2024-03-28T08:53:11Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/1631562019-08-06T09:27:07Zcom_10261_77com_10261_8com_10261_15com_10261_6col_10261_456col_10261_394
DIGITAL.CSIC
author
Vega Hidalgo, José A.
author
Fernández Filgueira, Cristina
author
Fontúrbel Lliteras, Mª Teresa
author
Jiménez Morillo, N. T.
author
Almendros Martín, Gonzalo
author
González-Pérez, José Antonio
funder
Ministerio de Economía y Competitividad (España)
2018-04-04T12:33:43Z
2018-04-04T12:33:43Z
2017-10-03
15as Jornadas de Análisis Instrumental (15 JAI), 3–5 octubre 2017 Barcelona
http://hdl.handle.net/10261/163156
http://dx.doi.org/10.13039/501100003329
To operationally characterize soil burn severity (SBS) in the field, a 5-level classification was proposed for temperate climate areas in forests and scrublands, useful in assessing post-fire erosion risks and to plan post-fire rehab activities [1]. In fact, this SBS classification is an operational tool currently used by forest managers [2]. This work describes the relationships between field SBS and molecular-level changes in the soil
organic matter (SOM). Direct analytical pyrolysis (Py-GC/MS, 400 ºC) [3] was used to study fireaffected soils under different SBS (1 to 5) at two scenarios: 1) burnt in the field by a wildfire, and 2) monoliths burnt experimentally in semi-natural conditions. Unburnt soils (SBS-0) were also studied. More than 100 pyrolysis compounds were identified and total abundances plotted in modified 3D van Krevelen diagrams (H/C vs. O/C vs relative abundance) [4]. Stepwise analysis of SOM changes was depicted in C-normalized subtraction surfaces: positive values indicate the extent to which SOM constituents are progressively destroyed or transformed by fire, whereas negative values point to net accumulation of newly-formed structures [5]. Moderate chemical changes occured between stages SBS-0 to SBS-3 with a progressive shifting to compounds with lower H/C and O/C ratios, suggesting dehydration and demethylation pathways and depletion of polymethylene structures, carbohydrate rearrangements, lignin demethoxylation and triterpene preservation. Clear SOM transformations occured at SBS-4 onwards with concentration of alkyl structures, mainly triterpenes that is interpreted as final distillates released from a condensed black carbon matrix. Progressive changes in terms of SBS were not linear for all compounds. The subtraction surfaces suggest two major stages with generation of pyrogenic compounds not existing at that concentration in the preceding stages: SBS (0¿1) generation of pyrolytic anhydrosugars, and a major compound-productive stage between SBS (3¿4) with generation of alkylated polycyclic hydrocarbons and phenols. Molecular-level changes in SOM after natural fire and heated soil monoliths were very similar. Nonetheless, the former showed incorporation of alkyl compounds and methoxyphenols, probably inputs of charred biomass from the standing
vegetation.
eng
closedAccess
Field burn severity indexes and its relation with soil organic matter molecular changes described by graphical statistical analysis of pyrochromatographic data
póster de congreso
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URL
https://digital.csic.es/bitstream/10261/163156/1/accesoRestringido.pdf
File
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42637ae8545636bc41605c1740a9a84e
15753
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accesoRestringido.pdf