盐碱土土壤无机CO_2通量与土壤盐碱属性的关系

Soil inorganic CO_2 flux in relation to soil pH and electric conductivity in saline/alkaline soils

土壤CO_2通量是陆地生态系统碳循环的第二大通量,其很小的变化就能严重改变大气CO_2浓度的平衡。本研究分析了土壤pH和EC对盐碱土土壤CO_2通量的重要组成—土壤无机CO_2通量的作用。实验于2010年6—9月在中国科学院新疆阜康荒漠生态站进行。采用高压灭菌的方法,将9种盐碱土的土壤无机CO_2通量从土壤CO_2通量中分离。结果表明,在土壤类型一定时,土壤无机CO_2通量主要受温度控制;低温有利于CO_2吸收,高温有利于CO_2释放。土壤pH可作为指示盐碱土土壤无机CO_2通量作用大小的指标;在低温和高温阶段,土壤pH对土壤无机CO_2通量的作用效果不同。土壤盐分较大的变化,才能造成土壤无机CO_2通量的显著差异。本研究分析了盐碱土土壤无机CO_2通量的特征,为盐碱土无机CO_2通量过程机制的推导提供证据。开展不同盐碱土土壤无机CO_2通量研究将极大促进干旱区盐碱土碳循环的解读。

Soil CO2 flux is the second largest flux of carbon cycle in terrestrial ecosystems, and its slight variation can result in a significant change in the balance of atmospheric CO2 concentration. This paper analyzed the effects of soil pH and electric conductivity （EC） on the soil inorganic CO2 flux, an important component of soil CO2 flux, in saline/alkaline soils. The experiment was conducted at the Fukang Desert Ecological Station, Xinjiang of Northwest China from June to September, 2010. The inorganic CO2 flux of nine saline/alkaline soils was differentiated from the soil CO2 flux by the method of sterilization with high pressure steam chamber. The results showed that for certain saline/alkaline soil, the soil inorganic CO2 flux was mainly controlled by temperature. Low temperature benefited the CO2 absorption by the saline/alkaline soils, whereas high temperature benefited the CO2 release. The soil pH could be used as a good indicator for the soil inorganic CO2 flux. At low and high temperatures, the effects of the soil pH on the soil inorganic CO2 flux differed. The soil salinity also had effects on the soil inorganic CO2 flux, but the effects could be significant only when the soil salinity had a considerable change. This study highlighted the characteristics of soil inorganic CO2 flux in saline/alkaline soils, which could provide evidence to educe the underlying inorganic mechanisms. The nonnegligible role of soil inorganic CO2 flux requires further investigation towards a better understanding of soil carbon cycle in saline/alkaline soils in arid lands.