greenhouse gas rote learn - (human activity produces lots of greenhouse gases cgp section p 78)

4 ggases that can act as greenhouse gases

- CO2

- methane

- nitrous oxide

- CFCs

3 ways humans produce CO2

- car exhausts

- industrial processes

- burning fossil fuels

how do humans prevent CO2 levels in the atmosphere decreasing

deforestation

why do we deforest (2)

for timber + to clear land for farming

one way that methane is naturally produced

rotting plants in marshland

2 man-made sources of methane

- rice growing

- cattle-rearing

one way nitrous oxides are released naturally

released naturally by bacteria in soils + the ocean

how can human acitivity increase the way that nitrous oxides are released naturally

a lot more nitrous oxides are released from soils after fertiliser is used

2 human ways that nitrous oxides are released

- vehicle engines

- industry

what are CFCs

man-made chemicals that are really powerful greenhouse gases

what were CFCs once used in

aerosol sprays (e.g. deo) and fridges

what other damage can CFCs do

they damage the ozone layer that prevents UV radiation from reaching the Earth

example of how some CFCs still remain + get released

by leaks from old fridges

what 5 problems does deforestation cause

- leaching

- infertile soil

- soil erosion

- disturbs evapotranspiration

- disturbs balance of CO2 and O2

leaching

when nutrients are washed out of the soil and into bodies of water by rain

when is leaching an especially big problem

when highly soluble chemical fertilisers are used

how does deforestation cause leaching

trees take up nutrients from the soil before they can be washed away (leached)

how does deforestation leave infertile soil

- trees take up nutrients from the soil

- but they return them to the soil when their leaves die

- but when trees are removed nutrients get leached away + do not get replaced

- makes infertile soil

how does deforestation cause soil erosion

- tree roots hold the soil together

- without them soil can be washed away by the rain (eroded) leaving infertile ground

what is evapotranspiration

it includes the processes of water evaporating from the Earth's surface + from plant transpiration

this water falls back to Earth as rain/hail/snow

how does deforestation effect evapotranspiration and what can this do

- it reduces evapotranspiration

- this can make the local climate drier

how does deforestation increase CO2 (death)

- carbon stored in wood

- decomposers produce CO2 when breaking down

how does deforestation increase CO2 - human activity

the stored carbon in trees is released as CO2 when burnt

how does deforestation stop CO2 levels being decreased/ decreases O2 levels

less photosynthesis

what minerals are put on fields as mineral fertilisers + can get leached

nitrates + phosphates

2 causes of eutrophication

- fertilisers

- pollution by sewage

how does pollution by sewage add extra nutrients

- sewage contains lots of phosphates from detergents e.g. washing powder

- it also contains nitrates from urine and faeces

when can minerals be leached easily

if too much fertiliser applied + it rains after

eutrophication

when mineral ions from the soil e.g. nitrates are leached and they run into lakes, rivers, ponds etc