洛川黄土/古土壤中有机碳的分布特征及其与粘土矿物的相关性

Distribution of organic carbon in the Luochuan loess/paleosol and its relationship with clay minerals

系统测定了陕西洛川黑木沟黄土/古土壤的总有机碳及其主要组分（稳定有机碳、矿物保护有机碳和化学稳定有机碳）的含量,并对总有机碳与粘粒含量及粘土矿物含量的相关性进行了分析。结果表明：（1）各层古土壤的总有机碳含量均高于其下伏的黄土层（S4例外）,而稳定有机碳、矿物保护有机碳以及化学稳定有机碳的平均含量在黄土与古土壤之间无明显差异;（2）黄土和古土壤中有机碳含量达到稳定所需要的时间不同,分别是140~250 ka和330~410ka;（3）总有机碳和化学稳定有机碳与粘粒呈正相关关系（相关系数r分别为0.46和0.54）,它们与粉粒和细砂粒的相关性较差,这说明粘粒是土壤固定有机碳的重要组分;（4）高岭石与总有机碳和化学稳定有机碳的相关性比较明显（r分别为0.74和0.61）,伊利石和蒙脱石与它们不相关或相关性较差。

The total organic carbon（TOC） and its major components,i.e.,stable organic carbon（StOC）,mineral-protected organic carbon（MOC）,and chemical resistant organic carbon（COC）,were analyzed for both loess and paleosol layers in Luochuan profile,and the correlations between the clay particle content,clay mineral content and TOC content were studied.The results are as follows：（1） the content of TOC is higher in paleosol（except for S4） than in loess,but the differences of the average content of StOC,MOC,COC are not obvious between loess and paleosol;（2） the loess and paleosol needed different time spans to reach the stabilization of the values of TOC： the former needed about 140~250 ka and the latter needed 330~410 ka;（3） the clay particle content is well correlated with TOC content and COC content（r=0.46,r=0.54）,whereas the slit content and the fine sand particle content are poorly corrected with TOC content and COC content.The results indicate that the clay particle is a significant composition for storage of carbon organic in soils;（4） kaolinite content is highly correlated with TOC content and COC content（r=0.74,r=0.61）,whereas illite and montmorillonite are not correlated or poorly correlated with TOC content and COC content.