Hydrogen isotope ratios of individual lipids in lake sediments as novel tracers of climatic and environmental change: a surface sediment test

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• 作者：Yongsong Huang ; Bryan Shuman ; Yi Wang and Thompson Webb
• 关键词：Climate change ; Hydrogen isotope ratios ; Lake sediments ; Lipids ; Modern calibration
• 刊名：Journal of Paleolimnology
• 出版年：2004
• 出版时间：April, 2004
• 年：2004
• 卷：31
• 期：3
• 页码：363-375
• 全文大小：402.3 KB

文摘

We determined hydrogen isotope ratios of modern lake-waters and individual lipids from surface sediments of 36 lakes in the eastern North America. The lakes selected lie on two transects (south–north transect from Florida to Ontario and east–west transect from Wisconsin to South Dakota) and encompass large temperature and moisture gradients, and a wide range of lake water δD values (>100‰). The study allows a rigorous test of the applicability of using δD values of sedimentary lipids as paleoclimatic and paleoenvironmental proxies. We examined a range of lipids including C₁₇n-alkane, straight chain fatty acids, phytol and sterols in both free extracts and ester-bound fractions in the solvent extracted sediments. Useful isotopic indicators are expected to show a linear correlation and constant fractionation factor between their δD values in surface sediments and modern lake water. Our results demonstrate that several lipid compounds, free and ester-bound palmitic acid (16:0), C₁₇n-alkane, and phytol are useful candidates for paleoclimate reconstructions, in addition to two sterols that have been suggested previously (. Compound-specific D/H ratios of lipid biomarkers from sediments as a proxy for environmental and climatic conditons. Geochim. Cosmochim. Acta 65: 213–222). Authigenic or biogenic carbonate in sediments is conventional material for paleoclimatic study using ocean and lake sediments. However, because majority of lake sediments do not contain suitable carbonate materials for isotopic study, hydrogen isotope ratios of these lipids provide invaluable new sources of paleoclimatic and paleoenvironmental information.