干旱区盐碱土剖面无机碳组分分布特征

通过分离土壤动态性无机碳，结合14C同位素技术，有效量化了盐碱土剖面无机碳组分的存储数量和年龄特征。结果表明：整个土壤剖面，盐土难溶性无机碳含量和可溶性无机碳含量明显高于碱土。无论是土壤难溶性无机碳储量还是可溶性无机碳储量，盐土和碱土中有近80%碳是存储在1 m以下，50%存储于3 m以下。相同土层，土壤可溶性无机碳储量约占土壤难溶性无机碳储量的30%。无论是盐土还是碱土，无机碳的年龄超过万年，而土壤可溶性无机碳的年龄明显低于土壤无机碳的年龄。研究结果证实尽管土壤可溶性无机碳储量较低，但其周转时间短，速率高，因此在参与现代碳循环的程度上明显要高于土壤无机碳。

Distribution of inorganic carbon composition in arid saline-alkali soil profiles

The key to estimating dissolved and non-dissolved inorganic carbon in saline-alkali soil is understanding the processes of carbonate accumulation. In order to effectively quantify inorganic carbon composition and their ages in saline-alkali soil，the paper introduced a convenient way to determine soil dissolved and non-dissolved inorganic content in these soils. Dynamics of soil inorganic carbon was separated by leaching soil，and inorganic carbon ages were determined by 14C isotope technology in this study. The results showed that average values of both dissolved and non-dissolved inorganic carbon contents in saline soil were higher than in alkaline soil. Through analyzing dissolved and non-dissolved inorganic carbon storages in saline and alkaline soil profiles at different depths，the paper found that there was significant soil dissolved inorganic carbon and soil non-dissolved inorganic carbon storage below 1 m depth：SIC and SDIC storage below 1 m depth accounted for more than 80% of that for the soil profile，and more than 50% carbon storage was below 3 m depth. At the same depth，the dissolved inorganic carbon storage is approximately 30% of the non-dissolved inorganic carbon storage. Clearly，most of this dissolved inorganic carbon cannot be in a stable form. The mean resident time of carbon in the saline and alkaline soil profiles were more than 10 000 years，and the mean resident time of soil dissolved inorganic carbon was significantly shorter than soil inorganic carbon. These conclusions were indicated that the faster turnover and higher input rate of soil dissolved inorganic carbon was proved though soil dissolved inorganic carbon storage was small in saline-alkali soils. So，soil dissolved inorganic carbon as an important fraction of the modern carbon cycle contribution is obvious higher than soil inorganic carbon.