基于Maxwell-Stefan扩散模型的土壤碳通量计算方法研究

Study on calculation method of soil carbon flux based on Maxwell-Stefan diffusion model

目前土壤碳通量的监测方法存在一定的缺点,导致无法长时间精确监测。针对这一问题,提出用Maxwell-Stefan扩散模型进行碳通量的计算,并建立开放型气室模型进行仿真研究。根据仿真程序生成的不同高度的浓度时间序列,基于Maxwell-Stefan扩散模型计算二氧化碳通量值,将计算结果与仿真设定值进行对比。其中,设定通量为0.5μmol·m-2·s-1时,计算结果为0.547μmol·m-2·s-1;设定通量为1.0μmol·m-2·s-1时,计算结果为0.969μmol·m-2·s-1;设定通量为2.0μmol·m-2·s-1时,计算结果为2.122μmol·m-2·s-1。运用该算法计算的误差均在10%以内。另外,与Fick扩散模型的计算结果进行对比,在3组实验下,Maxwell-Stefan模型计算所得的通量值都更加接近于设定值。本研究的结果表明,Maxwell-Stefan扩散模型适用于土壤呼吸碳通量的计算,并且具有较好的计算结果,从理论上验证了该模型用于土壤碳通量计算的可行性和准确性。

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 0.547μmol·m-2·s-1 when the set flux was 0.5μmol·m-2·s-1,the calculated result was 0.969μmol·m-2·s-1 when the set flux was 1.0μmol·m-2·s-1,and the calculated result was 2.122μmol·m-2·s-1 when the set flux was 2.0μmol·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.