Translating analytical pyrolysis fingerprints of soil organic matter to climatic variables

Póster presentado en el 1st Iberian Meeting in Separation Sciences & Mass Spectrometry, XIX Conference of the Spanish Society of Chromatography and Related Techniques (SECyTA), IX Conference of the Spanish Society of Mass Spectrometry (SEEM), VI Conference of the Mass Spectrometry Group of the Portuguese Society of Chemistry (SPQ). Santiago de Compostela, October 8th-11th (2019).
Environmental research about causes and effects of progressive soil desertification is attracting the attention of the scientific community. Factors that accelerate soil organic matter (SOM) mineralization may also induce structural changes in its molecular composition, but the specific impact of different climatic factors (annual precipitation, number of days with precipitations, temperature…) has not yet been the subject of systematic research. This study attempts to identify potential climatic molecular proxies in SOM, i.e., pyrolytic compounds correlated with specific climatic indices. A set of 16 Spanish soils under differing climatic conditions were selected. Molecular characterization of SOM was done by pyrolysis‐gas chromatography/mass spectrometry (Py‐GC/MS) applied to whole soil samples. Up to 193 compounds were identified corresponding to alkanes, alkylbenzenes, N‐compounds, olefins, phenols and carbohydrate derivatives. Simple and multiple correlations between pyrolytic and climatic ariables showed that the concentration of several compounds was significantly correlated (P < 0.05) with particular climatic variables. In a second stage, using van Krevelen [1,2] diagrams, it was possible to display different patterns of pyrolytic compounds responsive to specific climatic characteristics. Finally, extrapolation functions were applied to simulate SOM molecular composition under future climatic scenarios, e.g., changes in temperature, evapotranspiration, rainfall, etc. This study demonstrates the potential of Py‐GC/MS in identifying specific molecules and compound families useful for predicting climate impact on SOM, as well as for monitoring soil quality in terms of the progress of desertification
References [1] D.W. van Krevelen, Fuel 29, 269–284 (1950). [2] G. Almendros, Z. Hernández, J. Sanz, S. Rodríguez‐Sánchez, M.A. Jiménez‐González, J.A. González‐Pérez, J. Chromatogr. A. 1533, 164–173 (2018).
t Financial support by Spanish CICyT (grants CGL2013‐43845‐P & CGL2016‐78937‐R) is acknowledged. M.A.J.G. thanks Spanish MINECO (pre‐doctoral FPI fellowship BES‐2014‐069238).