Presentation Biogeochemistry

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Black Carbon

• Presentation Biogeochemistry

Gustafsson and Gschwend, 1997. Masiello, Druffel
and Currie, 2002. Middelburg, Nieuwenhuize and
Van Breugel, 1999. Mitra, Bianchi, McKee and
Sutula, 2002. Schmidt and Noack, 2000.
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Black carbon
Black Carbon
Highly condensed carbonaceous residue from
incomplete combustion processes Soot, charcoal,
char and elemental carbon
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Unit and Structure BC
Black Carbon
Schmidt and Noack, 2000
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Identification techniques
Black Carbon

• Optical
• Thermal
• Chemical
• Spectroscopic
• Molecular marker

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Compare 2 techniques
Black Carbon

• Thermal oxidation/HCl method for soot
• Thermal oxidation/HNO3 method for charcoal

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Relation 2 techniques
Black Carbon
Middelburg, Nieuwenhuize and Van Breugel, 1999
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Relation with oc, sc and charcoal
Black Carbon
Middelburg, Nieuwenhuize and Van Breugel, 1999
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Unidentified fraction OC
Black Carbon
Middelburg, Nieuwenhuize and Van Breugel, 1999
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Identification techniques
Black Carbon

• Optical
• Thermal
• Chemical
• Spectroscopic
• Molecular marker

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Black Carbon
Masiello, Druffel and Currie, 2002
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Black Carbon
Masiello, Druffel and Currie, 2002
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Degradation
Black Carbon

• Assumed to be inert because
• Identified in sediments of 65 Ma
• Down-core trend in size distribution
• It reacts very slow towards chemical oxidation
• Chemical and microbial mechanisms unknown

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Biogeochemical processes
Black Carbon

• BC is sink in global carbon cycle
• Affect the Earths radiative heat balance
• Catalytic effects on chemical reactions
• Tracer for Earths fire history
• Paleo-atmospheric oxygen concentrations

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Geological time table
Black Carbon
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Global Biogeochemical Cycle of BC
Black Carbon
Schmidt and Noack, 2000
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Flux calculation for the continental shelf
Black Carbon

• Sedimentation rates
• Observed surface BC inventories
• BC concentrations
• Area of the shelf region

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Determination sedimentation rates
Black Carbon
Gustafsson and Gschwend, 1998
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Comparison fluxes BC
Black Carbon
Gustafsson and Gschwend, 1998
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Global Biogeochemical Cycle of BC
Black Carbon
Schmidt and Noack, 2000
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Mississippi River BC input
Black Carbon

• Thermal oxidation followed by acidification
• Discharge in 1999 was 4,810-4 Pg
• 5 of total BC in oceanic and coastal sediments
• Santa Clara River 5,410-5 Pg

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Conclusion
Black Carbon

• Analyses of BC remains with uncertainties
• Degradation
• Effect of BC on the global carbon cycle has to be
  quantified