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Greenhouse Gas Emissions > Greenhouse Gas Emissions > Flashcards

Greenhouse Gas Emissions Flashcards

1
Q

What are the most common green house gases? (3)

A

Carbon Dioxide (CO2), Methane (CH4), Nitrous Oxide (N2O)

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2
Q

Soil carbon pool?

A

~1500Pg

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3
Q

Soil Nitrogen Pool?

A

~140Pg total nitrogen

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4
Q

What is the largest store of terrestrial organic Carbon?

A

Soil is the largest store of terrestrial Organic Carbon with ~1500Pg tonnes

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5
Q

How does carbon go into the soil?

A

The decomposition of leaf litter that falls of trees and the roots of trees is the majority

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6
Q

What are the two types of carbon?

A

Organic and Inorganic carbon

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7
Q

Examples of Inorganic Carbon.

A

Calcium Carbonates

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8
Q

Examples of Organic Carbon

A

Sugars and Lichens

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9
Q

What respires in the soil?

A

Roots and microbes

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10
Q

What is the total soil respiration for plant roots?

A

Approximately 50% but can range between 10-95% depending on the season and vegetation type

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11
Q

What is the NEE?

A

Net Ecosystem Exchange- the difference between the ecosystem respiration and photosynthesis

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12
Q

What is a Positive NEE?

A

When respiration is greater than photosynthesis

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13
Q

What is a Negative NEE?

A

When photosynthesis is greater than respiration (carbon sink)

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14
Q

What can change the input of carbon into the soil?

A

The climate and type of land use

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15
Q

Two types of carbon input in soil?

A

Above ground and below ground

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16
Q

Examples of above-ground carbon inputs.

A

Annual leaf litter fall, timer fall in the forest and animal residues

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17
Q

Examples of below-ground carbon inputs.

A

Plant roots, dead roots, carbon compounds releasing from living roots

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18
Q

Where are carbon rich soils?

A

Grassland areas as carbon is sequestered via the roots

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19
Q

What causes soil respiration?

A

Decomposition

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20
Q

What is soil respiration?

A

When carbon dioxide and methane are released during the process of decomposition

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21
Q

What is DOC? Why is it significant?

A

Dissolved Organic Carbon. It is released into rivers and rivers due to soil erosion

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22
Q

How much Carbon is emitted back into the atmosphere?

A

60-80%

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23
Q

What are the three organisms?

A

Macro-organisms
Meso organism
Microorganisms

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24
Q

Examples, size, and role of macro-organisms.

A

> 2mm
Larger animals such as moles and rabbits, earthworms, ants and insects.
They mix fresh organic material into the soil and bring organic matter into contact with soil microorganisms.
Allows microbes to access all parts of the organic residue

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25
Q

Examples, size and role of Meso Organisms.

A

2-0.2mm
Mites, nematodes
Feed on microorganisms and release nutrients contained in their bodies

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26
Q

Examples, size and role of microorganisms.

A

<0.2mm
Bacteria, fungi and algae
Responsible for the production of enzymes catalysing SOM decomposition reactions and are important for Nitrogen fixing and denitrifying

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27
Q

Name four bacteria types.

A

Autotrophs
Heterotrophs
Aerobes
Anaerobes

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28
Q

What are Autotrophs?

A

Bacteria and all algae that synthesise their cell substance from CO2 and energy from the sunlight

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29
Q

What are Heterotrophs?

A

Many species of bacteria and all fungi that require carbon in the form of organic molecules for growth

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30
Q

What are Aerobs?

A

They are active in unsaturated soils and require oxygen- the end product of respiration CO2 and release essential nutrients such as nitrogen

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31
Q

What are anaerobes?

End product

A

Active in absence of oxygen in saturated soils- the end product of respiration methane and carbon dioxide. Very slow decomposition

32
Q

Nitrogen Cycle

A
33
Q

What are the three forms of nitrogen?

A

NO3- nitrate
NH4+- ammonium
Organic Nitrogen

34
Q

Functions of NO3-

A

It is the preferred form of nitrogen nutrition for most species of plants. It is highly soluble in water. If nitrate is not assimilated by plants or microorganisms, it is leached from soils.

35
Q

Functions of NH4+

A

Plants are adapted to acidic soils and can utilise ammonium as their source of nitrogen nutrition, although most non-acidic soils can only utilise nitrate. It is soluble in water and attracted to negatively charges surfaces associated with clays and organic matter in soil. Not as mobile as nitrate

36
Q

Organic Nitrogen and examples

A

Nitrogen containing molecules. Amino acids, proteins and humic substances

37
Q

Gaseous forms of Nitrogen (6)

A 
N2 atmospheric dinitrogen gas
NO Nitric Oxide
NO2- Nitrogen dioxide
N2O- Nitrous oxide 
NH3 Ammonia
38
Q

What is N2?

A

Atmospheric dinitrogen gas

39
Q

What is NO?

A

A gas emitted to the atmosphere mostly as a result of combustions

40
Q

What is N2O?

A

Nitrous oxide- dentrification occurring in wet nitrate rich soils

41
Q

What is NH3?

A

Ammonia- usually occurs as a gas, vapour or liquid

42
Q

Why is nitrogen important for plants and farming?

A

They require nitrogen for photosynthesis. Increased Nitrogen inputs can lead to more food produced to feed more people- known as the green revolution

43
Q

How is nitrogen deficiency addressed?

A

By applying a form of nitrogen fertiliser

44
Q

Examples of nitrogen fertiliser

A

Compost (plant waste) or manure (animal waste)

45
Q

Why do soils rich in organic matter not require fertiliser?

A

Organic matter decomposes and releases NH4+ (ammonium) and NO3- (nitrate)

46
Q

Why is too much nitrogen in soil bad?

A

It can be harmful to plants as it can prevent plants from flowering and producing fruit (plant burn).
Excess nitrate often leaches into the groundwater and causes excess growth of algae (eutrophication)

47
Q

How can nitrous oxide be emitted to the atmosphere?

A

The action of anaerobic bacteria of inorganic fertiliser or organic animal manure applied to the soil

48
Q

What are temperature drivers of GHG emissions from the soil? (4)

A

Radiation
Exposure (soil cover)
Soil Colour (mineralogy)
Wildfires

49
Q

What are humidity drivers of GHG emissions from soils? (3)

A

Soil water content
Water filled space
Precipitation/drought (intensity and frequency)

50
Q

What are land cover drivers of GHG emissions from soils?

A

Transformation

Ecosystem Resilience

51
Q

What are land cover drivers of GHG emissions from soils?

A

Forestlands, grasslands, barrenlands, croplands, wetlands

52
Q

What are vegetation type drivers of GHG emissions from soils?

A

Age and type
Distribution
Leaf Area Index

53
Q

How can temperature affect GHG emissions?

A

Increases decomposition rates with temperature

54
Q

How can water affect GHG emission rates?

A

Soil moisture- not too try and not too wet- CO2 emission

Air and oxygen- more O2 higher decomposition

55
Q

What is methantrophy?

A

CH4 oxidation- the uptake from the atmosphere (uplands, forest, soil)

56
Q

Where is methane produced?

A

Anaerobic conditions (wetlands and rice fields)

57
Q

What is the C:N ratio?

A

The ratio of the mass of carbon to the mass of nitrogen in a substance

58
Q

Purpose of carbon and nitrogen for microbes.

A

Carbon is the source of energy and Nitrogen is the source of protein

59
Q

What happens if the ratio of C:N is >25?

A

There is not enough Nitrogen for microbial activity- microbes take nitrogen from plant supply or decay is delayed

60
Q

What happens if the C:N ration is 24?

A

This is the most favourable for microorganisms as they have to maintain their own C:N ratio to 8:1

61
Q

What happens if the C:N ration is <24?

A

Microbes will consume the material and leave excess nitrogen in the soil for plants or other microbes

62
Q

What happens when peatlands are drained?

A

Mass amounts of CO2 will be released into the atmosphere

63
Q

What do wetlands release and absorb?

A

Releases Carbon Dioxide and Methane and absorbs Carbon Dioxide

64
Q

What gases do peatlands emit and absorb?

A

Emits Carbon Dioxide and Methane and absorbs Carbon Dioxide

65
Q

What gases do pasture emit and absorb?

A

Emits carbon dioxide, methane and nitrous oxide and absorbs carbon dioxide

66
Q

What gases to arable lands emit and absorb?

A

Emits carbon dioxide and nitrous oxide and absorbs carbon dioxide

67
Q

What gases do grasslands emit and absorb?

A

Emits and absorbs carbon dioxide

68
Q

What gases do forest emit and absorb?

A

Emits carbon dioxide and absorbs carbon dioxide and methane

69
Q

What is soil respiration important?

A

soil respiration is part of the natural carbon cycle and it is a necessary process to release plant available nutrients into the soil

70
Q

Is all co2 produced in soil emitted?

A

No. Some is stored in small pores until rainfall events that will replace the soil-air with water

71
Q

Why is it important to increase the input of carbon into the soil?

A

So more carbon is absorbed from the atmosphere by plants than emitted to the atmosphere form soils

72
Q

How is methane produced in soil?

A

During aerobic decomposition of organic matter content together with CO2

73
Q

What are methanogens?

A

Bacteria responsible for the production of CH4

74
Q

What is the process of methane by methanogens called?

A

Methanogenesis

75
Q

Where is methane production typical?

A

Waterlogged soils such as peatlands and wetlands

76
Q

What can utilise methane?

A

Methanotrophic bacteria in oxic layers located above waterlogged soils
It can be uptakes directly from the atmosphere

Greenhouse Gas Emissions (6 decks)

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