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Carbon cycles lecture
 

Carbon cycles lecture

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by Dr. Xiaoming Zu, UPR Rio Piedras 2010

by Dr. Xiaoming Zu, UPR Rio Piedras 2010

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    Carbon cycles lecture Carbon cycles lecture Presentation Transcript

    • Carbon Cycles
      Xiaoming Zou
      Institute for Tropical Ecosystem Studies, University of Puerto Rico
    • Carbon cycles
      Carbon cycles
      Ocean
      Structure and properties
      Carbon distribution
      Atmosphere
      Structure and properties
      Carbon distribution
      Land
      Structure and properties
      Carbon distribution
      Global carbon cycles
      • Mechanisms for carbon stabilization and destabilization
      • Global environmental changes
      • Natural rhythms and disturbances
      • Climate
      • Geological events
      • Anthropogenic influence
      • Land use
      • Fossil fuel combustion
      • Fertilizers and pollutants
    • Ocean Structure and Properties
      Physical properties
      70% of earth surface
      0.02% of earth mass
      97% of total water on earth
      Twice as much area in the Southern Hemisphere as in the Northern Hemisphere
      Euphotic zone 50-100 m, surface ocean
      Deep ocean, up to an average of 4000 m
    • Ocean Structure and Properties
      Ocean circulation
      Surface water
      Well mixed
      Warm water
      Little change in temperature
      Movement caused by wind
      Earth rotation drives surface current from east to west along the equator
      Mean residence time 1700 years
    • Ocean Structure and Properties
      Ocean circulation
      Deep water
      Stratified
      Cold water with an average temperature of 3 C
      Sharp decrease in temperature in the thermocline, stable temperature further deeper
      Movement caused by water density and salinity
      Mean residence time 34000 years
    • Carbon Distribution in Ocean
    • Structure and Properties of the Atmosphere
      Structure and physical properties
      Troposphere (0-10 km)
      Stratosphere (10-50 km)
      Temperature
      Pressure (log P = - 0.06 A)
      Density
    • Global circulation
      Occurs in troposphere
      Upward near equator and at 60 degrees of latitude
      Downward at 30 and 90 degrees of latitude
      Structure and Properties of the Atmosphere
    • Carbon Distribution in Atmosphere
    • Atmospheric CO2 was much higher 390 M yrs ago than now
    • Lignin was evolved first in ferns 390 M yrs ago
      With lignin, plants could grow much taller and root deeply
    • Lignin decomposers were evolved at least 50 M yrs later
      Most coal formed during this mismatch
      between lignin producers and decomposers.
    • Before combustion of fossil fuel for more than 650 thousand years, atmospheric CO2 has fluctuated between180 and 300 parts per million.
    • Now things are changing again,mostly from the burning of fossil fuels.
    • Structure and Properties of Land
    • Carbon Distribution on Land
      Light
      Altitude
      Latitude
      Aspects
      Water
      Nutrients
    • Carbon Distribution on Land
    • Global Carbon Cycle
      Pools
      Atmosphere 750 x 10^15 g
      Ocean water 38,000 x 10^15 g
      Plant biomass 560 x 10^15 g
      Soil organic matter and soil biomass 1,500 x 10^15 g
      Total active pool: 40,000 x 10^15
      Organic sediments 1.56 x 10^22 g
      Inorganic sediments 6.5 x 10^22 g
    • Global Carbon Cycle
      Fluxes
      Terrestrial GPP 120 x 10^15 g/y
      Ocean GPP 92 x 10^15 g/y
      Terrestrial Rp 60 x 10^15 g/y
      Terrestrial Rd 60 x 10^15 g/y
      Deforestation 0.9 x 10^15 g/y
      Anthropogenic 6 x 10^15 g/y
      Ocean R 90 x 10^15 g/y
      River flow 0.8 x 10^15 g/y
    • Global Carbon Cycle
      Residence time
      Atmosphere: 750/152 = 4.9 years
      Plant biomass: 560/60 = 9.3 years
      Soil organic C: 1500/60 = 25 years
      Surface ocean: 1020/90 = 11.3 years
      Entire ocean: 3800/90 = 422
    • Mechanisms for Carbon Stabilization and Destabilization
      Reduction in decomposition of organic carbon
      Litter quality with high lignin content
      Land management (reduced earthworms, reduced O2 levels, increased N input, etc)
      Reduction in deforestation and combustion of fossil fuel
      Increase in primary productivity
      Iron fertilization in ocean
      Chemical fertilizers in land
      N2 fixation
      Increase inorganic carbon pool
      Increase ocean water pH
      Reduced acid rain
    • Greenhouse Effect
      1951-1997
      Carbon dioxide (70%), nitrous oxide, methane (23%), ozone, chlorofluorocarbons (CFCs), and water vapor
      A molecule of methane is 21 times more potent than a molecule of carbon dioxide as a heat-trapping gas
      Vegetation has migrated since postglacial warming, but has failed to keep pace with changing climate because the greenhouse effect waarms 50-100 times faster than postglacial warming
    • “Double loop" model of SOM dynamics
      CO2
      Non-lignin
      decomposers
      Geochemical processes
      Non-lignin decomposers
      Lignolytic
      Microbes
      Physical
      Protection
      Slow C
      Active C
      Passive C
      Labile C decomposing
      Microbes
      Chemical
      bonding
      Lignolytic
      Microbes
      Microbial C
      Geochemical processes
      LOC/N control
    • Global Environmental ChangesNatural rhythms
    • Global Environmental ChangesHuman Activities
      1980
      1994