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Preservation of microbial lipids in geothermal sinters 总被引:1,自引:0,他引:1
Lipid biomarkers are widely used to study the earliest life on Earth and have been invoked as potential astrobiological markers, but few studies have assessed their survival and persistence in geothermal settings. Here, we investigate lipid preservation in active and inactive geothermal silica sinters, with ages of up to 900 years, from Champagne Pool, Waiotapu, New Zealand. Analyses revealed a wide range of bacterial biomarkers, including free and bound fatty acids, 1,2-di-O-alkylglycerols (diethers), and various hopanoids. Dominant archaeal lipids include archaeol and glycerol dialkyl glycerol tetraethers (GDGTs). The predominance of generally similar biomarker groups in all sinters suggests a stable microbial community throughout Champagne Pool's history and indicates that incorporated lipids can be well preserved. Moreover, subtle differences in lipid distributions suggest that past changes in environmental conditions can be elucidated. In this case, higher archaeol abundances relative to the bacterial diethers, a greater proportion of cyclic GDGTs, the high average chain length of the bacterial diethers, and greater concentrations of hopanoic acids in the older sinters all suggest hotter conditions at Champagne Pool in the past. 相似文献
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Praveen Kandpal Rajbir Kaur R.S. Pandey 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(1):581-592
In this paper parallel flow velocity shear Kelvin-Helmholtz instability has been studied in two different extended regions of the inner magnetosphere of Saturn. The method of the characteristic solution and kinetic approach has been used in the mathematical calculation of dispersion relation and growth rate of K-H waves. Effect of magnetic field (B), inhomogeneity (P/a), velocity shear scale length (), temperature anisotropy (), electric field (E), ratio of electron to ion temperature (), density gradient () and angle of propagation () on the dimensionless growth rate of K-H waves in the inner magnetosphere of Saturn has been observed with respect to . Calculations of this theoretical analysis have been done taking the data from the Cassini in the inner magnetosphere of Saturn in the two extended regions of Rs ~4.60–4.01 and Rs ~4.82–5.0. In our study velocity shear, temperature anisotropy and magnitude of the electric field are observed to be the major sources of free energy for the K-H instability in both the regions considered. The inhomogeneity of electric field, electron-ion temperature ratio, and density gradient have been observed playing stabilizing effect on K-H instability. This study also indicates the effect of the vicinity of icy moon Enceladus on the growth of K-H instability. 相似文献
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Anand Mahesh Russell Sara Lin Yangting Wadhwa Meenakshi Marhas Kuljeet Kaur Tachibana Shogo 《Space Science Reviews》2020,216(5):1-25
Space Science Reviews - Spectral retrieval has long been a powerful tool for interpreting planetary remote sensing observations. Flexible, parameterised, agnostic models are coupled with inversion... 相似文献
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