Human activities have significant impacts on the environment. This document discusses several environmental issues affecting South Africa, including urbanization putting pressure on natural resources. Key human activities that impact the environment are listed such as agriculture, fishing, and energy production. The effects of human influences include impacts on biodiversity, coral reefs, and the nitrogen cycle. Pollution is also discussed, including the impacts of water pollution from sources like coal mining, and the health effects of water, air, and land pollution. Global environmental issues like ozone depletion and the greenhouse effect/global warming are explained. National environmental issues for South Africa include deforestation, overgrazing, and desertification.

1. UNIT 4:
HUMAN INFLUENCES ON THE
ENVIRONMENT

2. INTRODUCTION
Human impact on the
environment or
anthropogenic impact on
the environment includes:
Impacts on biophysical
environments,
biodiversity &
other resources.
The term anthropogenic
describes an effect or object
resulting from human activity.

3. ENVIRONMENTAL ISSUES IN SA
Many environmental issues affect SA  urbanization &
acts (LAWS) needed to survive.
Keeping up with developing world + meet high
demands of growing population, SA  exhausted its
many resources  severe environmental damage.
Continuous depleting & improper treatment of natural
resources  SA  only harming their environment.

4. HUMAN
ACTIVITIES THAT
HAVE AN
ENVIRONMENTA
L IMPACT:
Agriculture (FARMING)
Fishing
Irrigation
Meat production
Palm oil farming
Energy harvesting and consumption
Coal mining and burning
Manufacturing of products
Electricity generation
The use of fertilisers may cause eutrophication

5. THE EFFECTS OF HUMAN INFLUENCES
ON THE ENVIRONMENT
Human impact on biodiversity  significant.
Human impact on coral reefs  significant. Coral reefs are dying around the world. Coral reefs also face
high dangers from pollution, diseases, destructive fishing practices and warming oceans
Human impact on nitrogen cycle  diverse.
Humans  destroying habitats & reducing amount of land available for other organisms by building,
quarrying, farming and dumping waste.
Human activities  polluting water, air and land.

8. IMPACT OF POLLUTION
ON THE ENVIRONMENT

9. WATER POLLUTION
Water pollution 
contamination of water
bodies.
1
Water pollution 
pollutants are discharged
directly/indirectly into water
bodies without adequate
treatment to remove
harmful compounds.
2
Water pollution affects
plants & organisms living in
these bodies of water.
3

10. WATER POLLUTION
• One of SA biggest issues is the lack of clean water.
• Water around Africa  unevenly distributed
• meaning that 60% of water  situated in only 20% of
land.
• <10% of SA surface water is accessible
• majority of ground water lay under large rock formations
 becomes difficult to access.
• Climate change & its related effects on temperature &
precipitation may have an additional impact.

11. WATER POLLUTION – Coal Mining
• Coal mining  one of SA main energy source:
• huge negative impact on land’s water, air & soil quality.
• Acid mine drainage  result of excess coal mining.
• Process to neutralize Sulphuric Acid released from coal
mining  extremely slow.
• Clean, excess water  released from rock masses that are
broken through mining  mixed with sulphuric acid 
water becomes toxic.

12. WATER POLLUTION – Coal Mining
• Toxic, contaminated water
• kills plants & animals,
• dissolving aluminium & heavy minerals found in clean
water (increasing toxicity level).
• Rocks which contain calcium carbonate  able to neutralize
acidic water,
• SA does not have the rocks which contain these minerals.

13. 2 CATEGORIES OF SOURCES OF SURFACE
WATER POLLUTION
• Point source water pollution:
Contaminants that enter waterway from single, identifiable
source, such as a pipe or drain.
Examples of sources:
discharges from sewage treatment plant,
factory, or
city storm drain.

14. POINT SOURCE WATER POLLUTION

15. Non–point
source pollution
(NPS)
Diffused contamination 
does not originate from a
single discrete source.
Cumulative effect of small
amounts of contaminants
gathered from a large area.
• Common example: leaching out of
nitrogen compounds from fertilized
agricultural lands.
Nutrient runoff in stormwater
from "sheet flow" over an
agricultural field / forest
examples of NPS pollution.

16. SHEET FLOW 
• An overland flow / downslope movement of
water taking (thin, continuous film over
relatively smooth soil / rock surfaces)

17. NON-POINT SOURCES

18. Some of the main contributors to
water pollution are:
• Factories / Refineries
• Waste treatment facilities
• Mining
• Pesticides, herbicides &
fertilizers
• Human sewage
• Oil spills
• Failing septic systems
• Soap (washing car)
• Oil & antifreeze leaking from
cars
• Household chemicals
• Animal waste

19. IMPACT OF WATER POLLUTION ON
HUMAN HEALTH
• Increased incidence (tumours, ulcers)  nitrate pollution.
• Increased incidence (skin disorders)  contact with
pollutants.
• Increased incidence (constipation, diarrhoea, infections to
intestine.
• Dangerous effects on growing foetus  pregnant women.
• Concentration of pollutants  bio- accumulative pesticides
through secondary / tertiary food chain in case of non-
vegetarians.
• Still births, abortions and birth of deformed children.

20. HOW YOU
CAN HELP
TO PREVENT
WATER
POLLUTION
Don’t wash Don’t wash paint brushes in the sink
Clean up Clean up oil / liquid spills with kitty litter & sweet them up
Use Use non-toxic cleaning materials
Sweep Sweep your driveway instead of hosing it down
Avoid Avoid using pesticides & fertilizers that can run off into water
systems
Inspect Inspect your septic system every 3-5 years
Don’t throw Don’t throw trash, chemicals, solvents into sewer drains
Wash Wash car far away from storm water drains

21. AIR POLLUTION
What are the sources of air
pollution?
• Automobile emissions
• Tobacco smoke
• Combustion of coal
• Acid rain
• Noise pollution from
cars and construction
• Power plants
• Manufacturing buildings
• Large ships
• Paint fumes
• Aerosol sprays
• Wildfires
• Nuclear weapons

22. AIR POLLUTION IN SA
SA  developing region (low-grade fuels are used to
meet high demands) for food, energy.
SO2 & CO2 released in air 
due to deforestation & growing
amount of air pollution,
air pollutants in the
atmosphere are slowly
building up.

23. THE IMPACT OF AIR
POLLUTION ON HUMAN
HEALTH
• Principally affect the body's respiratory
system and the cardiovascular system.
• The health effects:
• biochemical and physiological
changes
• breathing, wheezing, coughing
• aggravation of existing respiratory
and cardiac conditions

24. HOW YOU
CAN HELP
TO
PREVENT
AIR
POLLUTION
Carpool or join a ride share with friends and co-workers
Don’t smoke
Keep your car maintenance up-to-date
If you have to drive, do your errands at one time
Don’t buy products that come in aerosol spray cans
Avoid using lighter fluid when barbecuing outside
When you drive accelerate slowly and use cruise control
Always replace your car’s air filter
Use a push or electric lawnmower rather than a gas-powered one
Don’t use harsh chemical cleaners that can emit fumes
Inspect your gas appliances and heaters regularly

26. LAND POLLUTION
• SELF STUDY
• KNOW THE SOURCE OF
LAND POLLUTION
• KNOW THE IMPACT LAND
POLLUTION HAS ON HUMAN
HEALTH
• KNOW HOW YOU CAN
PREVENT LAND POLLUTION

27. LAND POLLUTION
Land pollution is the deterioration (destruction) of the earth’s land surfaces,
often directly or indirectly as a result of man’s activities and their misuse of
land resources.
It occurs when waste is not disposed off properly, or can occur when humans
throw chemicals unto the soil in the form of pesticides, insecticides and
fertilizers during agricultural practices. Exploitation of minerals (mining
activities) has also contributed to the destruction of the earth’s surface.

28. GLOBAL
ENVIRONMENTAL
ISSUES
• OZONE DEPLETION
• GREENHOUSE EFFECT
• GLOBAL WARMING

29. OZONE
DEPLETION
Life on Earth is protected
from damaging effects of UV
radiation by a protective
layer of ozone molecules in
the atmosphere.
Satellite studies suggest that
the ozone layer has been
gradually thinning since
1975.

30. Ozone
layer
thickness
(Dobsons)
Fig. 55-23
Year
’05
2000
’95
’90
’85
’80
’75
’70
’65
’60
1955
0
100
250
200
300
350

31. Destruction of
atmospheric
ozone probably
results from
chlorine-
releasing
pollutants such
as CFCs
produced by
human activity.

32. The “ozone hole” has increased in size as ozone
depletion has increased.

33. • Ozone depletion causes DNA damage in plants & poorer
phytoplankton growth
• An international agreement signed in 1987 has resulted in a
decrease in ozone depletion:
• The Montreal Protocol on Substances that Deplete the
Ozone Layer (a protocol to the Vienna Convention for the
Protection of the Ozone Layer) is an international treaty
designed to protect the ozone layer by phasing out the
production of numerous substances that are responsible
for ozone depletion.
• As a result  ozone hole in Antarctica is slowly
recovering.
• Climate projections indicate that the ozone layer will
return to 1980 levels between 2050 and 2070.

35. GREENHOUSE EFFECT AND GLOBAL
WARMING
CO2, water vapour & other greenhouse gases reflect infrared
radiation back toward Earth;  greenhouse effect
Important for keeping Earth’s surface at a habitable
temperature.
Due to burning of fossil fuels, other human activities,
concentration of atmospheric CO2 has been steadily
increasing.

36. RISE IN
[CO2] AND
TEMP

37. • Increased levels of atmospheric CO2 are magnifying the greenhouse
effect, which could cause global warming and climatic change.
• Increasing concentration of atmospheric CO2 is linked to increasing
global temperature.
• Northern coniferous forests and tundra show the strongest effects of
global warming.
• A warming trend would also affect the geographic distribution of
precipitation.

38. • Global warming can be slowed by reducing energy needs and
converting to renewable sources of energy
• Stabilizing CO2 emissions will require an international effort.

40. Why is Global Warming important?
• Temperature increases will have significant impacts on
human activities, including:
• where we can live,
• what food we can grow,
• how and where we can grow food,
• and where organisms we consider pests can thrive.

41. To be prepared for the effects of these
potential impacts we need to know :
how much the Earth is warming,
how long the Earth has been warming,
and what has caused the warming
Answers to these questions provide us with a better basis
for making decisions related to issues such as water
resources and agricultural planning.

42. NATIONAL
ENVIRONMENTAL ISSUES

43. NATIONAL
ENVIRONMENTAL
ISSSUES
• DEFORESTATION
• OVERGRAZING
• DESERTIFICATION
• CROPS
• COMMERCIAL FORESTS
• WATER TABLE PROBLEMS
• MONOCULTURE EFFECTS BIODIVERSITY
• DEPOSIT OF TOXIC SUBSTANCES
• INTRODUCTION OF INVASIVE ALIEN
SPECIES INTO SOUTH AFRICA
• IMPACT ON BIODIVERSITY
• CONTROL MECHANISMS

44. DEFORESTATION
• Deforestation is the
permanent destruction of
indigenous forests and
woodlands.
• The term does not include
the removal of industrial
forests such as plantations of
gums or pines.
• Deforestation has resulted in
the reduction of indigenous
forests.

45. HOW DOES
DEFORESTATION
OCCUR?
conversion of forests and
woodlands to agricultural land to
feed growing numbers of people;
development of cash crops and
cattle ranching,
commercial logging destroys trees
as well as opening forests for
agriculture;
felling of trees for firewood and
building material;

46. CONSEQUENSES
OF
DEFORESTATION
Alteration of local and global climates
through disruption of the carbon and
water cycle
Soil erosion
Silting of water courses, lakes and
dams
Extinction of species which depend on
the forest for survival.
Desertification

48. OVERGRAZING
• Overgrazing occurs when plants are exposed to intensive
grazing for extended periods of time, or without sufficient
recovery periods.
• It can be caused by either livestock in poorly managed
agricultural applications, or by overpopulations of native or
non-native wild animals.
• Overgrazing reduces the usefulness, productivity, and
biodiversity of the land and is one cause of desertification
and erosion.
• Overgrazing is also seen as a cause of the spread of invasive
species of non-native plants and of weeds.

50. MONOCULTURE
EFFECTS
BIODIVERSITY
• Monoculture is the agricultural practice of producing or growing a single crop
or plant species over a wide area and for a large number of consecutive years.
• Monocultures can lead to the quicker spread of diseases, where a uniform crop
is susceptible to a pathogen.
• Therefore decreasing biodiversity.

51. DEPOSIT OF TOXIC SUBSTANCES IN THE
ENVIRONMENT
• Humans release many toxic chemicals, into the environment
e.g. Acid mine water
• In some cases, harmful substances persist for long periods in
an ecosystem .
• One reason toxins are harmful is that they become more
concentrated in successive trophic levels.
• Biological magnification concentrates toxins at higher trophic
levels, where biomass is lower.

52. • Pesticides such as DDT are
subject to biological
magnification in ecosystems.
• In the 1960s Rachel Carson
brought attention to the
biomagnification of DDT in
birds in her book Silent Spring

53. INTRODUCTION OF INVASIVE ALIEN
SPECIES INTO SOUTH AFRICA
• Invasive species, typically introduced to a new environment
by humans, often lack predators or disease.
• In total there are 200 species of plants that are declared
weeds or invaders in South Africa.
• E.G. Eucalyptus species, Port Jackson willow, Black wattle.

54. PORT JACKSON WILLOW
EUCALIPTUS
BLACK WATTLE

55. LOCAL ENVIRONMENTAL ISSUES

56. OVEREXPLOITATION OF LOCAL
INDIGENOUS RESOURCES
• Overexploitation is human harvesting of wild plants or
animals at rates exceeding the ability of populations of those
species to rebound
• Overexploitation by the fishing industry has greatly reduced
populations of some game fish, such as bluefin tuna
• DNA analysis can help conservation biologists to identify the
source of illegally obtained animal products.

57. OVEREXPLOITATION
OF BLUEFIN TUNA

58. • Population growth, urbanization and the unrestricted collection of
medicinal plants from the wild is resulting in an over-exploitation of
natural resources in southern Africa.
• Therefore, the management of traditional medicinal plant resources
has become a matter of urgency.

59. Problems
arising from
the
exploitation
of natural
resources
• Deforestation
• Desertification
• Extinction of species
• Forced migration
• Soil erosion
• Oil depletion
• Ozone depletion
• Greenhouse gas increase
• Extreme energy
• Water pollution
• Natural hazard/Natural disaster

60. SUSTAINABILITY OF LOCAL INDIGENOUS
RESOURCES IN SOUTH AFRICA
• The concept of sustainability helps ecologists establish long-
term conservation priorities.
• Sustainable development is development that meets the
needs of people today without limiting the ability of future
generations to meet their needs
• Sustainable development requires connections between life
sciences, social sciences, economics, and humanities

61. SOME OF S.A.
INDIGENOUS
RESOURCES
THAT
SHOULD BE
CONSERVED
AND
SUSTAINED
• Devil’s claw
• Rooibos
• Fynbos
• African potato
• Hoodia
• Pepperbark tree

62. DEVIL’S CLAW
• Devil’s claw is an herb.
• The botanical name, Harpagophytum, means “hook plant” in
Greek.
• The fruit is covered with hooks meant to attach onto animals
in order to spread the seeds.
• The roots and tubers of the plant are used to make
medicine.
• Devil’s claw is used for “hardening of the arteries"
(atherosclerosis), arthritis, gout, muscle pain (myalgia), back
pain, tendonitis, chest pain, gastrointestinal (GI) upset or
heart burn, fever, and migraine headache.

63. DEVIL’S CLAW

64. ROOIBOS • Rooibos is a member of the
legume family of plants
growing in South Africa's
fynbos.
• Traditional medicinal uses
of rooibos in South Africa
include alleviating infantile
colic, allergies, asthma and
dermatological problems.
• The plant is used to make a
herbal tea called rooibos
tea.
• Rooibos leaves are dried
and used to make tea,
though parts of the plant
are now used in skin care
formulas as well

65. AFRICAN POTATO (Hypoxis)
• Africa Potato is rich
in vitamins.
• Boosts energy,
improves immune
system and helps to
prevent virus
infections.
• Lowers high blood
pressure and blood
sugar levels.
• Older generations
drink it as a herbal
tea, creams and
tablet are also made
from this plant.

66. HOODIA
• Used as an appetite suppressant and
for treating indigestion and small
infections
• Hoodia is a leafless spiny succulent
plant with medicinal properties.
• It grows naturally in South Africa and
Namibia.
• The flowers smell like rotten meat
and are pollinated mainly by flies.

67. PEPPERBARK AND FYNBOS
• SELF STUDY
• FIND OUT MORE
ABOUT THE
MEDICINAL VALUE OF
THESE TWO PLANTS