Geography, carbon exchanges

Photosynthesis

respiration: process in which carbohydrates fixed in photosynthesis are converted to CO2 and water

decomposition: organism such as bacteria and fungi breakdown dead organic matter

combustion (natural and fossil fuel): occurs when organic material reacts or burns in the presence of oxygen.

weathering: in situ breakdown of rocks at or near the earths surface by chemical, physical + biological processes

precipitation

how the stores are affected:

  • atmospheric CO2 dissolves in rainwater to form weak carbonic acid.
  • rising concentrations of CO2 in the atmosphere, due to anthropocentric emissions, increased acidity of rainfall

how the stores are affected:

  • Respiration absorbs oxygen and releases CO2, increasing the atmospheric carbon store

how the stores are affected:

  • long, cold winters slow the decomposition of forest litter which builds up on forest floor.
  • fire shifts this log jam, freeing carbon and nutrient previously inaccessibly to forest trees
  • opens up forest canopy, creating new habitats and increasing biodiversity
  • affected by human activity, deliberate firing of forests for land cultivation or improve quality of grazing
  • combustion of fossil fuels: consumption continues to grow despite efforts

how the stores are affected: most weathering involves rainwater which contains dissolved CO2, derived from the soil as well as the atmosphere.

how the stores are affected:

  • using the suns energy, CO2 from the atmosphere + water, green plants + marine phytoplankton convert light energy to chemical energy (glucose) through the process of photosynthesis
  • plants use energy in the form of glucose to maintain growth, reproduction + other life processes.
  • releases CO2 to the atmosphere in respiration

photosynthesis = 6CO2 + 6H2O --> C6H120\6 + 6O2

carbonation =CaCO3 + H2CO6 --> Ca(HCO3)2

respiration = CH2O + O2 =CO2 + H2O + energy

magnitude of the process: - volume of carbon exchanged by respiration + photosynthesis each year is 1000x greater than that moving through the slow carbon cycle

magnitude of the process

how the stores are affected: extracting energy and releasing CO2 to the atmosphere and mineral nutrients to the soil.

the flux of carbon from the atmosphere --> terrestrial biomass (land, plants + phytoplankton) via photosynthesis

terrestrial biomass --> atmosphere

terrestrial biomass --> atmosphere

magnitude of the process: 120 GT year

human activity --> atmosphere

sedimentary rocks --> atmosphere

atmosphere --> sedimentary rocks

  • rainwater is a weak carbonic acid, slowly dissolves limestone + chalk in a process --> carbonation
  • process most effective beneath a soil cover because the higher concentration of CO2 soil = highly acidic

carbonation: releases carbon from limestones to streams, rivers, oceans and the atmosphere.

magnitude of process:

  • chemical weathering = 0.3bn tonnes of carbon atmosphere --> oceans every year
  • physical; weathering by freeze-thaw breaks rocks down into smaller particles, involves no chemical changes - increases area exposed to chemical attack
  • biological weathering by chelation, contribute to rock breakdown

magnitude of the process:

  • rates of decomposition depend on climatic conditions
  • faster rates occur in warm, humid env (tropical rain forest)
  • slower rates occurs in cold env (tundra or drylands like tropical deserts)

releases CO2 as well as sulphur dioxide and nitrogen oxygen etc.

magnitude of process (burning of fossil fuels): - transfers nearly 10 GT a year from geological store to the atmosphere, oceans + biosphere

terrestrial biomass --> soil

terrestrial biomass (via natural forest fires) --> atmosphere