Using charcoal, ATR FTIR and chemometrics to model the intensity of pyrolysis: Exploratory steps towards characterising fire events

• DOI: 10.1016/j.scitotenv.2021.147052
• Publication Date: 2021-04-13T08:38:26Z
• Authors: Mark Constantine; Scott Mooney; Brynn Hibbert; Chris Marjo; Michael Bird; Tim Cohen; Matt Forbes; Anna McBeath; Anne Rich; John Stride
• Keywords: anzsrc-for: 3709 Physical Geography and Environmental Geoscience; 550; anzsrc-for: 3702 Climate Change Science; 37 Earth Sciences; 3705 Geology; anzsrc-for: 37 Earth Sciences; anzsrc-for: 3705 Geology; 3709 Physical Geography and Environmental Geoscience; 41 Environmental Sciences; 15. Life on land; 3702 Climate Change Science; 01 natural sciences; 333; Fire intensity; anzsrc-for: 41 Environmental Sciences; 13. Climate action; Fire severity; Pyrolysis; 0105 earth and related environmental sciences

This study describes a multivariate statistical model (derived using partial least squares regression, PLS-R) that derives charring intensity (reaction temperature and duration) from the attenuated total reflectance (ATR) Fourier Transform Infrared (FTIR) spectra of charcoal. Data for the model was obtained from a library of charcoal samples produced under laboratory conditions at charring intensities (CI) relevant to wildfires and a series of feedstocks representing common tree species collected from Australia. The PLS-R model developed reveals the potential of FTIR to determine the charring intensity of charcoal. Though limited by the differences between laboratory-produced charcoal and the more heterogeneous and less-structured charcoal produced in a wildfire, the method was tested against fossil charcoal from a well-dated sediment core collected from Thirlmere Lakes National Park, Australia and showed a distinct change in CI that can be related to other climatic and environmental proxies. We suggest that the method has the potential to offer insights into the conditions under which natural charcoal is formed including the modelling of charring intensities of fossil charcoal samples isolated from sediments, archaeological applications or characterisation of contemporary fire events from charcoal in soils.