AN0019 – Measuring Isotopic CO2 and CH4 Soil Flux with the Picarro G2201-i

Stable carbon isotope measurements of CO2 and CH4 are frequently used to understand the sources and mechanisms contributing to soil gas flux. For example, isotopes of CO2 can be used to determine the relative contributions of root and microbial CO2 production to total soil CO2 flux. Alternatively, in systems where photosynthetic pathways have transitioned from C3 to C4 or vice versa (Figure 1a) isotopes can be used to determine relative contributions of carbon from each pathway to total soil respiration. Similarly, methane stable isotopes are used to differentiate biological versus geological sources of soil gas flux (Figure 1b) and can also be used to examine the mechanisms of methane production and oxidation. This application note outlines the configuration and use of the Picarro G2201-i dual carbon (CO2 & CH4 ) isotope analyzer to differentiate between C3 and C4 respiration sources at a transitional agricultural experiment in southern Sweden.

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