Coupled thermal analysis and infra-red gas analyzer (IRGA) based CO2/H2O evolved gas analysis for improved characterization of soil organic matter

摘要

Simultaneous thermal analysis [i.e., thermogravimetry (TG) and differential scanning calorimetry (DSC)] is increasingly used to characterize soil organic matter (SOM). However, important questions remain concerning how the soil mineral matrix affects TG-DSC results, which could confound the interpretation of relationships between thermal and biological SOM stability. The objective of this study was to explore the feasibility of using infrared gas analyzer (IRGA) based CO2/H2O evolved gas analysis (EGA) as a supplement or alternative to TG-DSC to improve the characterization of SOM. We subjected a set of 28 soil samples from across the U.S. to TG-DSC coupled with IRGA-based EGA. CO2-EGA and DSC thermal profiles were highly similar, with correlation coefficients generally ＞0.90. CO2/H2O-EGA was especially useful to identify SOM oxidative reactions normally hidden in DSC analysis by simultaneous endothermic reactions of soil minerals. Overall, this study demonstrated that IRGA-based CO2/H2O-EGA constitutes a relatively low-cost and simple complement to conventional TG-DSC analysis for SOM characterization.