Using Earth’s resources Flashcards
What do we use resources for?
Warmth
Shelter
Food
Transport
How do we produce resources?
Agriculture
Tree planting
Synthetic resources
Examples of agriculture
Growing cotton from a plant
So we can grow as much as possible for the needs
Examples of tree planting for fuel
Woodchips act as biofuel to power power stations
Examples of synthetic resources
Natural rubber = tree sap
Synthetic rubber = crude oil
Finite
Resources that cannot be replaced as quickly as they are used
For example fossil fuels and metals
Renewable
Resources that will never run out as they can be replaced as quickly as we use them
For example wood
What does drinking water have to require?
Low levels of dissolved salts
Low levels of microbes like bacteria
Potable water
Water that is safe to drink
Pure water
Has no dissolved substances in it
Just H2O molecules
Are potable and pure water the same?
No because potable water contains small dissolved substances in small amounts
Whereas pure water is 100% H2O
How does the Uk get most of our potable water?
Rain water because it contains low levels of dissolved substances
Where does rain water accumulate?
Aquifers
Lakes
Rivers
Reservoirs
= supplies of freshwater
How to produce potable water?
Choose a freshwater supply eg lake
Pass it through filter beds to remove leaves and dirt
Sterilise water to kill bacteria using chlorine, ozone or UV light
How to produce potable water if it’s too salty?
Use desalination
Reduces levels of dissolved minerals to a good level
Desalination methods
Distillation
Reverse osmosis = pass it through membranes
Cons of desalination methods
Use large amounts of energy so it’s expensive
Uses of water
Drinking
Personal hygiene (bath, shower)
Flushing the toilet
Washing laundry
Farming
What does waste water contain and why do we need to treat waste water?
It contains:
Large amounts of organic molecules such as urine and feces
Harmful bacteria
Stages of treating waste water
Sewage passed through mesh (screened) to remove solids and grit
Settle in large sedimentation tanks
Produces a liquid effluent and a solid sludge
The sludge sinks and is taken away to be digested by anaerobic bacteria
Without oxygen, the bacteria produces biogas fuel
This digested sludge used as fertilisers
Where is sewage first passed through and why?
Mesh to be screened and remove solid particles and grit
What does the sewage settle in and why?
Large sedimentation tanks to separate into liquid effluent and solid sludge
What does sludge do?
Sinks then taken away to be digested by anaerobic bacteria
Which, with no oxygen the bacteria produces biogas for fuel
What is the digested sludge used for?
Fertilisers in farming
What happens to the liquid effluent and why?
Bubbles air into the liquid supplying it with oxygen
So aerobic bacteria can begin to multiply
And thus digest the harmful microorganisms
This is because we need to discharge it back into the sea but before had too much harmful microorganisms
What happens if the waste water is from industry and needs to be treated?
It will contain harmful chemicals so it will have to have these harmful chemicals removed first
Easiest way to produce potable water
Use ground water from aquifers
Because once treated with chlorine it’s safe to drink
Cons of aquifers
Can be polluted with fertilisers from farms
So you need to test the water carefully
Cons of Making potable water from treated waste water
Requires many steps so only done if water is scarce
Cons of Making potable water from salt water
Requires a lot of energy so it’s expensive
How are most metals on earth found?
Reacted with oxygen = metal oxide
Aka ores