【摘要】 利用气相色谱—质谱等分析技术对黄土中的有机质总量、有机类脂物、干酪根等进行了分析,探讨黄土有机质的来源、演化和赋存状态;分析黄土有机组份的地球化学特征;有机类脂物和干酪根与土壤磁化率的关系;讨论了有机质对第四纪气候变化的环境指示意义。更多还原

【Abstract】 This paper describes the preliminary research on lipids from So to L₉ loess—paleosol sequence of Duanjiapo section near Xi’an,which include total organic matter content, lipid characteristics and magnetite of organic matter. The loess has a low content of organic matter （<1.5%）,its content and nature are related to environment states.The natural vegetation thrives when climate is warm/hu- mid and the content of organic matter is high.When it is dry/clod,the natural vegeta- tion is sparse and scattered and the content of organic matter is low.Therefore,the con- tent is a reflection of the biomass. The content curve of organic matter is similar to fine silt fraction （<1μm）curve. Muhivalent cations link organic colloids of each other and to clays to form aggre- gates.This organo-sih fraction also appears to be highly resistant to degradation of or- ganic matter.It changes the soil geochemical environment to one which is conductive to the formation of soil magnetite.The majority of organic matter was formed by natural vegetation decomposition during pedogenesis.This is an integrated environment,with small areas where reduction occurs.But the whole system is generally in one state of oxi- dization.更多还原