Abstract: The soil inorganic CO₂ flux in saline/alkaline soil of the arid land is a unique and brand-new phenomenon，which breaks the assumption that soil CO₂ fluxes are purely organic in origin. However，due to lack differentiation standard and quantitative data，the significance of soil inorganic CO2 flux to soil CO₂ flux and global carbon cycle is still uncertainty. The experiment was carried out from August to October in 2009 at the Fukang Station of Desert Ecology. To determine the potential contribution of soil inorganic CO₂ flux to total soil CO₂ flux，the soil inorganic CO₂ flux was differentiated by sterilization treatment（121 ℃，24 h） with pressure steam chamber. The results showed that soil properties had little change before and after sterilization treatment. Having its differentiation effect validated by the relationship between soil organic CO₂ flux and temperature, it showed that the sterilization was a reliable and valid method to differentiate soil inorganic CO₂ flux. The effect of soil inorganic CO₂ flux was larger than that of soil organic CO₂ flux，which could dominate the saline/alkaline soil CO₂ flux both in direction and magnitude. As a significant component of soil CO₂ flux in saline/alkaline soil，the differentiation and quantification of soil inorganic CO₂ flux are necessary to advance understanding of carbon cycle in arid land. Therefore, the non-negligible role of soil inorganic CO₂ flux as potential contribution to the arid land ecosystem carbon cycle requires further investigation towards a better understanding of arid land soil CO₂ flux and global soil carbon cycle.

Key words: soil CO₂ flux, oil inorganic CO₂ flux, saline soil, alkaline soil, pressure-steaming sterilization