干旱区绿洲土壤可溶性无机碳的空间分布特征

Spatial distribution pattern of soil dissolved inorganic carbon in an arid oasis

为认识干旱区水土作用下可溶性无机碳的动态特征,以民勤绿洲为例,利用地统计学、RS和GIS相结合的方法,从流域尺度上研究了0~10 cm土壤可溶性无机碳的空间分布特征。结果表明:民勤绿洲0~10 cm土壤可溶性无机碳的平均含量为0.056 g C·kg^(-1),线性模型为土壤无机碳分布特征的最优拟合模型;从空间分布来看,土壤可溶性无机碳含量呈从南向北逐渐降低的趋势,南部坝区含量最高,中部泉山区居中,北部湖区最低;同期土地利用类型图叠加表明,整个绿洲土壤可溶性无机碳主要分布在0.05~0.06 g C·kg^(-1)范围,耕地和沙地中的可溶性无机碳含量整体较高,而林地、草地和盐碱地中的可溶性无机碳含量则较低;土壤可溶性无机碳含量与HCO3-呈极显著正相关,与其他土壤离子呈显著负相关,而与pH呈弱的正相关。研究结果对于认识干旱区水土作用下表层土壤动态性碳传输具有显著意义。

Taking Minqin oasis as a case, and by using geostatistics, RS, and GIS, this paper studied the spatial distribution pattern of soil dissolved inorganic carbon （SDIC） in 0-10 cm layer at watershed scale, aimed to understand the dynamic characteristics of SDIC under effects of water and soil in arid areas. In the oasis, the average content of SDIC in 0-10 cm layer was 0.056 g C·kg-1, and the OneSample KolmogorovSmirnov （K-S） test showed that the SDIC content followed normal distribution, and the spatial distribution of the SDIC could be best fitted by a linear model with the application of variation function. The research based on Kriging method showed that the SDIC content decreased gradually from south to north, being the highest in Baqu, the southeastern part of Minqin oasis, followed by in Quanshan, the central part of the oasis, and the lowest in Huqu, the northern part of the oasis. The landscape maps overlaid land-use types in the same periods showed that the SDIC content in the oasis was mainly ranged in 005-0.06 g C·kg-1, being higher in cropland and sandy land, while lower in forest land, grassland, and saline land. Correlation analysis showed that the SDIC content was significantly positively correlated with HCO3- content, significantly negatively correlated with other salt ions and electrical conductivity, but weakly positively correlated with pH. This study could contribute to the understanding of the dynamic processes of surface soil carbon under effects of water and soil in arid-areas.