Combustion completeness and sample location determine wildfire ash leachate chemistry
Loading...
Date
2024-05-21
Journal Title
Journal ISSN
Volume Title
Publisher
American Geophysical Union
Abstract
Understanding past fire regimes and how they vary with climate, human activity, and vegetation patterns is fundamental to the mitigation and management of changing fire regimes as anthropogenic climate change progresses. Ash‐derived trace elements and pyrogenic biomarkers from speleothems have recently been shown to record past fire activity in speleothems from both Australia and North America. This calls for an empirical study of ash geochemistry to aid the interpretation of speleothem palaeofire proxy records. Here we present analyses of leached ashes collected following fires in southwest and southeast Australia. We include a suite of inorganic elemental data from the water‐soluble fraction of ash as well as a selection of organic analytes (pyrogenic lipid biomarkers). We also present elemental data from leachates of soils collected from sites in southwest Australia. We demonstrate that the water‐soluble fraction of ash differs from the water‐soluble fraction of soils, with trace and minor element concentrations in ash leachates varying with combustion completeness (burn severity) and sample location. Changes in some lipid biomarker concentrations extracted from ashes may reflect burn severity. Our results contribute to building a process‐based understanding of how speleothem geochemistry may record fire frequency and severity, and suggest that more research is needed to understand the transport pathways for the inclusion of pyrogenic biomarkers in speleothems. Our results also demonstrate that potential contaminant loads from ashes are much higher than from soils, with implications for the management of karst catchments, which are a critical water resource. © 2024 The Author(s). Geochemistry,Geophysics, Geosystems published by Wiley Periodicals LLC on behalf of American Geophysical Union. This is an open access article under the terms of the Creative Commons Attribution License, which permits use,distribution and reproduction in any medium, provided the original work is properly cited
Description
Keywords
Fires, Leachates, Chemistry, Climatic change, Australia, Ash content, Geochemistry, Soils, Natural disasters, Caves, Rain Water
Citation
Campbell, M., Treble, P. C., McDonough, L. K., Naeher, S., Baker, A., Grierson, P. F., Wong, H., & Andersen, M. S. (2024). Combustion completeness and sample location determine wildfire ash leachate chemistry. Geochemistry, Geophysics, Geosystems, 25(5), e2024GC011470. doi:10.1029/2024GC011470