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Post on 22-Dec-2015
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Figure 54-14
THE GLOBAL CARBON CYCLE
Organisms, chemicalprocesses in ocean:
40,000
All values in gigatons of carbon per year Atmosphere: 778 (during 1990s)
Net uptake viaphotosynthesisby plants: 3.0
Net uptake viaphotosynthesis,
chemical processes: 1.5
Rivers (erosion):0.8
Organisms, soil,litter, peat: 2190
Aquatic ecosystems Terrestrial ecosystems Human-induced changes
Land-use change(primarily deforestation):
1.6Fossil-fuel use:
6.3
Land use
Fossil fuel use
Year
An
nu
al f
lux
of
carb
on
(10
15g
)
6
5
4
3
2
1
01860 1880 1900 1920 1940 1960 1980
Figure 51.12a
Human-induced increases in CO2 flux over time
0–100100–200200–400400–600600–800>800
Productivity ranges (g/m2/yr)
Figure 51.3a
Terrestrial productivity
Figure 54-16
THE GLOBAL NITROGEN CYCLE
Nitrogen-fixingcyanobacteria: 15
All values in gigatons of nitrogen per year
Atmospheric nitrogen (N2)
Protein andnucleic acidsynthesis
Bacteria in muduse N-containingmolecules as energysources, excrete N2: 310
Decomposition ofdetritus into ammonia
Internal cycling:
1200
Industrialfixation: 100
Lightningand rain: 3
Internalcycling:
8000
Permanent burial: 10
Runoff: 36
Mud
Nitrogen-fixing bacteriain roots and soil: 202