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.