3-Dimensional fluorescence of solid organic matter (SOM) obtained in raw soil samples: a methodological challenge

• Grant number: 17/26660-8
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: March 01, 2018
• End date: January 24, 2019
• Field of knowledge: Physical Sciences and Mathematics - Geosciences
• Principal Investigator: Célia Regina Montes
• Grantee: Gustavo Targino Valente
• Host Institution: Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Associated research grant: 16/14227-5 - Climatic changes and environmental impacts in wetlands of Pantanal region (Brazil): quantification, control factors and long term temporal modeling, AP.PFPMCG.TEM

Abstract

Characterization of the soil organic matter and its dynamics are essential for understanding the processes associated with the emission of greenhouse gases into the atmosphere. Spectroscopic methods, including fluorescence techniques such as LIFS (laser induced fluorescence spectroscopy) and UV-Vis EEMFS (excitation-emission matrix UV-visible fluorescence spectrometry), are powerful tools for characterizing the soil organic matter when extracted and in solution. Difficulties arise when fluorimetry is performed directly on solid, bulk soil samples. Large amounts of OM, characterized by dark grey or black colors, interfere with the fluorescence emission of the solid, causing a weak or even zero emission response. In the case of low amounts of OM, the solid phase emission-absorbing interactions with the OM emissions are unknown. The objective of this postdoc is to elucidate the physical and chemical processes involved in the mechanisms of solid matter fluorescence in organic soils and to develop a methodology allowing their use.