时间梯度下油松松针中生物标志化合物分布特征研究

利用气相色谱-质谱(GC/MS)联用技术,对现代活体不同生长期油松松针中提取的生物标志化合物特征进行系统分析和研究,检测出丰富的类脂物分子,包括正构烷烃、饱和脂肪酸甲酯、脂肪酸乙酯和正烷基-2-酮等。随着生长期的增长,松针正构烷烃的碳数分布范围和主峰碳数不变,均呈现奇碳优势;正构烷烃∑C21-/∑C22+平均值为0.013,比值较低,显示高碳数正构烷烃优势,反映了样品采集区域(干旱荒漠地区)高等陆源有机质的特征;正构烷烃∑C21-/∑C22+比值和CPI、OEP随着生长期的增长均呈现规律性降低,记录了植物叶子生长过程中环境条件变化的相关信息;从生长初期(2个月)至枯萎过程中,脂肪酸甲酯、乙酯以及正烷基-2-酮类化合物均被检出,这3类化合物的形成主要是松针叶片在生长过程中的自身产物。样品中脂肪酸甲酯和正烷基-2-酮的∑C21-/∑C22+比值均随生长时间的增长呈现规律性增加,表明松针叶片低碳数脂肪酸甲酯(C13~C21)和小于C20的正烷基-2-酮随着生长期的增长明显增加。研究样品的脂肪酸乙酯的∑C21-/∑C22+比值较低,平均为0.007,显示高碳数脂肪酸乙酯占有明显优势。不同生长期松针中CPI值特征表明,脂肪酸甲酯具有显著奇碳优势、乙酯具有偶碳优势、正烷基-2-酮显示高碳数奇碳优势,此分布特征与现代土壤中该类型化合物的分布特征相近,表明它们可能是现代土壤中相应各类有机质的重要来源。

The Characteristics of Biomarkers in Pine Needles with Different Growing Periods

The characteristics of biomarkers extracted from needles of the modern living pine with different growing periods were systematically analyzed by gas chromatography-mass spectrometry（GC/MS）. Abundant biomarkers were recognized, including n-alkanes, n-ones and saturated fatty acid methyl esters， fatty acid ethyl esters. With the increasing of growing periods, the carbon number distribution ranges of n-alkanes from C₁₈ to C₃₇ were found, showing an odd carbon predominance with the maxima at nC₂₉ in all samples. The average ratio of ∑C₂₁^-/∑C₂₂⁺ of n-alkanes is lower(0.013), suggesting that terrestrial high plants are main origins of pine needles and record the typical characteristics of research region (arid and desert region). The ratio of ∑C₂₁^-/∑C₂₂⁺, OEP and CPI values of n-alkanes decrease regularly with the increasing of the growing periods record the related climate information; saturated fatty acid methyl esters， fatty acid ethyl esters and n-alkan-2-ones were all detected from the initial growth（2 months） to wilting, the result shows that the three types of compounds are formed mainly in the growth of pine needle leaves. The ratio of ∑C₂₁^-/∑C₂₂⁺ of fatty acid methyl esters and n-alkan-2-ones in all samples increase gradually with the increase of growing periods, indicating low carbon-numbered fatty acid methyl esters（C₁₃—C₂₁）and the n-alkyl-2-ones(＜C₂₀) might be a provenance of their own products during the growing periods of pine needles. The average ratio of ∑C₂₁^-/∑C₂₂⁺ of fatty acid ethyl esters is lower（0.007）, suggesting the fatty acid ethyl esters with high carbon-numbered predominance in samples. Furthermore at different growing periods of pine needles, the CPI values of fatty acid methyl esters and fatty acid ethyl esters show odd, even carbon predominance, respectively. And the CPI values of high carbon-numbered n-alkan-2-ones show odd carbon predominance. The distribution characteristics of these compounds are similar to those of them in the modern soil, indicating they might be the main sources of corresponding various organic matter in the modern soil.