作　　者： ; ; ;

机构地区： 中国科学院地球化学研究所环境地球化学国家重点实验室

出　　处： 《生态环境》 2008年第5期2031-2036,共6页

摘　　要： 以喀斯特地区植被恢复过程中典型坡地为研究对象,对坡地各个地形剖面土壤及土壤不同粒径组分中有机碳含量和有机质稳定碳同位素(δ13C值)组成进行了分析。结果显示:坡地土壤有机碳含量向下坡方向逐渐降低,上坡位两个剖面土壤砂粒(50～2000μm)中有机碳含量占50%以上,处于不稳定状态,易受到侵蚀作用破坏;而下坡位两个剖面中有机碳主要储存在粉粒(2～50μm)和粘粒(<2μm)土壤中,属于高度腐殖化的稳定有机碳。土壤有机质的δ13C值是评估SOC周转的一个良好指标,因粒径组成、剖面深度、植被和成土环境而不同。坡地各个土壤剖面中δ13C值的组成差异,较好地反映作物残体输入和土壤累积特征;输入土壤中的植物有机体由于分解程度不同而储存在不同粒径土壤中,因此各粒径中δ13C值对土层中有机质的储存和变化趋势具有较好的指示作用。 Taking the typical slope of vegetation recovery in Karst Area as the object of study, through analyzing the organic carbon contents and the stable carbon isotope composition （δ^13C value） of soil organic matter in bulk and particle size separates of soils profiles at different topographic positions. The results showed that soil organic carbon contents decrease gradually with the downhill direction. In the upper slope position two soil profiles, sandy soil （50-2 000 μm） organic carbon content accounts for above 50%, which is unstable organic carbon and easy to destruction by erosion; But in the lower slope position two soil profiles, the organic carbon mainly stored in the soil silt （2-50 μm） and soil clay （〈2 μm） which belong to stable soil organic carbon of highly humification. The change in δ^13C values was a useful index to evaluate turnover of SOC, which was significantly correlated to soil particle size, soil profiles depth, vegetation and soil-forming environment. The composition difference of δ^13C values in soil profile reflected input of plant residue and accumulation characteristic. The organic matter deposited in the different soil particle size because of the different degree of decomposition, therefore, the δ^13C value can help to identify storage and decomposition rate of soil organic matter.

关 键 词： 喀斯特地区 土壤有机质 坡地 稳定碳同位素 粒径组分

领　　域： [环境科学与工程]