Human impact on the environment

Human Impact on the
Environment

Homework
 Activities
 3.6.1 p323 (do after watching the DVD)
 3.6.2 p328
 3.6.4 p335
 3.6.7 p339
 3.6.8 p346
 3.6.9 p354
 3.6.10 p359
 3.6.11 p361
 3.6.12 p369
 3.6.13 p374
 3.6.15 p379
 3.6.17 p384

Definitions
anaerobic fungicide megafauna
fynbos herbicide monoculture
pathogenic pesticide rooibos
global warming climate change the greenhouse effect
the enhanced greenhouse effect greenhouse gas GHG greenhouse gas emissions(s)
carbon footprint methane deforestation
ozone depletion desertification biodiversity
fossil fuel(s) carbon tax aquifer
borehole wetland groundwater
surface water algal bloom eutrophication
thermal pollution alien invasive species food security
food insecurity bio-accumulation crop rotation
biological control genetic engineering/modification clone(s)
artificial selection natural selection hybrid
gene pool extinction event(s) urbanization
habitat destruction poaching mechanical control
chemical control indigenous endemic
endangered species list biodiversity ‘hot-spot’ sterols
sterolins landfill site dumpsite
phytoremediation

Human Impact on the environment:
Atmosphere and Climate Change
Water: Availability and Quality
Food Security
Loss of Biodiversity
Solid Waste Disposal

Key Concepts
TERMINOLOGY & DEFINITIONS
 Ozone Depletion: the ozone layer which prevents UV light from entering the
earth’s surface is being destroyed by CFC’s and pollution
 Greenhouse Effect: the UV light is being trapped within the earth’s
atmosphere by a “blanket” of mainly carbon dioxide
 Greenhouse gases: methane, nitrous oxide, carbon dioxide
 Deforestation: removal of natural forests
 Fossil Fuels: natural substances made deep within the earth by the
decomposition of plant and animal remains over millions of years
 Alien invasive species: these are plants and animals that are NOT
indigenous to a particular country. They are not native to that area.

Atmosphere and Climate Change – The
Greenhouse Effect
 Gasses bringing about the ‘greenhouse effect’ and leading to global
warming and climate change –
 water vapour,
 carbon dioxide,
 methane,
 nitrous oxide
 and ozone.
 The greenhouse effect is termed this way because greenhouses are actually hard
polycarbon plastic houses used by market gardeners to grow crops in winter.
 These plastic houses allow sunlight to come in and trap heat so that the temperature
for the green plants, that grow in these houses, is favourable in winter.
 In the same way high CO2 levels trap heat from UV radiation and prevent the UV
light from reflecting back into space.

The Greenhouse Effect
Left - Naturally occurring greenhouse gases—carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O)—normally
trap some of the sun’s heat, keeping the planet from freezing.
Right - Human activities, such as the burning of fossil fuels, are increasing greenhouse gas levels, leading to an enhanced
greenhouse effect. The result is global warming and unprecedented rates of climate change.
Will Elder, NPS (http://www.nps.gov/goga/naturescience/climate-change-causes.htm)

Greenhouse Gas Contribution to the
‘Greenhouse Effect’
Source of Greenhouse Gas
Carbon dioxide (CO2) 53% Respiration; decomposition; burning
fossil fuels; forest fires
Methane (CH4) 17% Cows; sheep; swamps; rice paddy
fields (rice paddies); natural gas
leakage; rubbish dumps; landfill sites;
water treatment works
Nitrous oxide (N2O) 5% Breakdown of organic matter in soil by
microbes; nitrogen fertilisers; burning of
fossil fuels and wood
Ozone (O3) 13% Naturally present in atmosphere;
formed when certain substances react
in sunlight
CFC’s 12% Fridges; foams; aerosol sprays; solvents
(See p326)

Global warming and Climate Change
 Increase in concentration of greenhouse
gasses (GHGs)  increase of average
temperature on Earth, called global warming.
 Global warming  ongoing change in the
Earth’s weather patterns, called climate
change.

Increase in emissions: A) Increase in
Carbon emissions
 Carbon dioxide – colorless, heavy gas, no smell, about 0.03%
of atmosphere. It is the most important greenhouse gas by
volume.
 Carbon dioxide is produced by:
 respiration;
 decomposition;
 burning fossil fuels
 Large volumes are released by power stations burning coal (mostly)
 Our demand for electricity for household and commercial use
pushes up the need to burn more fuels, increasing the amount of
CO2 released into the atmosphere.
 The transport of people and goods by motor vehicles burns
gasoline( petrol and diesel), which releases CO2 into the
atmosphere.
 forest and veld fires.

Increase in Carbon emissions – South Africa
 SA’s Co2 emissions have increased 7 times from 1950-2008
 From coal – 85% (119 million metric tons)
 From oil use – 11.6%
 Remaining 3.4% - Cement manufacture, natural gas, coke-oven gas use
 Sa is the 13th largest CO2 emitting country in the world and the largest on
the African Continent.
 Increase in populations growth leads to:
 Greater demand for transported goods;
 Increased burning of fossil fuels;
 Greater release of CO2 into the atmosphere.
 CO2 levels have increased 150% since 1750, form 315 parts per million in
1958 to 360 parts per million in 1990. (see Fig 3.6.5, p328)
Population growth

Increase in
Carbon
emissions –
South Africa

Carbon dioxide levels and Temperature
Source: http://www.uniglobetravelsa.co.za/212/a1137/co2-emissions-effects.html

Carbon Footprint
 Humans add CO2 to the atmosphere by:
 Traveling in motor vehicles using petrol or diesel as fuel;
 Using electrical appliances such as stoves and refrigerators;
 Using other fuels such as propane, liquid gas or kerosene;
 Burning wood and coal (See Table 3.6.2, p329)
 Calculate the amount of CO2 released:
 amount of energy used per month x emission factor for that energy source.
 When we add up the total of CO2 released per month from the use of various
energy sources, we get our ‘carbon footprint’.
 A heavy carbon footprint – releases a large quantity of CO2, causes much
damage to the environment.
 A light carbon footprint - releases a small quantity of CO2, causes less damage
to the environment.

Increase in emissions: B) Increase in
Methane Emissions
 Methane – 2nd most important greenhouse gas
 Sources:
 Micro-organisms in the intestines of herbivorous animals undergo
anaerobic respiration, release large amounts of methane
 Decomposition of organic wastes in land-fill sites
 Decomposition bacteria used in the treatment of waste water to
break down large particles in the water
 Agricultural activities, such as the growth of rice in paddies
 Mining releases methane trapped in the lower levels of the Earth
 The crystal structures of ice stores methane; when ice melts
methane is released
 The production, handling, transmission and combustion of fossil
fuels release methane
 The concentration of methane is much lower than that of
CO2, but the effect of global warming is 21 times higher!

Increase in emissions: C) Increase in
Nitrous Oxide Emissions
 The use of chemical fertilisers have increased dramatically.
 The use of nitrogen-rich fertilisers release nitrous oxides which have 300
times more heat-trapping capacity per unit of volume than CO2.

 Forests cover 1/3 of the total land surface of the Earth.
 Forests use CO2 during photosynthesis – they act as CO2 ‘sinks’.
 Deforestation – the process of changing land use from natural forests and forestry to a non-forest use,
such as agriculture, housing or mining.
 Reasons for deforestation:
 Many trees are chopped down for fuel
 There is a huge demand for wood and paper products
 Trees are cleared to provide grazing space for farm animals
 Trees are cleared to make space for roads
 Forests are cleared for the development of mining
 Indigenous forests are cleared and replaced by plantations and agricultural crops, since the bring in
more money.
 Deforestation increases GHGs in four ways:
 Number of plants  − CO2 captured by plants 
 Farms animals replace trees – methane produced 
 Wood and paper product production – energy use  and CO2 release 
 Huge increase in dead tree trunks  – termite population   and methane produced  
Increase in emissions: D) Deforestation
and Increase in GHGs

Increase in emissions: E) Ozone Depletion
and Increase in CO2 Levels
 Ozone molecule – 3x oxygen atoms (O3)
 Thin layer of ozone acts as a protective barrier around the
Earth and reduces the amount of dangerous ultraviolet
radiation from the sun.
 The ozone layer is becoming thinner – Ozone depletion
 Ozone depletions is caused by chemicals called
chlorofluorocarbons (CFCs) – used in refrigerators and
aerosols
 Ozone depletion increases CO2 levels by:
 More ultraviolet (UV) light from the sun reaches the Earth
 Many plants are affected – cannot remove CO2 normally
 Some plants die, others cannot photosynthesise normally
 More CO2 remains in the atmosphere
 So CO2 levels in the atmosphere are increased
 Other effects of ozone depletion:
 UV light  - skin cancer 
 UV light  - affects human immune system (early research)
Hole in the Ozone over Antarctica

Solutions to Ozone depletion
 International actions was taken - Montreal Protocol (1989) (p334)
 30 Nations world-wide agreed to reduce the use of CFCs
 Ozone depletion can be reduced by:
 Monitoring the elimination of CFCs as a propellant in aerosols
 National monitoring of skin cancer
 Increasing public awareness of skin cancer
 Investigating new ozone-friendly repellants (and refrigerators)
 Which sectors produce the most GHGs? (Figure 3.6.9 p335)
 Production and supply of energy – 25.9%
 Industry – 19.4%
 Forestry – 17.4%
 Agriculture – 13.5%

Annual Global GHGs Emissions by Sector
Annual South African GHGs Emissions by Sector

Effects of Global Warming
 Global warming has resulted in the following climate changes:
 An increase in the average global temperature
 Melting polar ice caps – rising sea-levels and coastal flooding
► Sea-levels are predicted to rise more than 1,5 m by 2050.
► Rising sea-levels cause flooding in coastal and low-lying areas
► Melting ice caps causes the Earth’s temperature to rise: (Fig. 3.6.10
p337)
► Ice reflects most of the sun’s rays, only a little is absorbed
► Water absorbs more of the sun’s rays than ice
► As ice turns to water, the Earth's temperature rises because:
1. The water’s increased ability to absorb heat from the
sun’s rays
2. Methane (a GHG), stored in the crystal structure of
ice, is released
► As the Earth’s temperature rises – more ice melts – global
temperature increases further
► The process continues in a cyclic fashion
► This is an example of positive feedback, a runaway process.
The retreat of Pedersen Glacier, Alaska. Left: summer 1917. Right: summer 2005.
Credits: NASA

Effects of Global Warming(2)
 Frequent floods and prolonged draughts
► Changes in rainfall patterns are expected
► Floods and/or draughts are expected
► Floods in low-lying areas, near the coasts and riverbanks (especially in informal
settlements) – affect housing and may cause overflow of sewer lines
► Overflow of sewer lines may cause sewage to spill into human settlement areas –
increasing the likelihood of water borne diseases like cholera.
 Desertification
► Periods of prolonged draught followed by heavy flooding – washes away fertile top soil.
► Frequent loss of top soil – soils unable to support plant life – the land turns into a desert.
 Reduced food productivity
► Some food-producing areas – become drier and less fertile
► Some food-producing areas – flooded by rising sea levels
► Food crops destroyed by hurricanes and tornadoes
► Soil erosion – reduces fertility of the soil
► High CO2 concentrations – unfavourable for many crop plants, favourable for many
weeds – decreases crop production

Effects of Global Warming(3)
 Reduced biodiversity (p338)
► Many species cannot adapt to thee climate changes and will become extinct (some are
extinct already).
 According to the National Climate Change Response White Paper(Oct 2011)
 By 2050 – SA coast will warm by 1-2˚C, the interior by 2-3 ˚C.
 By 2100 – SA coast will warm by 3-4˚C, the interior by 6-7 ˚C.
 Parts of the country – drier and with increased water evaporation – decrease in water
availability – will affect human health, agriculture, mining, electricity-generation and the
environment in general.
 Increase in occurrence and severity of veld and forest fires, extreme weather events,
floods and draughts.
 Rising sea-levels will negatively impact the coast and its people.
 Mass-extinctions of endemic plant- and animal species – will greatly reduce SA’s
biodiversity with consequent impacts on eco-system services.

Ways to Reduce Global Warming
 Reduce the use of fossil fuels
 Encourage the use of renewable energy sources – e.g. solar energy, wind
power
 Use nuclear energy (dangerous radiation for nuclear active waste is still a
problem)
 Re-plant forests – more trees act as a greater CO2 ‘sink’.
 Reduce global greenhouse emissions from various sources
 The Kyoto Protocol (Read p340-342)and the annual Conference of Parties (COP)
on climate change attempts to get different countries to reduce the release of
GHGs according to an agreed-upon plan.
 Other possible ways to reduce global warming:
 Boost energy efficiency – e.g. look for top energy star appliances
 ‘Greening’ transportation – more fuel-efficient vehicles and ‘green’ fuel
 Promote recycling and use renewable resources
 Ensuring sustainable development and management of natural resources

The Kyoto Protocol (1)
 The third session of the Conference of the Parties to the UN Framework Convention on Climate
Change (UNFCCC) took place in Kyoto, Japan in December 1997, resulting in the Kyoto Protocol.
 This working agreement of the signatories commits developed countries to reduce their collective
emissions of six greenhouse gases by at least 5 per cent of 1990 levels by 2012.
 The Kyoto agreement became legally binding on 16 February 2005 when 132 signatory countries
agreed to strive to decrease carbon dioxide emissions.
 The Kyoto Protocol now covers more than 170 countries globally, but this is only 60% of the
countries that release GHGs.
 According to the Protocol, governments are separated into two general categories:
 Developed countries (referred to as Annex 1 countries)
 Developing countries (referred to as Annex 2 countries)
 The biggest problem with the discussions is that different countries cannot agree upon how much
each country should reduce its green house gas emissions and in what period of time this should
happen
 The 36 developed countries were required to reduce the release of their own GHGs to levels
specified for each as in the agreement.
 The United States has not accepted the levels specified for it.

The Kyoto Protocol (2)
 As of January 2008, running through 2012 (referred to the first commitment period), Annex 1
countries have to reduce their GHG emissions by a collective average of 5,2% below their 1990
levels.
 For many countries, this is 15% below their expected GHG emissions in 2008.
 Milestones in Controlling Climate Change
 Yearly meetings of COP – Since the UNFCCC came into force in 1995, The various countries (parties) have
met every year to assess progress in dealing with climate change (Conference of Parties (COP))
 In 2005, at COP 11 in Montreal, Canada, countries were asked to extend their commitments beyond the
end of the first commitment period (2012).
 In 2007, at COP 13 in Bali, Indonesia, the Bali Action Plan was launched to extend long-term co-operative
action on climate change beyond 2012. The long-term plan was divided into 5 main categories:
 Shared vision;
 Mitigation; (The action of reducing the severity, seriousness, or painfulness of something)
 Adaptation;
 Technology;
 Financing
 The plan was to be agreed upon and accepted at COP 15 in Copenhagen.
From the Kyoto Protocol to COP 17

From the Kyoto Protocol to COP 17 (2)
 In 2009, at COP 15 in Copenhagen, Denmark, many hoped the Bali Action Plan would be
finalised and an agreement towards a fair, ambitious and equitable agreement , setting
the world towards a path to avoid dangerous climate change would be reached. But the
agreement was not formally accepted.
 In 2010, at COP 16 in Cancun, Mexico, Governments agreed:
 To continue work on identifying a goal for substantially reducing global emissions by 2050.
 To work towards identifying a time frame for the peaking of global emissions and wanted a second
commitment term for the Kyoto Protocol.
 In 2011, at COP 17, Durban, South Africa, the following was looked at:
 Details of the Bali Action Plan
 Goals for reducing GHG emissions by 2050
 Time frames for the peaking of GHGs
 A second commitment term for the Kyoto Protocol
 Development of a Green Climate Fund.
 The main agreements of COP17, known as the Durban Platform, were as follows:
 Agreement on a second commitment of the Kyoto Protocol, starting January 2013
 Development of a new legal climate change agreement, which will apply to all countries i.e.
developed as well as developing countries, to replace the Kyoto Protocol, as soon as possible, but
not later than 2015
 Establishment of the Green Climate Fund to help developing countries reduce carbon emissions
and control global warming (known as mitigation) as well as finding ways and means to manage
and adapt to these changes (known as adaptation).
Mitigation
the action of reducing
the severity, seriousness,
or painfulness of
something.
"the identification and
mitigation of pollution"
Did you know that…
• South African
Developing
Countries (SADC)
account for 2% of
global emissions.
• Africa contributes
to around 7% of
the world GHG
emissions.

After COP 17…
 2012: COP 18, Doha, Qatar
 The Conference produced a package of documents collectively titled The Doha Climate Gateway. The
documents collectively contained:
 An amendment of the Kyoto Protocol (to be ratified before entering into force) was made featuring a second
commitment period running from 2012 until 2020, limited in scope to 15% of the global carbon dioxide emissions.
 This limit is due to the lack of commitments of Japan, Russia, Belarus, Ukraine, New Zealand (nor the United States and
Canada, who are not parties to the Protocol in that period) and due to the fact that developing countries like China
(the world's largest emitter), India and Brazil are not subject to emissions reductions under the Kyoto Protocol.
 The conference made little progress towards the funding of the Green Climate Fund.
 2013: COP 19, Warsaw, Poland
 COP 19 was the 19th yearly session of the Conference of the Parties (COP) to the 1992 United Nations
Framework Convention on Climate Change (UNFCCC) and the 9th session of the Meeting of the Parties
(CMP) to the 1997 Kyoto Protocol (the protocol having been developed under the UNFCCC's charter).
 2014: COP 20, Lima, Peru
 From December 1-12, 2014, Lima, Peru will host the 20th yearly session of the Conference of the Parties
(COP) to the 1992 United Nations Framework Convention on Climate Change (UNFCCC) and the 10th
session of the Meeting of the Parties (CMP) to the 1997 Kyoto Protocol (the protocol having been
developed under the UNFCCC's charter).
 2015: COP 21, Paris, France
(Source: http://en.wikipedia.org/wiki/United_Nations_Climate_Change_conference#2012:_COP_18.2FCMP_8.2C_Doha.2C_Qatar)

South Africa’s Contribution Towards
Controlling Climate Change (p343)
 South Africa has accepted the UNFCCC and the Kyoto protocol.
 The government’s decisions for controlling climate change was laid out in the National
Climate Change Response White Paper in October 2011.
 South Africa has a two-fold approach for controlling climate change:
 Firstly, climate change is inevitable, so we must plan to adapt to climate change by increasing
the country’s ability to respond to emergencies and manage climate change in a sustainable
way.
 Secondly, South Africa must reduce greenhouse gasses. The plan is to allow GHG emissions to
peak between 2020-2025, then level off for the next ten years, thereafter GHG emissions must
decrease.
 The government has defined carbon budgets for different GHG emitting sectors. (p345)
 A carbon tax has been suggested in South Africa based on carbon content of fuels
 All fossil fuels contain carbon and the higher the content, the more greenhouse gases are
emitted
 A tax on the emission from vehicles has been proposed and is aimed at passenger cars
 Many businesses, the SA government and labours has signed a Green Economy Accord.
 In the accord, they commit to finding renewable energy sources (solar power, wind power
and bio-fuels), to improve the technology and efficiency of coal-fired power stations
(especially Eskom), and to improve the passenger rail system to ensure that South Africans
move from private transport to public transport.

Human Impact on the environment:
Atmosphere and Climate Change
Water Availability and Quality
Food Security
Loss of Biodiversity
Solid Waste Disposal

Water Availability and Quality (p347)
 Water availability is the amount of freshwater that is available for humans and for ecosystems that need
water
 Freshwater is water with low levels of dissolved salts and is needed for farming, mining, industry and for
ecosystems to function in a balanced, healthy way
 Although 70% of the Earth is covered in water only about 3% is fresh water of which 70% is frozen in
glaciers and ice sheets at both the North and South pole
 This means only about 1% is available as liquid fresh water
 There are two main supplies of freshwater available on Earth;
 surface water occurring in rivers and wetlands
 and groundwater which is found underground in aquifers (an underground layer of loose sand or rock with many
spaces and cracks filled with water)
 Surface water comes from rainfall that runs over the surface of the land by the process of runoff and
groundwater is formed when rainwater soaks into the soil by the process of infiltration (known as
groundwater recharge)
 The amount of freshwater available in South Africa is lower than the world average and is South Africa’s
most limited natural resource
 This is because of a low annual rainfall (450 mm) that is about half of the world average (860 mm per
year), variable rainfall (some years there is a drought and other years there are floods), high
evaporation rates and low surface runoff (low rainfall plus high evaporation rates)

Water Availability and Quality (p347) 2
 Most water needs in South Africa (77%) is met by surface water supplies which include rivers, lakes, dams
and wetlands
 Many smaller rivers have dried up because of farming or rivers are polluted by wastes and chemicals from human
activities
 About 14% of SA’s water is re-used water
 Approximately half of South Africa’s annual rainfall is stored in dams which are necessary to make sure
that communities do not run out of water during times of drought
 South Africa’s average rainfall is 450mm/year, but can vary from less than 100mm along the west coast to 1000mm
on the east coast.
 South Africa relies on dams and transfer schemes to ensure water is available to areas of high economic activity
and to help prevent flooding when there is an excess of water and runoff after heavy rains
 Wetland areas in South Africa act as sponges storing water in times of good rains and slowly releasing it
during drier times
 This helps prevent soil erosion and prevents ecosystems from running dry
 Wetlands also act as filters to clean water and are habitats for many species of organisms
 Unfortunately, 50% of South Africa’s wetlands have been destroyed through agriculture
 Groundwater (9% of SA’s water) availability is limited partly because there are few aquifers in South Africa
and few sources have been developed
 Most of South Africa’s aquifers occur in the Western Cape
 Groundwater could be used to meet future water needs but must be utilised at a slower rate that it is naturally
recharged

 Water availability is determined by:
 A) Increased temperatures – increases rate of evaporation and transpiration
 B) More frequent droughts and floods – changing rainfall patterns, increased soil
erosion
 C) Construction of dams, which serve the following purposes:
 Supplying water for household, commercial and industrial use.
 Supplying water for irrigation of crops
 Controlling flood waters
 Storing water to generate hydro-electric power
 Dams also have some disadvantages:
 People and their livelihoods are affected.
 The natural balance of the river is upset.
 Construction of dams help catch 70% of runoff of surface water in South Africa
 Dams flood areas above the dam wall and disturb the flow of water down the valley
below the dam wall . This can disturb and destroy ecosystems above and below the
dam wall and increases the amount of water lost by evaporation because of the large
surface areas of water held behind the dam wall

 D) The destruction of wetlands
Destruction of wetlands occur when they are drained so that the land may
be used for farming or mining
They may have water abstracted for irrigation of crops or become polluted
by chemicals from agriculture, mines and industry 50% of South Africa’s
wetlands have already been destroyed
 E) Poor farming practices, such as:
 growing crops that require lots of irrigation,
using overhead sprinkler systems and open-ditch irrigation systems for
irrigation (causes lots of evaporation)
ploughing downhill (in stead of ploughing Along the contours of the slope)
monoculture and the overuse of pesticides and herbicides
and overgrazing areas which increases runoff and soil erosion into rivers and
wetlands also impact on water availability
http://www.seasands.co.za/St.%20Lucia%20Wetl
ands%20-
%20A%20World%20Heritage%20Site.htm

 F) Exotic Plantations and Depletions of the Water Table
 Exotic plantations of pine and gum trees are grown to supply timber and paper
 These trees need a lot more water than indigenous trees and decrease the groundwater in the area
 G) Boreholes and the effect on aquifers
 The use of borehole leads to large amounts of water being extracted from aquifers and lowers the
water table
 If water is pumped out too fast, eventually the aquifer will dry up
 H) Cost
 I) Wastage – poor farming practices, leakages, inefficient use
 All human activities lead to pollution, which reduces the overall amount of freshwater that
is usable and it destroys aquatic ecosystems
 If water continues to be used at the current rate, South Africa will reach its limit of surface
freshwater by 2025
 This means that growth and development of the country will be negatively affected as
water becomes a limiting resource
 Ways to sustain water availability in South Africa include finding new supplies of water
(importing water and using more groundwater)
 South Africa can reduce the demand for water by practicing water conservation such as
saving water through re-using water from the shower or bath for the garden or retrofitting
(using dual-flush toilets and low-flow shower heads)
 Farmers can grow crops that need less water and use more efficient irrigation systems
 Good management of water resources can be implemented by rehabilitating degraded
and damaged rivers and wetlands and by protecting these areas with new laws

Water Quality (p355)
 Water quality is derived from the chemical, physical, biological and aesthetic properties of
water
 Chemical water quality refers to the type and concentration of dissolved substances such as salts
(calcium or sodium) and gases (oxygen and carbon dioxide) that is found in water
 Physical water quality refers to the pH (how acidic or alkaline the water is) and turbidity (how clear or
cloudy the water is)
 Biological water quality refers to the presence of microscopic organisms such as bacteria and viruses
e.g. cholera
 Aesthetic water quality refers to the taste, odour and appearance of the water
 Water usage can be classified into the following: domestic, agricultural, mining and industrial,
recreational and environmental
 Domestic use of water includes how water is used in the house for everyday purposes e.g. drinking,
bathing, washing clothes . It may be polluted by chemicals such as detergents or pathogenic bacteria
in sewage (Causing E.g. Cholera ,typhoid, hepatitis, dysentery)
 Agricultural use of water includes irrigation of crops and watering livestock on the farm . The water may
be polluted by pesticides, herbicides and fertilisers (which can cause algal blooms).
 Mining and industrial use of water includes getting minerals out of rocks and for generating electricity.
The water may be polluted by heavy metals, paints, solvents, varnish, glue, oil (caused by oil-spills),
fertiliser-industry wastes (casing algal bloom) and heat (causing thermal pollution).
 Recreational use of water includes swimming, boating and fishing while environmental use refers to
water being used as a habitat for plants and animals in ecosystems

Water Quality (p355) 2
 Drinking water must have levels of constituents that are safe for humans and water used to
irrigate crops need levels of constituents that are safe for plants (plants can tolerate higher
levels of chlorides than people can)
 The water quality of both surface and groundwater in South Africa is affected by natural
factors and human activities
 Natural factors include the geology of rocks that surface water flows over or groundwater
runs through
 The type of rock can determine how much silt is present in water through erosion and the types of
minerals that dissolve in the water
 The natural factor, hydrology refers to the amount of water that flows through the system
 This factor depends on the amount of rainfall and the season and can help dilute pollutants and
improve the chemical and biological water quality when large amounts of water flow through the
system
 The natural factor, ecology, refers to the types of plants, animals and micro-organisms that
are present in aquatic ecosystems
 Certain plants help filter silt and chemicals out of the water and improve the overall water quality
 Human activities include the ways that various sectors get rid of waste water and may have
a negative impact on the water quality in an area
 Examples include wastewater disposal from homes, agricultural drainage, industrial and mining waste
disposal and the introduction alien plants

Eutrophication and Algal Bloom (p356)
 Eutrophication may occur because of the high levels of nitrogen in sewage and
phosphorus in soaps and detergents, as well as fertilizers washed into lakes, rivers and
dams (from over-use of fertilizers)
 This will cause algae and other plants to grow rapidly (algal bloom), closing off the
sunlight
 The resulting death of plant-life will cause bacteria to increase and use up the
oxygen found in the water
 This in turn leads to massive death of living organisms and leaves the water
unhealthy for humans to use
 Agricultural drainage causes fertilisers and pesticides to soak into groundwater
supplies and to wash into rivers and wetlands
 This may lead to eutrophication and may add toxic chemicals to the water
 Industrial waste disposal includes pumping waste products into rivers
 This may lead to increasing the water temperature ( thermal pollution) which can kill
many aquatic organisms

Effect of Mining on Quality of Water (p356)
 Mining of coal and metal ores uses water which is returned to the environment after usage.
 Salt levels in water may increase from the disposal of sulphates, sodium and chlorides (especially in water from mining)
 Poisonous chemicals may be released into rivers and wetlands and will kill many living organisms and make the water unfit
to be used by humans
 Mining waste disposal is often pumped into holding dams or straight into rivers
 This may increase toxic metal content in the soil and acidity (pH 3,6) in the water
 The mine water is often very hot (47°C), contributing to thermal pollution
 Some metals such as mercury, may be stored in the flesh of plants and animals and build up along the food chain, killing
many living organisms (bio-accumulation)
 Gold mining releases highly acidic water which gets into groundwater and this dissolves metals found in the rock
containing pyrite (high sulphur content), eventually becoming sulphuric acid
 This water is called acid mine drainage
 As acid mine water fills up old mine shafts it eventually reaches the surface
 From here is washes into rivers and wetlands and moves into underground water supplies killing many living organisms
 Thermal Pollution is an increase of the temperature of rivers, lakes, streams and ground water, as a result of the release of
extremely hot water by industries
 Some organisms benefit, others are negatively affected:
 Directly, by reduced oxygen in the water (hot water has less oxygen than cold water)
 Indirectly, algal blooms caused by the heat and reduced oxygen and use more oxygen in turn
 Heating water increases the metabolisms of organisms in the water, causing them to need more food (disturbs balance in
ecosystems)

Alien Plants and Water Quality (p357)
 The introduction of alien species of plants( plants that are not indigenous to South Africa) into
waterways will decrease sunlight and oxygen levels making water unhealthy for animals and
humans e.g. Eichornia crassipes (water hyacinth)
 They form an almost continuous mat on the surface of the water
 Light cannot reach the lower levels of the water
 Photosynthesis is stopped in plants at this level
 The plants decompose and die
 The population of decomposer increase, using up large amounts of oxygen
 Many aquatic animals (fish, frogs, etc.) die because of a lack of oxygen
 Alien plants may also clog up the waterways, making boating and fishing, etc, impossible
 Millions of rands are spent clearing dams, lakes and rivers of these alien plants
 Some alien plants require more water for growth and may deplete ground waters

The need for water purification and recycling
(p359)  As water pollution increases in South Africa, reduced water
quality will lead to an increase in waterborne diseases such as
cholera and typhoid fever
 There will be a decrease in availability of suitable water for
drinking, agriculture, mining and industry
 This could have a negative impact on economic and social
development in South Africa and increase water treatment prices
 There could be damage to freshwater ecosystems which we
depend on for our water supplies
 Water purification and recycling will help reduce water pollution
and improve water quality
 If water is purified after use, it may be used over and over again
 Water needs to be purified and recycled because of the
following factors:
 Uneven distribution of water
 Water pollution
 The water may contain particles and ‘germs’ – needs to be
purified (boiled and treated with chemicals)
 Flood damage may case water to be contaminated by human
faeces
 Uneven access to purified water
 Recycling and Re-use should be the short-term goal

Food Security (p361)
 Food security means having access to sufficient, safe and nutritious food to meet
their daily dietary needs
 Food insecurity refers to situations where people run the risk of not having
sufficient food for at least some part of the year
 These factors are influenced by economic and political forces that are operating
in a country and can lead to food shortages, malnutrition and ultimately famine
 Some of the factors affecting food security are:
a. Exponential growth of
the human population

b. Droughts and floods (climate change)
c. Poor farming practices
 Monoculture – the cultivation of plant populations of a single species
 Pest control – The accumulation of pesticides increase as we move higher up the food chain. This is
called bio-accumulation. Natural enemies may be artificially introduced (biological control).
 Loss of topsoil and the need for fertilizers
 Crop rotation (p363)
 The over-use of fertilizers (p363)
 Overgrazing (p364)
 Too many animals, the food plants’ population is decreased
 Not controlling the grazing activity of the animals
 The Effects of Overgrazing
 Pasture is reduced
 Plants have a reduced leaf area, reducing the absorption of light for photosynthesis
 Plants area weakened and have a reduced root length
 Plants with shorter roots are vulnerable to droughts
 Weakened plants produce weaker and less seeds
 Weed plants colonize areas with reduced ground cover
 Reduced ground cover increases soil erosion
 The health of the animals are reduced
Food Security (p361) 2

d. Alien Plants and the Reduction of agricultural Land (p364)
 These plants are species that have been introduced and can out compete indigenous plants
 They decreases food production because they invade land and make the area unsuitable for
growing crops
 Since they have no natural enemies, they are able to grow quickly in an area
 Some alien plants deplete the nutrients in the soil and this means there are less nutrients available
for food crops
 Alien plants deplete water source since they often use more water than indigenous plants
Eucalyptus sp.
Prosopis sp.
Eichornia sp.
Salvinia sp.
Ricinus sp. Opuntia sp. Lantana sp.
Acacia sp – black and golden
wattles
Pinus sp.

e. Genetically Engineered Foods (GMOs) (p365)
 Artificial selection – the best crops are selected by the farmers, the cloned and grown
 Genetically engineered or modified foods or genetically modified organisms(GMO’s)
were developed to increase the yield, growth and food value of crops
 GMO’s are crop plants that are modified in a laboratory using molecular biology
techniques so that they are more resistant to herbicides (chemicals that kill weeds) or
have more nutritional value
 Genetic engineering / genetic modification
 During genetic engineering ,genes from other organisms are inserted into the DNA of the
organism that is being modified
 Scientists will isolate the gene for the desired characteristic, such as drought resistance, in
one plant and transfer this gene into another plant
 This plant then gains the resistance to drought, which can be passed on to other plants
 The use of pesticides may be drastically reduced if pest resistance is engineered into
crop plants
 Some of the drawbacks include a transference of the genetic modification into nearby
weeds which could lead to the evolution of super weeds
 This could cause problems since these new pests would be resistance to pesticides
 Some modifications put toxins into the plant that helps repel pests which could lead to the
evolution of super pests that would be resistant to pesticides
 This could lead to whole crops being destroyed and a loss of food security
 South Africa is one of the largest producers of GMO’s in Africa
 However, very little research has been done on the long term effects of genetically
modified foods on humans

f. Loss of wild varieties: the impact on the gene pool (p366)
 Loss of wild varieties of plants because of hybridisation has led to a reduction in genetic diversity
 A hybrid is the product of different plants that have been cross pollinated and many of these were
developed to produce more crops in less time
 This loss of diversity in plants leads to genetic erosion and affects the gene pool within a species by
reducing it in the wild
 The factors that have caused this loss of biodiversity include the clearing of land for agriculture and
towns, changing agricultural systems, overexploitation of indigenous species and replacing
indigenous species with hybrids and genetically modified plants
 This loss of genetic diversity means that it is less likely that plants will be able to adapt to changing
environmental conditions
 The loss of wild varieties of plants allows pest and disease to become more common and affects
crops by lowering the yields
 This reduces food security for humans
g. Food wastage (p367)
 Food wastage also threatens food security and includes food thrown away and not eaten
 This occurs during the storage, production and processing of food , caused by:
 Pest infestations
 Animal diseases
 Extremes of temperature and rainfall
 Machinery
 Demands of the marketplace
 Wastage results in the loss of 1.3 billion tons of food a year being lost (one third of global production)
 As a result small farmers lose income and there is an increase in prices to consumers who are already
poor (especially in developing country). This reduces food security for citizens in that country

Loss of Biodiversity – The Sixth extinction (p369)
 Biodiversity is the variety of habitats and communities that we find in ecosystems
 It includes the number of different species and the total of all of the genetic information
carried by living organisms and includes the evolutionary and ecological processes that
allows these organisms to exist over time
 Biodiversity is needed to maintain the balance found within the biosphere and help
humans survive
 Biodiversity ensures that humans have food, fresh water, medicines and fuel that we
obtain from our environment
 It ensures that the climate is regulated, floods are controlled (wetlands), diseases are kept
in check (predators eat the sick animals) and water is purified (filtering by wetlands)
 Biodiversity ensures that seeds are dispersed, nutrients are cycled (nitrogen and
phosphorus) and oxygen and soil continue to form
 It also helps with human quality of life by providing us with forms of recreation and
ecotourism
 As biodiversity declines, these things do not occur as they should and survival of humans
is jeopardized
 Ultimately, humans should develop while using the environment sustainably or in a way
that does not damage biodiversity permanently

Loss of Biodiversity – The Sixth extinction (p369)
2  South Africa is the third most diverse country in the world . For example, the Fynbos
biome contains 3% of all plant species found in the world and 70%of these are endemic
to this region
 Biodiversity on Earth naturally changes over time with new species taking the place of
those that go extinct
 Ecosystems may change in size and shape over time due to natural fires or wetlands
gradually increasing in silt and changing
 Geological processes, sea level changes and climate change may cause long-term
changes in biodiversity
 Usually one species disappears over a million years, with a new species developing at the
same rate, causing the number of species to stay constant over long periods of time
 When catastrophic events occur such as a large meteorite hitting the Earth, large numbers
of species may be wiped out in a relatively short period of time (a million years)
 However, human activities at present are causing hundreds of species to disappear a
day
 Because of this high loss of biodiversity, scientists believe that we are presently in the sixth
mass extinction
 This will eventually impact on human survival on Earth

 Some of the causes of the sixth major extinction include the following:
 Habitat destruction (p372)
 Poaching (p372)
 Poaching refers to the illegal hunting of animals, either for food or because certain body parts
can be sold for money
 The most damaging poaching is done when species are collected and sold for profit
 Rhino poaching
 The Black Rhinoceros in Africa are critically endangered since they are hunted for their horns which are
used in the Far East for medicinal reasons
 Elephant poaching
 Elephant tusks are used in carvings and jewellery and there are only about 500 000 African elephants
left in the wild when once there were millions (their numbers have increased since the ban on ivory)
 Poaching may also be applied to plants that are removed and sold for profit E.g. medicinal
plants
 Some wild animals are hunted for food (‘bush meat’) and are on the verge of extinction
 Suggestions for curbing poaching include well-armed policing of the habitats where the
protected organisms are found, international cooperation between police forces to track
down the organisers of criminal activity and stiffer laws that prohibit poaching
 Drastic measures such as dehorning rhinos have also been suggested to prevent poaching
(horns are made of keratin and grow back when removed)

 Some of the causes of the sixth major extinction include the following: (2)
 Alien Plant Invasions (p376)
Humans have transplanted animals and plants into areas in which they do not occur
naturally
Invasive alien species are organisms that reduce the biodiversity of an area by
competing with and replacing the indigenous species of the area
 In their natural habitats, alien species would be controlled by their natural predators and
pathogens
 However, invasive species have no natural enemies in the areas they are introduced into
and spread quickly
 In natural habitats, relationships form between indigenous plants and animals
 These are delicately balanced and are destroyed when an invasive species is introduced
since indigenous organisms cannot compete as well as alien species that have no natural
predators
 Alien invasive species may occur on land or in aquatic environments E.g. trout and bass
threaten indigenous fish such as Red-fin minnows and an invasive wasp that is affecting
honey bee populations
 Alien species may grow faster, mature earlier and produce more seeds than indigenous
species

Alien species can be controlled by:
 Mechanical control
 Mechanical methods involve chopping down plants or physically removing them
by hand and is very time consuming
 The plants tend to grow back and must be constantly monitored
 Chemical control
 Chemical control involves spraying herbicides on the plants and can pollute the
environment and is expensive
 Plants may develop a resistance to the herbicides over time, making this method
ineffective
 Biological control
 Biological methods involves introducing a natural enemy from the alien plant’s
environment and allowing it to reproduce and feed on the invasive plant. E.g.
Cactoblastis larvae feed on prickly pear leaves and seed pods reducing the
number of plants over time
 The control agent being used does not generally get rid of the pest completely
but will help keep the alien species population restricted

Indigenous knowledge Systems and
Sustainable Use of the Environment (p377)
 Sustainable use of the environment means using resources without harming the ability of future
generations to use that resource
 Sustainable use of resources also means that ecosystems be protected and managed wisely.
 Substances from indigenous plants are used for different reasons by humans.
 E.g. mopane worms as food and Devil’s claw for medicine
 The increased demand for plant-based products has led to the exploitation of many plants
 Traditional healers also depend on parts of many plants for their medicinal value
 Sometimes the entire plant is destroyed even though only part of it is used for medicine
 Nearly half of all plants used for medicinal reasons worldwide are threatened by over-harvesting
and loss of habitat
 Many medicinal plant nurseries have been established to help prevent extinction of some
medicinal plants
 After consulting with local traditional healers, a nursery will be established that grows the plants
required
 This prevents plants from being harvested from the wild and allows traditional healers to learn
cultivation techniques for growing the plants required

 Substances from indigenous plants such as the African potato, hoodia, rooibos Devil’s
claw and the pepper-bark tree all have economical and medicinal value in South
Africa
 Devil’s claw helps relieve back pain, fever , digestive problems and arthritis (p378)
 Rooibos helps strengthens bones , relieve stomach cramps, and is rich in antioxidants
and minerals (p380)
 Fynbos (p381) is found in the Western Cape Province. There are over 7300 plant species,
so 45% of SA’s flora is crammed into 4% of land. Also, 80% of the species are endemic to
this region. Ithe Western Cape is regarded as an international biodiversity hot-spot.
 The African potato boosts the immune system and slows the growth of tumours in cancer
(p382)
 Hoodia helps suppress the appetite (p384)
 The pepper-bark tree is used to treat malaria, colds, chest pains, coughs and general
body pains
 The inner bark is used as well as stems and roots and this eventually can kill the tree
 These indigenous plants can be managed sustainably by encouraging traditional
healers to grow their own plants and through improving education of the women who
generally gather the plants in the wild
 Encouraging traditional healers to be part of formal medical programs would
encourage training to be ongoing and help establish sustainable use of medicinal
plants
 Legislation should be passed to limit the numbers of plants that can be harvested at
one time and seeds of medicinal plants could be collected and distributed to
increase plant numbers
 It is important that indigenous species be sustainably harvested and managed
wisely

Solid Waste Disposal (p385)
 With the increase in human population numbers and consumption of goods, a tremendous increase in household and electronic waste,
industrial and hazardous waste has made it necessary to find ways of disposing these waste products
 Waste is any material that is considered of no use to the person using it and is then thrown away
 Waste is classified as solid, liquid and gaseous and needs to be disposed of in a safe, environmentally friendly way
 Each individual in South Africa generated between 0,5 to 2 kg of waste every day
 This means that South Africa generates about 15 million tons of domestic waste and 25 million tons of industrial waste each year
 The simplest and most cost effective way to get rid of waste is to bury it in landfills
 A landfill area is usually a deep hole where solid waste is dumped and buried between layers of soil
 Solid waste is taken to a landfill area and then dumped, usually by the municipality
 There are two types of landfills: general waste landfills and hazardous waste landfills
 The sites for hazardous waste landfills are carefully chosen to be in areas of low rainfall and away from urban areas
 It is designed to prevent the pollution of groundwater and to encourage decomposition of rubbish
 However, the way of disposing of waste often contributes to land, air and water pollution
 Sustainable management of dump sites must include the prevention of soil and water pollution since rainwater can seep into the area
with rubbish and produce a poisonous product known as leachate
 This can then poison the ecosystem around the dumpsite
 Rehabilitation of landfill areas that close down helps reduce pollution in the area
 A plastic liner is placed under the dumpsite area to prevent leaching into the groundwater
 The landfill is capped with clay that is impermeable to water and then topsoil and grass or other vegetation is added
 The growth of the plants stabilises the area and improves the appearance of the site (phytoremediation p388)
 The land may be used for recreational areas, such as parks and golf courses afterwards and is monitored for 30 years afterwards

Recycling waste (p389)
 As urbanisation and industrialisation increases, the volume of waste generated increases
 Landfill sites are unable to keep up with the amount of waste that is being produced
 Lack of dumping sites and lack of recycling facilities in many parts of South Africa means
that waste production will negatively impact on the environment
 Solid waste may block drainage gutters and cause flooding
 Some waste products are toxic and can poison the soil and animals that it
 The appearance of areas where dumping is taking place is destroyed and this can affect
tourism in an area
 Dumpsites that are not properly managed can be a breeding ground for diseases
 Various methods may be used to manage waste
 This includes the reduction of waste, re-using waste and recycling of waste products

Recycling waste (p389) 2
 Reduction of waste products can be accomplished by shopping carefully and
buying products in bulk which reduces the amount of packaging being used
 Purchasing products that are in re-useable containers, using rechargeable batteries,
 Using plastic bags that you have at home for shopping and using both sides of paper for
printing all help reduce the amount of waste that is produced
 Re-using products such as glass and plastic containers, plastic shopping bags,
sending unwanted toys and clothes to charities, and using office paper that is
printed on one side as scrap paper all help reduce the waste being produced
 Recycling is defined as the process whereby used materials or waste products
are recycled into new products
 Recycle waste products by separating plastic, glass, tin cans and paper and then
taking them to a recycling centre
 These can be used to make new products and provides employment
 It also reduces the consumption of raw materials and energy and reduces the levels of
air and water pollution
 Municipalities should initiate recycling programs in communities to help reduce waste
produced and dumped in landfill areas

Use of methane gas and (p390)
 Methane is a gas that is released as a result of decomposition of waste
 Methane is produced in dumpsites from the decay of organic matter by anaerobic bacteria
 Methane helps create global warming and is 72 times more effective than carbon dioxide as
a greenhouse gas
 Scientists have been researching ways to use the gas sustainably as a power source
 The gas collected from landfills can be used to generate electricity through gas recovery
systems and thus reduce pollution
 A number of wells are placed throughout the dump and connected to a vacuum
 This directs the gas to a processing plant and can be used to generate electricity using
turbines or piped into households and used for cooking
 Gas can be harvested while a landfill is still operational and for up to 50 years after closing
down a dumpsite

Disposal of nuclear waste
 Nuclear power can be used to generate electricity and originates from splitting
uranium atoms in a process called fission
 This process generates heat that produces steam and is used by a turbine to
generate electricity
 The Koeberg power station is the only nuclear power station on the African
continent
 Uranium produces nuclear waste that is radioactive and hazardous to living
organisms
 Nuclear waste takes over 100 000 years to break down
 Low-level waste such as clothing and insulation material used at the site as well
as intermediate- level waste such as contaminated scrap metal are stored in
steel drums and buried in trenches at special sites
 Highly radioactive used fuel rods are stored at Koeberg and Pelindaba and
dealing with nuclear waste safely remains an environmental issue

Homework
 Activities
 3.6.1 p323
 3.6.2 p328
 3.6.4 p335
 3.6.7 p339
 3.6.8 p346
 3.6.9 p354
 3.6.10 p359
 3.6.11 p361
 3.6.12 p369
 3.6.13 p374
 3.6.15 p379
 3.6.17 p384

 http://www.epa.gov/climatechange/ghgemissions/global.html
 http://tgh.co.za/our-work/case-studies/
 http://www.grida.no/graphicslib/detail/emissions-of-carbon-dioxide-in-africa-and-selected-oecd-countries_1400
 http://veggie.buntch.net/wp-content/uploads/2011/06/AfricanCo2emissionsinfographic.jpg
 http://www.redorbit.com/news/science/1112688716/deforestation-rainfall-090612/
 http://www.globalization101.org/ozone-depletion/
 http://www.c2es.org/facts-figures/international-emissions/sector
 http://safcei.org/safcei-world-environment-day-2013/
 http://en.wikipedia.org/wiki/Greenhouse_gas
 http://www.epa.gov/climatechange/ghgemissions/global.html
 http://grgandhi143.blogspot.com/2012/08/global-warming-effects-and-solutions.html
 http://warmgloblog.blogspot.com/2012/05/clouds-probably-amplify-effects-of.html
 http://www.solarpowernotes.com/what-is-global-warming.html#.U6qT3pQabIY
 http://solarwindgreenenergy.blogspot.com/2011/10/top-5-global-warming-solutions.html
 http://www.myseek.org/wp-content/uploads/2011/11/strategies-for-change.jpg
 http://learningfundamentals.com.au/resources/
 http://www.climatehotmap.org/global-warming-solutions/
 The Kyoto Protocol website: http://unfccc.int/kyoto_protocol/items/2830.php
 http://www.pearson.com/responsibility/responsible-business-practice/environment/annual-environment-review/climate-
footprint.html
 http://saugosblog.blogspot.com/p/climate-change.html

Human impact on the environment

Recomendados

Recomendados

Mais conteúdo relacionado

Mais procurados

Mais procurados (20)

Destaque

Destaque (20)

Semelhante a Human impact on the environment

Semelhante a Human impact on the environment (20)

Último

Último (20)

Human impact on the environment