a presentation on soil science

1. SOIL
CONTAMINATION
AND SOIL
POLLUTANTS

2. SOIL CONTAMINATION
Is the occurrence of
contaminants in soil above
a certain level causing
deterioration or loss of one
or more soil functions.

3. SOIL CONTAMINATION
OCCURS IN TWO(2) FORMS
 Point pollution caused by a specific event or series
of events to a particular place, such as a former
factory sites. This is relatively well mapped and
understood.
 Diffuse Pollution this involves low levels of
contaminants spread over very wide areas that
become lodged in the soil as it acts as a sink. This is
difficult to analyze and track. Examples of such
contaminants would be heavy metals or herbicides
or pesticides used in agriculture.

4. WHAT CAUSES SOIL
CONTAMINATION?

5. HUMAN ACTIVITIES
The most important
sources of contamination in
soils are those connected
with human activities.

6. How does it interact with other soil threats?
Soil contamination leads to decreased
activity of soil biodiversity and therefore to
a decline of aggregate stability and in
decomposition processes. Strong correlation
can also be seen between contamination and
erosion. A decline in aggregate stability and
organic matter caused by soil pollutants
increases the erodibility and therefore the
risk of wind and water erosion.

7. Landslides, flooding, wind
and water erosion may also
lead to pollutants being
transported off site as
solutes or particles and in
turn pollute the connected
aquatic environment or
soils downslope.

8. HOW DOES IT AFFECT SOIL
FUNCTIONS?
Biomass production – a contaminated soil
loses the productivity and the capacity to
support plants properly.
Storing, filtering and transforming – these
functions are all disrupted or prevented in
contaminated soil. In particular, organic
matter decomposition can be disrupted
affecting the cycling of nutrients.

9. Gene pool (biodiversity) –
plants, microorganisms and
enzyme activity in the soil is
disrupted and lessened in
contaminated soil, leading to a
decline in soil biodiversity.

10. SOIL POLLUTION
Is defined as the presence of toxic chemicals
(pollutants or contaminants) in soil, in high enough
concentration to pose a risk to human health
and/or the ecosystem.
In the case of contaminants which occur naturally
in soil, even when their levels are not high enough
to pose risk, soil pollution is still said to occur if the
levels of the contaminants in soil exceed the levels
that should naturally be present.

11. 2 MAIN CAUSES THROUGH
WHICH SOIL POLLUTION IS
GENERATED:
Natural causes
Anthropogenic (man-
made) causes

12. NATURAL POLLUTANTS
Natural processes can lead to an
accumulation of toxic chemicals in the soil
this type of contamination has only been
recorded in a few cases, such as the
accumulation of higher levels of perchlorate
in soil from Atacama Desert in Chile, a type of
accumulation which is purely due to natural
processes in arid environments.

13. MAN-MADE POLLUTANTS
Man-made contaminants are the main causes of
soil pollution and consist of a large variety of
contaminants or chemicals, both organic and
inorganic. They can pollute the soil either alone or
combined with several natural soil contaminants.
Man-made soil pollution is usually caused by the
improper disposal waste coming from industrial or
urban sources, industrial activities, and agricultural
pesticides.

14. TYPES OF SOIL POLLUTANTS
Biological agents – works inside the soil to
introduce manure and digested sludge
(coming from the human, bird and animal
excreta) into the soil
Agricultural practices – the soil of the crops is
polluted to a large extent with pesticides,
fertilizers, herbicides, slurry, debris, and
manure.

15. Radioactive pollutants – radioactive
substances such as Radium, Thorium,
Uranium, Nitrogen, etc. can infiltrate the soil
and create toxic effects.
Urban waste – consists of garbage and
rubbish materials, dried sludge and sewage
from domestic and commercial waste.
Industrial waste – steel, pesticides, textiles,
drugs, glass, cement, petroleum, etc. are
produced by paper mills, oil refineries, sugar
factories, petroleum industries and others.

16. MOST COMMON & PROBLEMATIC
SOIL POLLUTANTS
Lead (PB)
Mercury (HG)
Arsenic (AS)
Copper (CU)
Zinc (ZN)
Nickel (NI)
PAHS (Polyaromatic hydrocarbons)
Herbicides/insecticides

25. Thank You for
Listening and God
Bless Us All..