resources Flashcards
what are finite resources
resources that are being used up faster than they can be replaced, limited amount
what are renewable resources
resources that can be replaced at the same rate or an even faster rate that they are being used
examples of finite resources
- metal ores used to extract metal
- crude oil used to make polymers
- limestone to make cement or concrete
- crude oil to make petrol, diesel
what happens when the amount of resources needed aren’t met
- supplement natural resources
- use synthetic alternatives
supplementing natural resources
sometimes nature is unable to provide us with as much of a resource as we need to so we use agriculture to supplement the natural supply
synthetic alternatives
man made alternatives of a product are used
- polyester instead of cotton
- PVC instead of wood
sustainability vs renewability
- renewable resources are infinite, they can’t run out
(eg. sunlight and wind) - resources are sustainable when they can be maintained so that there is a supply for future generations
what is potable water
water that is safe for humans to drink, contains small amounts of salt and microbes
how can you make fresh water potable
- fresh water is taken from lakes… and any solid impurities (mud) are removed by filter beds, the water seeps through layers of sand.. and solids are removed
- the water is then sterilised by adding chlorine, ozone or uv lights
making salty water potable
- distillation
- reverse osmosis
distillation
impure water is heated, pure water evaporates and particles pass through condenser and is collected
reverse osmosis
when a force is exerted onto the impure water it passes through a semi-permeable membrane and contaminants are filtered out leaving clean water
how is waste water released back into the environment
1) screening
2) primary sedimentation
3) aerobic digestion
4) secondary sedimentation
5) clean water or anaerobic respiration
what is screening
a metal grid is used to trap large object sand grit from the water
what is primary sedimentation
the sold particles in the waster water are allowed to settle to the bottom and are then separated from the water (called effluent)
what is aerobic respiration
useful bacteria are added to the effluent and feed on the harmful ones or any remaining waste
(aerobic means it happens in the presence of water)
what is done with the now clean water
it is returned to the rivers
- sometimes it may need some extra sterilising
what is anaerobic respiration
useful bacteria is added to the sludge and feed on the harmful ones and the sludge is left to dry
(anaerobic means it happens without oxygen)
what is done with the products of anaerobic respiration
- dried sludge are sent to landfills but can be used as fertiliser or fuel to generate electricity
- biogas can be used as fuel
extracting metal from high grade ores
- displacement
- electrolysis
what is displacement
the metal is extracted by reacting it with different elements
what is electrolysis
the metal is extracted using an electrical current and involves high temperatures
extracting metal from low grade ores
- bioleaching
- Phytomining
what is bioleaching
bacteria is grown on the ore to absorb the metal and produces a liquid called leachate from which the metal is extracted
what is phytomining
plants are grown on the ore and absorb metal into their cells, they are burned or harvested to produce ash which the metal is extracted from
what is a life cycle assessment (LCA)
looks at the impacts of an item from every stage of its life
problems with (LCA)
allocating numerical values involves subjective judgements, is biased
how can we protect our resources and nature
reduce, reuse and recycle
