Transcript iGCSE Biology Section 4 lesson 4

IGCSE BIOLOGY
SECTION 4 LESSON 4
Content
Section 4
Ecology and
the
Environment
a) The organism in the
environment
b) Feeding relationships
c) Cycles within ecosystems
d) Human influences on the
environment
Content
Lesson 4
d) Human
influences on
the
environment
d) Human influences on
the environment
4.11 understand the biological consequences of pollution of
air by sulfur dioxide and by carbon monoxide
4.12 understand that water vapour, carbon dioxide, nitrous
oxide, methane and CFCs are greenhouse gases
4.13 understand how human activities contribute to
greenhouse gases
4.14 understand how an increase in greenhouse gases
results in an enhanced greenhouse effect and that this may
lead to global warming and its consequences
4.15 understand the biological consequences of pollution
of water by sewage, including increases in the number of
micro-organisms causing depletion of oxygen
4.16 understand that eutrophication can result from leached
minerals from fertiliser
4.17 understand the effects of deforestation, including
leaching, soil erosion, disturbance of the water cycle and of
the balance in atmospheric oxygen and carbon dioxide.
Air Pollution
Air Pollution
Air Pollution
Smoke
Sulphur
dioxide
Air Pollution
Smoke
Sulphur
dioxide
Lead
compounds
Carbon
monoxide
Oxides of
nitrogen
Air Pollution
SMOKE
Consists mainly of tiny particles of carbon and
tar which comes mostly from burning coal.
Particles blacken buildings and damage the
leaves of trees.
Much reduced since the Clean Air Act of 1956
Air Pollution
December 1952
Smoke + Fog = Smog
Cold fog, together with
the smoke from many
coal fires, caused a
‘pea-souper’.
Officials believe that
as many as 12,000
people in London may
have died as a result of
the smog.
Air Pollution
SULPHUR DIOXIDE and OXIDES OF
NITROGEN
Coal and oil contain sulphur and nitrogen.
When these fuels burn, they release sulphur
dioxide (SO2) and oxides of nitrogen (NO,
NO2)
Air Pollution
SULPHUR DIOXIDE and OXIDES OF
NITROGEN
These oxides can react with water in the
atmosphere to form acids (sulphuric acid
H2SO4 and nitric acid HNO3).
Air Pollution
SULPHUR DIOXIDE and OXIDES OF
NITROGEN
These acids then fall back down to the ground
as ACID RAIN. The nitrogen oxides are also
produced from car exhausts.
Air Pollution
Gases react with water in the
atmosphere to form …..
Sulphur dioxide
and nitrogen
oxides
ACID
RAIN
Nitrogen
oxides
Industry and power stations
Motor cars
Air Pollution
Gases react with water in the
atmosphere to form …..
Sulphur dioxide
and nitrogen
oxides
ACID
RAIN
Nitrogen
oxides
Industry and power stations
Motor cars
Acid rain
damages trees
directly, and
also affect
lakes and
rivers, making
them too
acidic for
plants and
animals
Air Pollution
Carbon
monoxide
Air Pollution
Carbon
monoxide
Haemoglobin
O2
O2
O2
O2
Air Pollution
Carbon
monoxide
CO
Haemoglobin
O2
O2
O2
O2
Air Pollution
carboxyhaemoglobin
Carbon
monoxide
Haemoglobin
CO
CO
CO
CO
understand that water vapour, carbon
dioxide, nitrous oxide, methane and
CFCs are greenhouse gases
What is a
greenhouse gas?
A greenhouse gas is any gas in the
atmosphere that contributes towards
the greenhouse effect (global
warming).
Carbon
dioxide
Nitrous
oxide
CFCs
Greenhouse
gases
Water
vapour
Methane
So what is
this
‘greenhouse
effect’?
The Greenhouse Effect
The Greenhouse Effect
The Greenhouse Effect
The Greenhouse Effect
Earth’s surface
absorbs
energy … and
warms up
The Greenhouse Effect
Warm surface radiates
energy back
Earth’s surface
absorbs
energy … and
warms up
The Greenhouse Effect
A proportion of the long
waves is absorbed by the
atmosphere
Warm surface radiates
energy back
Earth’s surface
absorbs
energy … and
warms up
The Greenhouse Effect
If the concentration of any off the greenhouse
gases were to increase, the greenhouse effect
would be increased and the Earth would get
warmer.
The Greenhouse Effect
If the concentration of any off the greenhouse
gases were to increase, the greenhouse effect
would be increased and the Earth would get
warmer.
Records show that the
concentration of CO2
has increased from
0.029 to 0.035 per
cent since 1860. it is
likely to go on
increasing as we burn
more and more fossil
fuel.
The Greenhouse Effect
• DEFORESTATION – reduces photosynthesis which removes CO2 (also
reduces the rate at which carbon dioxide is ‘locked up’ as wood)
• Burning - either chopped-down wood or industrial produces CO2
• increased micro-organism activity – on decaying material produces CO2
• herds of cattle – produce methane, CH4
• Rice fields also produce methane
The Greenhouse Effect
• DEFORESTATION – reduces photosynthesis which removes CO2 (also
reduces the rate at which carbon dioxide is ‘locked up’ as wood)
• Burning - either chopped-down wood or industrial produces CO2
• increased micro-organism activity – on decaying material produces CO2
• herds of cattle – produce methane, CH4
• Rice fields also produce methane
Cause increase in atmospheric
CARBON DIOXIDE and
METHANE
The Greenhouse Effect
• DEFORESTATION – reduces photosynthesis which removes CO2 (also
reduces the rate at which carbon dioxide is ‘locked up’ as wood)
• Burning - either chopped-down wood or industrial produces CO2
• increased micro-organism activity – on decaying material produces CO2
• herds of cattle – produce methane, CH4
• Rice fields also produce methane
Cause increase in atmospheric
CARBON DIOXIDE and
METHANE
WHICH CAUSES
GLOBAL WARMING
The Greenhouse Effect
The Greenhouse Effect
Consequences:
• substantial climate changes
• a rise in sea level
Eutrophication
This is the enrichment of natural
waters with nutrients which allow the
water to support an increasing amount
of plant life.
Human activity can lead to rapid
eutrophication and destruction of
aquatic life.
Eutrophication
A six-stage process
Eutrophication
A six-stage process
1. Inorganic fertilisers,
used by farmers on
their crops, may be
washed into lakes and
rivers. The fertiliser is
originally sprayed to
replace nutrients that
previous crops have
removed from the soil.
n.b. Untreated sewage has
the same effect as
excess fertiliser.
Eutrophication
A six-stage process
1. Inorganic fertilisers,
used by farmers on
their crops, may be
washed into lakes and
rivers. The fertiliser is
originally sprayed to
replace nutrients that
previous crops have
removed from the soil.
n.b. Untreated sewage has
the same effect as
excess fertiliser.
Eutrophication
A six-stage process
2. Growth. - of water
plants caused by the
fertiliser or sewage
happens rapidly. The
nitrogen in particular is
taken up quickly by the
plants and used to make
protein for growth of
new and existing shoots.
= ALGAL BLOOM
Eutrophication
A six-stage process
3. Death – of some of these
plants due to lack of
light from overcrowding. The plants
literally choke
themselves to death as
they try to gain
sufficient light from the
Sun, and more nutrients
from the water.
Eutrophication
A six-stage process
4. Micro-organisms which feed on dead
organisms now increase
massively in number.
These are the
putrefying bacteria
which breakdown dead
organic material via
respiration, and release
simpler substances for
recycling.
Eutrophication
A six-stage process
5. Oxygen – is used up
quickly by this huge
number of microorganisms. The process
of breakdown is
respiration, i.e. the
micro-organisms respire
the organic material and
use oxygen in doing so.
Eutrophication
A six-stage process
6. Suffocation – of fishes
and other aquatic
animals due to lack of
oxygen in the water.
Eventually almost all
oxygen is removed from
the water, so there is
insufficient for larger
organisms, and they
subsequently die.
Eutrophication
A six-stage process
6. Suffocation – of fishes
and other aquatic
animals due to lack of
oxygen in the water.
Eventually almost all
oxygen is removed from
the water, so there is
insufficient for larger
organisms, and they
subsequently die.
understand the effects of
deforestation, including leaching, soil
erosion, disturbance of the water
cycle, and of the balance
in atmospheric oxygen
and carbon dioxide.
Deforestation
“ … involves the
large scale
cutting down of
trees for timber,
and to provide
land for
agricultural uses.”
Deforestation
Leaching
Water
cycle
Soil
erosion
Effect on
atmosphere
Deforestation
Leaching
Water
cycle
Soil
erosion
Effect on
atmosphere
Deforestation
Leaching
Water
cycle
Removal of the trees
exposes the soil
beneath directly to
rain, which washes
nutrients out of the
soil into surrounding
streams and
waterways
Soil
erosion
Effect on
atmosphere
Deforestation
Leaching
Water
cycle
Soil
erosion
Effect on
atmosphere
Deforestation
Leaching
Water
cycle
The soil is physically
removed from its
location and washed
down into streams and
rivers where it will
accumulate (silt) and
effectively block
waterways.
Soil
erosion
Effect on
atmosphere
Deforestation
Leaching
Water
cycle
Soil
erosion
Effect on
atmosphere
Deforestation
Leaching
Water
cycle
With trees present,
much transpiration
occurs through the
leaves into the
atmosphere. When
trees are cut down
this water movement
is stopped.
Soil
erosion
Effect on
atmosphere
Deforestation
Leaching
Water
cycle
Soil
erosion
Effect on
atmosphere
Deforestation
Leaching
Water
cycle
Photosynthesis in the
leaves of trees
maintains the balance
in the atmosphere
between oxygen and
carbon dioxide.
Removing trees
disrupts this delicate
balance.
Soil
erosion
Effect on
atmosphere
Deforestation
http://www.global-greenhouse-warming.com/deforestation.html
Deforestation
Every second, an area of
rainforest equivalent to two
U.S. football fields is
destroyed.
http://www.global-greenhouse-warming.com/deforestation.html
End of Section 4 Lesson 4
In this lesson we have covered:
• the effects of human activity on the
environment
• air pollution
• acid rain
• carbon monoxide poisoning
• the greenhouse effect
• eutrophication
• deforestation