西藏湖泊正构脂肪酸分布特征及对古气候重建的启示

 脂肪酸广泛存在于各种地质载体，能够记录母源生存环境的相关信息。但关于脂肪酸的具体来源及分布特征的古气候意义尚不明确，导致脂肪酸相关指标在古气候重建中的应用较少。通过分析西藏干旱-半干旱区跨越3个气候带的湖泊和水洼的表层沉积物中的正构脂肪酸，揭示中、长链及部分短链正构烷脂肪酸的来源与正构烷烃的来源有关，可以相互对比验证。建立了指标与古气候要素的相关关系，发现正构脂肪酸含量、碳优势（CPI）指标随温度升高、降水增多而升高。提出了可用于古气候重建的中链占比（R-FA）指标，R-FA与年均气温和降水量成正比。

Distribution characteristics of n-fatty acids in the arid Tibet lakes: Implications for paleoclimatic studies

Fatty acids are widely distributed in various geological carriers, and can be taken as records of the living environment of the maternal sources. However, the specific sources and the paleoclimatic significance of the distribution characteristics of the fatty acids are still not completely clear, therefore, only a limited application of fatty acids is made in the paleoclimatic reconstruction. By analyzing the n-fatty acids in the surface sediments of lakes and puddles spanning three climatic zones in the arid/semi-arid Tibet, this paper reveals that the sources of middle, long chain n-fatty acids and a part of short chain ones are related to that of n-alkanes, which can be compared. The correlation between the indices and the paleoclimatic factors is established. It is shown that the content of the normal fatty acid and the CPI indices increase with the increase of the temperature and the precipitation. An R-FA indices for the paleoclimate reconstruction is proposed, which is proportional to the annual average temperature and precipitation.