air and water Flashcards
how was the early atmosphere of the earth formed
volcanoes released nitrogen and carbon dioxide gas. This condensed as it rose to cooler air and fell as rain, forming oceans.
Icy comets also brought water to earth and melted as they fell.
how did life first exist on earth
as bacteria that made energy by breaking down chemicals
it then evolved to use the energy of the sun to make its own energy via photosynthesis
what happened after plants had evolved and began to cover the earths surface
oxygen levels began to rise, meaning animals could evolve.
why has co2 decreased since the beginning of the earth
taken up by plants during photosynthesis. Animals then eat these plants, transferring the carbon to animal tissues.
these animals then die and form sedimentary rocks at the bottom of the ocean.
co2 also dissolved in water, forming insoluble carbonate compounds, which fell to the ocean floor to create carbonate rocks
why does levels of co2 fluctuate
seasonal differences in plants
what happens when fossil fuels are burnt
co2 is released into the atmosphere
what stores carbon dioxide
carbon sinks
how does the greenhouse effect work
radiation from the sun is of short wavelength and can pass through the atmosphere and not be absorbed by atmospheric gases.
these gases allow these wavelengths to pass through to the surface if the earth. the gases then absorb long wave radiation from the earth, causing an increase in temperature. this is beneficial as it keeps the earths temp stable.
As more gases build up in the atmosphere, they trap the long wave radiation, increasing the earths temp
stages of water treatment
sedimentstion
filtration
sterilisation
what is the term for drinkable water
potable
sedimentation process
let water sit and sediment falls to the bottom
filtration process
water passes through a sand bed, removes impurities through a filter
sterilisation process
add cl2 or o3 to the water to kill microorganisms. can also be done by irradiating with bright light
what is desalination of seawater
done by distillation or reverse osmosis. these require large amounts of energy and are expensive, so are only done when needed
