Molecular, 13C, and 14C evidence for the allochthonous and ancient origin of C16C18 n-alkanes in modern soils

Lichtfouse, Éric; Bardoux, Gérard; Mariotti, André; Balesdent, Jérôme; Ballentine, Donna C.; Macko, Stephen A.

doi:10.1016/s0016-7037(97)00021-5

Cited by 78 publications

(56 citation statements)

References 28 publications

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“…This specific distribution, typical of plant waxes (23), is also found in 'free' alkane fractions of organic extracts from plant and soil (24). Therefore, since humin C 27 -C 33 n-alkanes has somehow 'survived' pyrolytic conditions without apparent chemical degradation, then these compounds must have been trapped in the humin matrix.…”

Section: Linear Alkanesmentioning

confidence: 86%

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Occurrence of Biomarkers and Straight-Chain Biopolymers in Humin: Implication for the Origin of Soil Organic Matter

Lichtfouse

Leblond

Silva

et al. 1998

Naturwissenschaften

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Soil organic matter is a very complex mixture of compounds derived from the decay of living organisms such as plants, fungi and bacteria. The mechanisms that control the preservation of soil organic matter are poorly known. This is notably due to our scarce knowledge of the molecular structure of humin, the insoluble part of soil organic matter. Three major hypotheses have been proposed to explain the formation of soil organic matter: the plant alteration hypothesis, the microbial synthesis hypothesis and the chemical polymerisation hypothesis. Here we used a "biomarker" approach, developped mainly in sedimentary geochemistry, to gain some insight on the mechanims of preservation of soil organic matter. We analysed the compounds occurring in soil humin. We isolated humin from a maize crop soil by solvent extraction to remove free lipids, then by NaOH extraction to remove humic and fulvic acids, then by HF/HCl treatment to remove minerals. The humin residue was then pyrolysed at 600°C. The pyrolysate was fractionated into alkane/alkene and aromatic fractions by silica gel column chromatography. The fractions were analysed by gas chromatography coupled to mass spectrometry (GC-MS). We identified n-alkanes, n-alkenes, prist-1-ene, sterenes, hopenes and aromatic steroids in the humin pyrolysate. The results show that the stabilisation of soil humic substances may be achieved by selective preservation of lipids, involving three processes: encapsulation of small apolar molecules, chemical bonding of functionalized biomarkers, and preservation of straight-chain microbial polymers.

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Section: Linear Alkanesmentioning

confidence: 86%

“…Numbers refer to carbon numbers of n-alkanes and n-alkenes. Detailed procedures are reported elsewhere (16,17,24). A sample of maize crop soil (290 g) was thoroughly extracted with CHCl 3 -MeOH 3/1 v/v to remove free lipids, then with NaOH 0.1 M to remove fulvic and humic acids.…”

Section: Linear Alkanesmentioning

confidence: 99%

Occurrence of Biomarkers and Straight-Chain Biopolymers in Humin: Implication for the Origin of Soil Organic Matter

Lichtfouse

Leblond

Silva

et al. 1998

Naturwissenschaften

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“…The cross-polarization (CP) magic angle spinning (MAS) 13 C nuclear magnetic resonance (NMR) spectra were acquired with a Bruker Avance 300 MHz NMR spectrometer (Bruker Analytic, Billerica, MA, USA), equipped with a 4-mm H-X MAS probe, using the standard ramp-CP pulse program. The acquisition parameters were spectral frequency of 75 MHz for 13 C and 300 MHz for 1 H, spinning rate of 13 kHz, ramp-CP contact time of 2 ms, 1-s recycle delay, and line broadening of 50 Hz. The spectra were divided into the following chemical shift regions: paraffinic carbons (0-50 ppm); alcohols, amines, carbohydrates, ethers, methoxyl, and acetal carbons (50-110 ppm); aromatic and phenolic carbons (110-165 ppm); and carboxyl and carbonyl carbons (165-215 ppm).…”

Section: Elemental and Spectroscopic Analysesmentioning

confidence: 99%

“…Several studies have shown selective preservation of these aliphatic biopolymers in soils, with little or no alteration [12,13]. Nonhydrolyzable plant biopolymer (cutan) and root aliphatic biopolymer have been suggested to be responsible for the relative enrichment of forest soils in aliphatic components [14,15].…”

Section: Introductionmentioning

confidence: 99%

Sorption of phenanthrene and atrazine by plant cuticular fractions

Chefetz

2003

Environmental Toxicology and Chemistry

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Abstract-Several studies have shown selective preservation of plant cuticular materials in soils. However, very little is known about their function as sorbents for the hydrophobic organic contaminants (HOCs) in the soil. In this study, we investigated the sorption and desorption of phenanthrene and atrazine by cuticular fractions of pepper (bulk, dewaxed, nonsaponifiable, and nonhydrolyzable) to better understand the sorptive activity of cuticular matter in soils. The bulk and dewaxed cuticles exhibited carbonnormalized distribution coefficients (K oc ) for phenanthrene and atrazine in the range of that reported for soil humic substances, although both samples were rich in aliphatic structures. No hysteresis was observed in the desorption isotherms of either solute. The nonhydrolyzable residue exhibited a very high K oc value for atrazine, whereas the nonsaponifiable sample exhibited the lowest K oc value for both sorbates. Based on solubility parameter data, it is suggested that the nonsaponifiable sample be considered an intermediate between the physical and chemical mixture of pectin and cutan/lignin-like fractions, whereas the dewaxed cuticle is a chemical blending of cutin and pectin. The n-hexane-normalized sorption data suggest that the pepper cuticle can interact specifically with atrazine. This study leads to the conclusion that the contribution of aliphatic-rich plant biopolymers to the sorption of HOCs can be significant because of their preservation and accumulation in soils.

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“…-and the contribution of fossil-fuel-derived carbon to soil assessed according to lipid molecular composition and compound-specific isotopes (e.g., Lichtfouse et al, 1995Lichtfouse et al, , 1997Rethemeyer et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Opportunities and limitations related to the application of plant-derived lipid molecular proxies in soil science

Jansen

Wiesenberg

2017

SOIL

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Abstract. The application of lipids in soils as molecular proxies, also often referred to as biomarkers, has dramatically increased in the last decades. Applications range from inferring changes in past vegetation composition, climate, and/or human presence to unraveling the input and turnover of soil organic matter (SOM). The molecules used are extractable and non-extractable lipids, including ester-bound lipids. In addition, the carbon or hydrogen isotopic composition of such molecules is used. While holding great promise, the application of soil lipids as molecular proxies comes with several constraining factors, the most important of which are (i) variability in the molecular composition of plant-derived organic matter both internally and between individual plants, (ii) variability in (the relative contribution of) input pathways into the soil, and (iii) the transformation and/or (selective) degradation of (some of) the molecules once present in the soil. Unfortunately, the information about such constraining factors and their impact on the applicability of molecular proxies is fragmented and scattered. The purpose of this study is to provide a critical review of the current state of knowledge with respect to the applicability of molecular proxies in soil science, specifically focusing on the factors constraining such applicability. Variability in genetic, ontogenetic, and environmental factors influences plant n-alkane patterns in such a way that no unique compounds or specific molecular proxies pointing to, for example, plant community differences or environmental influences, exist. Other components, such as n-alcohols, n-fatty acids, and cutin-and suberin-derived monomers, have received far less attention in this respect. Furthermore, there is a high diversity of input pathways offering both opportunities and limitations for the use of molecular proxies at the same time. New modeling approaches might offer a possibility to unravel such mixed input signals. Finally, the transformation and turnover of SOM offer opportunities when tracing such processes is the purpose of applying a molecular proxy while imposing limitations when they obliterate the molecular proxy signals linked to other phenomena. For n-alkanes several modeling approaches have recently been developed to compensate for (selective) degradation. Still, such techniques are in their infancy and information about their applicability to classes of components other than n-alkanes is lacking. All constraining factors considered can have a significant influence on the applicability of molecular proxies in soil science. The degree of influence strongly depends on the type of molecular proxy and the environmental context in which it is applied. However, the potential impact of the constraining factors should always explicitly be addressed whenever molecular proxies are applied in a soil scientific context. More importantly, there is still a serious lack of available information, in particular for compound classes other than the n-alkanes. Therefore, we...

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Molecular, 13C, and 14C evidence for the allochthonous and ancient origin of C16C18 n-alkanes in modern soils

Cited by 78 publications

References 28 publications

Occurrence of Biomarkers and Straight-Chain Biopolymers in Humin: Implication for the Origin of Soil Organic Matter

Occurrence of Biomarkers and Straight-Chain Biopolymers in Humin: Implication for the Origin of Soil Organic Matter

Sorption of phenanthrene and atrazine by plant cuticular fractions

Opportunities and limitations related to the application of plant-derived lipid molecular proxies in soil science

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