topic 10 resources Flashcards
(47 cards)
what is portable water
water that has been treated or is naturally safe for humans to drink
what does pure water contain
H2O molecules
why isn’t portable water pure
because it contains lots of dissolved substances
what is the important thing to consider with portable water (3)
- that the levels of dissolved salts aren’t too high
- that it has a pH between 6.5 and 8.5
- there isn’t bacteria or microbes in the water
`what type of water is rainwater
``fresh water
what is fresh water
water that doesn’t have much dissolved in it
what are the 2 ways that water can collect as
surface water (in lakes,rivers or as groundwater (in rocks called aquifers)
what does surface water tend to usually do
dry up first
so where does the water come from for warmer places
groundwater
what are the 2 ways that freshwater can be treated by
- filtration
- sterilisation
how is filtration used to treat freshwater
a wire mesh screens out large twigs and then gravel and sand beds filter out any solid bits
how is sterilisation used to treat freshwater
the water is sterilised to kill any harmful bacteria or microbes. this can be done by bubbling chlorine gas through it or by using ozone or ultraviolet light
how is seawater treated in some very hot countries if there isn’t enough groundwater to provide portable water
by desalination
by what method can you test and purify a sample of water
by distillation
when you flush water where does the water go to
into the sewers and towards sewage treatment plants
what waste do agricultural systems produce
- nutrient run-off from fields
- slurry from animal farms
what must happen to sewage from domestic or agricultural sources and why
it has to be treated to remove any organic matter and harmful microbes before it is put back into freshwater sources like rivers
other than desalination, how else can seawater be treated
by a process that use membranes- reverse osmosis
how is seawater treated by membranes (steps)
-the salty water is passed through a MEMBRANE that only allows water molecules to pass through. Ions and larger molecules are TRAPPED by the membrane so separated from the water
why is distillation and reverse osmosis bad
-they require loads of energy so they are really expensive and are not practical for producing large quantities of fresh water
why is mining ores bad for the environment
because it uses loads of energy, scars the landscape, produces lots of waste and destroys habitats
2 examples of natural resources
cotton for clothing or oil for fuel
how can some natural products be replaced
by synthetic products or improved upon by man-made processes
how can rubber be extracted
by the sap of the tree
