TY - JOUR
T1 - Fire distinguishers
T2 - Refined interpretations of polycyclic aromatic hydrocarbons for paleo-applications
AU - Karp, Allison T.
AU - Holman, Alex I.
AU - Hopper, Peter
AU - Grice, Kliti
AU - Freeman, Katherine H.
N1 - Funding Information:
We gratefully acknowledge funding for this work provided to ATK from the Pennsylvania State Global Programs through a Graduate Student Travel Grant and the European Association of Organic Geochemists (EAOG) through the 2018 EAOG Research Award. ATK was supported by a National Science Foundation (NSF) Graduate Research Fellowship under Grant No. DGE1255832 . ATK thanks Sarah Ivory, Elizabeth Hajek, Mark Patzkowsky, and Erica Smithwick for constructive feedback on this manuscript. KG thanks the Australian Research Council (ARC) for support of a Discovery Outstanding Research Award for the burn experiments (#DP130100577) and ARC infrastructure grant # LE110100119 for compound specific equipment. The authors acknowledge Christiane Vitzthum von Eckstaedt and Caroline Jaraula for performing controlled burn experiments at Curtin University. We thank three anonymous reviewers for constuctive comments and suggestions that greatly improved this manuscript.
Funding Information:
We gratefully acknowledge funding for this work provided to ATK from the Pennsylvania State Global Programs through a Graduate Student Travel Grant and the European Association of Organic Geochemists (EAOG) through the 2018 EAOG Research Award. ATK was supported by a National Science Foundation (NSF) Graduate Research Fellowship under Grant No. DGE1255832. ATK thanks Sarah Ivory, Elizabeth Hajek, Mark Patzkowsky, and Erica Smithwick for constructive feedback on this manuscript. KG thanks the Australian Research Council (ARC) for support of a Discovery Outstanding Research Award for the burn experiments (#DP130100577) and ARC infrastructure grant # LE110100119 for compound specific equipment. The authors acknowledge Christiane Vitzthum von Eckstaedt and Caroline Jaraula for performing controlled burn experiments at Curtin University. We thank three anonymous reviewers for constuctive comments and suggestions that greatly improved this manuscript.
Publisher Copyright:
© 2020 Elsevier Ltd
PY - 2020/11/15
Y1 - 2020/11/15
N2 - Polycyclic aromatic hydrocarbons (PAHs), produced via incomplete combustion of organics, convey signatures of vegetation burned in the geologic past. New and published burn experiments reveal how the quantity, distributions, and isotopic abundances of fire-derived PAHs were influenced by fuel types, burn conditions, and also phase. PAH concentrations were higher in burn residues from moderate burn temperatures (400–500 °C), and significantly lower in residues from cooler (<300 °C) or hotter (>600 °C) conditions, especially when oxygen was limited. PAH forms tended to be smaller in smoke samples and larger in residues, consistent with molecular physical and chemical properties. Plant functional types were distinguished by relative amounts of retene and dimethyl phenanthrene isomers. Isotopically distinct photosynthetic pathways of the burned material were reflected in the δ13C values of PAHs, which faithfully captured biomass signatures as well as the ∼12‰ offset between C3 and C4 plant types. PAH size, alkylation, and isotope characteristics can differentiate combusted plant types and distinguish between air-borne and sedimentary transport mechanisms. New proxy approaches using PAH amounts, distributions, and isotope signatures can aid and refine interpretations of paleofire ecology in the geologic record.
AB - Polycyclic aromatic hydrocarbons (PAHs), produced via incomplete combustion of organics, convey signatures of vegetation burned in the geologic past. New and published burn experiments reveal how the quantity, distributions, and isotopic abundances of fire-derived PAHs were influenced by fuel types, burn conditions, and also phase. PAH concentrations were higher in burn residues from moderate burn temperatures (400–500 °C), and significantly lower in residues from cooler (<300 °C) or hotter (>600 °C) conditions, especially when oxygen was limited. PAH forms tended to be smaller in smoke samples and larger in residues, consistent with molecular physical and chemical properties. Plant functional types were distinguished by relative amounts of retene and dimethyl phenanthrene isomers. Isotopically distinct photosynthetic pathways of the burned material were reflected in the δ13C values of PAHs, which faithfully captured biomass signatures as well as the ∼12‰ offset between C3 and C4 plant types. PAH size, alkylation, and isotope characteristics can differentiate combusted plant types and distinguish between air-borne and sedimentary transport mechanisms. New proxy approaches using PAH amounts, distributions, and isotope signatures can aid and refine interpretations of paleofire ecology in the geologic record.
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U2 - 10.1016/j.gca.2020.08.024
DO - 10.1016/j.gca.2020.08.024
M3 - Article
AN - SCOPUS:85090573715
SN - 0016-7037
VL - 289
SP - 93
EP - 113
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
ER -