Water and carbon cycle

Question 1

What type of system is a drainage basin?

Answer 1

An open system

Question 2

What is the largest store of water in the world?

Answer 2

The oceans (97% of world’s water)

Question 3

What is it called when a system’s inputs and outputs are equal?

Answer 3

Dynamic equilibrium

Question 4

What is positive feedback?

Answer 4

When the input cause the outputs to amplify the effect causing it to move even further from its previous state.

Question 5

What is negative feedback?

Answer 5

When the inputs cause the outputs to decrease the effect of the input which keep the system closer to its previous state.

Question 6

What type of system is the global hydrological cycle?

Answer 6

A closed system because there are no inputs or outputs of water.

Question 7

What are the four inputs in the water cycle?

Answer 7

Precipitation, convectional, relief and frontal.

Question 8

What is river discharge?

Answer 8

The volume of water in cubic metres flowing in a river per second.

Question 9

What is lag time?

Answer 9

The amount of time between peak rainfall and peak discharge.

Question 10

What is sequestration?

Answer 10

When carbon from the atmosphere is captured and held by sedimentary rock or as fossil fuels. This carbon is sequestered until combusted.

Question 11

State four fast carbon flows.

Answer 11

Photosynthesis, respiration, combustion and decomposition.

Question 12

State an example of a slow carbon flow.

Answer 12

Sequestration, it takes millions of years.

Question 13

How are the water and carbon cycles related?

Answer 13

Both required for life and both are greenhouse gasses.

Question 14

Name a case study of a river and its drainage basin.

Answer 14

River Exe in the southwest of England.

Question 15

What will a change in the pattern of precipitation cause?

Answer 15

Water shortages in some areas.

Question 16

What could water shortages cause politically?

Answer 16

Conflict

Question 17

State 6 effects of climate change.

Answer 17

Pattern of precipitation changes, Extreme weather events become more frequent, Agricultural productivity will decrease leading to food shortages, Sea levels will rise, geographical range of species will change leading to changes in ecosystems causing them to be damaged and maybe not be able to cope, Plankton numbers will decline leading to knock-on effects in the marine food chain.

Question 18

State two greenhouse gas managing treaties which many countries have agreed to.

Answer 18

Kyoto Protocol (1997) and the Paris agreement (2015).

Question 19

Give an example of a negative feedback in the water cycle.

Answer 19

Temperatures increasing causing more evaporation creating more clouds leading to more of the Sun’s energy being reflected causing temperatures to decrease.

Question 20

State a negative feedback system in the carbon cycle.

Answer 20

Atmospheric C02 increases, more plants grow, plants absorb C02, atmospheric C02 decreases.

Question 21

state the effect of deforestation on soil.

Answer 21

Rainwater washes away nutrient-rich top soil which transfers stored carbon to the hydrosphere.

Question 22

What can increasing temperatures lead to in a rainforest?

Answer 22

Drought and forest fires.

Question 23

State four methods of managing a rainforest.

Answer 23

Selective logging, replanting, environmental laws and protection such as national parks.

Question 24

State three ways which carbon can be removed from the atmosphere.

Answer 24

Soil carbon sequestration, ocean sequestration and tree planting.

Question 25

State two benefits of soil carbon sequestration.

Answer 25

Reduces atmospheric carbon and enhances agricultural production.

Question 26

How much more carbon do soils contain than living plants and animals?

Answer 26

Three times more.

Question 27

How is carbon naturally returned to the soil?

Answer 27

Through animal excrement and decomposing plants and animals.

Question 28

State four things which affect the length of time carbon can be stored.

Answer 28

Climatic conditions, natural vegetation, soil texture and drainage.

Question 29

State five benefits of carbon sequestration.

Answer 29

Improve soil and water quality, decrease nutrient loss, reduce soil erosion, increase water conservation and increase crop production.

Question 30

State three management techniques for soil carbon sequestration.

Answer 30

Conservation tillage, cover cropping and crop rotation.

Question 31

What is conservation tillage?

Answer 31

Minimises or eliminates manipulation of the soil for crop production, mulch tillage leaves crop residues on soil surface, reduces soil erosion, improves water efficiency, increases carbon concentrations in the topsoil and reduces fossil fuel usage.

Question 32

What is cover cropping?

Answer 32

Using crops such as clover and small grains for protection and soil improvement between periods of regular crop production. Enhances soil structure by adding organic matter to the soil.

Question 33

What is crop rotation?

Answer 33

When the type of crops grown in an area is changed in a recurring pattern to mimic the diversity of a natural ecosystem. Increases level of soil organic matter.

Question 34

State two ways carbon usage can be reduced related to energy.

Answer 34

Energy efficient fuels and non-carbon energy sources.

Question 35

State one benefit and two drawbacks of nitrogen fertiliser.

Answer 35

Increases soil organic matter but a lot of carbon is released during its production, transport and application. It can run off agricultural land into waterways and have serious ecological consequences.

Question 36

When is the net rate of carbon uptake greatest in a forest?

Answer 36

When the forest is young. The carbon uptake slows with time.

Question 37

When is carbon in forests released?

Answer 37

When the trees are combusted or converted into short-lived products such as paper.

Question 38

How can carbon from a tree remain stored after the tree is cut down?

Answer 38

If the wood is used to make long-lived products such as furniture then the carbon is stored in the furniture and acts as a small carbon sink.

Question 39

In the river Exe, what varies a lot?

Answer 39

The river discharge.

Question 40

In the river Exe, how does the river discharge change over the year?

Answer 40

Rises and falls very quickly within each month, generally higher in the winter and lower in the summer but there are some outliers to this pattern such as a large river discharge suddenly in June.

Question 41

Where is the river Exe? Where is the source and where is the mouth?

Answer 41

In the south-west of England, the source is in Exmoor and the mouth is in Exmouth.

Question 42

What factors of Exmoor National Park and the surrounding areas of the river cause the river Exe to flow on the path it does?

Answer 42

A high altitude at the source and steep sided valleys on either side of the river until reaching Exeter and Exmouth where the gradient flattens out.

Question 43

What is drainage density?

Answer 43

The area the drainage basin takes up.

Question 44

What causes the river Exe to have such a large drainage density?

Answer 44

The three main tributaries: Barle, Clyst and Creedy.

Question 45

State three factors which cause the river Exe to have such a flashy discharge regime (rises and falls quickly)?

Answer 45

Its median altitude is 171m which is fairly high so 50% of the river is above that height and the maximum altitude is 516m which is also quite high and areas of higher altitude receive more rainfall. There also isn’t much woodland to intercept surface runoff and increase evapotranspiration. The rocks are not very permeable.

Question 46

What type of land makes up the highest proportion of land types in the river Exe drainage basin?

Answer 46

Grassland - grazing of animals like sheep and cattle.

Question 47

How is the river Exe as a whole affected by urban areas?

Answer 47

Not much, urban areas only make up 4.5% of the drainage basin. Urban areas may have a more significant local effect but aren’t significant in general.

Question 48

What is the geology like in the river Exe?

Answer 48

Most of the rocks (61.5%) are low permeability so there will be little Infiltration and percolation therefore more surface runoff.

Question 49

What does a flashy river discharge regime lead to?

Answer 49

Increased risk of flooding.

Question 50

Other than impermeable urban surfaces, state one human factor which increases the flood risk downstream which affects the river Exe.

Answer 50

Moorland drainage - digging trenches to drain water from farmland into the river which increases river discharge and surface runoff.

Question 51

What causes flooding in rural and agricultural areas?

Answer 51

Compaction of soil by cattle and machinery.

Question 52

What is Peatland restoration?

Answer 52

Restoring areas around the drainage basin of a river to more natural states to reverse some of the damage done to the area by human activity.

Question 53

State five positive impacts of peatland restoration.

Answer 53

Water treatment costs less due to there being less sediment and silt being caught in the water, slows the flow of the river which makes it less flashy, there are more regulated flows which reduces flood risk, due to the peatland staying wet it doesn’t oxidise with carbon so it doesn’t release as much carbon dioxide into the atmosphere, encourages the growth of sphagnum moss which acts as a natural sponge and can hold up to 20 times its own weight in water.

Question 54

State one disadvantage of peatland restoration.

Answer 54

Costs £2.2m to restore 2000 hectares of land.

Question 55

What is water abstraction?

Answer 55

Taking water from a river or other source for any purpose; usually for domestic or agricultural use.

Question 56

What are Milankovitch cycles?

Answer 56

The collective effects of changes in the Earth’s movements on its climate over thousands of years; the Earth ‘wobbling’ on its axis.

Question 57

What is the name for when the Earth is at its closest approach to the Sun?

Answer 57

Perihelion.

Question 58

What is the name for when the Earth is at the furthest distance from the Sun?

Answer 58

Aphelion.

Question 59

State two positive feedback systems in the carbon cycle.

Answer 59

Wildfires cause more carbon to be released into the atmosphere which increases global temperatures which makes wildfires more likely. Ice melting decreases the global albedo which causes less heat to be reflected which causes temperatures to increase so ice melts faster.

Question 60

What is the name of the transfer of carbon from the biosphere to the atmosphere due to cattle grazing.

Answer 60

Enteric fermentation.