State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, Xinjiang, China.
PLoS One. 2013 Nov 29;8(11):e82029. doi: 10.1371/journal.pone.0082029. eCollection 2013.
Soil inorganic carbon is the most common form of carbon in arid and semiarid regions, and has a very long turnover time. However, little is known about dissolved inorganic carbon storage and its turnover time in these soils. With 81 soil samples taken from 6 profiles in the southern Gurbantongute Desert, China, we investigated the soil inorganic carbon (SIC) and the soil dissolved inorganic carbon (SDIC) in whole profiles of saline and alkaline soils by analyzing their contents and ages with radiocarbon dating. The results showed that there is considerable SDIC content in SIC, and the variations of SDIC and SIC contents in the saline soil profile were much larger than that in the alkaline profile. SDIC storage accounted for more than 20% of SIC storage, indicating that more than 1/5 of the inorganic carbon in both saline and alkaline soil is not in non-leachable forms. Deep layer soil contains considerable inorganic carbon, with more than 80% of the soil carbon stored below 1 m, whether for SDIC or SIC. More importantly, SDIC ages were much younger than SIC in both saline soil and alkaline soil. The input rate of SDIC and SIC ranged from 7.58 to 29.54 g C m(-2) yr(-1) and 1.34 to 5.33 g C m(-2) yr(-1) respectively for saline soil, and from 1.43 to 4.9 g C m(-2) yr(-1) and 0.79 to 1.27 g C m(-2) yr(-1)respectively for alkaline soil. The comparison of SDIC and SIC residence time showed that using soil inorganic carbon to estimate soil carbon turnover would obscure an important fraction that contributes to the modern carbon cycle: namely the shorter residence and higher input rate of SDIC. This is especially true for SDIC in deep layers of the soil profile.
土壤无机碳是干旱和半干旱地区最常见的碳形态，其周转率非常长。然而，对于这些土壤中溶解无机碳的储存及其周转率却知之甚少。本研究在中国古尔班通古特沙漠南部的 6 个剖面中采集了 81 个土壤样本，通过放射性碳测年分析其含量和年龄，研究了盐碱性土壤剖面中整个土壤无机碳（SIC）和土壤溶解无机碳（SDIC）的分布特征。结果表明，SIC 中含有相当数量的 SDIC，盐土剖面中 SDIC 和 SIC 含量的变化明显大于碱土剖面。SDIC 储量占 SIC 储量的 20%以上，这表明盐碱性土壤中超过 1/5的无机碳不是以非可提取的形式存在的。深层土壤含有相当数量的无机碳，无论是 SDIC 还是 SIC，超过 80%的土壤碳都储存在 1 m 以下。更重要的是，盐土和碱土中 SDIC 的年龄都明显小于 SIC。SDIC 和 SIC 的输入速率分别为盐土 7.58-29.54 g C m(-2) yr(-1)和 1.34-5.33 g C m(-2) yr(-1)，碱土 1.43-4.9 g C m(-2) yr(-1)和 0.79-1.27 g C m(-2) yr(-1)。SDIC 和 SIC 停留时间的比较表明，用土壤无机碳来估计土壤碳的周转率会掩盖一个对现代碳循环有重要贡献的部分，即 SDIC 的停留时间较短且输入率较高。这对于土壤剖面深层的 SDIC 尤其如此。
