Abstract: There are certain disadvantages in the monitoring methods of soil carbon flux, which led to inability to accurately monitor for long period. To solve this problem, the present study proposed a method to calculate the carbon flux by using Maxwell-Stefan diffusion model, and establish an open-chamber in order for simulation. According to the multiple altitude of concentration, the carbon flux was calculated based on Maxwell-Stefan model, and was compared with the simulation settings. The calculated result was 0.547 μmol·m^-2·s^-1 when the set flux was 0.5μmol·m^-2·s^-1, the calculated result was 0.969 μmol·m^-2·s^-1 when the set flux was 1.0 μmol·m^-2·s^-1, and the calculated result was 2.122 μmol·m^-2·s^-1 when the set flux was 2.0 μmol·m^-2·s^-1. The error calculated by this method was less than 10%. In addition, compared with the calculation results of the Fick diffusion mode, the flux values calculated by the Maxwell-Stefan model were closer to the set values in three experiments. The experimental results proved that Maxwell-Stefan model was appropriate to calculate the carbon fluxes of soil respiration and it had favourable accuracy. The present study verified the feasibility and accuracy of the Maxwell-Stefan model in calculating soil carbon flux theoretically.

Key words: soil respiration, Maxwell-Stefan diffusion model, multicomponent, carbon flux