Lipids extracted from 26 modern soils collected from different climate zones in China and Mongolia are analyzed using gas chromatography- mass spectrometry. These extracts contain pseudo- homologous families of 5,5-di...Lipids extracted from 26 modern soils collected from different climate zones in China and Mongolia are analyzed using gas chromatography- mass spectrometry. These extracts contain pseudo- homologous families of 5,5-diethylalkanes (5,5- DEAs), 6,6-diethylalkanes, 5-butyl-5-ethylalkanes and 6-butyl-6-ethylalkanes, which are first detected in modern soils. All these pseudohomologous series display exclusively odd or exclusively even carbon numbers, clearly indicating a biosynthetic origin, and their carbon number distributions generally covary. The distributions of 5,5-DEAs exhibit strong regional variations, correlated with the spatial distributions of climate and vegetation. The lower molecular weight 5,5-DEAs, maximizing at C21 or C23, dominate in southeast and southwest China samples, while the higher molecular weight 5,5-DEAs with a mode at C29 dominate in cold, arid northwest China and Mongolia. The results demonstrate that the distribution of 5,5-DEAs can serve as a new independent proxy, indicating variations in soil ecosystems and climates, just like the well-known proxy of n-C15—21/n-C22—33 ratios.展开更多
基金The study was sup- ported by the National Natural Science Foundation of China （Grant No. 4042101） National Basic Research Program of China （Grant No.2005CB422001） President Fund Program of Chinese Academy of Sciences.
文摘Lipids extracted from 26 modern soils collected from different climate zones in China and Mongolia are analyzed using gas chromatography- mass spectrometry. These extracts contain pseudo- homologous families of 5,5-diethylalkanes (5,5- DEAs), 6,6-diethylalkanes, 5-butyl-5-ethylalkanes and 6-butyl-6-ethylalkanes, which are first detected in modern soils. All these pseudohomologous series display exclusively odd or exclusively even carbon numbers, clearly indicating a biosynthetic origin, and their carbon number distributions generally covary. The distributions of 5,5-DEAs exhibit strong regional variations, correlated with the spatial distributions of climate and vegetation. The lower molecular weight 5,5-DEAs, maximizing at C21 or C23, dominate in southeast and southwest China samples, while the higher molecular weight 5,5-DEAs with a mode at C29 dominate in cold, arid northwest China and Mongolia. The results demonstrate that the distribution of 5,5-DEAs can serve as a new independent proxy, indicating variations in soil ecosystems and climates, just like the well-known proxy of n-C15—21/n-C22—33 ratios.
