
• Larger loss of soil and nutrients
• Deposition of silt in tanks and reservoirs
• Reduced crop yield
• Imbalance in soil fauna and flora
By Dr. Kamini Roy

18. Prevention of soil pollution
• Excavation : It is removal of top polluted layer of the
soils by mechanical devices to expose uncontaminated
sub soil.
• It is followed by disposal of the soils to land fill sites
• Precautions associated with the excavation and transport
of polluted soils need to be taken.
• This is a rapid method of managing polluted sites which
has been widely employed in the past but it just relocates
the problem and hence is not a remedial treatment.
• With land space becoming costly, this strategy is
becoming less acceptable to industry, regulatory bodies
and the public.
By Dr. Kamini Roy

19. Excavation
By Dr. Kamini Roy

20. Other methods
• Addition of various amendments like gypsum,
organic matter, zeolites, lime, phosphorus
• Maintaining pH
• Controlling metal interactions
By Dr. Kamini Roy

21. • Excavation : It is removal of top polluted layer
of the soils by mechanical devices to expose
uncontaminated sub soil.
• A. True
• B. False
By Dr. Kamini Roy

22. • Zeolites are micro porous crystalline solids which
contain silicon, aluminium.
• They contain linked cages or cavities which are of
the right size to allow small molecules or heavy
metal atoms to enter.
• They are natural or synthetic
• E.g. MOR, mordenite-type
FAU, faujasite-type zeolite
By Dr. Kamini Roy

23. • Use of Organic matter: Bonding of organic matter with metals fix
the metals and leaving lesser metal immediately available for plants.
• CaCO3: Its application fixes heavy elements or reduces availability by
changing soil pH.
• Using organic chelates to enhance phytoextraction like EDTA or DTPA
By Dr. Kamini Roy

24. • Oxides of Mn and Fe : It reduces toxicity of heavy metals.
• By-products of industrial processes such as berginite and steel are
available at affordable cost.
• Vitrification : In this technology an electric current is used to melt the
soil at a temperature up to 20000C.
• The melted soil cools to form a chemically stable, leach resistant,
glass like solid mass.
• It encases and entrap inorganic pollutants.
• However, this procedure destroys the soil, thereby limiting future site
use.
By Dr. Kamini Roy

25. • Solidification : It involves the use of resistant material
which gets mixed with soil and then soil allowed to form a
solid product after some time.
• any materials have been used in solidification technology
including cement, fly ash, bitumen, and polythene.
• The resulting product is not a soil but can often be used as
a building or construction material.
By Dr. Kamini Roy

26. • Nanoremediation: Using nano-sized reactive agents to degrade or
immobilize contaminants is termed nanoremediation. The
nanomaterials then degrade organic contaminants through redox
reactions or adsorb to and immobilize metals such as lead or arsenic.
Nanomaterials are highly reactive because of their high surface area
per unit mass, and due to this reactivity nanomaterials may react
with target contaminants at a faster rate than would larger particles.
By Dr. Kamini Roy

27. Phytoremediation
• It is a new approach that uses specially selected metal accumulators
plants to remediate soil contaminated with heavy metals.
• It is safe and cheap technology to implement sustainable agriculture
• Selected plants absorb heavy metals from roots and translocate
them to shoots.
• Heavy metals are then removed by harvesting shoots and then
ashing
• E.g. Thlaspi caerulescens has been used successfully to decontimate
cadmium polluted soils.
By Dr. Kamini Roy

28. • Phytoremediation is a new approach that uses
specially selected metal accumulators plants
to remediate soil contaminated with heavy
metals.
• A. True
• B. False
By Dr. Kamini Roy

29. Phytoremediation
By Dr. Kamini Roy

30. Bioremediation
• These are biological methods for clean up of contaminated soils.
• It involves establishing appropriate micro organisms to grow and
carry out the metabolic activities to detoxify the contaminants.
• Different types of bacteria, fungi and other micro organisms are used
for treating polluted soils e.g. Pseudomonas pudita, Pleurotus
tuberegium (DDT, PCB’s)
By Dr. Kamini Roy

31. Eroded Soil and its reclamation
By Dr. Kamini Roy

32. Eroded soils
Soil erosion is defined as the detachment and transportation of soil mass from one place to another
through the action of wind, water in motion or by the beating action of rain drops
Erosion extensively occurs in poorly aggregated soils (low humus) and in a higher percentage of silt
and very fine sand. Erosion increases when soil remains bare or without vegetation.
Occurence
In India about 86.9% soil erosion is caused by water and 17.7% soil erosion is caused by wind. Out
of the total 173.6 Mha degraded land in India, soil erosion by wind and water accounts for 144.1 Mha
(Govt. of India, 1990). The surface soil is taken away by the runoff causing loss of valuable topsoil
along with nutrients, both native and applied. In India about 5334 million tones (16.35
tonnes/ha/year) of soil is being eroded annually due to agriculture and associated activities and 29%
of the eroded materials are permanently lost into the sea.
By Dr. Kamini Roy

33. • Soil erosion is defined as the detachment and transportation of
soil mass from one place to another through the action of wind,
water in motion or by the beating action of rain drops
• A. True
• B. False
By Dr. Kamini Roy

34. Types of erosion
a) Natural or geologic erosion ranges from very little in undisturbed lands to extensive in steep arid lands.
Geological erosion takes place, as a result of the action of water, wind, gravity and glaciers and it takes place, at
such slow rates that the loss of soil is compensated for the formation of new soil under natural weathering
processes. It is sometimes referred to as normal erosion.
b) Accelerated erosion caused by the disturbances of people (cutting forests, cultivating lands, constructing roads
and buildings etc.) and is increasing as the population increases. In this erosion, the removal of soil takes place at a
much faster rate than that of soil formation. It is also referred to as abnormal erosion.
By Dr. Kamini Roy

35. Causes of Water Erosion
Water erosion is due to the dispersive action, and transporting power of water. Water erosion of soil starts
when raindrops strike bare soil peds and clods, resulting the finer particles to move with the flowing water
as suspended sediments. The soil along with water moves downhill, scouring channels along the way.
Each subsequent rain erodes further amounts of soil until erosion has transformed the area into barren
soil. Water erosion may occur due to the removal of protective plant covers by tillage operation, burning
crop residues, overgrazing, overcutting forests etc. inducing loss of soil.
Raindrop / Splash Erosion
Rain drop splash erosion results from soil splash caused by the impact of falling rain drops. The continued
impact of raindrops compacts the soil and further seals the surface-so that water cannot penetrate into the
soil and as a result causing more surface run off.
By Dr. Kamini Roy

36. Sheet Erosion
Sheet erosion is the removal of a fairly uniform layer of surface soil by the action of rainfall and runoff
water on lands having a gentle or mild slope, and results in the uniform "skimming off of the cream" of the
top soil with every hard rain, In this erosion, shallow soils suffer greater reduction in productivity than deep
soils. It is slow process but dangerous. Movement of soil by rain drop splash is the primary cause of sheet
erosion.
Rill Erosion
Rill erosion is the removal of surface soil by running water, with the formation of narrow shallow channels
that can be levelled or smoothed out completely by normal cultivation. Rill erosion is more apparent than
sheet erosion. Rill erosion is more serious in soils having a loose shallow top soil. This type of soil erosion
may he regarded as a transition stage between sheet and gully erosion.
Gully Erosion
Gully erosion is the removal of soil by running water, with the formation of channels that cannot be
smoothed out completely by normal agricultural operation or cultivation. Gully erosion is an advanced
stage of rill erosion. Unattended rills get" deepened "and widened every year and begin to attain the form
of ‘gullies’. During every rain, the rain water rushes down these gullies, increasing their width, depth and
length.
By Dr. Kamini Roy

37. • Sheet erosion is the removal of a fairly uniform layer of surface
soil by the action of rainfall and runoff water on lands having a
gentle or mild slope, and results in the uniform "skimming off of
the cream" of the top soil with every hard rain.
• A. True
• B. False
By Dr. Kamini Roy

38. Stream Channel Erosion
Stream channel erosion is the scouring of material from the water channel and the cutting of banks by
flowing or running water. This erosion occurs at the lower end of stream tributaries. Stream bank erodes
either by runoff flowing over the side of the stream bank, or by scouring or undercutting. Scouring is
influenced by the velocity and direction of flow, depth and width of the channel and soil texture.
By Dr. Kamini Roy

39. Harmful Effects of Water Erosion/Constraints
Water erosion causes various damages to the lands as follows:
(i) Loss of top fertile soil. The surface soil lost as runoff consists of fertile soils and fresh or active
organic matter.
(ii) Accumulation of sand or other unproductive coarse soil materials on other productive lands. In the
plains, fertile lands have been made unproductive by the deposition or accumulation of soil material
brought down from the hills by streams and rivers.
(iii) Silting of lakes and reservoirs. Soil erosion from the catchment areas of reservoirs results in the
deposition of soil, thus reducing their storage capacity
(iv) Silting of drainage and water channels. Deposition of silt in drainage ditches in natural streams and
rivers reduces their depth and capacity and overflows and flooding of downstream areas increase
with damage to agricultural crops and also man-made structures.
(v) Decreases water table. With the increase in runoff, the amount of water available for entering the soil
is decreased. This reduces the supply of water to replenish the ground water in wells, the yield of well
is reduced.
(vi) Fragmentation of land. Water erosion especially gully erosion may divide the land into several valleys
and ridges and thus fields become smaller and more numerous. Crop rows are shortened, movement
from field to field is obstructed and a result the value of land is decreased.

40. Wind erosion
Soil erosion by wind has caused an accumulation of eroded particles in loess, a type of soil which makes
up some of the world's most fertile and productive regions. Soil conditions conducive to wind erosion are
most commonly found in arid and semi-arid areas where rainfall is insufficient and no vegetative cover on
the land. The most serious damage caused by wind erosion is the change in soil texture. Since the finer
soil particles are subject to movement by wind, wind erosion gradually removes silt, clay and organic
matter from the top soil, leaving the coarser soil material.
Threshold Velocity
Threshold velocity is the minimum wind velocity required to initiate the movement of soil particles.
Threshold velocity varies with the soil conditions and nature of ground surface.
By Dr. Kamini Roy

41. • Soil erosion by wind has caused an accumulation of eroded
particles in loess, a type of soil which makes up some of the
world's most fertile and productive regions.
• A. True
• B. False
By Dr. Kamini Roy

42. Wind erodes the soil in three steps. The soil particles are carried by the wind in three ways namely
saltation, suspension and surface creep.
Saltation: It is a process of soil movement in a series of bounces or jumps. Soil particles having sizes
ranging from 0.05 to 0.5 mm generally move in this process. Saltation movement is caused by the
pressure of the wind on the soil particle, and collision of a particle with other particles. The height of the
jumps varies with the size and density of the soil particles, the roughness of the soil surface, and the
velocity of the wind.
Suspension
Suspension represents the floating of small sized particles in the air stream. Movement of such fine
particles in suspension is usually started by the impact of particles in saltation. Once these fine particles
are picked up by the particles in saltation and enter the turbulent air layers, they can be lifted upward in
the air and .they are often carried for several miles before being redeposit elsewhere. Dust particles will
fall on the surface only when the wind subsides or the rain washes them down.
Surface Creep
Surface creep is the rolling or sliding of large soil particles along the ground surface. They are too heavy
to be lifted by the wind and are moved primarily by the impact of the particles in saltation rather than by
direct force of the wind. The coarse particles tend to move closer to the ground than the fine ones.
By Dr. Kamini Roy

43. By Dr. Kamini Roy

44. Impact of erosion on crop yield
Erosion reduces the capacity of the soil to hold water leading to severe water stress.
Erosion contributes to losses of plant nutrients, which wash away with the soil particles. Because sub-
soils generally contain fewer nutrients than top-soils, more fertilizer is needed to maintain crop yields.
This, in turn, increases production costs. Moreover, the addition of fertilizer alone cannot compensate for
all the nutrients lost when topsoil erodes.
Erosion reduces yields by degrading soil structure, increasing soil erodibility, surface sealing
Soil crusting is enhanced. Water infiltration is reduced, and seedlings have a harder time breaking
through the soil crust. Erosion reduces productivity because it does not remove topsoil uniformly over the
surface of a field. Typically, parts of an eroded field still have several inches of topsoil left; other parts may
be eroded down to the subsoil. This makes it practically impossible for a farmer to manage the field
properly, to apply fertilizers and chemicals uniformly and obtain uniform results. He is also unable to time
his planting, since an eroded part of the field may be too wet when the rest of the field is dry and ready.
By Dr. Kamini Roy

45. • Erosion contributes to losses of plant nutrients, which wash away
with the soil particles. Because sub-soils generally contain fewer
nutrients than top-soils
• A. True
• B. False
By Dr. Kamini Roy

46. Nutrient Behaviors of Eroded soils
• Eroded soils have a low total organic carbon content, and their humic
substances, humic acid carbon, and carbohydrates are lower compared with
soils that had never been cultivated (natural soils).
• The erosion mainly influences the active organic matter (respiration and water-
soluble organic matter).
• Total nitrogen correlates with the carbon fractions in the eroded soils.
By Dr. Kamini Roy

47. Control Measures for Eroded soils
Soil conservation measures, such as contour
ploughing, bunding, use of strips and terraces,
can decrease erosion and slow runoff water.
Mechanical measures, e.g., physical barriers
such as embankments and wind breaks, or
vegetation cover (and use of vegetative buffer
strips) and soil husbandry are important
measures to control soil erosion
By Dr. Kamini Roy

48. Best Management Practices: that are used to control erosion factors of both wind and water are
Crop rotation- improves the overall efficiency of nitrogen uptake and utilization in the soil. If certain
cover crops are planted in the winter, erosion and runoff is prevented when the ground thaws, and
nutrients are trapped in the soil and released to the spring crops.
Contour cultivation- On gently sloping land, a special tillage practice carried out on the contour of the
field can reduce the velocity of overland flow. Contour cultivation should not be carried out on steep
slopes because it will merely make the erosion situation worse.
Strip cropping- It is a technique in which alternate strips of different crops are planted in the same
field. There are three main types: contour strip cropping, field strip cropping, and buffer strip cropping. If
the strips are planted along the contour, water damage can be minimized; in dry regions, if the strips are
planted crosswise to the contour, wind damage is also minimized.
The most common crop choices for strip cropping are closely sown crops such as wheat, or other forages which are
alternated with strips of row crops, such as corn, soybeans, cotton, or sugar beets
Terraces- Constructing bench-like channels is otherwise known as terraces, enables water to be stored
temporarily on slopes to allow sediment deposition and water infiltration. There are three types of terraces:
bench terraces, contour terraces, and parallel terraces. It will control erosion in wetter areas by reducing
the length of the slope.
By Dr. Kamini Roy

49. Grassed Waterways - They force storm runoff water to flow down the center of an established grass
strip and can carry very large quantities of storm water across a field without erosion. Grass waterways
are also used as filters to remove sediment, but may sometimes lose their effectiveness when too much
sediment builds up in the waterways. To prevent this, it is important that crop residues, buffer strips, and
other erosion control practices and structures be used along with grass waterways for maximum
effectiveness.
Diversion structures- These are channels that are constructed across slopes that cause water to flow
to a desired outlet. They are similar to grass waterways and are used most often for gully control.
Drop structures - Are small dams used to stabilize steep waterways and other channels. They can
handle large amounts of runoff water and are effective where falls are less than 2.5 meters
Riparian strips - These are merely buffer strips of grass, shrubbery, plants, and other vegetation that
grow on the banks of rivers and streams and areas with water conservation problems. The strips slow
runoff and catch sediment. In shallow water flow, they can reduce sediment and the nutrients and
herbicides attached to it by 30% to 50%.
No-till planting- This planting system prepares a seedbed 2 inches wide or less, leaving most of the
surface undisturbed and still covered with crop residues. The result is a wetter, colder environment that
protects the seed and soil with its insulating effect of the surface residue.
By Dr. Kamini Roy

50. Acknowledge and Thanks
Author is immensely thankful to all the websites
and books whom I contacted to make these slides
more informative and attractive
By Dr. Kamini Roy

51. WE SHALL OVERCOME
Stay healthy
By Dr. Kamini Roy