Evaluating different methods for calculating the Carbon Preference Index (CPI): Implications for palaeoecological and archaeological research

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.

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

Natural Product Communications ◽

10.1177/1934578x20926073 ◽

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.

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

The APPEA Journal ◽

10.1071/aj90025 ◽

1991 ◽

Vol 31 (1) ◽

pp. 325 ◽

Cited By ~ 3

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.

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n-Alkane Profile of Argemone mexicana Leaves

Zeitschrift für Naturforschung C ◽

10.1515/znc-2010-9-1001 ◽

2010 ◽

Vol 65 (9-10) ◽

pp. 533-536 ◽

Cited By ~ 6

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.

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Penggunaan Parameter Geokimia Isoprenoid untuk Menentukan Tingkat Kematangan Minyak Bumi (Crude Oil) Sumur Minyak Langgak Riau

Jurnal Kimia VALENSI ◽

10.15408/jkv.v0i0.3142 ◽

2015 ◽

pp. 70-73 ◽

Cited By ~ 1

Author(s):

Emrizal Mahidin Tamboesai

Keyword(s):

Crude Oil ◽

Thermal Maturity ◽

Maturity Level ◽

Carbon Preference Index ◽

Preference Index ◽

Petroleum Wells ◽

Saturated Fraction ◽

Area Determination

In this study, crude oil samples from Distric Langgak, Riau were tested and characterized with isoprenoid parameters. Determination of thermal maturity level aims to determine the feasibility of petroleum wells to be exploited because there are many new wells of petroleum unexploited in the Riau area. Determination of maturity crude oil performed by analysis saturated fractions. Saturated fraction of the wells Langgak used to determine the maturity of crude oil based on parameters isoprenoid, n-alkane and carbon preference index were analyzed using gas chromatography-flame ionize detector (GC-FID). Based on the value Pr / Ph, Pr / n-C17, Ph / n-C18 and its CPI, the maturity level of petroleum from oil wells, Langgak levels of maturity and quality of the oil is indicated by the value of Pr / Ph (2.27), the value of Pr / n-C17 (0.57), the value of Ph / n-C18 (0.22) and the CPI (1.087) respectively.DOI :http://dx.doi.org/10.15408/jkv.v0i0.3142

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Leaf wax composition and distribution of Tillandsia landbeckii reflects moisture gradient across the hyperarid Atacama Desert

Plant Systematics and Evolution ◽

10.1007/s00606-021-01800-0 ◽

2022 ◽

Vol 308 (1) ◽

Author(s):

Sergio Contreras ◽

Manlio Landahur ◽

Karla García ◽

Claudio Latorre ◽

Mark Reyers ◽

...

Keyword(s):

Fatty Acids ◽

Atacama Desert ◽

Average Chain Length ◽

Carbon Preference Index ◽

Leaf Wax ◽

Preference Index ◽

Lipid Biomarker ◽

Northern Zone ◽

Structural Adaptations ◽

Total Average

AbstractIn the hyperarid Atacama Desert, water availability plays a crucial role in allowing plant survival. Along with scant rainfall, marine advective fog frequently occurs along the coastal escarpment fueling isolated mono-specific patches of Tillandsia vegetation. In this study, we investigate the lipid biomarker composition of the bromeliad Tillandsia landbeckii (CAM plant) to assess structural adaptations at the molecular level as a response to extremely arid conditions. We analyzed long-chain n-alkanes and fatty acids in living specimens (n = 59) collected from the main Tillandsia dune ecosystems across a 350 km coastal transect. We found that the leaf wax composition was dominated by n-alkanes with concentrations (total average 160.8 ± 91.4 µg/g) up to three times higher than fatty acids (66.7 ± 40.7 µg/g), likely as an adaptation to the hyperarid environment. Significant differences were found in leaf wax distribution (Average Chain Length [ACL] and Carbon Preference Index [CPI]) in the northern zone relative to the central and southern zones. We found strong negative correlations between fatty acid CPI and n-alkane ACL with precipitation and surface evaporation pointing at fine-scale adaptations to low moisture availability along the coastal transect. Moreover, our data indicate that the predominance of n-alkanes is reflecting the function of the wax in preventing water loss from the leaves. The hyperarid conditions and good preservation potential of both n-alkanes and fatty acids make them ideal tracers to study late Holocene climate change in the Atacama Desert.

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Trend reversal of soil n-alkane Carbon Preference Index (CPI) along the precipitation gradient and its paleoclimatic implication

Chemical Geology ◽

10.1016/j.chemgeo.2021.120402 ◽

2021 ◽

pp. 120402

Author(s):

Yan Yan ◽

Bingyan Zhao ◽

Luhua Xie ◽

Zhaoyu Zhu

Keyword(s):

Precipitation Gradient ◽

Soil N ◽

Carbon Preference Index ◽

Preference Index ◽

Trend Reversal

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

Quaternary Research ◽

10.1017/qua.2017.33 ◽

2017 ◽

Vol 88 (1) ◽

pp. 60-70 ◽

Cited By ~ 10

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.

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Direct gas chromatographic determination of pristane, phytane and the carbon preference index in crude oils

Journal of Chromatography A ◽

10.1016/s0021-9673(01)83749-3 ◽

1986 ◽

Vol 363 (2) ◽

pp. 303-308 ◽

Cited By ~ 3

Author(s):

Adnan H.H. Tameesh ◽

Mazin H. Hanna

Keyword(s):

Chromatographic Determination ◽

Crude Oils ◽

Carbon Preference Index ◽

Preference Index

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Alkanes from plants of the genus achillea

Journal of the Serbian Chemical Society ◽

10.2298/jsc9908443p ◽

1999 ◽

Vol 64 (7-8) ◽

pp. 443-446 ◽

Cited By ~ 10

Author(s):

Radosav Palic ◽

Timothy Eglinton ◽

Bryan Benitez-Nelson ◽

Geoffrey Eglinton ◽

Jasmina Velikovic ◽

...

Keyword(s):

Mass Spectrometry ◽

Gas Chromatography ◽

Capillary Gas Chromatography ◽

Carbon Number ◽

Carbon Preference Index ◽

Main Compound ◽

Preference Index

The hydrocarbon fractions of three species of Achillea L. have been analysed by capillary gas chromatography (GC) and GC-mass spectrometry(GC-MS) and were shown to consist of the conventional, odd-carbon number dominant distributions of n-alkane homologues (C22-C35 )-n-Nonacosane (C29) is the main compound (ca.40%), and the carbon preference index (CPI) is high (ca.11)

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