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.

Black carbon

Highly condensed carbonaceous residue from

incomplete combustion processes

Soot, charcoal, char and elemental carbon

Unit and Structure BC

Schmidt and Noack, 2000

Identification techniques

• Optical

• Thermal

• Chemical

• Spectroscopic

• Molecular marker

Compare 2 techniques

• Thermal oxidation/HCl method for soot

• Thermal oxidation/HNO3 method for charcoal

Relation 2 techniques

Middelburg, Nieuwenhuize and Van Breugel, 1999

Relation with oc, sc and charcoal

Middelburg, Nieuwenhuize and Van Breugel, 1999

Unidentified fraction OC

Middelburg, Nieuwenhuize and Van Breugel, 1999

Identification techniques

• Optical

• ThermalThermal

• Chemical

• Spectroscopic

• Molecular marker

Masiello, Druffel and Currie, 2002

Masiello, Druffel and Currie, 2002

Degradation

• 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

Biogeochemical processes

• BC is sink in global carbon cycle

• Affect the Earth’s radiative heat balance

• Catalytic effects on chemical reactions

• Tracer for Earth’s fire history

• Paleo-atmospheric oxygen concentrations

Geological time tableCenozoic Era Quarternary Period Holocene Epoch

Pleistocene Epoch

Tertiary Period Pliocene Epoch

Miocene Epoch

Oligocene Epoch

Eocene Epoch

Paleocene Epoch

Mesozoic Era Cretaceous Period

Jurassic Period

Triassic Period

Paleozoic Era Permian Period

Carboniferous Period

Devonian Period

Silurian Period

Ordovician Period

Cambrium Period

Global Biogeochemical Cycle of BC

Schmidt and Noack, 2000

Flux calculation for the continental shelf

• Sedimentation rates

• Observed surface BC inventories

• BC concentrations

• Area of the shelf region

Determination sedimentation rates

Gustafsson and Gschwend, 1998

Comparison fluxes BC

Gustafsson and Gschwend, 1998

Global Biogeochemical Cycle of BC

Schmidt and Noack, 2000

Mississippi River BC input

• Thermal oxidation followed by acidification

• Discharge in 1999 was 4,8*10-4 Pg

• 5% of total BC in oceanic and coastal sediments

• Santa Clara River 5,4*10-5 Pg

Conclusion

• Analyses of BC remains with uncertainties

• Degradation

• Effect of BC on the global carbon cycle has to be quantified