Carbon cycle

Question 1

Lithosphere

Answer 1

Carbon stored as both organic & inorganic compounds in rocks

Marine sediments & sedimentary rock - 100 million gtc - largest store

Soil organic matter - 1500 gtc

Fossil fuel deposits - 4100 gtc

Peat - 250 gtc

Question 2

Hydrosphere

Answer 2

Carbon stored in the oceans/water

Surface layer - sunlight penetrates = 900 GtC
Intermediate and deep layer = 37,000 GtC
Living organic matter = 30 GtC

When organisms die they sink into deep water –> decay releases CO2, some sink to ocean floor –> layers of carbon-rich sediment form –> rocks –> lock up carbon for millions of years

Question 3

Biosphere

Answer 3

3170 GtC

Amazon stores 1/5 of worlds carbon in biomass

Living vegetation, Plant litter, Soil humus, Peat

Question 4

Peat

Answer 4

forms in wetland conditions

almost permanent soil saturation –> anaerobic conditions –> slows down decomposition

Over 250 GtC

Question 5

Atmosphere

Answer 5

CO2 is a trace gas with 700-800 GtC stored in the atmosphere

GHG –> regulates global temps

Global warming attributed to increased anthropogenic CO2

CO2 from ice cores is used to give a proxy measure of CO2 in the past

Question 6

Carbon sink

Answer 6

Absorbs more co2 than it releaes

Question 7

Carbon source

Answer 7

Releases more co2 than it absorbs

Question 8

Geological component of the carbon cycle

Answer 8

Where the carbon cycle reacts with the rock cycle

Weathering, burial, subduction and volcanoes –> controlled atmospheric CO2 for millions of years

CO2 removed from atmosphere by dissolving in water forming carbonic acid (H2CO3)
–> chemical weathering –> falls as acid rain

Question 9

Photosynthesis

Answer 9

Marine plants in the euphoric zone as well as terrestrial plants convert CO2 into organic matter and oxygen

Question 10

Respiration

Answer 10

Use stored carbohydrates and oxygen to release energy for life functions

Releases CO2

Question 11

Decomposition

Answer 11

Physical, biological and chemical mechanisms that transfer organic matter into increasingly stable forms

Physical = animals, wind, plants, leaching and transport of water

Chemical = oxidation and condensation

Biological = feeding and digestion

Decomposers = break down cells & tissue into smaller biomolecules

Releases CO2 from respiring bacteria

Question 12

Transfers

Answer 12

Carbon sequestration = transfer of carbon from the atmosphere and can be both natural and artificial

Diffusion = oceans absorb CO2 from the atmosphere –> can cause coral bleaching

Weathering & erosion = rocks broken down and transferred into the ocean –> carbon used by marine organisms to make shells

Burial and compaction = sea shell fragments become compacted over time to form limestone and organic matter may form fossil fuels

Question 13

Carbon cycle changes over time

Answer 13

Natural and Human

Question 14

Natural changes to carbon cycle

Answer 14

Wildfires - transfer carbon from biosphere to atmosphere

Volcanoes - carbon stored within the earth is releases during eruptions –> mainly CO2

Question 15

Human changes to the carbon cycle

Answer 15

Fossil fuels - combustion transfers CO2 into the atmosphere from a long term sink

Deforestation - rapidly releases carbon stored in plants & disrupts forest carbon cycle

Farming practices - pastoral farming releases CO2 and Methane from animals –> ploughing releases CO2 stored in the soil

Question 16

Carbon budget

Answer 16

Balance between carbon inputs and outputs to a store at any scale

Question 17

Impact of carbon cycle in a rainforest

Answer 17

High rates of photosynthesis –> greater humidity –> greater cloud cover –> more precipitation

Deforestation reduces photosynthesis and respiration –> decreased humidity –> decreases cloud cover –> decreases precipitation –> droughts –> desertification