Instituto de Ciencias Agrarias, Consejo Superior de Investigaciones Científicas, Serrano 115 dpdo., Madrid, 28006, Spain.
Environ Sci Technol. 2012 Aug 21;46(16):8921-7. doi: 10.1021/es301375d. Epub 2012 Jul 30.
Simultaneous thermal analysis [i.e., thermogravimetry (TG) and differential scanning calorimetry (DSC)] is frequently used in materials science applications and is increasingly being used to study soil organic matter (SOM) stability. Yet, important questions remain, especially with respect to how the soil mineral matrix affects TG-DSC results, which could confound the interpretation of relationships between thermal and biogeochemical SOM stability. The objective of this study was to explore the viability of using infrared gas analyzer (IRGA) based CO(2)/H(2)O evolved gas analysis (EGA) as a supplement or alternative to TG-DSC to improve the characterization of SOM. Here, we subjected reference samples and a set of 28 diverse soil samples from across the U.S. to TG-DSC coupled with IRGA-based EGA. The results showed the technical validity of coupling TG-DSC and CO(2)-EGA, with more than 80% of the theoretically evolved CO(2)-C recovered during pure cellulose and CaCO(3) analysis. CO(2)-EGA and DSC thermal profiles were highly similar, with correlation coefficients generally >0.90. Additionally, CO(2)/H(2)O-EGA proved useful to improve the accuracy of baseline correction, detect the presence of CaCO(3) in soils, and identify SOM oxidative reactions normally hidden in DSC analysis by simultaneous endothermic reactions of soil minerals. Overall, this study demonstrated that IRGA-based CO(2)/H(2)O-EGA constitutes a valuable complement to conventional TG-DSC analysis for SOM characterization.
同步热分析（即热重分析（TG）和差示扫描量热法（DSC））常用于材料科学应用，并越来越多地用于研究土壤有机质（SOM）稳定性。然而，仍存在一些重要问题，特别是关于土壤矿物质基质如何影响 TG-DSC 结果的问题，这可能会混淆热学和生物地球化学 SOM 稳定性之间关系的解释。本研究的目的是探讨使用基于红外气体分析仪（IRGA）的 CO2/H2O 释放气体分析（EGA）作为 TG-DSC 的补充或替代方法来改善 SOM 特性的可行性。在这里，我们对参考样品和一组来自美国各地的 28 种不同土壤样品进行了 TG-DSC 与基于 IRGA 的 EGA 耦合实验。结果表明，TG-DSC 和 CO2-EGA 耦合的技术有效性，在纯纤维素和 CaCO3 分析中，理论上释放的 CO2-C 中有超过 80%被回收。CO2-EGA 和 DSC 热谱高度相似，相关系数通常>0.90。此外，CO2/H2O-EGA 对于提高基线校正的准确性、检测土壤中 CaCO3 的存在以及通过土壤矿物质的同时吸热反应识别通常隐藏在 DSC 分析中的 SOM 氧化反应都非常有用。总体而言，本研究表明，基于 IRGA 的 CO2/H2O-EGA 是 SOM 特性表征中常规 TG-DSC 分析的有价值的补充。
