C6.3 - Earth Systems Flashcards
What substances form the earths atmosphere from highest to least %
- nitrogen
- oxygen
- argon
- carbon dioxide
- trace amounts of other gases
What was the atmosphere like billions of years ago
- lots of volcanic activity
- release huge volumes of water vapour & carbon dioxide
- as earth cooled, water vapour condensed, formed oceans
- leaving atmosphere as mostly carbon dioxide
- small amounts of other gases: methane, ammonia
- little/no oxygen
How is it thought an oxygen-rich atmosphere developed on earth
- plants & algae appeared
- photosynthesis reduced amount of CO2 (absorbed) & increased amount of oxygen (released)
- first, oxygen reacted with metals in rocks, produce metal oxides
- as most of metals becomes oxidised, free oxygen began to accumulate in atmosphere
- eventually oxygen-rich atmosphere
Pollutants
Atmospheric pollutants
Substances released into environment that may cause harm to living things
Atmosphere = released into air
Examples of atmospheric pollutants as a result of burning fossil fuels
- carbon monoxide
- particulates
- oxides of nitrogen (NO, NO2)
- sulfur dioxide
How is carbon monoxide produced
During incomplete combustion of fuels that contain carbon
(coal, wood, in vehicle engine)
(in poor supply of air)
Problems with carbon monoxide
What does it cause
- toxic gas
- colourless, no smell / taste
- when breathed in, attached to haemoglobin protein in red blood cells
- reduces amount of oxygen bloodstream cab carry
= drowsiness, difficulty breathing, death
How are particulates produced
Small particles
- formed during incomplete combustion (in vehicle engines)
- in industrial processes (metal extraction)
Why are particulates dangerous
What do they cause
- smallest particulates settle deep in lungs when breathed in
= disease (bronchitis), breathing problems, increases chance of heart disease
How are oxides of nitrogen formed (NOx)
- nitrogen & oxygen in air don’t normally react
- nitrogen & oxygen react at high temps in vehicle engines
- forming nitrogen monoxide (NO)
- NO oxidised in air
- forming nitrogen dioxide (NO2)
Why are oxides of nitrogen dangerous
- nitrogen dioxide dissolves in moisture in clouds, forming acidic solutions
- falls as acid rain
How does sulfur dioxide form
What problems does sulfur dioxide cause
Fossil fuels contain small amounts of sulfur compounds
Impurities form sulfur dioxide when fuel burnt
- acid rain
- breathing difficulties
Acid rain
What problems can it cause
Rain containing acidic gases from air
- erodes stonework
- corrodes metals
- can kill trees
- can kill living things in rivers / lakes
Greenhouse effect
Interaction of infrared radiation with molecules in the atmosphere
Reducing the transfer of energy to space
Keeps earth & atmosphere warm enough for living things to exist
Explain how the greenhouse effect works
- Energy transferred by radiation from sun reaches earths surface
- Radiation warms up earths surface
- Infrared radiation emitted by earths surface
- some goes directly into space
- some absorbed by greenhouse has molecules in atmosphere - Greenhouse gas molecules emit infrared radiation in all directions, warming earths surface & atmosphere
How are different greenhouse gases released into the atmosphere
Carbon dioxide: combustion of fossil fuels
Methane: rice paddy fields, cattle, landfill waste sites, use of natural gas
Others: human / anthropogenic activities
What causes an enhanced greenhouse effect
- release of additional greenhouse gases (by human / anthropogenic activities)
- increases temp of earths atmosphere
What can the enhanced greenhouse effect cause
Global warming:
- melting ice caps
- rising sea levels
Climate change
- altered weather patterns
- flooding
- problems with farming
- problems with disease control
How can greenhouse house emissions be reduced
- reduce consumption of fossil fuels (use biofuels)
- use renewable energy resources (wind, solar energy) to generate electricity
- stop carbon dioxide escaping when fuels used (carbon capture)
What is done to protect against the effects of global warming
- flood barriers
- planting different crops
- designing buildings to withstand high winds
Carbon capture
Process by which carbon dioxide emissions are collected & stored & not allowed into atmosphere
Where does tap water originally come from
- lakes
- reservoirs
- aquifers
- rivers
- waste water
Aquifer
Layer of rock that stored water underground
What must be removed from water to make it safe to drink
- insoluble materials (leaves, particles from rocks / soil)
- soluble substances (salts, pollutants: pesticides, fertilisers)
- microorganisms
Potable water
Water safe for drinking
Stages in water treatment of fresh water
- passed through screen (bars of metal placed close together), catch large objects (leaves, twigs)
- settlement tank: sand & soil settle out
- aluminium sulfate & lime added, small particles of dirt clump together & sink to bottom, sludge dumped in landfill site & forms mud
- passed through filter (made of fine sand), removes remaining particles (mud, grit) so water clear
- small amount of chlorine added to kill bacteria
- pH checked & corrected so it is neutral
- stored in large tanks & service reservoirs, ready to be pumped to where its needed
What process is used to treat salt water
Desalination
= removes dissolved salts from water
Desalination (to removed salts from salt water)
Small scale: ‘reverse osmosis’ using ‘ultrafilters’ used to filter out salts
Large scale: simple distillation used
In what countries would desalination be worthwhile
- fresh water supplies limited
- cost of energy resources is low
