What on Earth have we been burning? Deciphering sedimentary records of pyrogenic carbon

Hanke, U. M. et al. (2017) What on Earth have we been burning? Deciphering sedimentary records of pyrogenic carbon. Environmental Science and Technology, 51(21), pp. 12972-12980. (doi: 10.1021/acs.est.7b03243) (PMID:28994589)

Abstract

Humans have interacted with fire for thousands of years, yet the utilization of fossil fuels marked the beginning of a new era. Ubiquitous in the environment, pyrogenic carbon (PyC) arises from incomplete combustion of biomass and fossil fuels, forming a continuum of condensed aromatic structures. Here we develop and evaluate 14C records for two complementary PyC molecular markers, benzene-polycarboxylic-acids (BPCAs) and polycyclic-aromatic-hydrocarbons (PAHs) preserved in aquatic sediments from a sub-urban and a remote catchment in the United States (U.S.) from mid-1700s to 1998. Results show that the majority of PyC stems from local sources and is transferred to aquatic sedimentary archives on sub-decadal to millennial time scales. Whereas a small portion stems from near-contemporaneous production and sedimentation, the majority of PyC (<90%) experiences delayed transmission due to ‘pre-aging’ on millennial timescales in catchment soils prior to its ultimate deposition. BPCAs (soot) and PAHs (precursors of soot) trace fossil fuel-derived PyC. Both markers parallel historical records of the consumption of fossil fuels in U.S., yet never account for more than 19% total PyC. This study demonstrates that isotopic characterization of multiple tracers is necessary to constrain histories and inventories of PyC, and that sequestration of PyC can markedly lag its production.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Mcintyre, Dr Cameron
• Authors: Hanke, U. M., Reddy, C. M., Braun, A. L.L., Coppola, A., Haghipour, N., McIntyre, C. P., Wacker, L., Xu, L., Mcnichol, A., Abiven, S., Schmidt, M. W.I., and Eglinton, T. I.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Environmental Science and Technology
• Publisher: American Chemical Society
• ISSN: 0013-936X
• ISSN (Online): 1520-5851
• Published Online: 10 October 2017
• Copyright Holders: Copyright © 2017 American Chemical Society
• First Published: First published in Environmental Science and Technology 51(21):12972-12980
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher.