Bacterial contribution to sedimentary organic matter; a comparative study of lipid moieties in bacteria and Recent sediments     

H. Goossens  W. Irene  C. Rijpstra  R.R. Düren  J.W. De Leeuw  P.A. Schenck 《Organic Geochemistry》1986,10(4-6)

A systematic study of the lipid composition of thirteen bacterial species and three Recent sediments (methanogenic sediment, cyanobacterial mat and evaporative gypsum crust) was undertaken in an attempt to recognize bacterial organic matter in sediments. A sequential method, which distinguishes between three different modes of occurrence of lipid moieties (free, OH⁻- and H⁺-labile), was applied. The acid-labile fractions are discussed.The three main groups of bacteria, archaebacteria, gram-positive eubacteria and gram-negative eubacteria, are easily distinguished. Methanogenic and extremely halophilic archaebacteria are characterized by the presence of diphytanyl glyceryl ether and the absence of fatty acids. The gram-positive eubacteria contain primarily iso- and anteiso-branched fatty acids whereas the gram-negative bacteria and sediments are dominated by β- and α-hydroxy fatty acids. A wide variety of H⁺-labile hydroxy fatty acids was observed which included several, as yet unknown, structures.β-Hydroxy fatty acids in this H⁺-labile mode of occurrence are exclusively present in bacteria. Their distribution patterns in sediments are considered “fingerprints” of past and present bacterial populations. The specific differences in β -hydroxy fatty acid compositions observed in the different bacteria and the three sediments investigated, suggest that amide-linked β-hydroxy fatty acid patterns are useful as markers of bacterial populations and therefore of environmental conditions.  相似文献   

Initial Fish-Farm Impact on Meiofaunal Assemblages in Coastal Sediments of the Western Mediterranean   总被引：4，自引：0，他引：4  

A Mazzola  S Mirto  R Danovaro   《Marine pollution bulletin》1999,38(12):420-1133

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Application of Glycerol Dialkyl Glycerol Tetraether Lipids in Paleoenvironment Reconstruction of Loess Deposits: A Review of Recent Progresses     

Shaohua Tian  Guoqiao Xiao  Huan Yang 《地球科学进展》2020,35(5):465-477

The Glycerol Dialkyl Glycerol Tetraethers (GDGTs) occur ubiquitously in a wide range of environments, such as loess, peat, lake, soil, and ocean, which vary compositionally in response to environmental changes, and provide a series of biomarker proxies for paleoenvironmental reconstruction. This paper introduced the structures and biological sources of GDGTs, and reviewed the recent progresses of the application of the GDGTs proxies in the paleoenvironmental reconstruction of loess deposits. The main progresses include: \mathrm{①} The GDGTs proxies have been widely used in reconstructing the climate changes in loess deposits, and have established the temperature changes of last 800 ka for the Chinese Loess Plateau; \mathrm{②}Temperature variations in Chinese Loess Plateau displayed significant correlation with the Northern Hemisphere insolation, which may be also regulated by the surface vegetation conditions; and \mathrm{③} In the Chinese Loess Plateau, the increase in monsoon precipitation during the last deglaciation significantly lagged behind the rise of temperature. However, problems still exist in the current studies. For instance, the GDGTs-based temperature is likely overestimated, probably reflecting the temperature of warm season, and relationships between GDGT indices and climate factors are still unclear. In the future, the development of new proxies and more accurate regional calibrations based on the separation of 6- methyl GDGTs are expected to provide more reliable paleoenvironmental information, and will provide essential evidence for the evolution of hydrothermal pattern and mechanisms behind climate changes in different regions.  相似文献   

烟台四十里湾表层沉积物有机质来源及环境意义   总被引：5，自引：3，他引：2  

刘东艳  申旭红  王玉珏  陈颖军  李丽 《海洋学报》2012,34(5):205-212

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Ancient Drought and Flooding Events Recorded by Microbial Lipids in China     

XIE Shucheng  Richard P. EVERSHED  Richard D. PANCOST 《《地质学报》英文版》2013,87(Z1):658-658

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Sesquiterpenoids in sediments of a hypersaline lagoon: A possible algal origin     

V. O. Elias  A. M. A. De Barros  A. B. de Barros  B. R. T. Simoneit  J. N. Cardoso 《Organic Geochemistry》1997,26(11-12)

Core samples were collected in Lagoa Vermelha, a hypersaline lagoon located about 100 km east of Rio de Janeiro (Brazil). The sediment composition is predominantly carbonate in amounts up to 93%. Analysis of δ¹³C of the total organic matter in the sediments showed that marine organic matter predominates throughout the core (δ¹³C ranges from −15.84 to −22.64‰ vs. PDB). Organic carbon contents (TOC) ranged from 0.81 to 13.28%. A series of cadinane-type sesquiterpenoids can be recognized in the gas chromatography-mass spectrometry data. Essentially the same components are present in all the samples, with variations only in their relative abundances. The most abundant compounds are α- and β-cubebene, α- and β-cedrene, cadinenes (different isomers), α-curcumene and calamenene, with minor amounts of calarene, humulene, calacorene and cadalene. Since this lagoon is surrounded by dunes with only minor vegetation typical of this environment (grasses, small non-resinous shrubs and no forest) with no potential source for sesquiterpenoids, a terrestrial origin for these compounds is excluded and an algal origin is more consistent with the locale and the recognition of sesquiterpenoids (including cadinol) in microbial mats from the lagoon. Only the natural product precursor sesquiterpenoids are present in the microbial mats with no detectable diagenetic derivatives (e.g. calamenene and cadalene). This indicates that the compounds in the mats are from recent input and those found in the sediments are most likely derived from former algal biomass in this lagoon, a fact confirmed by the recognition of a series of diagenetic aromatic components in the sediments. Surface sediments contain n-alkanes with no even-to-odd predominance indicating that microbial activity is higher in shallower sediments. Moreover, mass fragmentograms (m/z 191) of biomarkers revealed the presence of 17α(H),21β(H)-hopanes, the mature isomers, together with their ββ precursors and low amounts of the intermediates with the βα configuration (moretanes). This indicates a contribution of mature organic matter to these immature sediments.  相似文献   

Lipid biogeochemistry of Phormidium and Microcoleus mats     

Joan O. Grimalt  Rutger de Wit  Pilar Teixidor  Joan Albaigs 《Organic Geochemistry》1992,19(4-6)

A study on the predominant sources of organic matter and the main diagenetic processes in two different cyanobacterial mats from evaporite-controlled environments was performed. Fatty acids, hydrocarbons, alcohols, ketones and aldehydes were anlyzed in selected millimetre and submillimetre core sections. The changes in lipid composition were evaluated by comparison with the vertical distributions of the populations observed by optic microscopy and with the lipid patterns of enrichment cultures of species such as cyanobacteria, diatoms, purple bacteria, sulphate-reducers and methanogens obtained from the mats.The cyanobacteria Phormidium valderianum and Microcoleus chthonoplastes are the predominant primary producers, and occur almost as monocultures in the respective top layers. However, these mat-forming organisms only leave minor features in the solvent-extractable lipid sedimentary record. The predominant fatty acid distributions parallel the composition observed in the enrichment cultures of purple bacteria and appear mixed with acids characteristic of heterotrophic eubacteria such as sulphate-reducers. The concentrations of these lipids are, however, 5–10 times lower than the cyanobacterial acids from the top layer. De novo heterotrophic eubacterial synthesis is also observed in cases such as the highly branched isoprenoid eicosenes, the major hydrocarbon in the deep layers (>2 mm) of the Phormidium mat. Other major diagenetic changes involve dehydration and hydrogenation. These two processes take place concurrently under anoxic conditions and have been observed among the sterols and the isoprenoid alcohols. Significant amounts of 5ß(H)-stanols were observed in the more reducing sections where molecular indicators of methanogenic bacteria were also found.  相似文献   

Mid-chain ketocarboxylic acids in the remote marine atmosphere: Distribution patterns and possible formation mechanisms     

Kimitaka Kawamura  R. B. Gagosian 《Journal of Atmospheric Chemistry》1990,11(1-2):107-122

In remote marine aerosol samples collected from the North Pacific ocean, Enewetak Atoll, American Samoa, and New Zealand, series of mid-chain ketocarboxylic acids in the range of C₆-C₁₈ were detected. All the positional isomers, except for the 2-oxo and 3-oxo species, were detected for major ketoacid families (e.g. C₉, C₁₁ and C₁₃). Higher ketoacid concentrations (up to 19 ng/m³) were obtained in the northern North Pacific aerosol samples, which generally showed an odd carbon-numbered predominance with 5-oxoundecanoic acid being the major species. By contrast, lower concentrations were obtained in the lower-latitude or subtropical aerosol samples, where even carbon-numbered ketoacids were relatively abundant.The distribution patterns of the odd carbon-numbered ketoacids could not be explained by the primary emissions from source materials including terrestrial higher plants, soil particles, and ocean surfaces. We consider that the isomeric ketocarboxylic acids are produced in the atmosphere by the photochemical oxidation of semi-volatile monocarboxylic acids, which are counterparts of the oxidative degradation of unsaturated fatty acids emitted from seawater surfaces. Atmospheric production of the ketoacids is seemingly enhanced in the northern North Pacific, probably due to an enhanced primary productivity.  相似文献   

三种抑制剂对眼点拟微球藻的生长及脂肪酸组成的影响   总被引：1，自引：0，他引：1  

张继民  张学成  魏东 《中国海洋大学学报(自然科学版)》2002,32(2):266-272

研究了 DCMU、氟哒酮及亚油酸对眼点拟微球藻的生长、总脂含量及不饱和脂肪酸组成的影响。结果表明 :(1)当 DCMU的浓度在 0 .8μmol/ L以上时 ,眼点拟微球藻的生长抑制率达80 % ,其总脂占干重的百分含量减少了近 30 % ;在 1.0 μmol/ L 时 ,EPA占其总脂肪酸的相对百分含量增加了 10 8.6 1%。 (2 )当氟哒酮的浓度在 8.0μmol/ L以上时 ,眼点拟微球藻的生长抑制率为82 .9% ,其总脂占干重的百分含量下降了 2 1% ,而 EPA占其总脂肪酸的相对百分含量增加了6 0 %。(3)当亚油酸的最终浓度在 4 0 0 μmol/ L 以上时 ,眼点拟微球藻的抑制率达 6 4 %以上 ;大于30 0 μmol/ L、4 0 0 μmol/ L 时 ,EPA占其总脂的相对百分含量在 4 .77%以下 ;在 5 0 μmol/ L 以下时 ,EPA占其总脂肪酸的相对百分含量从对照组的 2 0 .96 %下降到 19.4 9%以下。结果表明 ,眼点拟微球藻在养殖中 ,当生物量增加到一定的程度时 ,可以用加入一定浓度的 DCMU或氟哒酮的方法来大幅度提高 EPA的含量。  相似文献   

多棘海盘车幽门盲囊极性脂和脂肪酸组分的研究   总被引：1，自引：0，他引：1  

李烈英  陈念红  孙作庆 《海洋科学》1995,19(5):49-52

对多棘海盘车（Ａｓｔｅｒｉａｓ ａｍｕｒｅｎｓｉｓ）幽门盲囊中总脂、极性脂及脂仿酸组分进行了研究。结果表明，总脂含量占湿重的７．８５％。磷脂中ＰＣ、ＰＥ、ＰＳ含量较高，ＰＩ和ＤＰＧ含量较低。主要的脂肪酸是１６：０，１８：０，１８：１（ｎ＝９），２０：１（ｎ＝９）。２０：１（ｎ＝７），２０：４（ｎ＝６），２０：５（ｎ＝３），２２：６（ｎ＝３），占总脂肪酸的７４％以上。其中以２０：１（ｎ＝９）最为丰富  相似文献