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The processes of the carbon cycle (Weathering (rain water mixed with dead…
The processes of the carbon cycle
Precipitation
atmospheric CO2 dissolves in rainwater
forms weak carbonic acid
increase of CO2 in the atmosphere (due to
anthropogenic
emissions have increased the acidity
the increased acidity has contributed to increased acidity in the ocean surface
#
potenially harmful effects on marine life
CO2 +H2O -> H2CO3
important for both fast + slow
slow: sequestration
Fast: water is key for humans + animals
photosynthesis
the flux of carbon form the atmosphere to land plants and phytoplankton is around 120 GT per yr.
using sun energy CO2 is used to convert light energy to glucose
plants use glucose to maintain growth, reproduction and other life processes
in doing so they release O2
CO2 + H2O -> (sun's energy and chlorophyll)= sugars + O2
Weathering
most weathering involves rainwater (which contains dissolved CO2
the rainwater slowly dissolves limestone and chalk (called carbonation)
carbonation releases carbon from limestones to streams, rivers, oceans and the atmosphere
the process is most effective beneath soil cover because higher concentrations of CO2 in the soils makes rainwater highly acidic
chemical weathering transfers 0.3 bil tons of carbon
e.g. Norber Brow in Yorkshire dales (limestone surface has been lowered by a half and into the past 13,000 yrs.
physical weathering increases the surface area exposed to chemical attack
rain water mixed with dead and decaying material in the soil form humid acids which is how rock minerals
process is important humid environments where decomposition is rapid + forest trees provide abundant leaf litter
respiration
process in which carbohydrates fixed in photosynthesis are converted to CO2 and water
plants + animals absorb oxygen which 'burns' these carbs and provides energy needed for metabolism + growth.
reverse of photosynthesis
respiration absorbs oxygen and releases carbon
respiration and photosynthesis are the most important processes in the fast carbon cycle
The volume of carbon exchanged by respiration and photosynthesis each yr. is 1000x great that that moving through the slow carbon cycle
Glocose (C6H12O6)+ 6O2 -> 6CO2 + 6H2O + Energy (ATP)
Decomposition
decomposer organisms such as fungi + bacteria breakdown dead organic matter, extract energy + release CO2 to the atmo and mineral nutrients to the soil
the fastest rates occur in warm, humid environments (e.g. rainforests)
In colder climates decomposition is slower
combustion
occurs when organic material reacts or burns in the presence of oxygen
releases CO2 as well as other gases
is a natural fuel used in many ecosystems
Wildfire caused by lightning strikes are essential of the health of some ecosystems
in long, cold winters slow the decomposition process leaving forest litter
the fires destroys the litter on the forest floor freeing up carbon and nutrients previously inaccessible to trees
also opens up the forest canopy creating new habitats and increasing biodiversity
also result from human activity
e.g. deliberate forest fires to clear space for cultivation
most important is the fossil fuels
despite international efforts to curb CO2 emissions ect. the global economy and their consumption continues to grow
Currently the burning of fossil fuels transfers nearly 10 GT of CO2 a yr. from geological store to the atmo, oceans and biosphere