Recapping my presentation @ AGU 2016

Last December I attended the AGU Fall Meeting. I presented preliminary data on correlated EGA thermograms and ¹³C NMR spectra, see https://agu.confex.com/agu/fm16/meetingapp.cgi/Paper/134661.

This project is an active collaboration with Johnathan Sanderman at the Woodshole Research Center, and Jeffrey Baldock at Commonwealth Scientific and Industrial Research Organisation (SCaRP). National-scale inventories typically include soil organic carbon (SOC) content, but not chemical composition or biogeochemical stability. While ¹³C NMR is highly effective for SOM characterization, it is typically too expensive and time consuming for use in large-scale SOC monitoring. Therefore, we seek to understand if analytical thermal analysis is a viable alternative to NMR. This project has involved analyzing 300 agricultural samples collected by SCaRP, which have been divided into four fractions: whole soil, coarse particulates (POM), untreated mineral associated (HUM), and hydrofluoric acid (HF)-treated HUM. All samples have been analyzed by DSC-EGA, but only the POM and HF-HUM fractions were analyzed by NMR. The thermal and NMR data were analyzed by PCA and overlain with 2D Shige software to ascertain positive and negative correlations (as well as the intensity of these correlations). I made 5 key points in my presentation:

1. Molecular composition is only part of the story.
2. This due to the fact that C stability depends on soil chemistry
3. Because thermal analysis a measure of biogeochemical stability, it may have great utility in assessing soil C dynamics
4. DSC-EGA, NMR correlation provides dense information on SOC composition, stability, and lability
5. We found strong positive and negative correlations between the CO₂ thermograms and NMR spectra using 2D Shige.

The audience was intrigued by our findings so far. Moving forward, I will explore how mineral associations and mineralogy impact thermal data. This will entail running correlations against the DSC data.