National 5
Environmental Science
Earth’s Resources
Name:
Class:
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Use the following table as a checklist for your Nat. 5 revision.
Remember to ask your teacher for help with anything you don’t understand.
Learning Outcomes/ Mandatory Course Key Content
Learned
notes
1 Overview of Earth systems and their interactions
a. Identification of the main Earth systems - geosphere, hydrosphere,
atmosphere and biosphere
b. Classification of resources into physical, biological, renewable and
non-renewable.
2 Geosphere
a. Definitions: weathering, transportation, erosion, deposition,
igneous, sedimentary, metamorphic , rock, mineral , porosity,
permeability.
b. Structure of the Earth: core (inner and outer), mantle, and crust
(oceanic and continental).
c. Rock cycle processes: erosion, weathering (physical, chemical,
biological, link with soil formation), transportation, deposition,
melting, effects of heat and pressure, and formation of igneous
(granite, basalt), sedimentary (sandstone, shale), and metamorphic
(marble, slate) rocks.
d. Relationship between rocks, minerals, and ores

rock: granite is mostly composed of quartz, biotite and
feldspar minerals
 minerals: quartz (silica and oxygen), calcium carbonate
(calcium, carbon and oxygen)
 ore: metallic iron can be economically extracted from iron
ores.
e. Properties of rocks: porosity and permeability.
f. Limestone: formation (formed in shallow tropical sea water as a
result of calcium carbonate precipitating out), extraction
(quarrying), processing (cutting, crushing), uses, and environmental
impacts of extraction and/or processing.
Uses of limestone: cement manufacture, construction, agriculture,
iron & steel manufacture.
g. Geological carbon cycle; the role of limestone as a carbon sink,
and chemical weathering (carbonic acid).
h. Iron ore: formation (formed in sea water as a result of oxygen
release by photosynthesising organisms; the oxygen combines with
dissolved iron in the ocean to form iron oxide), extraction (opencast
mining), processing (blast furnace), uses, and environmental
impacts of extraction and/or processing.
Processing: ore smelting in a blast furnace; inputs (iron ore,
limestone, oxygen, coke) and outputs (pig iron, slag, carbon
dioxide).
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Uses of iron: steel manufactured products, reinforced concrete, cast
iron and wrought iron products.
i. Crude oil: formation (formed from the remains of small animals
and plants that died and fell to the seafloor millions of years ago;
compression and heating of these remains within the Earth’s crust
forms oil), extraction (drilling), processing (fractional distillation),
uses, and environmental impacts of extraction, processing and uses.
Processing: fractional distillation (including role of temperature in
formation of outputs), graduation in molecule size.
Uses: domestic and industrial fuels, electricity generation, petrol,
diesel, fuel oil, plastics, tar, bitumen, lubricants, roofing felt,
medicines, and cosmetics.
Environmental impacts of crude oil products.
3 Hydrosphere
a. Definitions: evaporation, condensation, precipitation,
transpiration, run-off, infiltration, percolation, throughflow,
groundwater, groundwater flow.
b. Water cycle: evaporation, condensation, precipitation,
transpiration, run-off, percolation, infiltration, throughflow,
groundwater flow, storage.
c. Main stores of water: atmosphere, oceans, ice, freshwater (rivers,
streams, springs), groundwater (soil moisture, rock pores and
crevices), and aquifers.
d. Uses of water: industrial, domestic, and agricultural.
e. Issues arising from availability of water resources in Scotland and
the rest of the British Isles: drought and flooding.
Role of SEPA in flood warning and water quality.
f. Energy from water: hydro-electric, tidal, energy changes involved
(kinetic to electrical).
g. Requirements and considerations for siting hydro-electric and
tidal power stations:
Hydro-electric power (HEP): steep gradient, high precipitation,
narrow deep valley, impermeable geology, population density,
proximity to National Grid, current land use
Tidal: narrow channel, large water volume, large tidal stream,
population density, proximity to National Grid, current water use.
4. Biosphere
a. Definitions to include biomass, biofuels
b. Oceanic and freshwater resources: economically important
species of plants and animals.
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c. Terrestrial resources: economically important species of
domesticated and hunted animals, agricultural crops, forestry
(native and plantation).
d. Energy from biological resources: biomass (wood, peat).
Process of fermentation in formation of biofuels:conditions required
for formation of of peat (acidic and anaerobic), and methane as the
primary biogas.
5. Atmosphere
a. Definition to include natural greenhouse effect.
b. Composition of the atmosphere (nitrogen, oxygen, argon and
carbon dioxide), and the importance of the ‘natural’ greenhouse
effect.
c. Energy from wind, including energy changes involved (kinetic to
electrical).
d. Requirements and considerations for siting wind farms:
strong/steady wind flow, exposed site, population density,
proximity to National Grid, current land/water use.
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1.Overview of Earth Systems
a. Earth systems
Four major parts of Earth work together as a
complex system: rocks, water, air, and life. The
four parts are called the geosphere (land),
hydrosphere (water), atmosphere (air), and
biosphere (living organisms).
GEOSPHERE
(LAND)
The surface of the geosphere, where the rocky
part of our planet is in contact with water, air,
and/or life is generally where the spheres affect
each other. The processes that move matter and
energy from one sphere to another are called
sphere interactions.
b. Resources
A resource is something people use to survive, to generate wealth or simply
to enjoy. There are many resources found on Earth. They can be found in all
four of the Earth systems.
Resources can be categorised as physical or biological, and renewable and
non-renewable. The table below lists examples of each.
Physical Resources
Is it Renewable or Non-Renewable?
Biological Resources
Is it Renewable or Non-Renewable?
Exam Tips:
1. Don’t get confused between renewable and recyclable. For example,
aluminium is non-renewable but it can be recycled.
2. Soil is classified as a physical and biological resource as it contains a
mineral part from rock and an organic part, the humus.
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2. Geosphere
b. Structure of the Earth
The Earth consists of layers: core(inner and outer), mantle and crust.

The inner and outer cores are in the centre and are the hottest part of the
Earth. It is solid and made up of iron and nickel at high temperatures.

The mantle is the widest section of the Earth. It has a thickness of
approximately 2,900 km. The mantle is made up of semi-molten rock called
magma. In the upper parts of the mantle the rock is hard, but lower down the
rock is soft and beginning to melt.

The crust is the outer layer of the earth. The crust under the oceans is known
as the oceanic crust. It is about 10km thick and made up of rock rich in iron
and magnesium. The continental crust forms the land masses that we live
on. It is less dense than the oceanic but much thicker, between 30 and 50km.
It is made up of igneous, metamorphic and sedimentary rocks.
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c. The Rock Cycle
Rocks are continually changing from one type to another and back again, as
forces inside the earth bring them closer to the surface (where they are
weathered, eroded, and compacted) and forces on the earth sink them back
down (where they are heated, pressed, and melted). So the elements that
make up rocks are never created or destroyed — instead, they are constantly
being recycled.
To understand the rock cycle you need to be familiar with the terminology.
Match the terms with the correct definition.
Weathering
Erosion
Metamorphic
Igneous
Transportation
Term
Deposition
Sedimentary
Definition
The exposure and breaking down of rocks at the Earth’s surface over
long periods of time. There are three types of weathering:



Biological - is caused by plants and animals, eg plant roots
growing in the rock cracks. As they grow bigger, the roots
push open the cracks and make them wider and deeper.
Eventually pieces of rock may fall away.
Chemical - Rainwater is naturally slightly acidic because
carbon dioxide from the air dissolves in it. Minerals in rocks
may react with the rainwater, causing the rock to be
weathered.
Physical - is caused by physical processes such as changes in
temperature, freezing and thawing, and the effects of wind,
rain and waves.
Is the movement of the broken pieces that have been created by
weathering away from the site of weathering, eg a limestone cliff
may be weathered by freeze-thaw, a type of physical weathering.
This means that rock in the cliff becomes broken into smaller pieces.
Erosion happens when these pieces of rock fall away down the cliff.
The movement of rock fragments by water, wind, ice or gravity
from the place they were weathered, eg rivers and streams can
carry pieces of rock.
The settling of rock fragments and sediments after
transportation.
Rock that forms through the cooling of magma in the upper
crust or on the Earth’s surface.
Rock that is formed from weathered rock fragments which
have been eroded, transported, deposited and compacted.
Rock that has been subjected to heat and pressure.
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The Rock Cycle
The processes in the rock cycle are summarised in this diagram:
Add letters to show where the processes occur.
Letter
A
B
C
D
E
F
G
Description
Weathering breaks down rocks on the surface of the Earth. There are three types of
weathering (biological physical and chemical). Wind and water move the broken rock
particles away. This is called erosion.
Rivers and streams transport rock particles to other places. Rock particles are
deposited in lakes and seas.
Rock particles form layers.
Compaction and cementation presses the layers and sticks the particles together. This
creates sedimentary rock.
Rocks underground get heated and put under pressure, and are changed into
metamorphic rock.
Rocks underground that get heated so much they melt turn into magma. Magma also
comes from deeper inside the Earth, from a region called the mantle. Pressure can
force magma out of the ground, creating a volcano. When the magma (lava) cools
quickly, it turns into solid extrusive igneous rock. Magma that cools slowly
underground forms solid intrusive igneous rock.
Areas of rock can move slowly upwards, pushed up by pressure of the rocks forming
underneath. This is called uplift.
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There are three main types of rock: sedimentary, igneous and
metamorphic.
Formation of Sedimentary Rocks
A river transports pieces of broken rock as
it flows along. When the river reaches a
lake or the sea, its load of transported
rocks settles to the bottom. We say that
the rocks are deposited.
The deposited rocks build up in layers,
called sediments. This process is called
sedimentation.
The water is squeezed out from between the
pieces of rock and crystals of different salts
form.
The crystals form a sort of glue that sticks or
cements the pieces of rock together. This
process is called cementation.
Sedimentary rocks contain rounded grains in layers.
Examples of sedimentary rock are:




chalk
limestone
sandstone
shale
Sedimentary rocks may contain fossils of animals and plants trapped in the
sediments as the rock was formed.
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Formation of Igneous Rocks
The inside of the Earth is hot enough to melt rocks. Molten (liquid) rock forms
when rocks melt. The molten rock is called magma. When the magma cools
and solidifies, a type of rock called igneous rock forms.
Igneous rocks contain randomly arranged interlocking crystals. The size of the
crystals depends on how quickly the molten magma solidified. The more
slowly the magma cools, the bigger the crystals.
Examples of igneous rock are:
 obsidian
 basalt
 granite
 gabbro
Unlike sedimentary rocks, igneous rocks do not contain any fossils. This is
because any fossils in the original rock will have melted when the magma
formed.
Formation of Metamorphic Rocks
Metamorphic rocks are formed from other rocks that are changed because of
heat or pressure. Earth movements can cause rocks to be deeply buried or
squeezed. As a result, the rocks are heated and put under great pressure.
They do not melt, but the minerals they contain are changed chemically,
forming metamorphic rocks. When a metamorphic rock is formed under
pressure, its crystals become arranged in layers.
Remember that metamorphic rocks are not made from melting rock. (Rocks
that do melt form igneous rocks instead.)
Examples of metamorphic rocks include:
 slate
 marble
Metamorphic rocks sometimes contain fossils if they were formed from a
sedimentary rock, but the fossils are usually squashed out of shape.
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d. Relationship between Rocks, Minerals and Ores
A rock is made up of 2 or more minerals. All rocks are made of minerals.
Examples of rocks include:
 granite (a mixture of the minerals quartz, feldspar, and biotite).
A mineral is composed of the same substance throughout. There are more
than 3000 different minerals in the world. Minerals are made of chemicals either a single chemical element or a combination of chemical elements.
Examples of minerals include:
 quartz (containing silica and oxygen)
 calcium carbonate (containing calcium, carbon and oxygen)
The difference between rock and mineral is that a rock is made up of 2 or
more minerals, whereas a mineral is composed of the same substance
throughout.
An ore is a mineral occurring in sufficient quantity and containing enough
metal to permit its recovery and extraction from the rock it is in at a profit.
Therefore, rocks have minerals, which in large concentration are called ores
and these are mined for metals!
The following table shows the ores, their chemical formulae and the metals
that can be extracted from them.
Ore
Chemical Formula
Magnesite
MgCO3
Bauxite
Al2O3
Haematite
FeO3
Malachite
CuCO3
Uraninite
UO2
Cinnabar
HgS
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Metal
e. Properties of rocks
Interlocking grains
Rounded grains
Some types of rock have interlocking grains that fit tightly together, eg granite.
Other types have rounded grains, eg sandstone. This can have an effect of
their porosity and permeability.
Porosity is a measure of how much of a rock is open space. This space can
be between grains or within cracks or cavities of the rock. Rocks with rounded
grains are more likely to absorb water than rocks with interlocking grains. This
is because the water can get into the gaps between the grains.
Permeability is a measure of the ease with which water in this case can
move through a porous rock. Rocks with large rounded particles will let water
pass through more easily than rocks with small particles.
NB Some rocks can have a low permeability but a high porosity. This is
because a rock may have a high porosity due to a high percentage of pore
spaces between the grains, but a low permeability due to the pores not being
well connected so liquid cannot flow through easily.
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f. Limestone
Limestone is a sedimentary rock and consists mainly of calcium carbonate, (CaCO3).
It exists naturally in the Earth’s crust.
Formation of limestone.
Limestone is a sedimentary rock so it is formed in way described on page 8. Most
limestones form in shallow, calm, warm marine waters. That type of environment is
where organisms capable of forming calcium carbonate shells and skeletons can
easily extract the needed ingredients from ocean water. When these animals die their
shell and skeletal debris accumulate as a sediment that might form limestone.
Carbon in limestone is trapped and so takes it out of circulation in the carbon cycle
(look back to the Living Environment notes p17). This is known as a carbon sink.
The carbon will be released only when as the limestone weathers to form carbonic
acid.
Uses
Limestone has many uses including:

Construction. Limestone can be used as a building material in its raw state
but it can also be processed to make concrete and cement

Agriculture. Powdered limestone can be used to neutralise soils which are
too acidic for crop growth.

Chemical Industries. Limewater (a solution of calcium hydroxide) can be
used to test for the presence of carbon dioxide. Limewater goes cloudy when
carbon dioxide is present.
Extraction
Limestone is extracted from the Earth by quarrying. Many tonnes are quarried in the
UK every year. The need for limestone has to be balanced against the economic,
environmental and social effects. Some factors that have to be considered include:

effect on employment – increased job opportunities

pollution – noise, sound and air

traffic levels

visual effects of having a quarry
Processing
Slabs of limestone can be cut for building material or crushed for fill for roadbeds,
and concrete aggregate. It can be further crushed to a powder for agricultural lime,
and heated to melting, then crushed to make portland cement.
The Houses of Parliament are made from limestone.
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h. Iron Ore
Iron ore is found in sedimentary rock. The two most important mineral
deposits are iron oxides: haematite (Fe2O3) and magnetite (Fe3O4).
Formation of Iron Ore.
Iron ore is found in sedimentary rock so it is formed in way described on page
8. The iron ore deposits began forming when the first organisms capable of
photosynthesis began releasing oxygen into the waters. This oxygen
immediately combined with iron in the water to produce iron oxide.
Extraction
Iron ore is extracted from the Earth by opencast mining. The need for
limestone has to be balanced against the economic, environmental and social
effects. Some factors that have to be considered include:




effect on employment – increased job opportunities
pollution – noise, sound and air
traffic levels
visual effects of having a quarry
Processing
Raw material
Function in the smelting process
Iron ore, eg
Haematite
Contains the iron
Coke
burns in air to produce heat, and reacts
to form carbon monoxide
Limestone
helps to remove impurities from the iron
to form slag, a waste material
Air, containing
oxygen
allows the coke to burn, and so produces
heat and carbon monoxide
Iron is extracted from iron ore in a huge container called a blast furnace in a
process called smelting. Iron ores such as haematite contain iron oxide. The
oxygen must be removed from the iron oxide to leave the iron behind.
Here is the equation for the reaction:
iron oxide + carbon monoxide
Fe2O3 +
3CO
iron + carbon dioxide
→
2Fe +
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3CO2
Iron from the blast furnace contains impurities such as carbon. It is hard, but
too brittle for most uses. So, most iron from the blast furnace is converted into
steel by removing some of the carbon. This is done by blowing oxygen into
the molten metal. It reacts with the carbon producing carbon monoxide and
carbon dioxide. These escape from the molten metal leaving just enough
carbon to make steel. Other metals may also be added.
Uses
Iron has more uses than any other metal including:

Construction. Iron can be used as a construction material for
buildings, bridges , rail road, transportation (car, trains, boats, plane,
etc.) , tools (knife , machines,) etc.

Steel Production. Steel is a commonly used alloy made from iron and
a small amount of carbon but it makes a huge difference to the
strength. Steel can be around 1000 times stronger than iron in its pure
form.
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i. Crude Oil
Crude oil is a fossil fuel. It was formed over millions of years, from the
remains of dead sea creatures:
Formation
Crude oil is found trapped in some of the sedimentary rocks of the Earth's
crust.
Millions of years ago, huge numbers of plankton (microscopic animals and
plants) died and fell to the bottom of the sea. Their remains were covered by
mud.
As the mud sediment was buried by more sediment it started to change into
rock as the temperature and pressure increased. During this process plankton
remains were slowly changed into crude oil.
Discovery and Extraction
Geologists can often tell where oil is trapped
by looking at the structure of the rocks. Oil
tends to be trapped where rocks are domed
upwards, or where permeable rocks are in
contact with impermeable rocks at a fault
line. Oil companies can drill down through
the impermeable rocks to get it out. They are
then able to turn the oil into products we can
use.
Processing
Crude oil is a mixture of substances. These are separated into useful
products, such as fuels, using a process called fractional distillation.
Fractional distillation separates the mixture into a number of different parts,
called fractions. A tall column is fitted above the mixture, with several
condensers coming off at different heights. The column is hot at the bottom
and cool at the top. Substances with high boiling points condense at the
bottom, and substances with low boiling points condense at the top. Fractional
distillation works because the different substances in the mixture have
different boiling points.
Because they have different boiling points, the substances in crude oil can be
separated using fractional distillation. The crude oil is evaporated, and its
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vapours allowed to condense at different temperatures in the fractionating
column.
The diagram below summarises the main fractions from crude oil and their
uses. Complete the diagram to show the temperatures at which each product
condenses out at.
Temperature
(oC)
__________
__________
__________
__________
__________
__________
__________







Uses
The main fractions and their uses are as follows.
LPG - contains propane and butane, used in bottled cooking gas
petrol - fuel for cars
naphtha - used in the chemical industry
paraffin - aircraft fuels
heating oil - diesel and heating
fuel oils - fuel for ships and power stations
bitumen - surfaces for roads and roofs
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Environmental impact of crude oil products
When the products of crude oil are burnt (combustion), polluting gases are
released into the atmosphere. The main pollutants are carbon dioxide, sulphur
dioxide and oxides of nitrogen. Each of these can cause serious
environmental problems.
Match each of the pollutants mentioned in the passage to the correct
environmental problem in the table below:
Gas
Environmental Problem
It is a greenhouse gas, trapping heat in the atmosphere. The
global climate change hat results may cause sea levels to rise,
flooding to occur, more catastrophic storms and damage to
wildlife habitats.
It dissolves in moisture in the atmosphere to make acid rain. This
kills forests and turns lakes and oceans acidic, killing wildlife.
Along with sulphur dioxide, these also cause acid rain. They also
act as greenhouse gases and are associated with smog.
You will learn more about global warming in the Sustainability unit.
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3 Hydrosphere
b. The Water Cycle
The diagram below shows the processes involved in the water cycle.
Use the names of the process in the diagram to complete the table below.
Percolation
Infiltration
Term
Definition
The process of turning from liquid to gas/vapour.
The process of turning from gas/vapour into liquid.
Moisture that falls from the air to the ground (rain, sleet,
snow, hail, drizzle, fog, mist)
The process by which water is lost from plant leaves.
The precipitation that flows across the surface of the
ground.
The movement of water through soil depending on the
soil’s porosity and permeability.
The movement of water through soil by gravity.
Throughflow
The horizontal flow of water within soil.
Water that occupies pore spaces in soil and bedrock.
Groundwater flow
The movement of groundwater horizontally.
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c. Main stores of water
The main stores of water are:
-
A___________________
-
O___________________
-
I____________________
-
F___________________(R_________, S_________, S_________)
-
G___________________(S_______m________, R_______p_____)
-
A___________________
c. Uses of water
Examples:
Examples:
_____________________
_____________________
_____________________
_____________________
Examples:
______________
______________
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Impact of waste water
Water can become polluted from a variety of sources including the examples
described below:
Domestic - Sewage
In some densely populated areas the sewage works may become overloaded.
As a result the liquid being discharged into the river is rich in untreated
sewage. This pollutes the river because it provides food for bacteria which
rapidly multiply and use up the river water’s supply of dissolved oxygen. As a
result many river animals die.
The level of oxygen (and hence the level of pollution) may be estimated by
counting the number of indicator species in the water.
You should re-visit your notes on indicator species in the Living Environment
unit, p21.
Industrial – Thermal Pollution
Some industries use local river water to cool machinery. When the water is
returned to the river it is considerably warmer and causes thermal pollution.
The increase in the river water causes a decrease in the dissolved oxygen
content and a decrease in the variety of fish species in the river.
Whereas all the species of fish shown in the table could be present in water
containing 4mg/l of oxygen, only tench would be found at 1mg/l of oxygen.
Fish
Species
Minimum concentration of
dissolved oxygen needed for survival
(mg/l)
Trout
3.8
Minnow
3.2
Perch
1.3
Roach
1.1
Tench
0.8
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Agriculture – Eutrophication
A major problem with the use of fertilisers occurs when they're washed off the
land by rainwater into rivers and lakes. The resulting increase of nitrate or
phosphate in the water encourages algae growth, which forms a bloom over
the water surface. This prevents sunlight reaching other water plants, which
then die. Bacteria break down the dead plants and use up the oxygen in the
water so the lake may be left completely lifeless.
This increase of nitrate or phospate from fertilisers into water and the
problems they cause is known as eutrophication
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e. Water availability in the UK
There are issues arising from the availability of water in the UK. These
include:

Quality of available water – water may need to be treated before
it is suitable for human use as it may be contaminated with pollution
such as sewage or fertilisers.

Distribution - Areas which receive high amounts of rainfall tend to be
sparsely populated but areas of high population and therefore high
water demand tend also to be the driest areas, eg SE England.

Seasonal changes in supply – in summer when demand may be
higher due to irrigation, rainfall is at its lowest. Flooding and droughts
may also be an issue for some parts of the country at certain times of
the year.
SEPA (Scottish Environment Protection Agency)
Look back at your Living Environment notes p24.
SEPA plays an important role in flood warnings and water quality.
Flood Warning
SEPA is Scotland’s national flood forecasting and flood warning authority.
They deliver ‘Floodline’, which provides live flooding information and
advice on how to prepare for or cope with the impacts of flooding 24 hours
a day, 7 days a week. SEPA works with the Met Office to help forecast
when floods are likely to occur.
Water Quality
SEPA monitor the quality of our water
resources by collecting data from surveillance
points in rivers, lochs, groundwater and the
sea around Scotland. They monitor water
levels of and concentrations of certain
substances in the water, eg nitrates, sewage,
pesticide and other pollutants.
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f. Energy from water
Electricity can be generated using the energy of moving water. There are
three main ways in which this is achieved: hydro-electric, wave and tidal
power schemes. Energy produced in this way is renewable.
They all rely on the kinetic energy in the water source being converted to
movement energy in a turbine which is then converted into electrical energy.
Hydro-electric Power
A typical hydro plant is a system with three parts:

an electric plant where the electricity is produced;

a dam that can be opened or closed to control water flow;

a reservoir where water can be stored.
The water behind the dam flows through an intake and pushes against blades
in a turbine, causing them to turn. The turbine spins a generator to produce
electricity.
Wave Power
Wave power is electrical energy derived from ocean waves. It involves kinetic
energy of wind interacting with water and creating waves.
The waves move up the chamber.
The waves push the air up the chamber.
The air turns the turbine.
The turbine turns the generator.
The generator produces electricity.
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Tidal Power
Tidal power is electrical energy derived from underwater equipment that
captures the movement of ocean currents powered by gravity and the Earth’s
rotation.
Tidal currents are created by the flood (in-coming)
and ebb(out-going) tides. Tidal turbines are
essentially submersible wind turbines that use water
instead of air to turn the blades. The movement of
water turns the turbine. The turbine turns the
generator. The generator produces the electricity.
Unlike wind energy, the tide is predictable and so
produces electricity every day.
g. Requirements for siting hydro-electric, wave and tidal power stations.
Power Station Type
Site Requirements
-Steep gradient and narrow deep valley,
Hydro-electric
-Impermeable geology
-High precipitation
-proximity to the National Grid
-Environmental issues, eg destruction of habitat and settlements
Wave
Tidal
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4. Biosphere
b. Oceanic and freshwater resources
The Earth’s oceanic and freshwaters contain many economically important
species. Examples include:

_______________________________

_______________________________

_______________________________

_______________________________

_______________________________
c. Terrestrial resources
The Earth’s land contains many economically important species, some
domesticated some in the wild. Examples include:

_______________________________

_______________________________

_______________________________

_______________________________

_______________________________
d. Energy from biological resources
Biomass is the mass of living or recently living plants or animals
Biofuels are combustible biomass or fuels derived from biomass. Examples
include peat and biofuels.
Peat
Peat is formed in waterlogged, acidic fens and bogs over thousands of years
by the growth of mosses and other plants. When the moss dies, the
waterlogged bog provides anaerobic conditions (ie lacking in oxygen) which,
together with the acidity of the bog, prevent the total decomposition of the
moss. It accumulates in the bogs in a partially-decomposed state, forming
peat. Thick layers can accumulate over many years.
The amount of biomass it contains means it can be dried and burnt as a fuel,
which makes it an important energy source in some countries.
Sphagnum moss
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Biofuels
Biomass can be used to make biofuels (a fuel produced by living things),
including alcohol, biogas and wood. Biofuels are renewable unlike fossil fuels.
Energy can be obtained from biomass by burning the wood from fast-growing
trees, or by producing biofuels by the process of fermentation using bacteria
or yeast.
Fermentation is the process by which microorganisms such as yeast and
bacteria convert organic molecules into other products. Fermentation occurs
in anaerobic conditions (ie in the absence of oxygen). Biofuels such as
bioethanol and methane and alcohol can be produced in this way.
Bioethanol
Alcohol (ethanol) is made from plant sugars using yeast. It can be used as a
biofuel (a fuel produced by living things) by mixing it with petrol. This mixture
is called gasohol and it is used in countries such as Brazil.
Plant sugar
yeast in anaerobic conditions
Alcohol + Carbon Dioxide
Biogas
Biogas is produced when organic material, such as dead plant and animal
waste, rots in anaerobic conditions due to the action of bacteria. It is mostly
methane with some carbon dioxide. It also contains traces of other gases,
such as hydrogen, nitrogen and hydrogen sulphide (which smells of rotten
eggs).
Biogas occurs naturally in the digestive systems of animals, septic waste
tanks, marshes. It is also produced in landfill sites where household waste including food scraps - has been buried. Its release must be controlled
because it can burn or explode, which would stop the site being used for a
long time.
Biogas can be produced commercially in a digester which can then be used to
provide heat and electricity.
Plant and animal waste
bacteria in anaerobic conditions
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Methane + Carbon Dioxide
5. Atmosphere
b. Composition of the Atmosphere
The Earth's atmosphere has remained much the same for the past 200 million years.
The pie chart shows the proportions of the main gases in the atmosphere.
It is clear that the main gas is nitrogen. Oxygen - the
gas that allows animals and plants to respire and
fuels to burn - is the next most abundant gas. These
two gases are both elements and account for about
99% of the gases in the atmosphere. The remaining
gases, such as carbon dioxide, water vapour and
argon, are found in much smaller proportions.
The amount of carbon dioxide in the atmosphere is
maintained through a balance between processes
such as photosynthesis, respiration and combustion.
The Natural Greenhouse Effect (you will study the enhanced greenhouse effect in the
Sustainability unit)
If it were not for greenhouse gases trapping heat in the atmosphere, the Earth would
be a very cold place. Greenhouse gases keep the Earth warm through a process
called the greenhouse effect.
Carbon dioxide is a greenhouse gas. It absorbs heat energy and prevents it escaping
from the Earth’s surface into space. The greater the amount of carbon dioxide in the
atmosphere, the more heat energy is absorbed and the hotter the Earth becomes.
1. Sun’s rays enter the Earth’s
atmosphere
2. Heat is reflected back from the
Earth’s surface
3. Heat is absorbed by carbon
dioxide (greenhouse gas) and as a
result becomes trapped in the
Earth’s atmosphere
4. The Earth becomes
hotter as a result.
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c. Energy from wind power
Electricity can be generated using the energy of moving air. Energy produced
in this way is renewable.
It relies on the kinetic energy in the wind being converted to movement
energy in a turbine which is then converted into electrical energy.
d. Requirements for siting wind farms
Power Station Type
Site Requirements
Wind
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