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| Titel |
Pyrogenic carbon from tropical savanna burning: production and stable isotope composition |
| VerfasserIn |
G. Saiz, J. G. Wynn, C. M. Wurster, I. Goodrick, P. N. Nelson, M. I. Bird |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 6 ; Nr. 12, no. 6 (2015-03-20), S.1849-1863 |
| Datensatznummer |
250117872
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| Publikation (Nr.) |
 copernicus.org/bg-12-1849-2015.pdf |
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| Zusammenfassung |
| Widespread burning of mixed tree–grass ecosystems represents the major
natural locus of pyrogenic carbon (PyC) production. PyC is a significant,
pervasive and yet poorly understood "slow-cycling" form of carbon present
in the atmosphere, hydrosphere, soils and sediments. We conducted 16
experimental burns on a rainfall transect through northern Australian
savannas with C4 grasses ranging from 35 to 99% of total biomass.
Residues from each fire were partitioned into PyC and further into
recalcitrant (HyPyC) components, with each of these fluxes also partitioned
into proximal components (>125 μm), likely to remain close to the site of
burning, and distal components (<125 μm), likely to be transported from the
site of burning. The median (range) PyC production across all burns was 16.0
(11.5) % of total carbon exposed (TCE), with HyPyC accounting for 2.5
(4.9) % of TCE. Both PyC and HyPyC were dominantly partitioned into the
proximal flux. Production of HyPyC was strongly related to fire residence
time, with shorter duration fires resulting in higher HyPyC yields. The
carbon isotope (δ13C) compositions of PyC and HyPyC were generally
lower by 1–3‰ relative to the original biomass, with marked
depletion up to 7‰ for grasslands dominated by C4 biomass.
δ13C values of CO2 produced by combustion were computed by mass
balance and ranged from ~0.4 to 1.3‰. The depletion of
13C in PyC and HyPyC relative to the original biomass has significant
implications for the interpretation of δ13C values of savanna soil
organic carbon and of ancient PyC preserved in the geologic record, as well
as for global 13C isotopic disequilibria calculations. |
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