Possible ecological and environmental significance of the predominance of even-carbon number C20-C30n-alkanes

Dembicki, Harry; Meinschein, W. G.; Hattin, Donald E.

doi:10.1016/0016-7037(76)90177-0

Cited by 115 publications

(19 citation statements)

References 26 publications

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“…Its carbon distribution ranges from C 21 or C 24 to C 31 with a maximum at C 29 , showing an odd carbon predominance. The n-alkan-2-one in red earth is believed to come from lipids and carbohydrate of higher plants.…”

Section: Distribution Characteristics and Climate Implications Of N-amentioning

confidence: 99%

“…It has been reported that n-alkanes of different biogenesis possesses have different composition and distribution characteristics, which can be used to estimate the sedimentary environments, climate conditions and biogenesis [28,29] . The carbon number distribution of n-alkanes in the studied samples is shown in Figure 3.…”

Section: Distribution Characteristics and Climate Implications Of N-amentioning

confidence: 99%

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Distribution of lipids in modern soils from various regions with continuous climate (moisture-heat) change in China and their climate significance

et al. 2007

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Total 26 modern soil samples were collected from various regions under different climate conditions from tropical to arid temperate in China and systematically analyzed for their organic matters by GC/MSin order to evaluate climatic impacts on soil organic components. Abundant lipids molecules were recognized, including n-alkanes, n-alkenones, and long-chain branched alkanes. We find the predominance of main peaks of long-chain n-alkanes (nC 29 , nC 31 , nC 33 ) and short-chain ones (nC 16 , nC 17 , nC 18 ) records information of soil generation in warm-humid and cold-dry regions. The proportion of n-alkanes (nC 16 +nC 17 +nC 18 ) to (nC 29 +nC 31 +nC 33 ) varies in good agreement with moisture-heat conditions and thus probably can serve as a new index for climate change. The ratios of C 21 − /nC 22 + , nC 17 /nC 31 and (nC 15 +nC 17 +nC 19 ) / ( nC 27 +nC 29 +nC 31 ) of n-alkanes, indicating respectively input ratios of lower bacterial alga, aquatic organisms, and higher plants and terraneous organisms, co-vary well in different climate regions from forest to grassland and desert, suggesting that they have also reflected the difference of climates between monsoon region and inland one. The C 21 − /C 22 + ratio of n-alkan-2-one records largely the discrepancy of temperature from north to south of China bordered by the Qinling Mountains, but less humidity. The C 21 − /C 22 + ratio of n-alkan-3-ones changes well with climatic factors, such as temperature and humidity. The biogenic source of series A-D long-chain branched alkanes may be derived from some kinds of special epiphyte that most likely live in weak oxic-anoxic and moisture-heat environments, suggesting their distribution record as well some information on climatic change. All these researches demonstrate that the distributions of lipids molecules in modern soils in China record well signals of climates from quite different climatic regions, and can serve as important climatic proxies to reveal climatic change over China.lipids molecule, modern soil, climate (moisture-heat) continuously changing regions, climate index, ChinaAt present, the use of molecular fossils to reconstract paleoclimate and ancient human activities has become an important part of molecular stratigraphy [1][2][3][4][5][6] . Molecular fossils have the characteristics of stable compounds, long-time preservation and wide distribution, being good indication of climate and environmental change and providing great information on provenience of parent materials, redox degree of organic matters, development status of bacteria and microorganisms in

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Section: Distribution Characteristics and Climate Implications Of N-amentioning

confidence: 99%

Section: Distribution Characteristics and Climate Implications Of N-amentioning

confidence: 99%

Distribution of lipids in modern soils from various regions with continuous climate (moisture-heat) change in China and their climate significance

et al. 2007

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“…CPI values of 1.0 or less are usually taken as indication of progressive catagenic processes. Numerous bitumens and crude oils have values of CPI less than unity; there are no known organisms that are able to produce larger amounts of even/odd carbon alkanes (Dembicki et al, 1976).…”

Section: Discussionmentioning

confidence: 99%

Effect of microbial activity on buried cyanobacterial organic matter

Bubela¹,

Philp

Gilbert

1984

Geomicrobiology Journal

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The biomass from which hydrocarbons were formed and the organisms responsible for its production are usually deduced by the use of biochemical markers. In the present study, using a simulated sedimentary system, cyanobacterial organic matter was buried in sediments and exposed to sequential environmental changes ranging from microaerobic conditions at ambient temperature to strongly reducing conditions at a biologically extreme temperature and pressure. Significant changes occurred in the composition of hydrocarbons and fatty acids isolated from the biomass that masked the characteristic patterns exhibited by the original cyanobacterial material. The changes depended on the particular environmental conditions to which the organic matter was exposed. The results stress the need for caution in interpreting biochemical markers in terms of their source material in sediments.

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“…The association between saline waters, the accumulation of organic-rich sediments and the evolution of the resulting evaporitic carbonates into source rocks has been noted by many, including: Woolnough (1937), Sloss (1953), Moody (1959), Dembicki et al (1976), Oehler et al (1979), Malek-Aslani (1980), Kirkland and Evans (1981), Hite et al (1984), Jones (1984), Eugster (1985), Sonnenfeld (1985), ten Haven et al (1985), Warren 1986, Busson (1988, Evans & Kirkland (1988), Edgell (1991), Hite & Anders (1991), Beydoun (1993), Benali et al (1995), Billo (1996), Carroll (1998) and Schreiber et al (2001). Heresy or not, the notion that much of the oil sealed by evaporite salts may also have also been sourced in sediments deposited in earlier less saline, but still related, evaporitic (mesohaline) conditions, is worthy of consideration.…”

Section: Introductionmentioning

confidence: 99%

Evaporitic source rocks: mesohaline responses to cycles of “famine or feast” in layered brines

Warren¹

2010

Quaternary Carbonate and Evaporite Sedimentary Facies and Their Ancient Analogues

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Organic matter in modern saline systems tends to accumulate in bottom sediments beneath a density-stratified mass of saline water where layered hydrologies are subject to oscillations in salinity and brine level. Organic matter is not produced at a constant rate in such systems; rather, it is generated in pulses by a halotolerant community in response to relatively short times of less stressful conditions (brackish to mesohaline) that occur in the upper part of the layered hydrology. Accumulations of organic matter can occur in any layered brine lake or epeiric seaway when an upper less-saline water mass forms on top of nutrient-rich brines, or in wet mudflats wherever waters freshen in and above the uppermost few millimetres of a microbial mat. A flourishing community of halotolerant algae, bacteria and archaeal photosynthesizers drives the resulting biomass bloom. Brine freshening is a time of "feast" characterized by very high levels of organic productivity. In a stratified brine column (oligotrophic and meromictic) the typical producers are planktonic algal or cyanobacterial communities inhabiting the upper mesohaline portion of the stratified water mass. In mesohaline holomictic waters, where light penetrates to the water bottom, the organic-producing layer is typically the upper algal and bacterial portion of a benthic laminated microbialite characterized by elevated numbers of cyanobacteria.Short pulses of extremely high productivity in the upper freshened part of a stratified brine column create a high volume of organic detritus settling through the column and/or the enhanced construction of benthic microbial mats in regions where freshened waters reach the hypersaline base of the column. With the end of the freshening event, ongoing intensely arid conditions mean that salinity, temperature and osmotic stress increase rapidly in the previously freshened water mass. This leads to a time of mass dieoff of the once flourishing mesohaline community ("famine"). First, these increasingly salty waters no longer support haloxene forms. Then, halotolerant life dies back, and finally by the halite precipitation stage, only a few halophilic archaea and bacteria remain in the brine column (typically acting as heterotrophs and fermenters). Repeated pulses of organic matter, created during a feasting event followed by a famine event, create laminated organic-enriched sediment on an anoxic bottom.There are three, possibly four, major mesohaline density-stratified settings where organic-rich laminites (petroleum source rocks) accumulated in ancient "famine or feast" saline settings: (1) basin-centre lows in marine-fed evaporitic drawdown basins, associated with basinwide evaporites; (2) mesohaline intra-shelf lows on epeiric platforms, associated with platform evaporites; (3) saline-bottomed lows in under-filled perennial saline lacustrine basins; (4) closed seafloor depressions in halokinetic deepwater marine slope and rise terrains. An inherently restrictive hydrology means that the same mesohaline settings show a prop...

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Possible ecological and environmental significance of the predominance of even-carbon number C20-C30n-alkanes

Cited by 115 publications

References 26 publications

Distribution of lipids in modern soils from various regions with continuous climate (moisture-heat) change in China and their climate significance

Distribution of lipids in modern soils from various regions with continuous climate (moisture-heat) change in China and their climate significance

Effect of microbial activity on buried cyanobacterial organic matter

Evaporitic source rocks: mesohaline responses to cycles of “famine or feast” in layered brines

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