Testing Thermal Oxidation and 14C Concentration as an Analogue for Traditional Soil Fractionation Methods
Abstract
Soil organic matter (SOM) is comprised of a complex mixture of organic molecules representing many stages of decomposition and stabilization. While effective and reproducible, traditional methods of fractionating along physical and chemical properties have known flaws including significant time and effort required to obtain fractions. Recent developments in thermal oxidation have shown promise in rapidly separating soil carbon (C) pools by gradually increasing temperature to >900˚C and analyzing carbon dioxide (CO2) release at each temperature (thermogram). This work seeks to identify or confirm which physical and chemical pools can be considered analogous with thermally derived pools in terms of C content and age distribution, and whether thermal oxidation performs as a suitable proxy for real-world C destabilization mechanisms. Using novel collection techniques, CO2 can be captured from user-defined temperature ranges and analyzed for radiocarbon (14C) concentration. Temperature ranges are selected using open-access Python packages, which invert thermograms and model SOM activation energy distribution. Previous work has shown that C age generally increases significantly with temperature. Bulk soils and traditional fractions collected for the CarboEurope project are fractionated through thermal oxidation and compared with existing 14C data. Data produced using this method allow for modeling C cycling in pools determined by thermometric properties. These C age distribution data will be applied toward constraining existing models of the global C cycle. Future applications of this method include analysis of soil archives, allowing significantly greater data collection from limited soil volume.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.B23G2615S
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCESDE: 0428 Carbon cycling;
- BIOGEOSCIENCESDE: 0486 Soils/pedology;
- BIOGEOSCIENCESDE: 1630 Impacts of global change;
- GLOBAL CHANGE