Soil pollution

1. SOIL POLLUTION

2. SOIL POLLUTION
• 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 an adverse effects
on plant growth and animal health.
(FAO and ITPS, 2015).
• It is defined as the change in Physical,
Chemical and Biological Conditions of
the soil by any natural or anthropogenic
mean resulting in degradation in soil
quality.

3. Soil Pollutants
Soil Pollutant is any
Soild, Liquid and
gaseous substance that
detrimentally alter the
natural condition of the
Soil and ultimately
cause Soil Pollution.
Sources
Agriculture, Excessive use of
fertilizers and pesticides,
Industrial Processes,
Deforestation, Spills and Leaks,
Littering, Waste Disposal,
Mining, Construction,
Transportation, Landfills,
Chemical Waste, Nuclear Waste,
Acid Rain, Illegal Dumping

4. Sources of Soil Pollutants:
Natural/Geogenic Sources Anthropogenic Sources
Several soil parent
materials - sources of certain
heavy metals.
Industrial Activities
 Volcanic Eruptions Mining
Soils & rocks are also
source of Radioactive gas
Radon.
Urban and transport
infrastructures
Volcanic eruptions and
forest fires- release toxic
elements.
Waste and sewage
generation and disposal
PAH’s - occur naturally in
soil
Military actives and wars
Agricultural and Livestock
activities

5. Agriculture sources of Soil Pollution

6. Sources of Soil Pollution

7. Types of Soil Pollution:
 Point Source Pollution:
caused by a specific event or a
series of events within a particular area
in which contaminants are released to
the soil, and the source and identity of
the pollution is easily identified.
Examples:
former factory sites, inadequate waste
and wastewater disposal, uncontrolled
landfills, excessive application of
agrochemicals, spills of many types,
and many.

8. Diffuse Pollution:
Diffuse pollution is pollution that is spread over very wide areas, accumulates in
soil, and does not have a single or easily identified source.
Examples :
Nuclear power and weapons activities; uncontrolled waste disposal and
contaminated effluents released in and near catchments; excess nutrients and
agrochemicals that are transported downstream by surface runoff;agricultural
use of pesticides and fertilizers which also add heavy metals, flood events etc.
Fig. Transport pathway of pesticides in the environment

9. Agricultural Pollution Pollution by industrial effluents
Pollution by Solid wastes Pollution due to urban activities

10. Main Pollutants in Soil
Systematic categorization of the main pollutants in soil. Source: Swartjes.2011

11.  Heavy Metals & Metalloids:
o Heavy metals - the group of metals and metalloids of relatively high atomic mass (>4.5
g/cm3 ) such as Pb, Cd, Cu, Hg, Sn, and Zn.
o Heavy metals are the most persistent and complex kind of pollutants to remediate in
nature.
o They not only degrade the quality of the atmosphere, water bodies, and food crops, but
also threaten the health and well-being of animals and human beings.
 Nitrogen & Phosphorous fertilizers
o Nitrogen pollution influences soil organic matter decomposition, as it affects
microbial community composition and activities as well as soil acidity and salinity
o These nutrients are able to leach into the groundwater or be transported to surface
water bodies by runoff, causing eutrophication or leading to high nitrate
concentrations.
o Many heavy metals have also been documented in phosphate and nitrate fertilizers
including As, Cd, Cr, Hg, Pb, and Zn.

12.  Pesticides:
o pesticides are also associated with heavy metal contamination of soils.
o The impact of plant protection products on soil functions and ecosystem
services highlighted the severe impact of copper-based fungicides on
earthworms and microbial biomass.
o These fungicides are widely used in organic viticulture to control vine fungal
diseases
 Polycyclic Aromatic Hydrocarbons:
o Polycyclic aromatic hydrocarbons accumulate in soils because of their
persistence and hydrophobicity and tend to be retained in the soil for long
periods of time.
 Persistent Organic Compound:
o Soils are the main environmental sink for these persistent pollutants.
o POPs form stable bonds with soil organic matter, where they remain in a non-
extractable form.

13.  Radionuclide:
o Radionuclides are present in the environment both as a naturally
occurring substance and as one of anthropogenic origin.
o Radionuclides in the soil are taken up by plants, thereby becoming
available for further redistribution within the food chain.
 Emerging Pollutants:
o Emerging pollutants (EPs) refers to a large number of synthetic or
naturally occurring chemicals that have recently appeared in the
environment and are not commonly monitored
o The adsorption behaviour of pharmaceuticals can vary vastly in
different soil types as their occurrence in both ionized and unionized
forms affects their interaction with different compounds in the soil.

14. IMPACTS OF SOIL POLLUTION
SOIL POLLUTION, PLANT UPTAKE AND FOOD CHAIN CONTAMINATION
If a contaminant is highly toxic to
plants at low concentrations and is
not easily translocated to shoots,
fruits or tubers to pose a hazard to
animals and humans, it is unlikely
to enter the food chain and become
a hazard. This concept was termed
the Soil-Plant Barrier.
The pathways of contamination
within the food chain by the
transfer of soil pollutants
through plants are shown in Fig.

15. Group 1: the elements that pose a low risk of food chain
contamination.
•Elevated concentrations of these elements in foods usually
indicate direct contamination through soil or dust accumulation.
Group 2 : elements that are
strongly absorbed by soil
surfaces.
These elements could,
however, pose a risk to
grazing animals (or
humans) if contaminated
soil is ingested.
Group 3 comprises the elements that are readily taken up by
plants, but that are phytotoxic at concentrations that pose little
risk to human health.
Group 4 consists of elements that are at the highest risk for food
chain contamination as they pose risks to human or animal
health at plant tissue concentrations that are not generally
phytotoxic
Metals/metalloids classified in groups according to potential
food-chain risk via plant uptake

16. Excess heavy metals such as arsenic, cadmium, lead and
mercury in soils can also impair plant metabolism and
decrease crop productivity
Once metals enter plant tissues, they may interfere with
several metabolic processes, reducing plant growth and
causing toxicity and finally plant death.
Cadmium can accumulate in different edible tissues causing
reduction of root, stem and leaf growth, decreasing net
photosynthesis and water use efficiency and altering nutrient
uptake
These pollutants also pose risks to food security, water
resources, rural livelihoods and human health.
High levels of lead, for example, accelerate the production of
reactive oxygen species, causing lipid membrane and
chlorophyll damage that further leads to the alteration of
photosynthetic processes and of the overall growth of the
plant

17. IMPACT OF SOIL POLLUTION ON AGRICULTURE
SYNTHETIC FERTILIZERS: Modern agriculture practices
accelerate soil pollution with the intensive use of fertilizer and
pesticides. When pollutants reach high levels in the soil, not
only do soil degradation processes take place, but crop
productivity can also be affected.
ACIDIFICATION AND CROP LOSS: Acidification of agricultural soils
may contribute to further soil pollution, through the mobilization of
toxic heavy metals. When soil nutrient availability increases, microbial
biomass and activity increases as well, but the microbial biodiversity is
altered, causing imbalances in the nutrient cycle.
 Imbalance in Soil Flora and Fauna.
 Increased erodobility

18. MANURE:
 Application of untreated manure may lead to heavy metal
pollution, which not only results in adverse effects on
various parameters, but also causes changes in the size,
composition and activity of the microbial community
affecting nutrient cycling and reducing nutrient availability.
 A High proportion of antibiotics given to livestock is poorly
assimilated in the animals’ guts and is excreted in urine and
faeces.
 Untreated manure can thus contain high amounts of
veterinary antibiotics that can lead to a rapid increase in
Urban Wastes In Agriculture: High levels of heavy metals such as
Pb, Cd, Cu, Zn, Cr, Ni, and salts remain in the amendments and
may affect soil properties and inhibit plant growth.
PESTICIDES: some organochlorine pesticides suppress
symbiotic nitrogen fixation, resulting in lower crop yields.

19. HUMAN HEALTH RISKS ASSOCIATED WITH SOIL POLLUTION
risks from elemental contamination (e.g. As, Cd, Pb);
organic chemical contamination (e.g. PCBs, PAHs, POPs)
 pharmaceutical contamination (e.g. estrogen, antibiotics).
soil pathogens such as anthrax and prions,
micronutrient deficiencies,
under-nutrition due to degraded soils.

20. The uptake of metals by plants from soils may result in a significant risk to
health.
 The absorption by plant roots is one of the main routes of entrance of heavy
metals into the food chain, and varies according to the level of consumption.
Cadmium and lead are the most toxic elements for man. Cadmium absorbed
via food intake can penetrate through the placenta during pregnancy, damaging
membranes and DNA and disrupting the endocrine systems, and can induce
kidney, liver and bone damage.
The toxic effects of Pb affect several organs, causing biochemical imbalance in
the liver, kidneys, spleen and lungs, and causing neurotoxicity, mainly in infants
and children.
Mercury may induce changes in human neural and gastric systems and can
lead to death. Arsenic is absorbed in the body orally or inhaled and is stored
mainly in the liver, kidneys, heart and lungs, with smaller amounts
accumulating in muscle and nerve tissue, and has been defined as carcinogenic
Nickel causes gastric, liver, and kidney defects and neurological effects . Zinc
is associated with anemia and tissue lesions, and while the negative effects of
copper are rare, liver and kidney damage in infants is possible if exposure is
prolonged

21. IMPACT OF SOIL POLLUTION ON ENVIRONMENT
Soil pollution causes a chain reaction.
It alters soil biodiversity, reduces SOM and soils capacity to filter.
Soil becomes unavailable to grow food.
Can cause even more harm because a lack of plants on the soil will cause
more erosion.
The pollutants will change the makeup of the soil and the types of
microorganisms that will live in it.
Thus it's possible for soil pollution to change whole ecosystems.

22. Soil As A Pollutant
 Soil naturally contributes to air pollution by releasing volatile compounds
into the atmosphere - so the more toxic compounds soil contains, the greater
the air pollution it creates.
Soil can lead to water pollution if toxic chemicals leach into groundwater or
if contaminated runoff or sewage, which can contain dangerous heavy metals,
reaches streams, lakes, or oceans.
Soils with high levels of N & P can leach into waterways, causing algal
blooms, resulting in death of aquatic plants due to depleted dissolved oxygen.
Soil pollution allows great quantities of nitrogen to escape through ammonia
volatilization and denitrification and the decomposition of organic materials in
soil can release sulfur dioxide and other sulfur compounds, causing acid rain.
Soil pollution may alter plant metabolism and reduce crop yield and cause
trees and plants that may absorb soil contaminants to pass them up the food
chain.

23. Treatment methods for Contaminated Soil
Main remediation methodologies and their effects on soil pollutants (√ = main process, (√) = subsidiary process limited in

24. Thermal Desorption
•Thermal Desorption is a process where
heat is used to remove contaminants
from soil.
•It increases the volatility of
contaminants.
• The volatilized contaminants are
either collected or thermally destroyed.
• It consists of Desorber and Offgas
Treatment.
•These include organic wastes
composed of Hydrocarbons such as oil
refining wastes, fuels, PCB’s, Pesticides
and paint wastes.

25. Soil Stabilization
Stabilization is the process of blending
materials with a soil to improve properties of
the soil.
Soil stablization is a process by which a soils
physical property are transformed to provide
long term permanent strength gains.
It is accomplished by increasing the shear
strength and overall bearing capacity of soil.
Stabilization reduces the power of hazardous
substances and contaminants in the
environment through both physical and
chemical .
Stabilization is being used for a variety of
engineering work like construction of road.

26. The soil stabilization process begins in the laboratory where
soils samples are analyzed to determine how much chemical
modifier is necessary to permanently stabilize the soil.
After the application rate is determined, soil stabilization at the
construction site can commence as follows

27. Soil Washing
Soil Washing is the process in which
water is used to remove contaminants
from soil
Such as organic, inorganic and
radioactive contaminants.
The process works by dissolving
contaminants in the wash solution.
Most organic and inorganic
contaminants bind to clay, silt and
organic soil particles.
Washing separates the small particles
from the large particles.
Separated material is smaller in
volume and more easily disposed.

28. Soil Disposal
This can be the simplest solution to
contaminated land, excavate, haul and
dispose of the contaminated soils.
Air Sparging
This technique is used for the treatment of saturated soils
and groundwater contaminated by volatile organic compounds (VOCs)
like petroleum hydrocarbons.
Air Sparging is a subsurface contaminant remediation technique that involves the
injection of pressurized air into contaminated ground watercausing hydrocarbons to
change state from dissolved to vapor state.
The air is then sent to the vacuum extraction systems to remove the contaminants. The
extracted air or "off vapors" are treated to remove any toxic contaminants.

29. Soil Chemical Oxidation
Chemical Oxidation is an in situ remediation
technology that can be applied to soils for
many different contaminants.
It is a chemical technology where strong
oxidants are injected or mechanically mixed
into the treatment zone to promote destructive
abiotic degradation reactions.
Chemical oxidation involves the injection or
direct mixing of chemical oxidants into soil
Chemox (Chemox oxygen breathing Appratus)
involves oxidizing contaminants with the
purpose of reducing the concentration.

30. Bioremediation is the use of biological
processes to degrade, transform, or
essentially remove contaminants
from contaminated sites.
•The removal of organic waste by
microbes for environmental cleanup is
essence of bioremediation.
•Bioremediation exploits various naturally
occurring mitigation processes:
-Natural Attenuation
-Biostimulation
-Bioaugmentation
Types of Bioremediation:
-In-situ bioremediation
-Ex-situ bioremediation
Bioremediation

31. In situ remediation: is
performed directly on the site
without excavating soil
contaminants or
Disturbance to the soil structure.
Ex situ remediation: is
performed indirectly process,
excavation of contaminated soil,
which is transported to a special
landfill, where treated.
In-situ & Ex-situ Remediation

33. Phytoremediation:
 Phytoremediation is the use of
special type of plants to
decontaminate soil or water by
inactivating metals in the
rhizosphere or translocating them
in the aerial parts.
 There are different categories of
phytoremediation,including
phytoextraction,phytofiltration,ph
ytostabilization,phytovolatization
andphytodegradation,depending
on the mechanisms of remediation.

34. Prevention and control of Soil Pollution:
1. Get a better understanding of the soil environment quality baseline.
 carrying out sensitizations and surveys on soil pollution
 establishment of soil environmental quality monitoring networks to
ensure improved monitoring frequency.
 Strengthening data sharing and establishing the pattern of sharing
will help in guaranteeing immediate solutions when the need arises.
2. Develop necessary legislation on soil pollution control
 urban and rural planning, agricultural practices, and land
management should be revised and updated to include contemporary
soil pollution control and prevention measures.
 measures should be put in place to promote continuous improvement
of soil pollution control standards.

35. 3. Proper management of agricultural land and the practice of organic
farming
 Poor utilization of land is a major concern in the prevention and control of soil
pollution.
 The crop related control measures include crop rotation, strip cropping,
planting along the contours, protector belt, crop residues, and use of organic
composts.
 In areas with excessive pollution or surface degradation, reforestation should be
done.
 mechanical method of soil pollution control includes the use of contour holding
system, gully control, and making bunds.
4. Proper Solid Waste Treatment
 Acidic and alkaline waste can be neutralized before they are disposed of to avoid
soil contamination.
 waste materials should also be categorized based on the degree of
contamination.
 Materials that are mildly or moderately contaminated should be treated in
controlled environments before release into the natural environments while
those that are heavily contaminated should be put under strict management,

36. 5. Ensure proper investigation of reclaimed land.
 Need to conduct soil investigation and evaluation.
 establishing practical management and control measures depending on the
purpose of the land.
 the responsible body must take the necessary precautions to not only manage and
mitigate the risks but to also prevent the contamination of adjacent soils.
6. Strictly control the pollution of new soil.
 thorough research should be conducted to ensure whether the land is suitable for
the intended use.
 Supervision of unutilized land is also key.
 Governments are also encouraged to enhance spatial planning and management
based on the capacity of environment and soil.
7. Strengthen policies that manage pollution sources.
strictly control the mining and industrial pollutants.
To ensure accountability, the companies in the specified area should conduct soil
research at least once annually
Surrounding soil should also be monitored on a regular basis
the government should take stronger measures against people, businesses, and
companies that breach the policies.

37. 8. Transfer treatment and remediation costs to polluting companies
To ensure the sustainability of the project, the individuals and companies that
pollute the soil should be held responsible for the treatment and remediation costs.
To ensure consistency, the government should formulate treatment and
remediation plans as well as identify responsible entities, identify key tasks, and
develop projects database for easy management.
9. Embrace technological research and development
research on soil pollution prevention and control should be advanced by
strengthening technological research.
promoting research on common technologies that relate to soil pollution diagnosis,
research, and development of advanced data collection and mapping equipment,
and soils contamination risk management and control.
10. Promote objective assessment and accountability among all stakeholders
immediate resolutions focused towards correct disposal of garbage, proper
treatment of sewage sludge, minimized the use of agro-chemicals, reforestation,
construction of drainage systems, and strengthening chemical use related laws.

38. References:
Alexander, M. 1999. Biodegradation and bioremediation. 2nd ed edition.
San Diego, Academic Press. 453 pp.
FAO. 2003. International Code of Conduct on the Distribution and Use of
Pesticides. Rome, Italy, Food and Agriculture Organization of the United
Nations. (also available at
http://www.fao.org/docrep/005/Y4544E/y4544e00.htm
Logan, T.J. 2000. Soils and Environmental Quality. In M.E. Sumner, ed.
Handbook of Soil Science, pp. G155–G170. Boca Raton, Fla, CRC Press.
Logan, T.J. 2000. Soils and Environmental Quality. In M.E. Sumner, ed.
Handbook of Soil Science, pp. G155–G170. Boca Raton, Fla, CRC Press.
Loganathan, B.G. & Lam, P.K.S., eds. 2012. Global contamination trends
of persistent organic chemicals. Boca Raton, CRC Press. 638 pp.
Oliver, M.A. & Gregory, P.J. 2015. Soil, food security and human health:
a review: Soil, food security and human health. European Journal of Soil
Science, 66(2): 257–276. https://doi.org/10.1111/ejss.12216
WHO. 2010. Preventing Disease Through Healthy Environments. Action
is needed on chemicals of major public health concern. , p. 6. Geneva,

39. Be the Solution to Soil Pollution