Community Bibliography

The transformation and mobility of charcoal black carbon in a fire-impacted watershed

Author(s): A.M. Grannas, W.C. Hockaday, S. Kim, P.G. Hatcher
Year of Publication: 2007
Journal Title: Geochimica et Cosmochimica Acta
ISSN: 0016-7037
Volume: 71
Issue: 14
Date Name: 2007
Start Page: 3432
Abstract: The incomplete combustion of fossil fuels and biomass has resulted in the global-scale distribution and accumulation of black carbon (BC) in the environment. Recently, the molecular identity of BC in the dissolved phase has been distinguished from that of natural organic matter. However, many of the processes that control BC cycling remain unidentified. We investigate changes in soil charcoal particle morphology and chemical composition using surface area analysis, scanning electron
microscopy, energy dispersive X-ray spectroscopy, chemical oxidation, and 13C NMR spectroscopy. A comparison of soil charcoals differing in age by 100 years shows that aged charcoal has lower specific surface areas, higher BC/OC ratios, direct associations with soil minerals and microbial biomass, and a greater abundance of non-aromatic carbon. The water-soluble portion of soil charcoal and dissolved organic matter (DOM) from the watershed were also characterized by electrospray ionization mass spectrometry. Aqueous charcoal extracts are comprised mostly of condensed aromatic ring structures (CARS)
which are also present in soil pore, river, and ground water samples. We present indirect evidence and a chemical rationale for a microbial BC dissolution mechanism. Furthermore, the speciation of CARS in the soil solution versus river and ground water provides molecular evidence of reactivity in the dissolved phase. The dissolution and export of soil BC are presently unmeasured fluxes with important implications for the global carbon cycle.
End Page: 3445
Subjects: POLYCYCLIC AROMATIC-HYDROCARBONS
FUNGUS SPOROTRICHUM-PULVERULENTUM
HUMIC ACIDS
BLACK CARBON
STATE C-13 NMR
WHITE-ROT FUNGUS
CHEMICAL-COMPOSITION
MARINE-SEDIMENTS
GEOCHEMISTRY & GEOPHYSICS
NATURAL ORGANIC-MATTER
MASS-SPECTROMETRY
Digital Object Identifier: 10.1016/j.gca.2007.02.023
Link to Full Text: Full Text