Characterization of unusual sterols and long chain diols, triols, keto-ols and n-alkenols in El Junco Lake, Gal谩pagos

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• 作者：Alyssa R. Atwood ; John K. Volkman ; Julian P. Sachs
• 刊名：Organic Geochemistry
• 出版年：January, 2014
• 年：2014
• 卷：66
• 期：Complete
• 页码：80-89
• 全文大小：842 K

文摘

A variety of lipid biomarkers were identified in sediments from El Junco Lake, Gal谩pagos and their sources investigated for potential use in paleoclimate applications. A series of unusual sterols was also found, including 4伪-methylgorgostanol, reported in only four species of dinoflagellates to date. We also tentatively assigned 22,23-methylene-4伪-methyl-24-ethylcholest-5-en-3尾-ol, the mass spectrum of which matched a sterol found in resting cysts of the dinoflagellate Peridinium umbonatum. In addition, we identified the novel sterol 4伪,22,23,24-tetramethyl-5伪-cholest-22E-en-3尾-ol. Based on the unique sterol distribution, we hypothesize that a dinoflagellate from the genus Peridinium was the primary source of dinosterol and the novel sterols throughout the sediment record. The source specificity and abundance throughout the 3.7 m of recovered sediment make dinosterol an excellent target for hydrogen isotope analysis for use as a paleohydrological proxy in future studies. The abundant C₃₀ and C₃₂ 1,蠅20-diols and keto-ols, C₂₉ 9,10-diol and C₂₉ 1,蠅9,蠅10-triol likely derive from the ferns Azolla microphylla and Cyathea weatherbyana, while sources of the C₃₀ 1,蠅16-diol and keto-ol, C₃₂ 1,蠅18-diol and keto-ol, and the C₃₀-C₃₂ n-alken-1-ols are likely limited to aquatic microalgae. Due to their source specificity, these diol, triol, keto-ol, and n-alkenol biomarkers present further tools for studying past environmental and climatic change.