Application of Combustion Module Coupled with Cavity Ring-Down Spectroscopy for Simultaneous Measurement of SOC and δ13C-SOC

Abstract EN

Quantifying the decomposition of soil organic carbon (SOC) fractions under climate change is essential to predict carbon-climate feedbacks.

The accuracy and utility of a combustion module coupled with cavity ring-down spectroscopy (CM-CRDS) system were assessed for simultaneously determining SOC and δ13C-SOC.

Using a range of standard materials as well as soil samples, we compared the results of the CM-CRDS system with those from other systems for determining C content and δ13C value.

The CM-CRDS system can determine a vast range of δ13C values from −7.639‰ to −34.318‰.

The δ13C values measured at C content > 0.2 mg C, corresponding to 1000 ppmv of CO2, were relatively stable.

However, below a content of 0.2 mg C, the δ13C values appeared unsteady and seemed to be affected by background signal.

We found that, with the increase of C content, the recovery rates (RRs) for soil samples also increased.

On the contrary, the RRs for inorganic materials were much lower than organic material and soil samples.

Overall, the CM-CRDS system provides a valid alternative method to determine SOC and δ13C-SOC for a sample simultaneously.