Using the Earth's Resources Flashcards
What is potable water?
- safe for human consumption
- doesn’t have to be chemically pure
How do you make water potable?
- reduce the concentrations of dissolved minerals and salt found in water
- drastically reduce the number of microbes found in it
- doesn’t have to be chemically pure
Portable water can be obtained from:
- fresh water (easiest)
- seawater (most expensive - high energy consumption to remove salt)
- waste water (treatment with the most steps)
Treating seawater:
Seawater must be desalinated (have the salt removed) to make it potable. Two methods:
- Distillation: boiling seawater creates steam, which then condense to give pure water
- Reverse osmosis: seawater is passed through a selective membrane that only allows water molecules through
What are natural resources?
Natural resources form without human involvement. They usually come from the Earth’s crust, oceans or atmosphere and are used for energy, building materials and food.
What are the two categories of natural resources?
non-renewable - regenerated at a much slower rate than we use them (e.g. fossil fuels)
renewable - regenerated at about the same/or faster rate than we use them (e.g. fresh water)
Ways of supplementing the Earth’s natural resources:
- synthetic products (man-made)
- agriculture - natural foods are now available in much larger quantities
Why must we treat waste water before releasing it into the environment?
to avoid polluting our environment
3 main sources of waste water:
1) agriculture - nutrient run-off and slurry (natural fertiliser).
2) industry - water becomes contaminated with chemicals during manufacturing
3) domestic - washing up, having a shower, using the toilet
What are we trying to remove from waste water by treating it?
- organic matter
- harmful microbes
- harmful chemicals
Sewage treatment process:
1) screening - sewage is examined to remove grit and any large items
2) sedimentation - separation of sewage into heavier sludge and lighter effluent (liquid), which are digested by bacteria
Producing potable water with fresh water:
1) water is collected
2) water is filtrated to remove insoluble solids
3) water is then sterilised - to kill microbes
What is the environmental damage of mining metal ores ?
- large mounds of rock are left behind, scarring the landscape
- creates air and noise pollution
- habitats are destroyed, which threatens biodiversity
What properties makes copper a useful metal?
- good conductor of electricity
- good conductor of heat
- unreactive
- malleable
Why are copper-rich ores in short supply?
historical overexploitation
What are alternative methods of extracting copper?
- Phytomining
- Bioleaching
Phytomining:
1) Plants growing on contaminated land absorb copper ions as they grow
2) These plants are harvested and burned, producing ash that contains high concentration of copper compounds
Bioleaching:
1) Bacteria are mixed with low-grade ores
2) The bacteria convert the copper into a solution rich in copper compounds called leachate solution
(disadvantage = very slow process)
