Holocene vegetation signals in the Alashan Desert of northwest China revealed by lipid molecular proxies from calcareous root tubes

2017 ◽  
Vol 88 (1) ◽  
pp. 60-70 ◽  
Author(s):  
Zhuolun Li ◽  
Youhong Gao ◽  
Lang Han
Keyword(s):  
Higher Plants ◽  
Relative Concentration ◽  
Northwest China ◽  
Pollen Concentration ◽  
Carbon Preference Index ◽  
Effective Moisture ◽  
Preference Index ◽  
Desert Regions ◽  
Root Tube ◽  
Long Chain

AbstractIn the hinterland of deserts, it is difficult to reconstruct paleovegetation using fossil pollen because of the low pollen concentration. Therefore, an efficient method is needed to reconstruct the paleovegetation of desert regions. In this study, 34 Holocene calcareous root tube (CRT) samples were collected from the Alashan Desert in northwest China, and lipid molecular proxies from CRTs were selected to address this deficiency. The results show that n-alkanes mainly maximized at C27, C29, and C16, and that the carbon preference index is close to 1. Thus, the sources of n-alkanes from CRTs were the roots of higher plants and microorganisms, and thus changes in n-alkanes from CRTs could reveal variations in vegetation cover. The n-alkane Cmax of long-chain n-alkanes (C>25) in CRTs, maximizing at C27, indicated that vegetation in the Alashan Desert was characterized by shrub vegetation during the Holocene. Changes in the ratio of (C27+C29)/(C31+C33) indicated that the biomass of shrub vegetation increased during the period 7–2 cal ka BP. Moreover, the relative concentration of short-chain to long-chain n-alkanes decreased from 7 to 2 cal ka BP, suggesting that the effective moisture decreased during that period.

scholarly journals Nonacosan-10-ol and n-Alkanes in Leaves of Pinus pinaster

2020 ◽  
Vol 15 (5) ◽  
pp. 1934578X2092607
Author(s):  
Biljana Nikolić ◽  
Marina Todosijević ◽  
Iris Đorđević ◽  
Jovana Stanković ◽  
Zorica S. Mitić ◽  
...  
Keyword(s):  
Chain Length ◽  
Pinus Pinaster ◽  
Cuticular Wax ◽  
Short Chain ◽  
Average Chain Length ◽  
Carbon Preference Index ◽  
Preference Index ◽  
Long Chain

In leaf cuticular wax of Pinus pinaster, content of nonacosan-10-ol is high (77.1% on average). n-Alkanes ranged from C18 to C35 with the most dominant C29 (24.8%). The carbon preference index (CPItotal) ranged from 3.1 to 5.6 (4.0 on average), while the average chain length (ACLtotal) ranged from 14.0 to 17.0 (14.8 on average). Long-chain n-alkanes ( n-C25-35) strongly dominated (80.1%) over middle-chain ( n-C21-24 = 18.9%) and short-chain ( n -C18-20 = 0.9%) n-alkanes.

scholarly journals n-Alkane Profile of Argemone mexicana Leaves

2010 ◽  
Vol 65 (9-10) ◽  
pp. 533-536 ◽  
Author(s):  
Indranil Bhattacharjee ◽  
Anupam Ghosh ◽  
Nandita Chowdhury ◽  
Soroj Kumar Chatterjee ◽  
Goutam Chandra ◽  
...  
Keyword(s):  
Carbon Number ◽  
Epicuticular Waxes ◽  
Carbon Preference Index ◽  
Argemone Mexicana ◽  
Mature Leaves ◽  
Preference Index ◽  
Chain Lengths ◽  
First Time ◽  
Long Chain ◽  
Carbon Number Predominance

An n-hexane extract of fresh, mature leaves of Argemone mexicana (Papaveraceae), containing thin-layer epicuticular waxes, has been analysed for the first time by TLC, IR and GLC using standard hydrocarbons. Seventeen long-chain alkanes (n-C18 to n-C34) were identified and quantified. Nonacosane (n-C29) was established as the n-alkane with the highest amount, whilst octadecane (n-C18) was the least abundant component of the extracted wax fraction. The carbon preference index (CPI) calculated for the hydrocarbon sample with the chain lengths between C18 and C34 was 1.2469, showing an odd to even carbon number predominance.

Composition of lipids from the First Lusatian lignite seam of the Konin Basin (Poland): relations to vegetation, climate and carbon cycling during the mid-Miocene Climatic Optimum

2020 ◽  
Author(s):  
Achim Bechtel ◽  
Marek Widera ◽  
Michal Woszczyk
Keyword(s):  
Carbon Cycling ◽  
Carbon Isotopic Composition ◽  
Carbon Preference Index ◽  
Pentacyclic Triterpenoids ◽  
Global Database ◽  
Preference Index ◽  
Air Temperatures ◽  
Relative Abundances ◽  
Climatic Optimum ◽  
Long Chain

<p>Samples of detrital lignite have been collected for organic geochemical and carbon isotope analyses from the First Lusatian lignite seam at the Adamów, Jóźwin IIB and TomisÅ‚awice opencast mines, deposited after the last peak of the Mid-Miocene Climatic Optimum. The aim of the study is to improve the chemotaxonomic value of biomarkers by relating the results to existing paleobotanical data, and to gain information about the influencing factors on δ<sup>13</sup>C of lignite and lipids. Furthermore, biomarker and isotopic proxies are tested for their applicability in paleoclimate studies.</p><p>The relative abundances of mid-chain (C<sub>23</sub>, C<sub>25</sub>) <em>n</em>-alkanes and their 1–2‰ higher δ<sup>13</sup>C values compared to long-chain <em>n</em>-alkanes (C<sub>29</sub>, C<sub>31</sub>) argue for a minor contribution of macrophytes (graminoids, etc.) to peat formation, enhanced during periods of raised water level. The presence of ferruginol and dehydroferruginol testifies the contribution of taxodioid Cupressaceae. The abundances of pimarane-type diterpenoids and the presence of non-aromatic abietane-derivatives argue for the contribution of Pinaceae. Based on the presence of lupeol and lupane-type triterpenoids, an input of Betulaceae can be concluded. The contribution of further angiosperms cannot be specified based on the composition of pentacyclic triterpenoids. However, the results indicate mixed vegetation, and are in agreement with paleobotanical data highlighting abundant conifers of the Cupressaceae and Pinaceae families, as well as angiosperms of various families (e.g., <em>Nyssa, Quercus, Fagus</em>), including Betulaceae (e.g., <em>Alnus, Betula, Corylus</em>). Based on the relationship between the carbon preference index of <em>n</em>-alkanes and mean annual air temperatures, obtained from a global database of peatlands, an average temperature of 24.5 °C is obtained. This value is significantly higher as estimated from paleobotanical data (15.7–19.7 °C), probably due to the influence of changes in vegetation on carbon preference index.</p><p>The relative abundances of diterpenoids versus di- plus angiosperm-derived triterpenoids in detrital lignite samples revealed variable contributions of gymnosperms and angiosperms during the middle Miocene. Consistent with these results, a positive relationship exists between the di-/(di- + tri-) terpenoid biomarker ratios and δ<sup>13</sup>C of lignite samples, indicating the dominating role of varying gymnosperm/angiosperm contributions on the carbon isotopic composition of lignite. The C-isotope data of long-chain n-alkanes, diterpenoids, and angiosperm-derived triterpenoids co-vary within the profiles, arguing for an overall control of changes in δ<sup>13</sup>C of atmospheric CO<sub>2</sub> on δ<sup>13</sup>C of plant lipids. Fluctuations in δ<sup>13</sup>C of individual compounds may also be related to changes in carbon cycling within the peat, humidity and air temperature.</p>

scholarly journals Nonacosan-10-ol and n-Alkanes in Needles of Pinus halepensis

2020 ◽  
Vol 15 (5) ◽  
pp. 1934578X2092097
Author(s):  
Biljana Nikolić ◽  
Marina Todosijević ◽  
Iris Đorđević ◽  
Jovana Stanković ◽  
Zorica S. Mitić ◽  
...  
Keyword(s):  
Chain Length ◽  
Pinus Halepensis ◽  
Cuticular Wax ◽  
Average Chain Length ◽  
Carbon Preference Index ◽  
Preference Index ◽  
Long Chain

In needle cuticular wax of Pinus halepensis, nonacosan-10-ol is high (77.08% on average). n-Alkanes ranged from C18 to C35 with the most dominant C27 and C29 (32.4% and 25.8%, respectively). The carbon preference index ranged from 3.2 to 5.4 (3.4 on average), while the average chain length ranged from 14.0 to 18.0 (17.2 on average). Long-chain n-alkanes strongly dominated (95.1%).

scholarly journals Origin and Maturity of Biomarker Aliphatic Hydrocarbon in Wondama Coal Indonesia

2020 ◽  
Vol 3 (2) ◽  
pp. 107
Author(s):  
Yulfi Zetra ◽  
R Y Perry Burhan ◽  
Arga D. Pratama ◽  
Agus Wahyudi
Keyword(s):  
Depositional Environment ◽  
Bituminous Coal ◽  
Higher Plants ◽  
Aliphatic Hydrocarbon ◽  
Carbon Preference Index ◽  
Hydrocarbon Biomarkers ◽  
Preference Index ◽  
R Ratio ◽  
Gas Chromatography Mass Spectroscopy

Organic geochemical characterization of Wondama coal samples from the Lengguru Folding Belt has been carried out through the study of its aliphatic hydrocarbon biomarkers. This study is to determine the origin, depositional environment and maturity of coal which is useful for determining the use of coal as an energy source. Aliphatic hydrocarbon biomarkers were identified by using gas chromatography-mass spectroscopy methods which showed the presence of n-alkane homologs (n-C15 - n-C33), which was dominated by n-C31. This indicates that the organic material originates from Angiosperms of terrestrial higher plants. The ratio of pristane to phytane (Pr/Ph) with value of 3.74 indicates that the Wondama coal is buried in an oxic depositional environment. The Carbon Preference Index (CPI) value of 7.82 and the C31αβS/(S + R) ratio of 0.27 indicate low maturity of Wondama coal and is classified into a sub-bituminous coal ranks.

scholarly journals Syngenetic rapid growth of ellipsoidal silica concretions with bitumen cores

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hidekazu Yoshida ◽  
Ryusei Kuma ◽  
Hitoshi Hasegawa ◽  
Nagayoshi Katsuta ◽  
Sin-iti Sirono ◽  
...  
Keyword(s):  
Organic Matter ◽  
Early Diagenesis ◽  
Ph Change ◽  
Carbon Preference Index ◽  
Diffusion Growth ◽  
Silica Precipitation ◽  
Precipitated Silica ◽  
Preference Index ◽  
Decomposition Of Organic Matter ◽  
Growth Diagram

AbstractIsolated silica concretions in calcareous sediments have unique shapes and distinct sharp boundaries and are considered to form by diagenesis of biogenic siliceous grains. However, the details and rates of syngenetic formation of these spherical concretions are still not fully clear. Here we present a model for concretion growth by diffusion, with chemical buffering involving decomposition of organic matter leading to a pH change in the pore-water and preservation of residual bitumen cores in the concretions. The model is compatible with some pervasive silica precipitation. Based on the observed elemental distributions, C, N, S, bulk carbon isotope and carbon preference index (CPI) measurements of the silica-enriched concretions, bitumen cores and surrounding calcareous rocks, the rate of diffusive concretion growth during early diagenesis is shown using a diffusion-growth diagram. This approach reveals that ellipsoidal SiO2 concretions with a diameter of a few cm formed rapidly and the precipitated silica preserved the bitumen cores. Our work provides a generalized chemical buffering model involving organic matter that can explain the rapid syngenetic growth of other types of silica accumulation in calcareous sediments.

scholarly journals Disruption of Very-Long-Chain-Fatty Acid Synthesis Has an Impact on the Dynamics of Cellulose Synthase in Arabidopsis thaliana

Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1599
Author(s):  
Xiaoyu Zhu ◽  
Frédérique Tellier ◽  
Ying Gu ◽  
Shundai Li
Keyword(s):  
Fatty Acid ◽  
Cell Biology ◽  
Higher Plants ◽  
Threshold Level ◽  
Cellulose Synthase ◽  
Chain Fatty Acid ◽  
Cellulose Synthesis ◽  
Cellulose Content ◽  
Long Chain Fatty Acid ◽  
Long Chain

In higher plants, cellulose is synthesized by membrane-spanning large protein complexes named cellulose synthase complexes (CSCs). In this study, the Arabidopsis PASTICCINO2 (PAS2) was identified as an interacting partner of cellulose synthases. PAS2 was previously characterized as the plant 3-hydroxy-acyl-CoA dehydratase, an ER membrane-localized dehydratase that is essential for very-long-chain-fatty acid (VLCFA) elongation. The pas2-1 mutants show defective cell elongation and reduction in cellulose content in both etiolated hypocotyls and light-grown roots. Although disruption of VLCFA synthesis by a genetic alteration had a reduction in VLCFA in both etiolated hypocotyls and light-grown roots, it had a differential effect on cellulose content in the two systems, suggesting the threshold level of VLCFA for efficient cellulose synthesis may be different in the two biological systems. pas2-1 had a reduction in both CSC delivery rate and CSC velocity at the PM in etiolated hypocotyls. Interestingly, Golgi but not post-Golgi endomembrane structures exhibited a severe defect in motility. Experiments using pharmacological perturbation of VLCFA content in etiolated hypocotyls strongly indicate a novel function of PAS2 in the regulation of CSC and Golgi motility. Through a combination of genetic, biochemical and cell biology studies, our study demonstrated that PAS2 as a multifunction protein has an important role in the regulation of cellulose biosynthesis in Arabidopsis hypocotyl.

A GEOCHEMICAL METHOD FOR ASSESSMENT OF THE THERMAL HISTORIES OF SEDIMENTS: A TWO-WELL CASE STUDY FROM THE GIPPSLAND BASIN, AUSTRALIA

1991 ◽  
Vol 31 (1) ◽  
pp. 325 ◽  
Author(s):  
R. Alexander ◽  
P.G. Kralert ◽  
R. Marzi ◽  
R.I. Kagi ◽  
E J. Evans
Keyword(s):  
Heat Flow ◽  
Stable Phase ◽  
Carbon Preference Index ◽  
Preference Index ◽  
History Of ◽  
Thermal Histories ◽  
Gippsland Basin ◽  
Geochemical Method ◽  
Kinetics Of

The ester content in kerogen is depleted as sediment maturation progresses in a process which has been shown to correlate with change in the carbon preference index (CPI) of the associated soluble organic matter. We have carried out accurate laboratory measurements of the kinetics of the reaction which causes ester depletion in sediments, and we show how this information can be used to assess the thermal history of sediments. Two wells were selected, Grunter-1 and Volador-1, to provide samples from the Latrobe Group in the Gippsland Basin. The CPI values were measured to assess the extent of reaction at points down each well, and these values were then used with the kinetic parameters for the ester depletion process to obtain thermal histories which are consistent with the available maturity information.This treatment enabled the heat flow from 50 Ma to the present to be assessed and it suggests that at both locations a constant low heat flow during the Gippsland stable phase was followed by a gradual increase from the beginning of the Miocene to present-day values.

Disentangling the effect of thermal and microbial degradation on the distribution pattern of n-alkanes in sediments: Implication for paleo-fire studies

2020 ◽  
Author(s):  
Vijayananda Sarangi ◽  
Sayak Basu ◽  
Prasanta Sanyal
Keyword(s):  
Organic Matter ◽  
Thermal Degradation ◽  
Distribution Pattern ◽  
Microbial Activity ◽  
Microbial Degradation ◽  
Relative Concentration ◽  
Short Chain ◽  
Western India ◽  
Long Chain ◽  
Insignificant Correlation

<p>Biomass burning is an important component of major biomes as it acts as an ecological forcing factor in controlling the vegetation composition as well as biomass production. Thus long-term paleo-fire records are required to understand the extent to which future fire regimes will affect ecosystem health and the global carbon balance. Unfortunately, paleo-fire proxies such as charcoal analysis, dendrochronology and archaeological relicts are often fragmented and difficult to interpret owing to their poor preservation in the natural archives. To resolve the uncertainties associated with the existing paleo-fire proxies, biomarker-based investigations (n-alkanes) provide a new avenue for gaining insight into the paleo-fire events due to their relatively stable chemical property and source-specific distribution in sediments. For instance, laboratory and field-based experiments have shown that a significant amount of short-chain n-alkanes (predominantly C<sub>18</sub>) are produced at the expense of long-chain n-alkanes during thermal degradation of plant-derived organic matter. This modification of primary carbon chain-length can thus be used as a tool to decipher paleo-fire events. However, this characteristic distribution pattern of n-alkane in the soil can also result from microbial degradation of plant-derived organic matter. Therefore, it is vital to disentangle the effect of thermal and microbial degradation on the distribution pattern of n-alkane before using it for paleo-fire reconstructions. For this purpose, published n-alkane distribution records from two distinct climatic settings have been compared. The site-A is located in arid Banni grassland, western India (with a history of repeated fire events) whereas, site-B is situated at the sub-humid region of southern peninsular India (Lake Ennamangalam). The n-alkane distribution in both the sites exhibits a dominance of short-chain homologues with prominent even-over-odd preference (EOP). The cross-plot between the relative concentration of C<sub>18</sub> (dominant in short-chain) and C<sub>29</sub> (dominant in long-chain) homologues shows positive and significant correlation (R<sup>2</sup> = 0.9, p < 0.05, n=19) at site-A, whereas statistically insignificant correlation (R<sup>2</sup> = 0.2, p < 0.05, n=19) has been obtained from site-B. In case of thermal events, production of short-chain n-alkanes (predominantly C<sub>18</sub>) is related to the temperature-dependent breakdown of long-chain n-alkanes. Subsequently, the concentration of C<sub>18</sub> and C<sub>29</sub> homologues are expected to be well correlated, as observed in site-A. On the contrary, in a depositional setting dominated by microbial activity, multiple sources of C<sub>18</sub> homologue may produce an insignificant correlation, as observed from site-B. Therefore, it can be suggested that short-chain n-alkanes at site-A are a product of thermal degradation while microbial activity controlled the distribution of short-chain n-alkanes at site-B. This claim is further supported by the ratio between the relative concentration of C<sub>18</sub> and C<sub>19</sub> homologues (P<sub>Factor</sub>) which are much higher at site-A (11 to 62) compared to that of the site-B (1 to 10). Higher production of C<sub>18</sub> homologue during thermal degradation perhaps is producing the offset in the P<sub>Factor</sub> values for site-A and B. Our observations will be useful to recognise paleo-fire events that have been previously overlooked owing to the fragmentary nature and limited preservation of existing proxies.</p>

scholarly journals Distribution and sources of n-alkanes in surface sediments of Taihu Lake, China

2016 ◽  
Vol 42 (1) ◽  
pp. 49-55 ◽  
Author(s):  
Yunlong Yu ◽  
Yuanyuan Li ◽  
Zhigang Guo ◽  
Hua Zou
Keyword(s):  
Surface Sediment ◽  
Surface Sediments ◽  
Taihu Lake ◽  
Higher Plants ◽  
Complex Mixture ◽  
Dry Weight ◽  
Short Chain ◽  
Sediment Samples ◽  
Total Concentrations ◽  
Long Chain

Abstract The last study on n-alkanes in surface sediments of Taihu Lake was in 2000, only 13 surface sediment samples were analysed, in order to have a comprehensive and up-to-date understanding of n-alkanes in the surface sediments of Taihu Lake, 41 surface sediment samples were analyzed by GC-MS. C10 to C37 were detected, the total concentrations of n-alkanes ranged from 2109 ng g−1 to 9096 ng g−1 (dry weight). There was strong odd carbon predominance in long chain n-alkanes and even carbon predominance in short chain n-alkanes. When this finding was combined with the analysis results of wax n-alkanes (WaxCn), carbon preference index (CPI), unresolved complex mixture (UCM), hopanes and steranes, it was considered that the long chain n-alkanes were mainly from terrigenous higher plants, and that the short chain n-alkanes mainly originated from bacteria and algae in the lake, compared with previous studies, there were no obvious anthropogenic petrogenic inputs. Terrestrial and aquatic hydrocarbons ratio (TAR) and C21−/C25+ indicated that terrigenous input was higher than aquatic sources and the nearshore n-alkanes were mainly from land-derived sources. Moreover, the distribution of short chain n-alkanes presented a relatively uniform pattern, while the long chain n-alkanes presented a trend that concentrations dropped from nearshore places to the middle of lake.

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