中文摘要：

选取重庆市四种类型土壤（矿子黄泥、紫色潮土、灰棕潮土和缙云山黄壤腐殖层），采用低浓度高锰酸钾氧化法研究了活性有机质（LOM）在不同粒级土壤团聚体中的分布特征，结果表明：1）不同类型土壤有机质全量和活性状态存在明显差异，缙云山黄壤腐殖层有机质和活性有机质总量远高于农业土壤；2）灰棕潮土和紫色潮土0．25～0．5mm粒径团聚体LOM含量最高；矿子黄泥不同粒径团聚体LOM含量相差不大；缙云山黄壤腐殖层0．5～1mm粒径团聚体LOM含量最高；3）土壤粒级团聚体的质量占土壤总质量的百分比是控制活性有机质分配量的主导因素。

英文摘要：

Four major types of soil, in Chongqing, namely mineral yellow mud, purple alluvial soil, grey-brown alluvial soil and humus layer of yellow soil in JinYun Mountain, were sampled and airried, then separated and sifted into size differentiated aggregates using dry-sieve method. Oxidation with low concentration potassium permanganate was used to analyze the distribution of LOM in size differentiated aggregates of soils, The results demonstrates that： （1）soils differ widely in total soil organic matter level and labile organic matter（LOM）level, with those from JinYun mountain being the highest in both levels; （2）grey-brown alluvial soil ranks the highest in terms of LOM proportion in total soil organic matter concerning 0.25-0.5mm sized aggregates, followed by purple alluvial soil, while mineral yellow mud appear to have slight difference in the LOM level in different sized aggregates . Addition- ally, humus layer of yellow soil from J inYun mountain proves to have highest;LOM share in 0.5-1mm sized aggregates; （3）the distribution of LOM in size differentiated aggregates of soils vary and depend primarily on their mass distributions in all sorts of soils.