why is water important to life on earth

  • Allows organic molecules to mix and form more complex structures

  • Solvent: life needs a solvent to dissolve and transport material around the body. Water is, so far as we know, is the only common liquid that is capable of this (some studies have suggested that liquid methane would have similar properties, but this is not as common)

  • Temperature regulation of the planet: oceans, which occupy 71% of the Earth’s surface. It can help to moderate temperatures by absorbing heat, storing it and releasing it slowly. Clouds made up of tiny water droplets reflect around a fifth of incoming solar radiation and lower surface temperatures. At the same time water vapour, a potent greenhouse gas, absorbs longwave radiation from the Earth helping to maintain average global temperatures almost 15 degrees C higher than they would be otherwise.

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what are the uses of water for plants(flora)

  • photosynthesis takes place in the leaves of plants combining CO2, sunlight and water to make glucose and starches (sugars).

  • Respiration: a process that occurs in animals and plants that converts glucose to energy though its reaction with oxygen. Water and CO2 is released in the process. 

  • Transpiration: evaporation of water from the leaves helping to keep the plant cool (this is because it takes quite a bit of energy to heat up water and make it evaporate- change from liquid to gas)

  • Metabolic processes- water is a catalyst for many important chemical reactions

  • Transport agent for nutrients- e.g. from the roots to the rest of the plant

  • Animals (FAUNA), which manufacture their own food need water for:

  • Respiration: a process that occurs in animals and plants that converts glucose to energy though its reaction with oxygen. Water and CO2 is released in the process.

  • Sweating/panting and Metabolic processes- water is a catalyst for many important chemical reactions and Transport agent for nutrients to where it is needed

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what are the uses of water for economic activity

  • Generate electricity (e.g. Hydroelectric Power)

  • Irrigate crops

  • Recreational facilities

  • is Drinking water

  • Sewage (waste disposal)

  • Food manufacturing

  • Brewing

  • Steel making

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why is carbon important on earth

Carbon is the backbone of life on Earth. We are made of carbon, we eat carbon, and our civilizations—our economies, our homes, our means of transport—are built on carbon.

Carbon is an essential element to all living things on Earth; plants and animals. It also plays a major role in controlling the global climate, particularly temperature and in defining the acidity of rain, rivers, and oceans. The carbon cycle involves the storage and movement of carbon.

Carbon is one of the most common chemical elements on Earth. Due to its ability to bond with other elements, it is incredibly important. It is estimated to form the basis of 95% of all compounds. Carbon is found all over the planet. It is found in rock (carbonate e.g. limestone), as CO2 gas in the atmosphere and dissolved CO2 is found in oceans.

Carbon is present in nearly every molecule in living organisms on the planet. It is found in 80% of the world’s primary energy e.g. coal and oil.

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biological significance of carbon part 1

Carbon is essential to life. It plays an essential role in biology because of its ability to form many bonds, up to four per atom, in a seemingly endless variety of complex organic molecules. Many organic molecules contain carbon atoms that have formed strong bonds to other carbon atoms, combining into long chains and rings. Such carbon chains and rings are the basis of living cells. For instance, DNA is made of two intertwined molecules built around a carbon chain.

The bonds in the long carbon chains contain a lot of energy. When the chains break apart, the stored energy is released. This energy makes carbon molecules an excellent source of fuel for all living things.

Living things get almost all their carbon from carbon dioxide, either from the atmosphere or dissolved in water. Photosynthesis by green plants and photosynthetic plankton uses energy from the sun to split water into ox.ygen and hydrogen. The oxygen is released to the atmosphere, fresh water and seas, and the hydrogen joins with carbon dioxide to produce carbohydrates.

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biological significance of carbon part 2

Some of the carbohydrates are used, along with nitrogen, phosphorus and other elements, to form the other monomer molecules of life. These include bases and sugars for RNA and DNA, and amino acids for proteins.

Living things that do not photosynthesise have to rely on consuming other living things for their source of carbon molecules. Their digestive systems break carbohydrates into monomers that they can use to build their own cellular structures. Respiration provides the energy needed for these reactions. In respiration oxygen re-joins carbohydrates, to form carbon dioxide and water again. The energy released in this reaction is made available for the cells.


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economic significance of carbon part 1

Carbon is unique among the elements in its ability to form strongly bonded chains, sealed off by hydrogen atoms. These hydrocarbons, extracted naturally as fossil fuels (coal, oil and natural gas), are mostly used as fuels. A small but important fraction is used as a feedstock for the petrochemical industries producing polymers, fibres, paints, solvents and plastics etc.

Smelting. Impure carbon in the form of charcoal (from wood) and coke (from coal) is used in metal smelting. It is particularly important in the iron and steel industries.

Graphite is used in pencils, to make brushes in electric motors and in furnace linings. Activated charcoal is used for purification and filtration. It is found in respirators and kitchen extractor hoods.

Lightweight structures. Carbon fibre is finding many uses as a very strong, yet lightweight, material. It is currently used in tennis rackets, skis, fishing rods, rockets and aeroplanes.

Cutting and drilling. Industrial diamonds are used for cutting rocks and drilling. Diamond films are used to protect surfaces such as razor blades. Hardware and electronics. The more recent discovery of carbon nanotubes, other fullerenes and atom-thin sheets of graphene has revolutionised hardware developments in the electronics industry and in nanotechnology generally.


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economic significance of carbon part 2

It is a raw material for manufacturing (oil is used in the production of many things such as plastic and paint). Wood is used in construction and paper-making while agricultural crops not only provide food but also materials such as cotton and oils for products such as soap.

Fuel. The utilisation of fossil fuels has enabled large-scale industrial development and largely supplanted water-driven mills, as well as the combustion of wood or peat for heat. A small portion of hydrocarbon-based fuels are biofuels derived from atmospheric carbon dioxide, and thus do not increase the net amount of carbon-dioxide in the atmosphere, that the combustion of fossil fuels


Water and carbon cycling between the land, oceans, and atmosphere through open and closed systems.

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carbon cycle

at a global level the carbon cycle can be considered as a closed system as only energy (from the sun) is entering and leaving the system. No materials enter or leave the system. At smaller scales the carbon cycle, like the water cycle, is an open system. Carbon moves between stores by several processes:

  • Photosynthesis: Carbohydrate molecules are produced from carbon dioxide and water using energy from light.

  • Respiration: Carbon dioxide is released into the atmosphere by organisms through the process of respiration. Plants create energy for respiration by breaking down stored glucose (sugars). Carbon dioxide is given off as a by-product.

  • Decomposition: Carbon dioxide is returned to the atmosphere when living organisms die: their cells break down as a result of physical (wind and water), chemical (leaching and oxidation) and biological mechanisms (carried out by bacteria and fungi).

  • Fossil fuel combustion: Hydrocarbon (fossil fuel) combustion takes place rapidly in the presence of oxygen and releases carbon dioxide. Around 85% of global energy consumption is derived from coal, oil and gas fuels. Traditional societies burn biomass on demand

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carbon on land

  • Dominated by photosynthesis of plants absorbing CO2 from the atmosphere

  • Carbon is stored within biomass, such as tropical and temperate forests

  • Carbon is transferred to the soil via leaf litter, roots and plant debris upon decomposition

  • Bacterial action in decomposition releases CO2 back to the atmosphere

  • Carbon is cycled quite rapidly though organic (living) systems between the atmosphere, vegetation (dominant biomass) and soils and is called the fast carbon cycle. 

  • Human impact on this sub-cycle is considerable. The clearing of nature vegetation for urbanisation and agriculture is a major change to the biomass component and affects the carbon exchange between atmosphere and soil. Clearing vegetation by burning releases much stored carbon the atmosphere very rapidly.

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carbon in the oceans

  • Carbon is stored in the oceans as dissolved CO2, as bicarbonate ions in solution, and as the tissues (especially calcium carbonate skeletons and shells) of marine organisms.The inputs of carbon are from the atmosphere (dissolved CO2 in a direct exchange with ocean surfaces, as bicarbonate ions brought by rivers as a result of weathering carbonate terrestrial rocks, and a small input from subterranean volcanoes

  • Phytoplankton in surface waters absorb CO2 in photosynthesis. They are fed on by zooplankton

  • A carbon pump operates within oceans transferring carbon from upper layers to the sea bed. A constant ‘snow’ of carbon deposits sinks with gravity as a result of marine organisms dying and zooplankton feeding on phytoplankton and discharging excrement

  • Carbon accumulates as/within ocean sediment in shallow seas (in deeper oceans it is often re-dissolved) leading to the natural sequestration of carbon by removing it to a long-term store within ocean bed deposits. Human impacts on the oceans are only now becoming understood, but the warming of oceans as a result of climate change is believed to have a considerable impact on the ocean carbon cycle. Warner seas are less able to absorb CO2 from the atmosphere and cause a reduction in phytoplankton activity. 

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carbon in the atmopshere

  • Atmospheric carbon is usually the form of carbon dioxide (CO2) or methane (CH4). Both are natural greenhouse gases, with methane being over 29 times more powerful in absorbing solar radiation, but much shorter-lived in the atmosphere, than CO2 (about 12 years opposed to 50). 

  • Carbon dioxide combines with water molecules in clouds to form carbonic acid, and naturally-acidic rain. This leads to terrestrial weathering and can contribute to ocean acidification

  • Outputs from the atmosphere include absorption by surface vegetation and by oceans in the atmosphere-ocean gas exchange

  • Human impacts on the carbon cycle are most directly implicated in increasing atmospheric CO2 through the burning of fossil fuels

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the fast carbon cycle

The time it takes carbon to move through the fast carbon cycle is measured in a lifespan. The fast carbon cycle is largely the movement of carbon through life forms on Earth, or the biosphere. Between 1015 and 1017 grams (1,000 to 100,000 million metric tons) of carbon move through the fast carbon cycle every year.

The transfer of carbon between the oceans, atmosphere, soils and living organisms is ten to one thousand times faster than the slow carbon cycle. Although carbon storage is small in the atmosphere, plants and soil they are a very important element of the carbon cycle. 

CO2 is absorbed by phytoplankton by photosynthesis after which it is transformed into carbohydrates and stored in their tissues. 

Respiration by living organisms releases CO2 to the atmosphere. 

CO2 is exchanged between the atmosphere and oceans with CO2 dissolved in surface water and a return of CO2 to the atmosphere by ventilation. 

Carbon is returned to the surface of the Earth as acid rain to start the cycle again (note atmospheric CO2 can also dissolve directly into ocean waters).

Individual carbon atoms are stored in the ocean for, on average 350 years

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the slow carbon cycle

carbon takes between 100-200 million years to move between rocks, soil, ocean, and atmosphere in the slow carbon cycle. On average, 1013 to 1014 grams (10–100 million metric tons) of carbon move through the slow carbon cycle every year. The long carbon cycle involves the long-term storage of carbon. Marine organisms, such as shellfish and phytoplankton, build their shells by combining calcium with carbon. When they die they accumulate on the ocean floor. Over millions of years, these organisms become compressed and become carbon-rich sedimentary rocks. This carbon is usually stored in rocks for around 150 million years. Oil and gas can also be formed from the accumulation of plankton. Oceanic crust, containing sedimentary rock, is subducted causing the crust to melt. CO2 that was stored in the rock is released into the atmosphere through volcanic eruptions. Sedimentary rocks near the surface release CO2 as they are chemically weathered (e.g. via carbonation). The chemical weathering, such as carbonation, occurs because the CO2 in the atmosphere dissolves in rainwater forming a weak (carbonic) acid releasing CO2 into the atmosphere and resulting in the rest being carried in solution into rivers and eventually the sea (where it can be used to make CaCO3 shells)On land partly decomposed organic material can be buried. Under pressure, these form carbonaceous rocks such as coal, lignite, oil and natural gas. Fossil fuels such as coal, oil and gas store carbon for millions of years (carbon sink).

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water cycle part 1

At global level water flows in a closed system between the atmosphere, oceans, land and the biosphere. The flow of this can be shown in the water cycle. The speed at which water moves around the water cycle can be days to millions of years. The global water cycle consists of three main stores:

Oceans (biggest)


Atmosphere (smallest)

Water moves between stores by several processes:


  • Precipitation: a vital component of how water moves through Earth’s water cycle, connecting the ocean, land and atmosphere. It is any product of the condensation of atmospheric water vapour that falls quickly out of a cloud. E.g. drizzle, rain, sleet, snow, hail. It occurs when a local portion of the atmosphere becomes saturated with water vapour and the water condenses.

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water cycle part 2

  • Evapotranspiration: the sum of evaporation and plant transpiration. Actual evapotranspiration cannot be any greater than precipitation, and will usually be less because some water will run-off in rivers and flow to the oceans. 

  • Runoff: occurs when falling rain cannot be absorbed by soil and, instead, flows over the surface. It occurs in nature when the soil is saturated with water, or in urban environments when there is asphalt instead of soil on the ground

  • Groundwater flow: water that collects or flows beneath the Earth’s surface, normally following a downward gradient

  • Condensation: The process by which molecules of water vapor in the air become liquid water.

  • Evaporation: The process by which water molecules in liquid water escape into the air as water vapor.

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water cycle: inputs and outputs

The land can be further divided into polar ice and glaciers, groundwater, lakes, soils, and rivers. The biosphere can also be regarded as a store of water, albeit small.

Inputs of water to the atmosphere include water vapour evaporated from the oceans, soils lakes, and rivers, and vapour transpired through the leaves of plants. Together these processes are known as evapotranspiration. 

Moisture leaves the atmosphere as precipitation (e.g. snow, hail, rain) and condensation (e.g. fog). Ice sheets, glaciers, and snowfields release water by ablation (melting and sublimation). 

Precipitation and meltwater drain from the land surface as run-off into rivers. Most rivers flow into the oceans. A large part of water falling as precipitation on the land reaches rivers only after infiltrating and flowing through the soil. 

After infiltrating the soil, water under gravity may percolate into permeable rocks or aquifers. This groundwater eventually reaches the surface as springs or seepages and continues to run-off.

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carbon cycle :inputs and output

The global carbon cycle comprises five main stores, which can be subdivided

  • Permafrost and ice

  • Oceans

  • Atmosphere

  • Sea floor sediments and rocks

  • Terrestrial Biomass and soil

  • Fossil fuels

Carbonate rocks, such as limestone, chalk and deep ocean sediments are by far the largest stores of carbon. Most of the carbon that is not stored in carbonate rocks and sediments is found in the oceans as dissolved CO2. Carbon storage in the atmosphere, plants and soils is relatively small although they play a very important role in the circulation of carbon. Carbon moves between these stores in a series of flows.


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part 1 what are the main characteristics of the ma



  • soil moisture

  • root uptake


  • transpiration



  • water which freezes

  • accumulation of snow

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part 2 what are the main characteristics of the ma


  • melting

  • ablation

  • sublimation



  • evapotranspiration

  • evaporation

  • transpiration


  • precipitation

  • condensation

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part 3 what are the main characteristics of the ma



  • precipitation

  • through flow and ground flow


  • evaporation



  • infiltration

  • percolation


  • throughflow

  • groundwater flow

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characteristics of the main inputs and outputs of

atmosphere: input= respiration,combustion and decomposition

outputs= photosynthesis and dissolve- ocean

biosphere: inputs=photosynthesis

outputs= decomposition and respiration

ocean: inputs=weathering, precipitation, and dissolved CO2


pedosphere: inputs =decomposition

outputs: respiration of bacteria and diffusion

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carbon exchange and sequestration key terms

carbon exchange 

is the process involved in moving carbon around the cycle and include photosynthesis, precipitation, weathering, respiration, decomposition, and combustion

carbon sequestration

 the general term used to the transfer of carbon from the atmosphere to long term storage in vegetation, soils rocks/sediments or oceans


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processes and pathways in the water cycle

There are many process in the water cycle including:








Catchment hydrology

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catchment hydrology

Catchment Hydrology= A river basin or drainage basin is an area of land drained by a river and its tributaries. Catchment hydrology is the study of hydrology in drainage basins. The drainage basin water cycle may be defined as a single river basin bounded by its own watershed and the sea.

The drainage basin water cycle is an open system. This means that it has inputs and outputs- energy from the sun and precipitation enter the system and water leaves it. At certain times the volume of water in the system may vary, sometimes significantly (this would not be the case in a closed system).

Inputs include condensation, precipitation and solar energy.

Outputs move moisture out of the drainage basin and include evaporation and transpiration from vegetation (collectively known as evapotranspiration), runoff into the sea and percolation of water to underlying rock strata into underground stores. Stores include puddles, channel storage, groundwater storage, water stored on vegetation (interception) following precipitation.

Transfers or flows include percolation, overland flow, infiltration, stemflow, throughflow and overland flow.

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Transpiration is the diffusion of water vapour to the atmosphere from the leaf pores (stomata) of plants. It is responsible for around 10 percent of moisture in the atmosphere. Like evaporation, transpiration is influenced by temperature and wind speed. It is also influenced by water availability to plants. For, example, deciduous trees shed their leaves in climates with either dry or cold seasons to reduce moisture loss through transpiration.

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Evaporation is the phase change of liquid water to vapour and is the main pathway by which water enters the atmosphere. Heat is needed to bring about evaporation and break the molecular bonds of water. It is important to note that this energy input does not produce a rise of temperature of the water. Instead the energy is absorbed as latent heat and released later in condensation. This process allows vast quantities of heat to be transferred around the planet. 

Latent heat is the heat required to convert a solid into a liquid or vapour, without change of temperature

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Vegetation intercepts a proportion of precipitation, storing it temporarily on branches, leaves and stems. Eventually this moisture either evaporates (interception loss) or falls to the ground. Rainwater that is briefly intercepted before dripping to the ground is known as throughfall. During periods of prolonged or intense rainfall, intercepted rainwater may flow to the ground along branches and stems as stemflow. 


Factors such as wind speed, type of vegetation (e.g. higher surface area = bigger interception losses),

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infiltration, throughflow, groundwater flow and ru

Rain falling to the ground and not entering storage follows one of two flow paths to streams and rivers. 

Infiltration by gravity into the soil and lateral movement or throughflow to stream and river channels. Overland flow across the ground surface as a sheet or as trickles to stream and river channels. Overland flow occurs by two possible mechanisms (both are contested):

Rainfall intensity exceeds infiltration capacity (speed at which water can infiltrate the ground)

Rainfall always infiltrates the soil, regardless of intensity, and overland flow only occurs when the ground becomes saturated with water and the water table rises to the surface (saturated overland flow)

If soils are underlain by permeable rocks, water seeps or percolates deep underground. This water then migrates slowly through the rock pores and joints as groundwater flow, eventually emerging at the surface as springs or seepages. Where groundwater flows into an aquifer, recharge occurs

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Cryospheric Processes (frozen water)

Ablation is loss of ice from snow, ice sheets and glaciers due to a combination of melting, evaporation and sublimation. Meltwater is an important component of river flow in high latitudes and mountain catchments in the spring and summer.

Rapid thawing of snow in upland Britain is a common cause of flooding in adjacent lowlands (e.g. Welsh uplands and the Lower Severn Valley). 

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what are the two main ways a parcel of air can be

1. Diabatic processes: involving direct energy exchange e.g. the heating or cooling of the air as it moves across a hot or cold surface 

2. Adiabatic processes: do not involve net energy exchange and involve heating by compression or cooling by expansion

How do adiabatic process work?

Imagine you have air molecules moving around in a chamber. If the air is compressed the molecules move faster because the energy in the system per volume has increased (so there is more energy available for particles to move)- the resulting in the air becoming warmer. 

When the air is expanded the molecules move slower because the energy in the system per volume has decreased (so there is less energy available for particles to move) resulting in the air becoming cooler. 

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Lapse rates and cloud formation

The lapse rate is the rate at which an atmospheric variable (normally temperature in the Earth’s atmosphere) changes with altitude. This can be applied to an entire section of the atmosphere such as the troposphere or a small parcel of gas. As long as there is no condensation involved the temperature of a rising parcel decreases at a fixed rate with increasing altitude. This is rate called the dry adiabatic lapse rate (= 10 degrees C per km). 

If an air parcel rises high enough it will eventually get so cold that it cannot hold the water vapour any longer; this is the height at which saturation occurs. It is also called the lifting condensation level because further lifting will cause condensation, where water moves from the gaseous to liquid phase and clouds form. 

The process of condensation releases energy so the rate to which the air temperature changes with altitude will be less. The air parcel still expands and still cools down but much less than before due to the fact that energy is released via condensation. Above the lifting condensation level air parcels cool at the moist (or saturated) adiabatic lapse rate (5 degrees C per km).

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environmental lapse rate

The dry and moist lapse rates apply to an air parcel, they do not refer to the overall change in temperature with altitude. The Environmental Lapse Rate (ELR) is the rate of decrease of temperature with altitude in the stationary atmosphere at a given time and location. Cloud formation in stable air is unlikely. The ELR varies from time and place and is dependent on ground radiation, solar radiation etc. Solar radiation causes surface heating during the day; this generally leads to high temperatures on the surface and consequently a higher environmental lapse rate in the lower atmosphere. Terrestrial radiation causes surface cooling during the night, which typically results in a lower environmental lapse rate. 


The horizontal transfer of air is called advection is another factor that influences the environmental lapse rate.

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Three principle mechanisms can cause the lifting o

Adiabatic cooling occurs when lifting air expands.

Lifted over mountain barrier (Orographic lifting): occurs when mountains act as barriers to the flow of air. Air ascends the mountain slope causes adiabatic cooling which often generates clouds. This is why many of the rainiest places are located on windward mountain slopes. When air reaches the leaward side of the mountain, much of the moisture has been lost so the air descends, contracts and warms adiabatically and condensation and precipitation are not likely. 

Frontal lifting: when less dense warm air is forced to rise over cooler, denser air as a weather fronts move. Most common in winter.

Convection: when solar energy passes through the atmosphere and heats the surface, where the air becomes less dense than the air around it, making it rise. When it rises it is called atmospheric instability. When the air reaches a point where it does not rise further it is called atmospheric stability. 

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types of clouds

Cumuliform clouds

Flat bases. Substantial vertical development. Often forms when air is heated locally through contact with the Earth’s surface- causes heated air parcels to rise freely though the atmosphere by convection and expands due to fall in pressure with altitude and cools

As cooling reaches due point condensation begins and cloud forms

Precipitation influences the water cycle

Stratiform clouds

Develop where an air mass moves horizontally across a cooler surface (e.g. the ocean)- a process termed advection. 

Precipitation, influences water cycle

Cirrus clouds or wispy clouds

Form at high latitude

Consist of small crystals

Do not produce precipitation, have little influence on the water cycle

Fog= Condensation at or near the ground produces dew and fog. Both types of condensation deposit large amounts of moisture on vegetation and other surfaces


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processes and pathways in the carbon cycle







Photosynthesis is a process used by land plants and marine phytoplankton convert light energy into chemical energy that can later be released to fuel the organisms’ activities (energy transformation). This chemical energy is stored in carbohydrate molecules, such as sugars, which are manufactured from carbon dioxide and water.


Respiration is the reverse of photosynthesis. It releases energy by breaking sugars. CO2 is released into the atmosphere. 

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 involves the breakdown of rocks, in situ, close to or on the surface of the Earth. Weathering occurs by physical, biological or chemical processes. Chemical weathering typically involves rainwater that is weak carbonic acid (acid rain). CO2 gas in the atmosphere dissolves and CO2 is absorbed from the soil as the water flows through it. Carbonate rocks such as limestone are weathered through carbonation or solution weathering. As the rock comes into contact with acidic water it reacts and changes the calcium carbonate into calcium bicarbonate which is soluble and dissolves. Running water carries it away to rivers and oceans. Carbonation also results in carbon dioxide retuning to the atmosphere. 0.3 billion tonnes of carbon are transferred from rocks to the atmosphere and oceans every year

Physical weathering widens cracks in rocks allowing more water to access the rock. Also, physical weathering results in small pieces of rock being broken off which results in them having a greater surface area that can be attacked by chemical weathering.Biological weathering contributes to the breakdown of rock. Rainwater mixed with dead and decaying organic material in the soil forms humid acids which attack rock minerals. This is important in humid tropical environments where decomposition is rapid and forest trees provide abundant leaf litter

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decomposition and combustion


Carbon is released as CO2 when living organisms dies and are decomposed by microorganisms such as fungi and bacteria. The temperature has a significant impact on the rate of decomposition. Humid environments such as the tropical rainforest have rapid rates whereas colder environments such as arctic tundra have slow rates of decomposition.

Combustion= When organic material burns combustion occurs. This causes carbon to be released as CO2. Combustion happens naturally by wildfires caused by lightning strikes. This leads to increased nutrient and carbon recycling and leads to growth being stimulated. This is essential to a number of ecosystems including grasslands in East Africa.Human activities cause a significant amount of combustion. Burning fossil fuels such as coal, oil and gas results in stored carbon being released in CO2. This leads to a net increase in CO2 in the atmosphere. Burning biomass fuel is regarded as being carbon neutral because new crops have been planted and are absorbing CO2 from the atmosphere when plant-based materials are being burned. As long as the system is sustainably managed there is no net increase in CO2.

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physical pump ( carbon sequestration

Mixing of surface and deep ocean water by vertical currents resulting in a more even distribution of carbon- laterally and vertically

CO2 enters the ocean from the atmosphere by diffusion

Surface ocean currents transport the water to the poles where it cools becomes denser and sinks

This downwelling occurs in a few places in the oceans e.g. the North Atlantic between Greenland and Iceland

Downwelling carries dissolved carbon to the ocean depths where carbon molecules may remain for centuries

Deep ocean currently, eventually, transport the carbon to areas of upwelling

There cold, carbon rich-water rises to the surface and CO2 diffuses back into the atmosphere

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biological pump ( carbon sequestration)

The exchange of carbon between the oceans and atmosphere by the actions of marine organisms. Nearly half of all carbon fixation by photosynthesis takes place in the oceans. Around 50 gigatons of carbon is drawn from the atmosphere via this every year. 

Phytoplankton, floating near the ocean surface combines sunlight, water and dissolved CO2 to produce organic material. 

Phytoplankton may be consumed by animals (e.g. zooplankton) in the marine food chain or die naturally. Either way the carbon, locked up in the phytoplankton, accumulates in sediments on the ocean floor or is decomposed and released into the ocean as CO2.

Other marine organisms like coccolithophores, forams, molluscs and crustaceans extract carbonate ions from the sea water to make shells/skeletons of calcium carbonate. Most of this ends up in ocean sediments and, over time, turns into rock like chalk and limestone.

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Terrestrial plants, especially trees in rainforests and boreal forests, contain vast stores of carbon. Most of this carbon extracted from atmospheric CO2, through photosynthesis, is stored for decades. 

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water cycle in the amazon key points

  • >2000mm rainfall per year, evenly distributed throughout the year

  • 10% of this rainfall is intercepted

  • Intercepted rainfall accounts for 20-25% of all evaporation

  • High rates of evapotranspiration

  • Strong evapotranspiration-precipitation feedback (50% of all rainfall is returned by evapotranspiration)

  • Rapid run off due to high and intense rainfall and well drained soils

  • Large stores of moisture in the atmosphere, relative humidity is high

  • Trees play a vital role in the processes of interception, storage and transpiration of water

  • 50% of all precipitation within the Amazon basin is recycled by evapotranspiration.

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physical factors affecting the water cycle


Impermeable catchments (e.g large parts of the Amazon basin are an ancient shield area comprising impermeable crystalline rocks) have minimal water storage capacity resulting in rapid runoff. Permeable and porous rocks such as limestone store rainwater and slow runoff


Most of the amazon basin comprises extensive lowlands.in areas of gentle relief, water moves across the surface or throughflow to streams and rivers.in the west the Andes create steep catchments with rapid runoff. Widespread inundation across extensive floodplains occur annually storing water for several months and slowing its movements into rivers


High temperatures throughout the year generate high rates of evapotranspiration.convection is strong leading to high atmospheric humidity, the development of thunderstorm clouds and intense precipitation. Water is cycled continually between land, forest trees and the atmosphere by evaporation, transpiration, and precipitation

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carbon cycle in th

The Amazons humid equatorial climate creates ideal conditions for plant growth. Net primary productivity is high. 

Net primary productivity (NPP): Amount of energy made available by plants to animals, only at the herbivore level, and is expressed as kg/m2/yr.Net primary productivity is affected by temperature, the availability of water, carbon dioxide (CO2), nutrients and the efficiency of conversion of light energy to the chemical energy of carbohydrates. The biomass of tropical rainforests is larger than that of other vegetation. Measurements show that tropical rainforests typically have biomass values on the order of 400 to 700 metric tons per hectare, greater than most temperate forests and substantially more than other vegetation with fewer or no trees.  Since water, light, and high temperatures are readily available in the Amazon, and there is a dense concentration of green plants at all levels from the lower stories to the canopy, it is no wonder that these forests have very high levels of productivity.

 Compared to other forest ecosystems, exchanges of carbon between the atmosphere, biosphere and soil are rapid. Warm, humid conditions ensure speedy decomposition of dead organic matter and the quick release of CO². Meanwhile rates of carbon fixation through photosynthesis are high.

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carbon cycle stores in the amazon

Rainforest Soils: Latosoil ,Rainforest soils are known as latosols. They are very nutrient poor because:

• Although there is a constant supply of new leaf litter and dead organic matter onto the soil surface, it is broken down very quickly because the warm, wet climate is ideal for micro-organisms.

• The growing season continues all year, so as soon as dead organic matter is broken down the nutrients are re-absorbed by plants. This means that few nutrients remain in the soil.

• Nutrients are also leached down the soil column by heavy rainfall.

There is a thin layer of nutrients in the top layer of soil, where organic matter is decaying. Trees keep their roots close to the surface in order to capitalize on these nutrients. Leaching occurs as a result of the high precipitation and is increased greatly by deforestation. Biomass: Significantly more carbon is stored within the biomass of the rainforest than the soils.

  • In Amazonia, the biomass is between 400 to 700 tonnes per hectare (ha).  1 km2 = 100 ha.

  • The biomass of trees represents 60% of all the carbon in the ecosystem.

  • Large rainforest trees store 180 tonnes C/ha above ground and 40 tonnes C/ha in their roots

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carbon cycle flows in the amazon

  • rapid carbon exchanges between the atmosphere, biosphere, and soil.

  • High rates of carbon fixation through photosynthesis (High NPP).

  • Warm humid conditions speed up the decomposition of dead organic material via fungi and bacteria and a quick release of CO2.

Key points: Large scale: High levels of net primary productivity lead to high biomass in tropical rainforests and as a result, carbon storage is high in trees.

  • Carbon exchanges between the atmosphere, biosphere, and soil are rapid

  • Rates of carbon fixation through photosynthesis are high

  • Rapid breakdown and recycling of organic material. 

  • Amazon Rainforest major global reservoir of global carbon-absorbing 2.4 Billion tonnes per year

  • Net Primary Productivity (NPP) is high, on average 2500 grams/m2/year

  • Carbon stored in biomass – 400-700 tonnes/hectare  and Soil Carbon Stores 90-200 tonnes/ha 

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physical factors affecting the carbon cycle

Temperature: High temperatures lead to rapid vegetation growth due to the high rates of photosynthesis which leads to the large biomass of the Amazon; this stores approximately 100 Billion tonnes of Carbon. High temperatures accelerate most of the processes such Photosynthesis, decomposition, evaporation, transpiration…

Vegetation: 60% of rainforest carbon is stored in the above-ground biomass of trees. Large amounts of water and carbon are therefore stored in the vegetation within the Amazon rainforest. Large amounts of vegetation increase the interception rate, slowing how much precipitation reaches the ground, vegetation increases the amount of leaf litter which increases infiltration. Vegetation increases the lag time on the hydrograph as it slows waters journey to the river.

Organic Matter in Soil: Leaf litter and dead organic matter accumulate temporarily at the soil surface. There is rapid decomposition and minerals are quickly taken up in the tree root systems. CO2 is emitted and returned to the atmosphere.

Mineral composition of rocks: Carbonates are largely absent from the mineral composition of the igneous and metamorphic rocks of the Amazon Basin. Close to the Andes in the west there are outcrops of limestone which form a significant regional carbon store.

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the main causes of deforestation

  1. Cattle ranching: 65%

  2. Slash and burn subsistence agriculture: 20%

  3. Commercial agriculture: 10%

  4. Logging: 2-3%

  5. Mining, roads, urbanisation, dams: 1-2

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human factors affecting the water cycle

In tht the upper maderia drainage basin human activity has changed flows and stores.  Deforestation has reduced water storage in trees, soils which have been eroded, permeable rocks due to more rapid runoff and in the atmosphere. At the same time, fewer trees mean less evapotranspiration and so less precipitation. Runoff and speed of runoff has increased meaning higher flood risk.

defor deforestation has a huge impact on the water cycle & has the potential to change the climate at local & regional scales. Converting rainforest to grassland increases run-off by a factor of 27, and half of all rain falling on grassland goes directly into rivers. Rainforest trees are a crucial part of the water cycle, extracting moisture from the soil, intercepting rainfall & releasing it to the atmosphere through transpiration, as well as stabilizing forest albedo & ground temperatures. This cycle sustains high atmospheric humidity which is responsible for cloud formation & heavy convectional rainfall. Deforestation breaks this cycle & can lead to permanent climate change.

The impact of deforestation on water cycles is not just local. Projections of future deforestation in Amazonia predict a 20% decline in regional rainfall as the rainforest dries out & forest trees are gradually replaced by grassland. Nor is it just deforested areas that experience a reduction in rainfall: disruption of the regional water cycle means that forests hundreds of kilometers downwind of degraded sites are affected too.

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human factors affecting the carbon cycle

Present-day deforestation is most severe in the tropical rainforest. In the primary rainforest, unaffected by human activity, the biomass of trees represents about 60% of all carbon in the ecosystem. The above-ground carbon biomass in the rainforest is approximately 180 tonnes/ha. Most of the remaining carbon is found in the soil as roots & dead organic material. Deforestation exhausts the carbon biomass store. Croplands & pasture contain only a small amount of carbon compared to forest trees. For example, the biomass of grasslands in areas of former rainforest is 16.2tonnes/ha, & soya cultivation it is just 2.7tonnes/ha. At the same time deforestation drastically reduces inputs of organic material to the soul. Soils depleted of carbon & exposed to strong sunlight, support fewer decomposer organisms, thus reducing the flow of carbon from the soil to the atmosphere.

In tropical rainforests, the principal store of plant nutrients such as calcium, potassium & magnesium is forest trees. Rainforest soils contain only a small reservoir of essential nutrients & the forest is only sustained by a rapid nutrient cycle. Deforestation destroys the main nutrient store – the forest trees - & removes most nutrients from the ecosystem. Nutrients no longer taken up by the root systems of trees are washed out of soils by rainwater; & soils without the protective cover of trees, are quickly eroded by run-off.

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strategies to manage tropical rainforests

  • Protection through legislation

  • Improving agriculture techniques

  • Projects to reforest area

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