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