干旱-半干旱区兰州兴隆山现代森林典型植被和土壤中类脂物分子特征及其意义

利用GC－MS对西北干旱区-半干旱区兰州兴隆山森林区典型植被与现代土壤样品中可抽提的类脂物进行了系统分析，检测出包括正构烷烃和α正构脂肪酮等一系列类脂物分子化石。在未进行族分离的情况下，检出兴隆山现代森林木本植物的正构烷烃以C₂₇或C₂₉为主峰，草本植物则以C₃₁为主峰；  土壤样品中均保留有很强的、几乎均势的C₂₇，C₂₉和C₃₁信号； α正构脂肪酮具有明显的奇碳优势，植物中以C₂₃，C₂₅或C₂₉为主峰，土壤样品以C₂₇或C₂₉为主峰；  其反映的信息是植被与微生物共同作用的结果。本研究为理解现代土壤和古土壤中类脂物所指示的植被信息、进一步探讨类脂物分子在植被(有机质)-微生物-土壤-湖泊沉积体系中存在与相互转换关系这一基础理论问题提供了科学资料。同时，为分子化石分析方法的改进和不同处理过程所得数据之间的对比和科学解释提供资料。

ACYCLIC ALKANES OF TYPICAL PLANTS AND MODERN SOILS AT XINGLONG MOUNTAIN IN SEMIARID AREA|NW CHINA

Using Gas Chromatography Mass Spectrometry(GC MS)to measure the organic compounds of living plants and modern soils in different bioclimatological areas is of great importance to understand the environmental influence on organic signals obtained from geological archives. A series of biomarkers，including  n-alkanes and n-alkan-2-ones，were identified from typical plants，such as broadleaved deciduous trees and conifers as well as from modern soils collected from the Xinglong Mountain，North West  China. The n-alkanes of vegetations were changeable even though the trees had carbon number peakings at C₂₇ and C₂₉，whereas grasses at C₃₁. On the other hand，the carbon numbers in the forest soil show not only the C₂₇ and C₂₉ peaks，but also a strong peak at C₃₁. The CPIh value of plant had a large variation from 1.47～12.27. Both Rl/Rh and ACL values show obvious changes but generally with a similar trend. The CPI^_h，R_l /R_h and ACL indices from soils show very similar patterns and clearly indicates that the organic matters in the soil were originated from higher plants. However，the range of these indices in soil sections changed systematically from the top to the bottom，indicating that microbial and physicochemical processing had a significant effect on molecular signals in the organic matter，which means the microorganism and bacteria had unneglectable contribution to the property of the organic matter. Large amount of n-alkan-2-one，characterizing preferential odd carbon numbers were identified. They were dominated by high carbon numbers which peaked at C₂₇ and C₂₉，indicating that the n-alkan-2-one in soil samples were originated from higher plants，while the appearance of n-alkan-2-one with low carbon numbers indicating that microorganism may have played an important role in soil formation processes. The distribution patterns of n-alkan-2-one were comparable to that of n-alkanes in soils，implying that they had a close relationship to each other and the n-alkan-2-one might be resulted from the oxidization of n-alkanes. Lipid of typical plants and from the soils in modern forests at Xinglong Mountain demonstrated that plants were the main contributors to organic matters in underlying soil. The changes of organic matters in soils were closely related to microbial activities. Although the lipids from soils were affected by various factors，this study identified the sources of organic matters of soil. Further study on the plant soil microorganism system may help us to have better interpretation on lipid signals from the soil and paleosol.